Exercise 3-2. Digital Modulation EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION. PSK digital modulation

Size: px
Start display at page:

Download "Exercise 3-2. Digital Modulation EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION. PSK digital modulation"

Transcription

1 Exercise 3-2 Digital Modulation EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with PSK digital modulation and with a typical QPSK modulator and demodulator. DISCUSSION OUTLINE The Discussion of this exercise covers the following points: PSK digital modulation The M-ary PSK waveform QPSK constellations A typical QPSK modulator Symbol rate and bandwidth Demodulation and detection QPSK demodulation Detection and conversion of the raw data signals Carrier recovery DISCUSSION PSK digital modulation PSK uses multiple phases as modulation symbols. As already mentioned, all forms of M-ary PSK have a constant envelope, making them less sensitive to fading and nonlinearity. As the number of bits per symbol increases, the spectral efficiency increases but so does the error rate in the presence of noise. QPSK, which transmits two bits par symbol, offers a good compromise in many systems. Since all forms of PSK suffer from phase ambiguity (see Phase ambiguity in Exercise 3-3), differential encoding is often used. This eliminates the phase ambiguity at the cost of a slightly greater error rate for the same transmitted power. This can be compensated for, however, by a small increase in transmitter power. a Although the Satellite Communication System uses DQPSK (differential quadrature phase-shift keying), it is important to understand QPSK and the operation of a QPSK modulator and demodulator. Differential encoding is presented in Exercise 3-3. Festo Didactic

2 Ex. 3-2 Digital Modulation Discussion The M-ary PSK waveform * Filters are usually used near the output of a PSK modulator in order to restrict the bandwidth. This and other circuit particularities may result in amplitude variations in the PSK signal. Such amplitude variations, however, do not convey information. Only the phase of the waveform conveys information. With all forms of PSK, a sinusoidal waveform is varied in phase while keeping the amplitude * and frequency constant. Equation (3-5) shows the general expression for an M-ary PSK waveform. where (3-5) is the PSK signal waveform for phase is time is the peak amplitude is the carrier frequency in radians/s ( ) is the reference phase angle is phase is an integer ranging from 1 to The phase of the PSK waveform has discrete values equal to, where is the size of the symbol alphabet and takes on the values {1, 2, }. With quadrature PSK (QPSK), for example, there are four possible phases so. QPSK constellations The ideal PSK constellation has equidistant phase states and constant amplitude, resulting in a circular symmetry. With QPSK, the phases are separated by 90, as shown in Figure Q A B C D B A I C D a) QPSK ( ) B Q A B C D A C I D b) QPSK ( ) Figure QPSK constellation and waveforms. 214 Festo Didactic

3 Ex. 3-2 Digital Modulation Discussion Figure 3-48 shows two common representations of the QPSK constellation. The constellation points are arbitrarily labeled A, B, C and D, each of which represents one of the four possible dibits 00, 01, 10, and 11. The mapping between the dibits and the constellation points depends on the modulator circuit. Beside each constellation in Figure 3-48 is a plot showing all four phases (modulation symbols) as sinusoids. In each of these representations, the four phases are spaced 90 ( radians) apart. The only difference between these representations is the choice of the reference phase angle ( 0 in Equation (3-5)). A typical QPSK modulator A QPSK signal can be generated by independently modulating two carriers in phase quadrature ( and ) and summing the result, as shown in Figure I/Q Modulator Binary Data (baseband) Serial to Parallel Converter Level Converter I Channel Q Channel Low-Pass Filter QPSK Signal (IF) Level Converter Low-Pass Filter QPSK Symbol Generator QPSK Signal Generator Figure Simplified block diagram of a QPSK modulator (with no encoder). The Serial to Parallel Converter acts as a symbol generator, grouping the incoming data bits into symbols called dibits (groups of two consecutive bits). Each time two bits have been clocked serially into its buffer, the Serial to Parallel Converter outputs one dibit in parallel at its two outputs. The grouping into dibits is arbitrary and can start at any bit. For this reason, it is not possible to predict the dibits that will be generated from a given series of binary data bits. However, regardless of how the data bits are grouped into dibits at the transmitter, the demodulator in the receiver will correctly reconstruct the original data. One bit of each dibit is sent to the I channel of the QPSK signal generator; the other bit is sent to the Q channel. Each channel works independently to processes the stream of bits it receives. The Level Converter in each channel converts the data into a baseband bipolar pulse stream that can be applied to one input of the mixer. To restrict the bandwidth of the QPSK signal, a Low-Pass Filter is usually used before the mixer in each channel of the modulator in order to provide the desired spectral shaping. Since the modulator multiplies the baseband carriers by the baseband signal, this is equivalent to low-pass filtering the IF modulated signal. Festo Didactic

4 Ex. 3-2 Digital Modulation Discussion Filtering the signal in the baseband avoids using more a expensive filter that operates at the intermediate frequency. Nonetheless, an IF band-pass filter (not shown in Figure 3-49) is used in some cases to filter the QPSK signal before upconversion. The I/Q modulator consists of two product mixers as well as a local oscillator which generates the sinusoidal carriers and. Each mixer performs modulation by multiplying a carrier by a bipolar pulse stream. Theoretically, the carriers have no dc offset. When the bipolar pulse is positive, the carrier is passed unchanged. When the bipolar pulse is negative, the mixer inverts the phase of the carrier. In this way, each mixer generates a BPSK signal. a Ideal product mixers act as signal multipliers, producing an output signal equal to the product of the two input signals. In practice, high-frequency components have characteristics that deviate from theoretical ideals. For example, the mixers used in the Earth Station Transmitter I/Q Modulator require an input signal with a dc offset of roughly 0.5 V rather than 0 V. Orthogonal signals can be summed, transmitted in a channel and (theoretically) perfectly separated in the demodulator without any mutual interference. If the levels of the bipolar pulses,, etc. are +1 and -1, the peak amplitude of the waveform that is represented by Equation (3-6) is. The factor could be included in this equation to normalize the amplitude to unity. The two BPSK signals are summed to produce the QPSK signal which occupies a bandwidth centered on the frequency of the carrier. Because these two BPSK signals are generated using two carriers in quadrature, the BPSK signals are orthogonal, and the QPSK demodulator will be able to demodulate them separately. The output signal of the modulator is a sinusoidal carrier with four possible phases, each of which represents a two-bit symbol. This signal can be represented by Equation (3-6). (3-6) where is the QPSK signal waveform is the I-channel bipolar pulse stream,, is the Q-channel bipolar pulse stream,, is the angular frequency Figure 3-50 shows an example of the theoretical waveforms present in a modulator with no filtering. The bipolar I-channel and Q-channel pulses have levels of +1 and -1. The QPSK signal shown in Figure 3-50 has discontinuities which increase the bandwidth of the signal. The Low-Pass Filters shown in Figure 3-49 smooth the discontinuities and decrease the effective bandwidth. a Figure 3-50 shows all waveforms synchronized in time. In a real system, processing delays will cause successive signals to be slightly offset in time. 216 Festo Didactic

5 Ex. 3-2 Digital Modulation Discussion Figure 3-50 shows the dibit 11 mapped to the constellation point in the first quadrant. Other mappings are possible. Such mappings usually use a Gray code to ensure that only one bit changes between adjacent symbols. As a result, QPSK modulators map the dibits 00 and 11 to opposite quadrants. Data Bit Stream,, 1 I-Channel Pulses,, (even bits) Q-Channel Pulses,, (odd bits) I-Channel BPSK Signal Q-Channel BPSK Signal QPSK Signal Constellation Points and Dibits This is an example, other mappings are possible. The I-channel may represent the MSB or the LSB of each symbol Figure QPSK signal generation from two BPSK signals (no differential encoding). Symbol rate and bandwidth Because each symbol represents two bits, the rate that the symbols occur in the QPSK signal (the symbol rate) is one half the bit rate. Table 3-5 compares the symbol rates and bandwidths for BPSK and QPSK. Table 3-5. Symbol rate and bandwidth for BPSK and QPSK. Modulation Bits per symbol Symbol rate vs. Bit rate Main-lobe bandwidth BPSK 1 QPSK 2 The bandwidth of a modulated signal depends on the rate of change in the signal (i.e. the symbol rate) and not on the magnitude of each change. For this reason, using QPSK rather than BPSK will reduce by one-half the bandwidth required for a given bit rate. Alternatively, using QPSK can double the bit rate for a given Festo Didactic

6 Ex. 3-2 Digital Modulation Discussion signal bandwidth. This is illustrated by the unfiltered amplitude spectra in Figure 3-51, where fc is the carrier frequency. Main-lobe bandwidth BPSK Amplitude f c-2r b f c-r b f c f c+r b f c+2r b Main-lobe bandwidth QPSK Amplitude f c-4r s f c-3r s f c-2r s f c-r s f c f c+r s f c+2r s f c+3r s f c+4r s Figure BPSK and QPSK amplitude spectra (for equal bit rates). The modulated signal is called a double-sideband suppressed-carrier signal, since the spectrum is symmetric about the carrier frequency and there is no isolated signal at the carrier frequency. Figure 3-51 shows that the main-lobe bandwidth of a BPSK signal is and that of a QPSK signal with the same bit rate is. Therefore, the theoretical spectral efficiency of QPSK is twice that of BPSK. Most of the power in the signal spectrum is spread over the main lobe, which is centered on the carrier frequency; the lobes diminish in importance with their distance from the carrier frequency. In theory, there is no limit to the bandwidth but, as with FM signals, the contribution of frequencies far from the carrier is negligible. For this reason, there is no universal definition of bandwidth for digital signals. Some common definitions are given below. Main-lobe bandwidth, or null-to-null bandwidth: the width of the main spectral lobe of the power spectral density bounded by spectral nulls if they exist. The majority of the signal power for many digital modulation methods is contained between the first two nulls of the spectrum. Fractional power containment bandwidth: the amount of spectrum width needed to contain a certain percentage of the signal s power. The most common percentage used is 99%. Nyquist bandwidth: the minimum theoretical bandwidth necessary to propagate a signal. The Nyquist bandwidth is equal to the symbol rate. 218 Festo Didactic

