Digital Communications Training Systems

Transcription

1 Digital Communications Training Systems LabVolt Series Datasheet Festo Didactic en 120 V - 60 Hz 06/2018

2 Table of Contents General Description 2 Topic Coverage 3 Features & Benefits 3 List of Available Training Systems 3 Additional Equipment Required to Perform the Exercises 3 Optional Equipment 4 Optional Manual(s) 4 Available Training Systems 4 Equipment Description 13 Optional Equipment Description 39 General Description The Digital Communications Training Systems form a complete and operational communications program, as well as a powerful educational tool. They use IC technology to implement signal modulators and demodulators that operate at standards employed in digital communications technology. The systems are equipped with various features that enhance hands-on learning: easy access to test points, fault-insertion switches, safety shielding and full short-circuit protection, silk-screened block diagrams and component labels, and fully-integrated courseware. The Digital Communications Training Systems allow instructors to achieve a wide range of educational objectives at various levels. The modularity of the systems allows students to quickly assemble a functioning communications network by using coaxial cables. Fully compatible signal levels and protocols are fed among modules from front panel connection points. Because the system is composed of prewired, functioning modules and connections between modules are made with shielded cables, the routing and trimming of student connections do not affect system performance and measurements. Important test points or test busses are brought out to 9-pin connectors on the front panels of modules for easy access. The courseware included with the Digital Communications Training Systems guides students through hands-on exercises in voltage and signal measurements, alignment, calibration, and signal tracing. Clearly stated objectives, background discussions, step-by-step procedures, and review questions are included in each selfcontained exercise. A troubleshooting unit included at the end of each volume enables instructors to use fault insertion switches that introduce malfunctions at the module and system levels. The instructional modules are supported by sixteen different instrumentation modules that are separated into two groups. The first group comprises instrumentation modules that are identical to those used in the Analog Communications Training System, Series These are: Power Supply / Dual Audio Amplifier, Model 9401 Dual Function Generator, Model 9402 Frequency Counter, Model 9403 True RMS Voltmeter / Power Meter, Model 9404 Spectrum Analyzer, Model 9405 RF / Noise Generator, Model 9406 The second group includes the following ten instrumentation modules that are specific to the Digital Communications Training System: Enclosure / Supply Regulator, Model Festo Didactic

3 Clock Generator, Model 9421 Pseudo-Random Binary Sequence Generator, Model 9422 Bit Error Rate Indicator, Model 9423 Logic Analyzer, Model 9424 DC Voltmeter / DC Source, Model 9425 Low Pass Audio Filter, Model 9426 Synchronous Audio Generator, Model 9427 Signal Interruptor/Selector, Model 9428 Noise Measurement Filters, Model 9429 The Frequency Counter, True RMS Voltmeter / Power Meter, and Spectrum Analyzer mentioned above can be replaced with the Data Acquisition and Management for Telecommunications (LVDAM-COM), Model The LVDAM-COM system provides modern and versatile equipment for measuring, observing, and analyzing signals in telecommunications systems. It consists of a set of computer-based instruments running on a personal computer under the Microsoft Windows operating environment. The LVDAM-COM system also includes a dual trace oscilloscope with a 40 MHz bandwidth. Topic Coverage Pulse Modulation and Sampling Digital Modulation Modems and Data Transmission Troubleshooting Features & Benefits Uses IC technology to implement signal modulators and demodulators Correlated courseware guides students through hands-on exercises in voltage and signal measurements, alignment, calibration, and signal tracing Equipment protected short-circuit and over-voltage One of the most comprehensive of its kind in the marketplace Modular system with switches to insert faults and teach troubleshooting Silk-screened block diagrams and component labels LVSIM-DCOM software program also available Estimated entire program duration: 170 hours List of Available Training Systems Qty Description Model number 1 Digital Communications Training System Digital Communications Add-On Digital Communications Training System with LVDAM-COM 8085-B0 Additional Equipment Required to Perform the Exercises Festo Didactic 3

4 Qty Description Model number 1 1 Training on Pulse Modulation and Sampling, 1.6 days TF 1 2 Training on Digital Modulation, 1.4 days TF 1 3 Training on Modems and Data Transmission, 1.2 days TF Optional Equipment Qty Description Model number 1 Dual Trace Oscilloscope FM/PM Receiver Baseband Channel / Brickwall Filter Time Division Multiplexer Time Division Demultiplexer T1/CEPT PCM Transceiver Clock Recovery Line Coder Line Decoder Dust Cover (Modules) Dust Cover (Module Rack) Optional Manual(s) Model Qty Description number 1 Baseband Data Transmission (Student Manual) Available Training Systems Digital Communications Training System The Digital Communications Training System consists of thirteen instructional modules supported by sixteen instrumentation modules. The instructional modules offer hands-on training in the following digital communications techniques: Pulse Amplitude Modulation (PAM) Pulse Width Modulation (PWM) Pulse Position Modulation (PPM) Pulse Code Modulation (PCM) Differential Pulse Code Modulation (DPCM) Delta and Continuously Variable Slope Delta (CVSD) Modulation Amplitude Shift Keying (ASK) 2 Optional product training. Price provided on demand. For details and options