7 Ex. 3-2 Digital Modulation Discussion The International Telecommunication Union (ITU) and the National Telecommunications and Information Administration (NTIA) in the U.S.A. use the following definitions to qualify the bandwidth. Necessary bandwidth: For a given class of emission, the width of the frequency band which is just sufficient to ensure the transmission of information at the rate and with the quality required under specified conditions. For M-ary modulation, the necessary bandwidth is defined by: (3-7) where is the necessary bandwidth is the bit rate is the size of the symbol alphabet is a design factor that depends on the implementation When the design factor, the necessary bandwidth equals the null-to-null bandwidth. The Nyquist bandwidth corresponds to. Depending on the system design and the performance required, the design factor may range roughly from 0.6 to 1.5. Occupied bandwidth: The width of a frequency band such that, below the lower and above the upper frequency limits, the mean powers emitted are each equal to a specified percentage of the total mean power of a given emission. Unless otherwise specified for the appropriate class of emission, the value of should be taken as 0.5%. This is the same as the fractional power containment bandwidth with a specified percentage of 99%. Authorized bandwidth: The NTIA defines this as the necessary bandwidth (bandwidth required for transmission and reception of intelligence) and does not include allowance for transmitter drift or Doppler shift. Demodulation and detection With analog modulation, the demodulator attempts to recover the original analog waveform as accurately as possible from the noisy and distorted signal at the demodulator input. With digital modulation however, accurate recovery of the original waveform is unnecessary. Instead the demodulator only tries to determine, once per symbol interval, which symbol is being transmitted from among all of the available symbols. The QPSK signal has four possible waveforms, or signal states (phases), each representing one dibit of data. The role of the demodulator is therefore to determine which of the four phases was sent during each symbol interval and to map this phase back to the dibit it represents. Since the modulator shifted the spectrum of the baseband data pulses up to the carrier frequency, the first step required to recover the data is to shift the Festo Didactic

8 Ex. 3-2 Digital Modulation Discussion spectrum of the received signal back down to the baseband. The term demodulation is often used to specifically refer to this operation, although this term is also used to refer to the entire process of recovering the original data from the modulated signal. The second step is to decide what data each of the pulses in the demodulated signal represents. This is called detection. During transmission through the channel, the signal is usually corrupted by noise. This can be represented in the constellation diagram as a displacement of the constellation points. Figure 3-52 shows the constellation points for a large number of symbols in a noisy QPSK signal. In this figure, the horizontal and vertical axes divide the signal space into four regions. The axes also represent the decision boundaries for deciding which symbol is being received. Each constellation point corresponds to the head of a phasor. The distance of the point from the origin shows the amplitude of the corresponding waveform and the angle from the I-axis shows the phase of the waveform. Figure Constellation of received QPSK signal with Gaussian noise. Although the noise affects both the amplitude (distance from the origin) and the phase (angle from the axis) of each received symbol waveform, only the phase is considered by the demodulator. As long as noise displaces a constellation point within the same region of the signal space, the demodulator can correctly recover the data. When the noise changes the phase of a symbol waveform so much that the constellation point crosses a decision boundary and moves into a different region, an error occurs and the recovered data is incorrect. 220 Festo Didactic

9 Ex. 3-2 Digital Modulation Discussion QPSK demodulation The QPSK demodulation process is performed using two mixers and two carrier signals in phase quadrature, as shown in Figure The carriers are generated by a carrier recovery circuit such as a Costas loop. The demodulator is able to separately demodulate the I- and Q-channel BPSK signals that were combined in the modulator because these two BPSK signals are orthogonal (they were generated using two carriers in phase quadrature). I Channel Level Converter Sample & Hold Decision Circuit QPSK Input Clock Recovery Recovered Clock Parallel to Serial Converter Data Output Q Channel Level Converter Sample & Hold Decision Circuit Carrier Recovery Figure Simplified QPSK demodulator circuit. An idealized QPSK waveform can be represented by Equation (3-8). (3-8) where is the QPSK signal waveform is the I-channel bipolar pulse stream,, is the Q-channel bipolar pulse stream,, is the angular frequency Festo Didactic

10 Ex. 3-2 Digital Modulation Discussion In order to demodulate the I-channel portion of this waveform, it is multiplied by the in-phase carrier as shown in Equation (3-9). (3-9) where is the output waveform of the I-channel mixer is the I-channel bipolar pulse stream is the Q-channel bipolar pulse stream is the angular frequency The output of the I-channel mixer consists of an analog signal containing bipolar data pulses and high-frequency components and. Similarly, the output of the Q-channel mixer contains the bipolar data pulses and high frequency components. These signals are shown in Figure QPSK signal I-Channel Mixer Output Q-Channel Mixer Output Figure Unfiltered QPSK demodulator mixer outputs. 222 Festo Didactic

11 Ex. 3-2 Digital Modulation Discussion Detection and conversion of the raw data signals The integrator in each channel of the demodulator removes the high-frequency components leaving only the raw data pulses. In a practical system, two low-pass filters perform the integration. Since the integrated signal in each channel is a time-varying analog signal, these two signals must be converted onto digital signals that represent the dibits. This is called detection and is accomplished in each channel by a sample and hold circuit followed by a decision circuit. The sample and hold circuits are triggered by a clock signal that is recovered from the received signal. The decision circuit makes a decision as to which binary state each sample represents. This circuit determines the decision boundaries (the axes in Figure 3-52). The output of the each decision circuit is a stream of fixed-amplitude data pulses each of which represents one bit of a dibit. In this way, one dibit, consisting of one bit from each channel, is generated per symbol interval. The Parallel to Serial Converter combines the dibits into bits in order to recover the original data stream. Carrier recovery The type of demodulator shown in Figure 3-53 uses two reference signals: and. These signals are recovered copies of the phase-quadrature carrier signals used in the modulator. This type of receiver is termed coherent. The I-channel carrier is produced by a local oscillator which is made to lock on to one of the phases in the QPSK signal. The Q-channel carrier is generated from the I-channel carrier using a 90 phase shift circuit. One type of circuit used for carrier recovery and demodulation is the Costas loop. This circuit uses a voltage-controlled oscillator (VCO) to generate a carrier. A feedback loop containing an integrator produces a control voltage that is applied to the VCO in order to keep it a constant frequency and phase. Like all circuits used in carrier recovery, the Costas loop is affected by phase ambiguity. Festo Didactic

12 Outline PROCEDURE OUTLINE The Procedure is divided into the following sections: System startup Symbol generation Differential encoding Level converters and low-pass filters Identifying the QPSK constellation points Digital demodulation Signal spectrum and bandwidth PROCEDURE System startup 1. If not already done, set up the system and align the antennas visually as shown in Appendix B. 2. Make sure that no hardware faults have been activated in the Earth Station Transmitter or the Earth Station Receiver. b Faults in these modules are activated for troubleshooting exercises using DIP switches located behind a removable panel on the back of these modules. For normal operation, all fault DIP switches should be in the O position. 3. Turn on each module that has a front panel Power switch (push the switch into the I position). After a few seconds, the Power LED should light. 4. If you are using the optional Telemetry and Instrumentation Add-On: Make sure there is a USB connection between the Data Generation/Acquisition Interface, the Virtual Instrument, and the host computer, as described in Appendix B. Turn on the Virtual Instrument using the rear panel power switch. b If the TiePieSCOPE drivers need to be installed, this will be done automatically in Windows 7 and 8. In Windows XP, the Found New Hardware Wizard will appear (it may appear twice). In this case, do not connect to Windows Update (select No, not this time and click Next). Then select Install the software automatically and click Next. Start the Telemetry and Instrumentation application. In the Application Selector, do not select Work in stand-alone mode. b If the Telemetry and Instrumentation application is already running, exit and restart it. This will ensure that no faults are active in the Satellite Repeater. 224 Festo Didactic

13 Symbol generation In this section, you will observe how the Serial to Parallel Converter generates symbols (dibits) from the bits in the input data stream. 5. Make the connections shown in Figure BIT CLOCK BIT CLOCK OUTPUT Earth Station Transmitter Binary Sequence Generator (BSG) DATA DATA INPUT 5 Digital Modulator I Q I Q IF 1 OUTPUT Up Converter 1 Up Converter 2 RF OUTPUT Satellite Repeater RF OUTPUT Earth Station Receiver Down Converter 2 IF 2 OUTPUT Down Converter 1 Digital Demodulator I Q I Q Figure Connections for unmultiplexed digital transmission. 6. On the Earth Station Transmitter, make the following adjustments: Data Source... Sampler Scrambler... Off Clock & Frame encoder... Off Configure the binary sequence generator to produce the sequence at a bit rate of 20 Mbit/s. Use the oscilloscope to observe the following signals: Channel Connect to Signal Ch 1 Transmitter TP4 Serial to Parallel Converter input Ch 2 BSG1 Sync. Sequence generator sync. signal Festo Didactic

14 Using the Telemetry and Instrumentation Add-On In the Telemetry and Instrumentation application, your could make the following settings and connections: Digital Output Settings Digital Output 1 Source... BSG1 Signal... Data Digital Output 3 Source... BSG1 Signal... Sync. Generator Settings Binary Sequence Generator (BSG) 1 Generation Mode... User Entry Binary Sequence Bit Rate BIT CLOCK Data Generation/ Acquisition Interface DIGITAL OUTPUT 1 (BSG1 Data) DIGITAL OUTPUT 3 (BSG1 Sync.) DATA INPUT 5 CH1 IN CH2 IN EXT TRIG TP4 Digital Modulator I Q BIT CLOCK OUTPUT I Q Virtual Instrument Figure 3-56 shows an example of the signals. Oscilloscope Settings: Channel 1 Scale * mv/div Channel 2 Scale... 5 V/div Time Base s/div Trigger Source... Ch 2 Trigger Level V Trigger Slope... Rising * with x10 probe Serial to Parallel Converter input (TP4) BSG1 Sync. signal Figure Serial to Parallel Converter input and BSG1 Sync. signal. 226 Festo Didactic

15 Observe the sequence displayed on the oscilloscope and make sure the sequence of bits and the bit rate correspond to the settings on the generator. Note that the sync. signal contains a pulse approximately aligned with the beginning of each repetition of the configured binary sequence. a The bit pattern at TP4 is delayed roughly 0.04 s with respect to the sync. signal because of cable lengths and processing delays in the transmitter. 7. Before observing the signals at the output of the Serial to Parallel Converter, read the following information, then use Table 3-6 below to predict the Serial to Parallel Converter output. The Serial to Parallel Converter As mentioned in the Discussion, the Serial to Parallel Converter converts the incoming data bits into two-bit symbols called dibits. In normal use, the signals at all DATA INPUTs on the Earth Station Transmitter are sampled either by the Sampler or the Clock & Frame Encoder, and perhaps the Scrambler. As these circuits are clocked by the Bit Clock, the channel bit rate at the input of the Serial to Parallel Converter is 20 Mbit/s, regardless of the bit rate at any of the DATA INPUTs. For example, if the data at DATA INPUT 5 consists of alternating 1s and 0s ( ) at a bit rate of 5 Mbit/s, the data at the input of the Serial to Parallel Converter is interpreted as at 20 Mbit/s, that is, four channel bits for each bit at DATA INPUT 5. If the bit rate at DATA INPUT 5 is 20 Mbit/s, there is one channel bit at the input of the Serial to Parallel Converter for each bit at DATA INPUT 5 The Serial to Parallel Converter groups the 20 Mbit/s data bits into dibits and outputs one bit of each dibit into the I-channel (TP6) and the other bit into the Q-channel (TP7). The grouping into dibits is arbitrary and can start at any bit. When the data at the input of the Serial to Parallel Converter consists of a repeating sequence with an even number of bits, there are two possible conditions: A) the grouping starts with the first bit of the sequence or B) the grouping starts with the second bit of the sequence. For example, the repeating bit sequence 1100 can produce the repeating dibits or (If the grouping starts with any other bit, the result is equivalent to condition A or B, since the sequence repeats indefinitely.) A repeating bit sequence with an odd number of bits is equivalent to a bit sequence which is twice as long and with an even number of bits. For example, the repeating bit sequence 110 is equivalent to the repeating bit sequence This bit sequence always produces the dibit sequence (since is equivalent to ). Festo Didactic

16 The first row of Table 3-6 shows the data bits from the configured Binary Sequence. After 10 bits, the sequence begins to repeat. A and B in the table represent the two conditions (the two ways the data bits can be grouped into dibits). Fill in the two Dibit rows of this table, grouping the data bits into dibits, starting with 00 for condition A and 01 for condition B. Table 3-6. Serial to Parallel Converter input and outputs. Condition A Condition B Data Bits Dibit Value Dibit Value A dibit is a two-digit binary number. According to the normal writing convention, the first (leftmost) bit is the most significant bit (MSB) and the second is the least significant bit (LSB). In Table 3-6, represent each of the dibits as a decimal value equal to 2 MSB + LSB. This will help you to see the order of the dibits. 8. Use the oscilloscope to observe the following signals: Channel Connect to Signal Memory Ch 1 Transmitter TP6 Serial to Parallel Converter I-output Memory Ch 2 Transmitter TP7 Serial to Parallel Converter Q-output Ch 1 Transmitter TP4 Serial to Parallel Converter input Ch 2 Transmitter TP5 Symbol Clock EXT TRIG BSG1 Sync. Sequence generator sync. signal a The upper output (TP6) of the Serial to Parallel Converter is referred to as the I-output and the lower output (TP7) as the Q-output. Figure 3-57 shows an example of what you should observe (the colors have been altered so as to have a white background). The memory traces have been positioned toward the bottom of the graticule. 228 Festo Didactic

17 Data bits (TP4) Symbol Clock (TP5) Dibits: SB (I-TP6) SB (Q-TP7) Value Figure Serial to Parallel Converter signals. The upper trace in Figure 3-57 shows data bits at the input of the Serial to Parallel Converter; is the bit interval. The second trace shows the symbol clock; is the symbol interval. The third and fourth trace show the I- and Q-outputs of the Serial to Parallel Converter. Together, these two signals represent the dibits, or symbols. Figure 3-57 shows one of the conditions (A or B) shown in Table 3-6. The Serial to Parallel Converter signals In the Earth Station Transmitter, data bits are clocked into the Serial to Parallel Converter one at a time by the symbol clock. The first bit of a dibit is clocked in as the symbol clock goes high; the second bit is clocked in as the symbol clock goes low. The Serial to Parallel Converter outputs the dibit at the next falling edge of the symbol clock. Therefore, a new dibit is generated at each falling edge of the symbol clock. Each dibit generated by the Serial to Parallel Converter is represented electrically by two pulse signals which are accessible at TP6 (I-channel) and TP7 (Q-channel). Each of these signals has two states: high (roughly 3 V) representing 1 and low (roughly 0 V) representing 0. When the system was designed, one of these signals was arbitrarily chosen to represents the MSB of each dibit and the other to represent the LSB. Group the data bits in this figure into dibits referring to the symbol clock. Then compare these grouped data bits with the generated dibits. Determine which channel I (TP6) or Q (TP7) represents the MSB of each dibit and which represents the LSB, according to the usual writing convention. Identify the LSB and the MSB trace in the figure. Then, under several dibits, write the decimal values of the dibits. b You may find it helpful to draw directly on Figure 3-57, drawing arrows between 5 consecutive pairs of data bits and the 5 corresponding dibits. Festo Didactic

18 Does the sequence of dibits shown in Figure 3-57 represent Condition A or B in Table 3-6? Give the bit interval, the bit rate, the symbol interval and the symbol rate. Explain the difference between the bit rate and the symbol rate. 9. Connect the probes to TP6 and TP7 of the transmitter. Restart the binary sequence generator several times while comparing the current dibits (TP6 and TP7) with those stored in memory. b If you are using the Telemetry and Instrumentation Add-On, use the Restart BSGs button on the Instrumentation tab. Does the Serial to Parallel Converter always produce the same series of dibits? Explain. Since the data consists of a repeating series of data bits, the Serial to Parallel Converter generates a repeating series of symbols. This series can contain a maximum of four different symbols: 00, 01, 10, and 11. How many different symbols are generated with Condition A? How many different symbols are generated with Condition B? What are the different symbols generated in each condition? 10. Use the oscilloscope to observe the following signals: Channel Connect to Signal Memory Ch 1 Transmitter TP5 Symbol Clock Ch 2 BSG1 Sync. Sequence generator sync. signal Ch 1 Transmitter TP4 Serial to Parallel Converter input Figure 3-58 shows the two conditions you may observe. b To show a different condition, connect TP5 to Channel 1 of the oscilloscope and restart the binary sequence generator several times until the condition changes, then memorize the TP5 signal and display the TP4 signal in Channel Festo Didactic

19 Symbol Clock BSG Sync. signal Data bits Dibits (a) Condition (b) Condition Figure BSG sync. signal, symbol clock, data bits, and dibits. Figure 3-58 shows the timing of the various signals involved and the dibits that are generated. The BSG Sync. signal contains a pulse approximately aligned with the first bit in the data sequence. The Serial to Parallel Converter receives the first data bit when the symbol clock goes high and the second when it goes low, and generates the dibit at the next falling edge of the symbol clock. Each half cycle of the symbol clock corresponds to one channel bit interval (0.05 s). Although the binary sequence generator receives its clock signal from the Earth Station Transmitter, there is no synchronization between the beginning of a repeating data sequence and the state of the symbol clock. The symbol clock can be either low or high as the data sequence begins. This is why the same repeating sequence can generate two different repeating series of symbols. With the present settings, these two different series of symbols are referred o as conditions A and B. Identify the two conditions in Figure Festo Didactic

20 Differential encoding In this section, you will simply observe the Differential Encoder input and output signals. Differential encoding is covered in detail in Exercise Connect the probes to TP6 and TP7. Obtain the same condition (A or B) shown in Figure 3-57 (if necessary, restart the binary sequence generator several times to obtain this condition). Then observe the following signals on the oscilloscope: Channel Connect to Signal Memory Ch 1 Transmitter TP6 Differential Encoder I-input Memory Ch 2 Transmitter TP7 Differential Encoder Q-input Ch 1 Transmitter TP8 Differential Encoder I-output Ch 2 Transmitter TP9 Differential Encoder Q-output EXT TRIG BSG1 Sync. Sequence generator sync. signal Figure 3-59 shows an example. Input TP6 TP7 Output TP8 TP9 Figure Differential Encoder signals. Does the Differential encoder alter the symbols it receives from the Serial to Parallel Converter? 232 Festo Didactic

21 Level converters and low-pass filters 12. Compare the signals at the input and the output of one of the Level Converters. Figure 3-60 shows an example of the signals at the input and output of the Q-channel Level Converter. a For technical reasons, the Level Converters invert the applied input. The signals are again inverted by the low-pass filters. TP9 Q OUTPUT Figure Q-channel level converter input and output signals. According to theory, why is it necessary to convert the I- and Q-channel digital signals from the Differential Encoder into bipolar pulse signals? 13. Observe the signals at the output of the Low-Pass Filters. Figure 3-61 shows the relationship between the output signals of the Serial to Parallel Converter, the Level Converters, and the low-pass filters. a For technical reasons, the low-pass filters add a dc offset to the signals. This is necessary because of the characteristics of the mixers used in the I/Q Modulator. As already mentioned, the low-pass filters invert the signals already inverted by the Level Converters. Festo Didactic

22 Level Converter inputs Level Converter outputs Low-Pass Filter outputs Figure DQPSK Modulator signals. What is the purpose of the low-pass filters? Identifying the QPSK constellation points In this section, you will observe the QPSK signal constellation at the output of the Serial to Parallel Converter and determine which dibit corresponds to each constellation point. 14. Connect the oscilloscope probes as follows: Channel Connect to Signal Ch 1 (X) Transmitter TP6 Serial to Parallel Converter I-output Ch 2 (Y) Transmitter TP7 Serial to Parallel Converter Q-output EXT TRIG BSG1 Sync. Sequence generator sync. signal Turn the Scrambler on. On the oscilloscope, set the Trigger Source to EXT. Adjust the Channel 1 (X) and Channel 2 (Y) scale to 100 mv/div. Set the Display Format to X-Y. Adjust the trace position controls in order to approximately center the pattern displayed on the oscilloscope, as shown in Figure a a In the Telemetry and Instrumentation application, using a more sensitive scale setting under the present conditions will result in an over scale condition. On some oscilloscopes, the EXT TRIG input is disabled when using the X-Y display format. In this case, the EXT TRIG connection is unnecessary. 234 Festo Didactic

23 b If you have a second oscilloscope, use one to display the signals in the normal format and the other to display them in the X-Y format. Oscilloscope Settings: Channel 1 (X) Scale mv/div Channel 2 (Y) Scale mv/div Format... X - Y Mode... Normal Sampling Window s Trigger Source... EXT Trigger Level... 2 V Trigger Slope... Rising Figure Positioning the X-Y trace on the oscilloscope. Turn the Scrambler and the Clock & Frame Encoder off. Once again, configure binary sequence generator BSG1 to produce the sequence at a bit rate of 20 Mbit/s. Set the Display Mode of the oscilloscope to Dots. The oscilloscope now displays the QPSK signal constellation as shown in either Figure 3-63a or b. This figure shows the observed constellations as well as a representation of the ideal constellations. b b If you are using the Telemetry and Instrumentation Add-On, set the Sampling window to 100 s. If you are using a conventional oscilloscope, you may find that adjusting the contrast improves the appearance of the constellation. The oscilloscope displays the constellation points one after the other. On some oscilloscopes, if you freeze the display (using Single Refresh or Stop, depending on the model), or if you capture the screen, you will likely see only the constellation point displayed at that instant. If necessary, turn persistence on to simultaneously display all of the constellation points that are currently being visited. Festo Didactic

24 (a) Condition (b) Condition Figure Observed (above) and ideal (below) QPSK constellations for conditions A and B. When displaying a constellation using the X-Y display format, the oscilloscope continually samples the X- and Y-channel signals. It displays one point for each sample taken. Each of these points represents a signal state that is visited. The position of the point depends on the instantaneous values of the two signals. If the signals used to display the constellation are almost perfectly rectangular pulses of uniform amplitude (see Figure 3-64a), only one point appears in each quadrant that is visited. On the other hand, when the pulses have imperfections such as tilt, overshoot, ringing, and noise (see Figure 3-64b), successive samples taken by the oscilloscope have slightly different values. As a result the points in the constellation, as displayed on an oscilloscope, are constantly being displaced. Instead of one point in each of the quadrants that is visited, multiple points may be displayed. Since only four significant signal states are possible for a QPSK signal, however, it is only important to note which quadrants are visited. (a) Nearly ideal pulses (b) Non-ideal pulses Figure Pulses. 236 Festo Didactic

25 Restart the binary sequence generator several times until you have observed both conditions shown in Figure Refer to Table 3-6 and identify the two conditions (A and B) shown in Figure Set the Binary Sequence to 00. This results in a repeating series of 00 dibits at the output of the Serial to Parallel Converter. Observe the resulting constellation point. Then set the Binary Sequence to 11. Write in the boxes in Figure 3-65 the dibits that corresponds to the two constellation points you observed. a The mapping of dibits to constellation points depends on the system design and how the signals are displayed on the oscilloscope. A number of different mappings are possible. The current connections and configuration correspond to one of the possible mappings. Figure Dibits in the QPSK constellation. Set the Binary Sequence to 01 or 10. This produces a data stream consisting of alternating 1s and 0s. Interrupt and restart the binary sequence generator several times and note that the oscilloscope does not always display the same constellation point. Because the Serial to Parallel Converter divides the input data into dibits starting at an arbitrary point, a sequence of alternating 1s and 0s at the input can produce two different dibit sequences at the output: 1) or 2) Note which constellation point is currently displayed. Set the oscilloscope to the Normal Display Mode and Normal Display Format (not X-Y). Note which output of the Serial to Parallel Converter is high (1) and which is low (0). Refer to your answer to Step 8 to determine which output channel represents the MSB and which represents the LSB of each dibit. This will allow you to identify the repeating dibit at the output of the Serial to Parallel Converter. In Figure 3-65, identify the displayed dibit as well as the last remaining dibit. Festo Didactic

26 16. Adjust the binary sequence generator to produce a 3-bit pseudo-random sequence at 2 Mbit/s. In the Telemetry and Instrumentation application, make the following settings: Generator Settings Binary Sequence Generator (BSG) 1 Generation Mode... Pseudo-Random n... 2 Bit Rate Display the constellation on the oscilloscope. How many constellation points are present? Explain. Generate a pseudo-random sequence of 7 bits (a pseudo-random sequence with n = 3). How many constellation points are present? Digital demodulation 17. Once again, configure binary sequence generator BSG1 to produce the sequence at a bit rate of 20 Mbit/s. On the Earth Station Receiver, lock the Costas loop, as shown in the procedure of Exercise 1-1. Then make the following adjustments: On the Earth Station Transmitter: Data Source... Sampler Scrambler... Off Clock & Frame encoder... Off On the Earth Station Receiver: Descrambler... Off Use the oscilloscope to observe the following signals: Channel Connect to Signal Memory Ch 1 Receiver I OUTPUT Costas loop I-output Memory Ch 2 Receiver Q OUTPUT Costas loop Q-output Ch 1 Receiver TP2 I Level Converter output Ch 2 Receiver TP3 Q Level Converter output 238 Festo Didactic

27 I OUTPUT Q OUTPUT TP2 TP3 Figure Costas loop and Level Converter output signals. Figure 3-66 shows an example. Describe the operation of the Level Converters. 18. Use the oscilloscope to observe the following signals: Channel Connect to Signal Memory Ch 1 Receiver TP2 I Level Converter output Memory Ch 2 Receiver TP3 Q Level Converter output Ch 1 Receiver TP4 I DATA Ch 2 Receiver TP5 Q DATA Figure 3-67 show an example. Does the Sampler/Differential Decoder alter the symbols it receives? Festo Didactic

28 TP2 TP3 TP4 TP5 Figure Sampler/Differential Encoder signals. 19. Store the decoded symbols at the receiver in the oscilloscope memory. Then compare the decoded symbols at the receiver with the unencoded symbols at the transmitter, ignoring the delay. Are they identical? 20. Configure the binary sequence generator to produce a 32-bit sequence with several 1s at the beginning, followed by 0s, at a bit rate of 20 Mbit/s. For example, in the Telemetry and Instrumentation application, make the following settings: Generator Settings Binary Sequence Generator (BSG) 1 Generation Mode... User Entry Binary Sequence Bit Rate Use the oscilloscope to observe the following signals: Channel Connect to Signal Ch 1 Transmitter DATA INPUT 5 Transmitted Data Memory Ch 1 Transmitter TP4 Serial to Parallel Converter input Memory Ch 2 Receiver TP6 Parallel to Serial Converter output Ch 2 Receiver DATA OUTPUT 5 Received Data 240 Festo Didactic

29 Figure 3-68 shows an example. DATA INPUT 5 TP4 TP6 DATA OUTPUT 5 Figure Transmitted and received data. Is the transmitted data correctly recovered by the receiver? Festo Didactic

30 Signal spectrum and bandwidth In this section, you will observe the spectrum of the modulated DQPSK signal and compare it with the spectrum of the baseband modulating signal. You will determine the bandwidth of these signals. 21. Configure a binary sequence generator to produce a long pseudo-random sequence at 20 Mbit/s. Observe the baseband binary sequence on the oscilloscope and then on the spectrum analyzer. Using the Telemetry and Instrumentation Add-On For example, in the Telemetry and Instrumentation application, make the following settings: Digital Output Settings Digital Output 1 Source... BSG1 Signal... Data Digital Output 3 Source... BSG1 Signal... Sync. Generator Settings Binary Sequence Generator (BSG) 1 Generation Mode... Pseudo-Random n Bit Rate The present connections will display the binary sequence on the oscilloscope. Use the following connections to observe the spectrum of the baseband binary sequence: BIT CLOCK OUTPUT Digital Modulator Earth Station Transmitter I Q I Q BIT CLOCK Spectrum Analyzer Interface Binary Sequence Generator (BSG) DATA Probe Buffer Frequency Converter CH1 or 2 IN Virtual Instrument Data Generation/Acquisition Interface 242 Festo Didactic

31 Oscilloscope Settings: Channel 1 Scale... 5 V/div Time Base s/div Trigger Source... EXT Trigger Level V Trigger Slope... Falling triggered on BSG1 Sync. signal Figure 3-69 and Figure 3-70 show examples of the time and frequency domain representations of a baseband pseudo-random binary sequence. Spectrum Analyzer Settings: Maximum Input dbm Scale db/div Averaging... 4 Time Window... Rectangular Frequency Range... DC 360 MHz? Frequency Span... 5 MHz/div Center Frequency Hz Figure PRBS on the oscilloscope (, ). a Figure PRBS spectrum (, ). In the PRBS spectrum, the peaks at multiples of the bit rate are due to imperfections in the waveform of the data signal and should be ignored. Describe the spectrum of a random data signal. Festo Didactic

32 What is the main-lobe bandwidth of a baseband random data signal? Spectrum Analyzer Settings: Maximum Input dbm Scale db/div Averaging... 4 Time Window... Rectangular Frequency Range... DC 360 MHz? Frequency Span... 5 MHz/div Center Frequency Hz 22. Connect the output of the binary sequence generator to DATA INPUT 5 of the Earth Station Transmitter. On the Earth Station Transmitter, make the following adjustments: Data Source... Sampler Scrambler... Off Clock & Frame Encoder... Off Observe the spectrum at the I OUTPUT of the DQPSK Modulator. Figure 3-71 shows an example. Figure I OUTPUT spectrum. Compare this spectrum with that of the baseband PRBS and explain the differences. 244 Festo Didactic

33 Spectrum Analyzer Settings: Maximum Input dbm Scale db/div Averaging... 4 Time Window... Rectangular Frequency Range... DC 360 MHz Frequency Span... 5 MHz/div Center Frequency Hz External attenuator db 23. Reconnect the I OUTPUT to the I INPUT. Then observe the spectrum of the IF 1 OUTPUT signal from the DQPSK Modulator. Figure 3-72 shows an example. Figure IF 1 OUTPUT spectrum. Compare this spectrum with that of the baseband PRBS and explain the differences (general shape, bandwidth, center frequency). The cut-off frequency of the I- and Q-channel low-pass filters is 10 MHz. explain why this is an appropriate cut-off frequency for these filters. 24. Configure the binary sequence generator to transmit only 0s (alternatively, disconnect the BNC cable at DATA INPUT 5 of the Earth Station Transmitter). Use the oscilloscope to observe the signals at the inputs to the I/Q Modulator (TP10 and TP11). Are these signals changing or are they each at a constant level? Festo Didactic

34 Explain what has happened to the spectrum. 25. Reconfigure the binary sequence generator to transmit a long pseudorandom sequence (alternatively, reconnect the BNC cable at DATA INPUT 5 of the Earth Station Transmitter). Then disconnect the BNC cables at the I INPUT and Q INPUT of the DQPSK Modulator. Explain what happens to the spectrum. 26. Reconnect the BNC cables at the I INPUT and Q INPUT of the DQPSK Modulator. Observe the spectrum at the RF OUTPUT. Compare this spectrum with that of the IF 1 OUTPUT signal. Spectrum Analyzer Settings: Maximum Input dbm Scale... 5 db/div Averaging... 8 Time Window... Rectangular Frequency Range GHz Frequency Span... 5 MHz/div Center Frequency Hz External attenuator db Figure RF OUTPUT spectrum. 246 Festo Didactic

35 Ex. 3-2 Digital Modulation Conclusion 27. When you have finished using the system, exit any software being used and turn off the equipment. CONCLUSION In this exercise, you observed how digital QPSK modulation and demodulation works. You saw that the incoming data bits are converted into dibits by the Serial to Parallel Converter, which acts as a symbol generator, and that the dibits are level converted and filtered before being multiplied with two carrier signals in phase quadrature. You observed the QPSK constellation and identified the constellation points. You also observed the spectrum and bandwidth of the filtered QPSK signal. REVIEW QUESTIONS 1. What is the purpose of the symbol generator in a QPSK modulator? 2. Why are the baseband I- and Q-channel signals in the modulator often lowpass filtered before I/Q modulation? 3. The QPSK modulator generates the QPSK signal by generating two independently modulated BPSK signals and combining them. What property allows these two BPSK signals to be demodulated separately in the QPSK demodulator? 4. Explain how two mixers and two carriers in phase quadrature are used to demodulate a QPSK signal. Festo Didactic

36 Ex. 3-2 Digital Modulation Review Questions 5. Why is it necessary to regenerate a carrier in the QPSK demodulator? 248 Festo Didactic

Exercise 3-3. Differential Encoding EXERCISE OBJECTIVE DISCUSSION OUTLINE. Phase ambiguity DISCUSSION

Exercise 3-3. Differential Encoding EXERCISE OBJECTIVE DISCUSSION OUTLINE. Phase ambiguity DISCUSSION Exercise 3-3 Differential Encoding EXERCISE OBJECTIVE When you have completed this exercise, you will e familiar with the technique of differential encoding used with QPSK digital modulation. DISCUSSION

More information

Exercise 3. Differential QAM (DQAM) EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION. Review of phase ambiguity

Exercise 3. Differential QAM (DQAM) EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION. Review of phase ambiguity Exercise 3 Differential QAM (DQAM) EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the use of differential encoding, using the ITU-T V.22 bis recommendation, to overcome

More information

The Discussion of this exercise covers the following points: Filtering Aperture distortion

The Discussion of this exercise covers the following points: Filtering Aperture distortion Exercise 3-1 PAM Signals Demodulation EXERCISE OBJECTIVE When you have completed this exercise you will be able to demonstrate the recovery of the original message signal from a PAM signal using the PAM

More information

Exercise 1. QAM Modulation EXERCISE OBJECTIVE DISCUSSION OUTLINE. The QAM waveform DISCUSSION

Exercise 1. QAM Modulation EXERCISE OBJECTIVE DISCUSSION OUTLINE. The QAM waveform DISCUSSION Exercise 1 QAM Modulation EXERCISE OBJECTIVE When you have completed this exercise, you will e familiar with QAM modulation, with the characteristics of QAM signals and with the QAM signal constellation.

More information

Frequency Agility and Barrage Noise Jamming

Frequency Agility and Barrage Noise Jamming Exercise 1-3 Frequency Agility and Barrage Noise Jamming EXERCISE OBJECTIVE To demonstrate frequency agility, a radar electronic protection is used against spot noise jamming. To justify the use of barrage

More information

Exercise 4. Angle Tracking Techniques EXERCISE OBJECTIVE

Exercise 4. Angle Tracking Techniques EXERCISE OBJECTIVE Exercise 4 Angle Tracking Techniques EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the principles of the following angle tracking techniques: lobe switching, conical

More information

Department of Electronics & Telecommunication Engg. LAB MANUAL. B.Tech V Semester [ ] (Branch: ETE)

Department of Electronics & Telecommunication Engg. LAB MANUAL. B.Tech V Semester [ ] (Branch: ETE) Department of Electronics & Telecommunication Engg. LAB MANUAL SUBJECT:-DIGITAL COMMUNICATION SYSTEM [BTEC-501] B.Tech V Semester [2013-14] (Branch: ETE) KCT COLLEGE OF ENGG & TECH., FATEHGARH PUNJAB TECHNICAL

More information

The Discussion of this exercise covers the following points:

The Discussion of this exercise covers the following points: Exercise 3-2 Frequency-Modulated CW Radar EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with FM ranging using frequency-modulated continuous-wave (FM-CW) radar. DISCUSSION

More information

PGT313 Digital Communication Technology. Lab 3. Quadrature Phase Shift Keying (QPSK) and 8-Phase Shift Keying (8-PSK)

PGT313 Digital Communication Technology. Lab 3. Quadrature Phase Shift Keying (QPSK) and 8-Phase Shift Keying (8-PSK) PGT313 Digital Communication Technology Lab 3 Quadrature Phase Shift Keying (QPSK) and 8-Phase Shift Keying (8-PSK) Objectives i) To study the digitally modulated quadrature phase shift keying (QPSK) and

More information

Digital modulation techniques

Digital modulation techniques Outline Introduction Signal, random variable, random process and spectra Analog modulation Analog to digital conversion Digital transmission through baseband channels Signal space representation Optimal

More information

Satellite Communications Training System

Satellite Communications Training System Satellite Communications Training System LabVolt Series Datasheet Festo Didactic en 220 V - 60 Hz 07/208 Table of Contents General Description 2 System Configurations and Capabilities 3 Topic Coverage

More information

EE 400L Communications. Laboratory Exercise #7 Digital Modulation

EE 400L Communications. Laboratory Exercise #7 Digital Modulation EE 400L Communications Laboratory Exercise #7 Digital Modulation Department of Electrical and Computer Engineering University of Nevada, at Las Vegas PREPARATION 1- ASK Amplitude shift keying - ASK - in

More information

Exercise 1-3. Radar Antennas EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION OF FUNDAMENTALS. Antenna types

Exercise 1-3. Radar Antennas EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION OF FUNDAMENTALS. Antenna types Exercise 1-3 Radar Antennas EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the role of the antenna in a radar system. You will also be familiar with the intrinsic characteristics

More information

Exercise 2-2. Antenna Driving System EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION

Exercise 2-2. Antenna Driving System EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION Exercise 2-2 Antenna Driving System EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the mechanical aspects and control of a rotating or scanning radar antenna. DISCUSSION

More information

TSEK02: Radio Electronics Lecture 2: Modulation (I) Ted Johansson, EKS, ISY

TSEK02: Radio Electronics Lecture 2: Modulation (I) Ted Johansson, EKS, ISY TSEK02: Radio Electronics Lecture 2: Modulation (I) Ted Johansson, EKS, ISY 2 Basic Definitions Time and Frequency db conversion Power and dbm Filter Basics 3 Filter Filter is a component with frequency

More information

Department of Electronic and Information Engineering. Communication Laboratory. Phase Shift Keying (PSK) & Quadrature Phase Shift Keying (QPSK)

Department of Electronic and Information Engineering. Communication Laboratory. Phase Shift Keying (PSK) & Quadrature Phase Shift Keying (QPSK) Department of Electronic and Information Engineering Communication Laboratory Phase Shift Keying (PSK) & Quadrature Phase Shift Keying (QPSK) Objectives To familiar with the concept of describing phase

More information

Satellite Communications: Part 4 Signal Distortions & Errors and their Relation to Communication Channel Specifications. Howard Hausman April 1, 2010

Satellite Communications: Part 4 Signal Distortions & Errors and their Relation to Communication Channel Specifications. Howard Hausman April 1, 2010 Satellite Communications: Part 4 Signal Distortions & Errors and their Relation to Communication Channel Specifications Howard Hausman April 1, 2010 Satellite Communications: Part 4 Signal Distortions

More information

Recap of Last 2 Classes

Recap of Last 2 Classes Recap of Last 2 Classes Transmission Media Analog versus Digital Signals Bandwidth Considerations Attentuation, Delay Distortion and Noise Nyquist and Shannon Analog Modulation Digital Modulation What

More information

Thus there are three basic modulation techniques: 1) AMPLITUDE SHIFT KEYING 2) FREQUENCY SHIFT KEYING 3) PHASE SHIFT KEYING

Thus there are three basic modulation techniques: 1) AMPLITUDE SHIFT KEYING 2) FREQUENCY SHIFT KEYING 3) PHASE SHIFT KEYING CHAPTER 5 Syllabus 1) Digital modulation formats 2) Coherent binary modulation techniques 3) Coherent Quadrature modulation techniques 4) Non coherent binary modulation techniques. Digital modulation formats:

More information

Exercise 6. Range and Angle Tracking Performance (Radar-Dependent Errors) EXERCISE OBJECTIVE

Exercise 6. Range and Angle Tracking Performance (Radar-Dependent Errors) EXERCISE OBJECTIVE Exercise 6 Range and Angle Tracking Performance EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the radardependent sources of error which limit range and angle tracking

More information

ELEC3242 Communications Engineering Laboratory Frequency Shift Keying (FSK)

ELEC3242 Communications Engineering Laboratory Frequency Shift Keying (FSK) ELEC3242 Communications Engineering Laboratory 1 ---- Frequency Shift Keying (FSK) 1) Frequency Shift Keying Objectives To appreciate the principle of frequency shift keying and its relationship to analogue

More information

CHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY NH-67, TRICHY MAIN ROAD, PULIYUR, C.F , KARUR DT.

CHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY NH-67, TRICHY MAIN ROAD, PULIYUR, C.F , KARUR DT. CHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY NH-67, TRICHY MAIN ROAD, PULIYUR, C.F. 639 114, KARUR DT. DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING COURSE MATERIAL Subject Name: Analog & Digital

More information

TSEK02: Radio Electronics Lecture 2: Modulation (I) Ted Johansson, EKS, ISY

TSEK02: Radio Electronics Lecture 2: Modulation (I) Ted Johansson, EKS, ISY TSEK02: Radio Electronics Lecture 2: Modulation (I) Ted Johansson, EKS, ISY An Overview of Modulation Techniques: chapter 3.1 3.3.1 2 Introduction (3.1) Analog Modulation Amplitude Modulation Phase and

More information

Lecture 3: Wireless Physical Layer: Modulation Techniques. Mythili Vutukuru CS 653 Spring 2014 Jan 13, Monday

Lecture 3: Wireless Physical Layer: Modulation Techniques. Mythili Vutukuru CS 653 Spring 2014 Jan 13, Monday Lecture 3: Wireless Physical Layer: Modulation Techniques Mythili Vutukuru CS 653 Spring 2014 Jan 13, Monday Modulation We saw a simple example of amplitude modulation in the last lecture Modulation how

More information

CHAPTER 2 DIGITAL MODULATION

CHAPTER 2 DIGITAL MODULATION 2.1 INTRODUCTION CHAPTER 2 DIGITAL MODULATION Referring to Equation (2.1), if the information signal is digital and the amplitude (lv of the carrier is varied proportional to the information signal, a

More information

P a g e 1 ST985. TDR Cable Analyzer Instruction Manual. Analog Arts Inc.

P a g e 1 ST985. TDR Cable Analyzer Instruction Manual. Analog Arts Inc. P a g e 1 ST985 TDR Cable Analyzer Instruction Manual Analog Arts Inc. www.analogarts.com P a g e 2 Contents Software Installation... 4 Specifications... 4 Handling Precautions... 4 Operation Instruction...

More information

Implementation of Digital Signal Processing: Some Background on GFSK Modulation

Implementation of Digital Signal Processing: Some Background on GFSK Modulation Implementation of Digital Signal Processing: Some Background on GFSK Modulation Sabih H. Gerez University of Twente, Department of Electrical Engineering s.h.gerez@utwente.nl Version 5 (March 9, 2016)

More information

DIGITAL COMMUNICATIONS SYSTEMS. MSc in Electronic Technologies and Communications

DIGITAL COMMUNICATIONS SYSTEMS. MSc in Electronic Technologies and Communications DIGITAL COMMUNICATIONS SYSTEMS MSc in Electronic Technologies and Communications Bandpass binary signalling The common techniques of bandpass binary signalling are: - On-off keying (OOK), also known as

More information

An Investigation into the Effects of Sampling on the Loop Response and Phase Noise in Phase Locked Loops

An Investigation into the Effects of Sampling on the Loop Response and Phase Noise in Phase Locked Loops An Investigation into the Effects of Sampling on the Loop Response and Phase oise in Phase Locked Loops Peter Beeson LA Techniques, Unit 5 Chancerygate Business Centre, Surbiton, Surrey Abstract. The majority

More information

Lecture 3 Concepts for the Data Communications and Computer Interconnection

Lecture 3 Concepts for the Data Communications and Computer Interconnection Lecture 3 Concepts for the Data Communications and Computer Interconnection Aim: overview of existing methods and techniques Terms used: -Data entities conveying meaning (of information) -Signals data

More information

Communication Systems Lab

Communication Systems Lab LAB MANUAL Communication Systems Lab (EE-226-F) Prepared by: Varun Sharma (Lab In-charge) Dayal C. Sati (Faculty In-charge) B R C M CET BAHAL DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING Page

More information

Exercise 2-1. PAM Signals EXERCISE OBJECTIVE DISCUSSION OUTLINE. Signal sampling DISCUSSION

Exercise 2-1. PAM Signals EXERCISE OBJECTIVE DISCUSSION OUTLINE. Signal sampling DISCUSSION Exercise 2-1 PAM Signals EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the generation of both natural and flat-top sampled PAM signals. You will verify how the frequency

More information

Exercise 1-4. The Radar Equation EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION OF FUNDAMENTALS

Exercise 1-4. The Radar Equation EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION OF FUNDAMENTALS Exercise 1-4 The Radar Equation EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the different parameters in the radar equation, and with the interaction between these

More information

Exercise 3-2. Cross-Polarization Jamming EXERCISE OBJECTIVE

Exercise 3-2. Cross-Polarization Jamming EXERCISE OBJECTIVE Exercise 3-2 Cross-Polarization Jamming EXERCISE OBJECTIVE To introduce the concept of antenna polarization. To demonstrate the effect of crosspolarization jamming on a tracking radar s angular error signal.

More information

MODULATION AND MULTIPLE ACCESS TECHNIQUES

MODULATION AND MULTIPLE ACCESS TECHNIQUES 1 MODULATION AND MULTIPLE ACCESS TECHNIQUES Networks and Communication Department Dr. Marwah Ahmed Outlines 2 Introduction Digital Transmission Digital Modulation Digital Transmission of Analog Signal

More information

Deceptive Jamming Using Amplitude-Modulated Signals

Deceptive Jamming Using Amplitude-Modulated Signals Exercise 3-1 Deceptive Jamming Using Amplitude-Modulated Signals EXERCISE OBJECTIVE To demonstrate the effect of AM noise and repeater inverse gain jamming, two angular deceptive EA used against sequential

More information

Third-Method Narrowband Direct Upconverter for the LF / MF Bands

Third-Method Narrowband Direct Upconverter for the LF / MF Bands Third-Method Narrowband Direct Upconverter for the LF / MF Bands Introduction Andy Talbot G4JNT February 2016 Previous designs for upconverters from audio generated from a soundcard to RF have been published

More information

EE 460L University of Nevada, Las Vegas ECE Department

EE 460L University of Nevada, Las Vegas ECE Department EE 460L PREPARATION 1- ASK Amplitude shift keying - ASK - in the context of digital communications is a modulation process which imparts to a sinusoid two or more discrete amplitude levels. These are related

More information

Digital Modulation Lecture 01. Review of Analogue Modulation Introduction to Digital Modulation Techniques Richard Harris

Digital Modulation Lecture 01. Review of Analogue Modulation Introduction to Digital Modulation Techniques Richard Harris Digital Modulation Lecture 01 Review of Analogue Modulation Introduction to Digital Modulation Techniques Richard Harris Objectives You will be able to: Classify the various approaches to Analogue Modulation

More information

Objectives. Presentation Outline. Digital Modulation Lecture 01

Objectives. Presentation Outline. Digital Modulation Lecture 01 Digital Modulation Lecture 01 Review of Analogue Modulation Introduction to Digital Modulation Techniques Richard Harris Objectives You will be able to: Classify the various approaches to Analogue Modulation

More information

Lecture 6. Angle Modulation and Demodulation

Lecture 6. Angle Modulation and Demodulation Lecture 6 and Demodulation Agenda Introduction to and Demodulation Frequency and Phase Modulation Angle Demodulation FM Applications Introduction The other two parameters (frequency and phase) of the carrier

More information

Costas Loop. Modules: Sequence Generator, Digital Utilities, VCO, Quadrature Utilities (2), Phase Shifter, Tuneable LPF (2), Multiplier

Costas Loop. Modules: Sequence Generator, Digital Utilities, VCO, Quadrature Utilities (2), Phase Shifter, Tuneable LPF (2), Multiplier Costas Loop Modules: Sequence Generator, Digital Utilities, VCO, Quadrature Utilities (2), Phase Shifter, Tuneable LPF (2), Multiplier 0 Pre-Laboratory Reading Phase-shift keying that employs two discrete

More information

Outline. EECS 3213 Fall Sebastian Magierowski York University. Review Passband Modulation. Constellations ASK, FSK, PSK.

Outline. EECS 3213 Fall Sebastian Magierowski York University. Review Passband Modulation. Constellations ASK, FSK, PSK. EECS 3213 Fall 2014 L12: Modulation Sebastian Magierowski York University 1 Outline Review Passband Modulation ASK, FSK, PSK Constellations 2 1 Underlying Idea Attempting to send a sequence of digits through

More information

B.Tech II Year II Semester (R13) Supplementary Examinations May/June 2017 ANALOG COMMUNICATION SYSTEMS (Electronics and Communication Engineering)

B.Tech II Year II Semester (R13) Supplementary Examinations May/June 2017 ANALOG COMMUNICATION SYSTEMS (Electronics and Communication Engineering) Code: 13A04404 R13 B.Tech II Year II Semester (R13) Supplementary Examinations May/June 2017 ANALOG COMMUNICATION SYSTEMS (Electronics and Communication Engineering) Time: 3 hours Max. Marks: 70 PART A

More information

Mobile & Wireless Networking. Lecture 2: Wireless Transmission (2/2)

Mobile & Wireless Networking. Lecture 2: Wireless Transmission (2/2) 192620010 Mobile & Wireless Networking Lecture 2: Wireless Transmission (2/2) [Schiller, Section 2.6 & 2.7] [Reader Part 1: OFDM: An architecture for the fourth generation] Geert Heijenk Outline of Lecture

More information

UNIT 2 DIGITAL COMMUNICATION DIGITAL COMMUNICATION-Introduction The techniques used to modulate digital information so that it can be transmitted via microwave, satellite or down a cable pair is different

More information

QUESTION BANK EC 1351 DIGITAL COMMUNICATION YEAR / SEM : III / VI UNIT I- PULSE MODULATION PART-A (2 Marks) 1. What is the purpose of sample and hold

QUESTION BANK EC 1351 DIGITAL COMMUNICATION YEAR / SEM : III / VI UNIT I- PULSE MODULATION PART-A (2 Marks) 1. What is the purpose of sample and hold QUESTION BANK EC 1351 DIGITAL COMMUNICATION YEAR / SEM : III / VI UNIT I- PULSE MODULATION PART-A (2 Marks) 1. What is the purpose of sample and hold circuit 2. What is the difference between natural sampling

More information

PULSE CODE MODULATION TELEMETRY Properties of Various Binary Modulation Types

PULSE CODE MODULATION TELEMETRY Properties of Various Binary Modulation Types PULSE CODE MODULATION TELEMETRY Properties of Various Binary Modulation Types Eugene L. Law Telemetry Engineer Code 1171 Pacific Missile Test Center Point Mugu, CA 93042 ABSTRACT This paper discusses the

More information

The Discussion of this exercise covers the following points:

The Discussion of this exercise covers the following points: Exercise 1-3 Satellite Payloads and Telemetry EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the payload of a communications satellite and with the principles of TTC

More information

Chapter 6 Passband Data Transmission

Chapter 6 Passband Data Transmission Chapter 6 Passband Data Transmission Passband Data Transmission concerns the Transmission of the Digital Data over the real Passband channel. 6.1 Introduction Categories of digital communications (ASK/PSK/FSK)

More information

Department of Electronic and Information Engineering. Communication Laboratory

Department of Electronic and Information Engineering. Communication Laboratory Department of Electronic and Information Engineering Communication Laboratory Frequency Shift Keying (FSK) & Differential Phase Shift Keying (DPSK) & Differential Quadrature Phase Shift Keying (DQPSK)

More information

Chapter 2 Channel Equalization

Chapter 2 Channel Equalization Chapter 2 Channel Equalization 2.1 Introduction In wireless communication systems signal experiences distortion due to fading [17]. As signal propagates, it follows multiple paths between transmitter and

More information

EXPERIMENT NO. 4 PSK Modulation

EXPERIMENT NO. 4 PSK Modulation DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING ECOM 4101 (ECE 4203) COMMUNICATIONS ENGINEERING LAB II SEMESTER 2, 2016/2017 EXPERIMENT NO. 4 PSK Modulation NAME: MATRIC NO: DATE: SECTION: PSK MODULATION

More information

Quadrature Amplitude Modulation (QAM) Experiments Using the National Instruments PXI-based Vector Signal Analyzer *

Quadrature Amplitude Modulation (QAM) Experiments Using the National Instruments PXI-based Vector Signal Analyzer * OpenStax-CNX module: m14500 1 Quadrature Amplitude Modulation (QAM) Experiments Using the National Instruments PXI-based Vector Signal Analyzer * Robert Kubichek This work is produced by OpenStax-CNX and

More information

Charan Langton, Editor

Charan Langton, Editor Charan Langton, Editor SIGNAL PROCESSING & SIMULATION NEWSLETTER Baseband, Passband Signals and Amplitude Modulation The most salient feature of information signals is that they are generally low frequency.

More information

Basic Communication Laboratory Manual. Shimshon Levy&Harael Mualem

Basic Communication Laboratory Manual. Shimshon Levy&Harael Mualem Basic Communication Laboratory Manual Shimshon Levy&Harael Mualem September 2006 CONTENTS 1 The oscilloscope 2 1.1 Objectives... 2 1.2 Prelab... 2 1.3 Background Theory- Analog Oscilloscope...... 3 1.4

More information

Digital Audio Broadcasting Eureka-147. Minimum Requirements for Terrestrial DAB Transmitters

Digital Audio Broadcasting Eureka-147. Minimum Requirements for Terrestrial DAB Transmitters Digital Audio Broadcasting Eureka-147 Minimum Requirements for Terrestrial DAB Transmitters Prepared by WorldDAB September 2001 - 2 - TABLE OF CONTENTS 1 Scope...3 2 Minimum Functionality...3 2.1 Digital

More information

PRODUCT DEMODULATION - SYNCHRONOUS & ASYNCHRONOUS

PRODUCT DEMODULATION - SYNCHRONOUS & ASYNCHRONOUS PRODUCT DEMODULATION - SYNCHRONOUS & ASYNCHRONOUS INTRODUCTION...98 frequency translation...98 the process...98 interpretation...99 the demodulator...100 synchronous operation: ω 0 = ω 1...100 carrier

More information

C06a: Digital Modulation

C06a: Digital Modulation CISC 7332X T6 C06a: Digital Modulation Hui Chen Department of Computer & Information Science CUNY Brooklyn College 10/2/2018 CUNY Brooklyn College 1 Outline Digital modulation Baseband transmission Line

More information

The Digital Linear Amplifier

The Digital Linear Amplifier The Digital Linear Amplifier By Timothy P. Hulick, Ph.D. 886 Brandon Lane Schwenksville, PA 19473 e-mail: dxyiwta@aol.com Abstract. This paper is the second of two presenting a modern approach to Digital

More information

Exercise Generation and Demodulation of DPSK Signal

Exercise Generation and Demodulation of DPSK Signal Exercise Generation and Demodulation of DPSK Signal EXERCISE OBJECTIVE When you have completed this exercise, you will see the operation principle and characteristics of the DPSK signal generator by measuring

More information

QUESTION BANK SUBJECT: DIGITAL COMMUNICATION (15EC61)

QUESTION BANK SUBJECT: DIGITAL COMMUNICATION (15EC61) QUESTION BANK SUBJECT: DIGITAL COMMUNICATION (15EC61) Module 1 1. Explain Digital communication system with a neat block diagram. 2. What are the differences between digital and analog communication systems?

More information

Exercise 2-2. Spectral Characteristics of PAM Signals EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION. Sampling

Exercise 2-2. Spectral Characteristics of PAM Signals EXERCISE OBJECTIVE DISCUSSION OUTLINE DISCUSSION. Sampling Exercise 2-2 Spectral Characteristics of PAM Signals EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the spectral characteristics of PAM signals. You will be able to

More information

Signal Processing for Digitizers

Signal Processing for Digitizers Signal Processing for Digitizers Modular digitizers allow accurate, high resolution data acquisition that can be quickly transferred to a host computer. Signal processing functions, applied in the digitizer

More information

Local Oscillator Phase Noise and its effect on Receiver Performance C. John Grebenkemper

Local Oscillator Phase Noise and its effect on Receiver Performance C. John Grebenkemper Watkins-Johnson Company Tech-notes Copyright 1981 Watkins-Johnson Company Vol. 8 No. 6 November/December 1981 Local Oscillator Phase Noise and its effect on Receiver Performance C. John Grebenkemper All

More information

OBJECTIVES EQUIPMENT LIST

OBJECTIVES EQUIPMENT LIST 1 Reception of Amplitude Modulated Signals AM Demodulation OBJECTIVES The purpose of this experiment is to show how the amplitude-modulated signals are demodulated to obtain the original signal. Also,

More information

) #(2/./53 $!4! 42!.3-)33)/.!4! $!4! 3)'.!,,).' 2!4% ()'(%2 4(!. KBITS 53).' K(Z '2/50 "!.$ #)2#5)43

) #(2/./53 $!4! 42!.3-)33)/.!4! $!4! 3)'.!,,).' 2!4% ()'(%2 4(!. KBITS 53).' K(Z '2/50 !.$ #)2#5)43 INTERNATIONAL TELECOMMUNICATION UNION )454 6 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU $!4! #/--5.)#!4)/. /6%2 4(% 4%,%(/.%.%47/2+ 39.#(2/./53 $!4! 42!.3-)33)/.!4! $!4! 3)'.!,,).' 2!4% ()'(%2 4(!.

More information

UTILIZATION OF AN IEEE 1588 TIMING REFERENCE SOURCE IN THE inet RF TRANSCEIVER

UTILIZATION OF AN IEEE 1588 TIMING REFERENCE SOURCE IN THE inet RF TRANSCEIVER UTILIZATION OF AN IEEE 1588 TIMING REFERENCE SOURCE IN THE inet RF TRANSCEIVER Dr. Cheng Lu, Chief Communications System Engineer John Roach, Vice President, Network Products Division Dr. George Sasvari,

More information

Lecture 9: Spread Spectrum Modulation Techniques

Lecture 9: Spread Spectrum Modulation Techniques Lecture 9: Spread Spectrum Modulation Techniques Spread spectrum (SS) modulation techniques employ a transmission bandwidth which is several orders of magnitude greater than the minimum required bandwidth

More information

Jitter in Digital Communication Systems, Part 1

Jitter in Digital Communication Systems, Part 1 Application Note: HFAN-4.0.3 Rev.; 04/08 Jitter in Digital Communication Systems, Part [Some parts of this application note first appeared in Electronic Engineering Times on August 27, 200, Issue 8.] AVAILABLE

More information

COMPUTER COMMUNICATION AND NETWORKS ENCODING TECHNIQUES

COMPUTER COMMUNICATION AND NETWORKS ENCODING TECHNIQUES COMPUTER COMMUNICATION AND NETWORKS ENCODING TECHNIQUES Encoding Coding is the process of embedding clocks into a given data stream and producing a signal that can be transmitted over a selected medium.

More information

Radio Technology and Architectures. 1 ENGN4521/ENGN6521: Embedded Wireless L#1

Radio Technology and Architectures. 1 ENGN4521/ENGN6521: Embedded Wireless L#1 Radio Technology and Architectures 1 ENGN4521/ENGN6521: Embedded Wireless L#1 Radio (Architectures) Spectrum plan and legal issues Radio Architectures and components 2 ENGN4521/ENGN6521: Embedded Wireless

More information

Lecture Topics. Doppler CW Radar System, FM-CW Radar System, Moving Target Indication Radar System, and Pulsed Doppler Radar System

Lecture Topics. Doppler CW Radar System, FM-CW Radar System, Moving Target Indication Radar System, and Pulsed Doppler Radar System Lecture Topics Doppler CW Radar System, FM-CW Radar System, Moving Target Indication Radar System, and Pulsed Doppler Radar System 1 Remember that: An EM wave is a function of both space and time e.g.

More information

Chapter 7. Multiple Division Techniques

Chapter 7. Multiple Division Techniques Chapter 7 Multiple Division Techniques 1 Outline Frequency Division Multiple Access (FDMA) Division Multiple Access (TDMA) Code Division Multiple Access (CDMA) Comparison of FDMA, TDMA, and CDMA Walsh

More information

I-Q transmission. Lecture 17

I-Q transmission. Lecture 17 I-Q Transmission Lecture 7 I-Q transmission i Sending Digital Data Binary Phase Shift Keying (BPSK): sending binary data over a single frequency band Quadrature Phase Shift Keying (QPSK): sending twice

More information

END-OF-YEAR EXAMINATIONS ELEC321 Communication Systems (D2) Tuesday, 22 November 2005, 9:20 a.m. Three hours plus 10 minutes reading time.

END-OF-YEAR EXAMINATIONS ELEC321 Communication Systems (D2) Tuesday, 22 November 2005, 9:20 a.m. Three hours plus 10 minutes reading time. END-OF-YEAR EXAMINATIONS 2005 Unit: Day and Time: Time Allowed: ELEC321 Communication Systems (D2) Tuesday, 22 November 2005, 9:20 a.m. Three hours plus 10 minutes reading time. Total Number of Questions:

More information

EXPERIMENT WISE VIVA QUESTIONS

EXPERIMENT WISE VIVA QUESTIONS EXPERIMENT WISE VIVA QUESTIONS Pulse Code Modulation: 1. Draw the block diagram of basic digital communication system. How it is different from analog communication system. 2. What are the advantages of

More information

HD Radio FM Transmission. System Specifications

HD Radio FM Transmission. System Specifications HD Radio FM Transmission System Specifications Rev. G December 14, 2016 SY_SSS_1026s TRADEMARKS HD Radio and the HD, HD Radio, and Arc logos are proprietary trademarks of ibiquity Digital Corporation.

More information

DIGITAL COMMUNICATION

DIGITAL COMMUNICATION DIGITAL COMMUNICATION TRAINING LAB Digital communication has emerged to augment or replace the conventional analog systems, which had been used widely a few decades back. Digital communication has demonstrated

More information

BER Performance Comparison between QPSK and 4-QA Modulation Schemes

BER Performance Comparison between QPSK and 4-QA Modulation Schemes MIT International Journal of Electrical and Instrumentation Engineering, Vol. 3, No. 2, August 2013, pp. 62 66 62 BER Performance Comparison between QPSK and 4-QA Modulation Schemes Manish Trikha ME Scholar

More information

Outline. Communications Engineering 1

Outline. Communications Engineering 1 Outline Introduction Signal, random variable, random process and spectra Analog modulation Analog to digital conversion Digital transmission through baseband channels Signal space representation Optimal

More information

Combinational logic: Breadboard adders

Combinational logic: Breadboard adders ! ENEE 245: Digital Circuits & Systems Lab Lab 1 Combinational logic: Breadboard adders ENEE 245: Digital Circuits and Systems Laboratory Lab 1 Objectives The objectives of this laboratory are the following:

More information

Modulation and Coding Tradeoffs

Modulation and Coding Tradeoffs 0 Modulation and Coding Tradeoffs Contents 1 1. Design Goals 2. Error Probability Plane 3. Nyquist Minimum Bandwidth 4. Shannon Hartley Capacity Theorem 5. Bandwidth Efficiency Plane 6. Modulation and

More information

Channel & Modulation: Basics

Channel & Modulation: Basics ICTP-ITU-URSI School on Wireless Networking for Development The Abdus Salam International Centre for Theoretical Physics ICTP, Trieste (Italy), 6 to 24 February 2006 Channel & Modulation: Basics Ryszard

More information

Wireless Communication Fading Modulation

Wireless Communication Fading Modulation EC744 Wireless Communication Fall 2008 Mohamed Essam Khedr Department of Electronics and Communications Wireless Communication Fading Modulation Syllabus Tentatively Week 1 Week 2 Week 3 Week 4 Week 5

More information

Chapter 4. Part 2(a) Digital Modulation Techniques

Chapter 4. Part 2(a) Digital Modulation Techniques Chapter 4 Part 2(a) Digital Modulation Techniques Overview Digital Modulation techniques Bandpass data transmission Amplitude Shift Keying (ASK) Phase Shift Keying (PSK) Frequency Shift Keying (FSK) Quadrature

More information

March, 2003 IEEE P /131r0. IEEE P Wireless Personal Area Networks

March, 2003 IEEE P /131r0. IEEE P Wireless Personal Area Networks Project Title IEEE P802.15 Wireless Personal rea Networks IEEE P802.15 Working Group for Wireless Personal rea Networks (WPNs) PHY Proposal Using Dual Independent Single Sideband, Non-coherent M and Defined

More information

Outline / Wireless Networks and Applications Lecture 3: Physical Layer Signals, Modulation, Multiplexing. Cartoon View 1 A Wave of Energy

Outline / Wireless Networks and Applications Lecture 3: Physical Layer Signals, Modulation, Multiplexing. Cartoon View 1 A Wave of Energy Outline 18-452/18-750 Wireless Networks and Applications Lecture 3: Physical Layer Signals, Modulation, Multiplexing Peter Steenkiste Carnegie Mellon University Spring Semester 2017 http://www.cs.cmu.edu/~prs/wirelesss17/

More information

Digital Communication

Digital Communication Digital Communication Laboratories bako@ieee.org DigiCom Labs There are 5 labs related to the digital communication. Study of the parameters of metal cables including: characteristic impendance, attenuation

More information

Design Implementation Description for the Digital Frequency Oscillator

Design Implementation Description for the Digital Frequency Oscillator Appendix A Design Implementation Description for the Frequency Oscillator A.1 Input Front End The input data front end accepts either analog single ended or differential inputs (figure A-1). The input

More information

Learning Material Ver 1.1

Learning Material Ver 1.1 Data Formatting & Carrier Modulation Transmitter Trainer and Carrier Demodulation & Data Reformatting Receiver Trainer ST2106 & ST2107 Learning Material Ver 1.1 An ISO 9001 : 2000 company 94, Electronic

More information

INTRODUCTION TO COMMUNICATION SYSTEMS LABORATORY IV. Binary Pulse Amplitude Modulation and Pulse Code Modulation

INTRODUCTION TO COMMUNICATION SYSTEMS LABORATORY IV. Binary Pulse Amplitude Modulation and Pulse Code Modulation INTRODUCTION TO COMMUNICATION SYSTEMS Introduction: LABORATORY IV Binary Pulse Amplitude Modulation and Pulse Code Modulation In this lab we will explore some of the elementary characteristics of binary

More information

SETTING UP A WIRELESS LINK USING ME1000 RF TRAINER KIT

SETTING UP A WIRELESS LINK USING ME1000 RF TRAINER KIT SETTING UP A WIRELESS LINK USING ME1000 RF TRAINER KIT Introduction S Kumar Reddy Naru ME Signal Processing S. R. No - 05812 The aim of the project was to try and set up a point to point wireless link.

More information

Downloaded from 1

Downloaded from  1 VII SEMESTER FINAL EXAMINATION-2004 Attempt ALL questions. Q. [1] How does Digital communication System differ from Analog systems? Draw functional block diagram of DCS and explain the significance of

More information

B SCITEQ. Transceiver and System Design for Digital Communications. Scott R. Bullock, P.E. Third Edition. SciTech Publishing, Inc.

B SCITEQ. Transceiver and System Design for Digital Communications. Scott R. Bullock, P.E. Third Edition. SciTech Publishing, Inc. Transceiver and System Design for Digital Communications Scott R. Bullock, P.E. Third Edition B SCITEQ PUBLISHtN^INC. SciTech Publishing, Inc. Raleigh, NC Contents Preface xvii About the Author xxiii Transceiver

More information

CME312- LAB Manual DSB-SC Modulation and Demodulation Experiment 6. Experiment 6. Experiment. DSB-SC Modulation and Demodulation

CME312- LAB Manual DSB-SC Modulation and Demodulation Experiment 6. Experiment 6. Experiment. DSB-SC Modulation and Demodulation Experiment 6 Experiment DSB-SC Modulation and Demodulation Objectives : By the end of this experiment, the student should be able to: 1. Demonstrate the modulation and demodulation process of DSB-SC. 2.

More information

RF Basics 15/11/2013

RF Basics 15/11/2013 27 RF Basics 15/11/2013 Basic Terminology 1/2 dbm is a measure of RF Power referred to 1 mw (0 dbm) 10mW(10dBm), 500 mw (27dBm) PER Packet Error Rate [%] percentage of the packets not successfully received

More information

Time division multiplexing The block diagram for TDM is illustrated as shown in the figure

Time division multiplexing The block diagram for TDM is illustrated as shown in the figure CHAPTER 2 Syllabus: 1) Pulse amplitude modulation 2) TDM 3) Wave form coding techniques 4) PCM 5) Quantization noise and SNR 6) Robust quantization Pulse amplitude modulation In pulse amplitude modulation,

More information

Department of Electronics and Communication Engineering 1

Department of Electronics and Communication Engineering 1 UNIT I SAMPLING AND QUANTIZATION Pulse Modulation 1. Explain in detail the generation of PWM and PPM signals (16) (M/J 2011) 2. Explain in detail the concept of PWM and PAM (16) (N/D 2012) 3. What is the

More information

Chapter 2 Direct-Sequence Systems

Chapter 2 Direct-Sequence Systems Chapter 2 Direct-Sequence Systems A spread-spectrum signal is one with an extra modulation that expands the signal bandwidth greatly beyond what is required by the underlying coded-data modulation. Spread-spectrum

More information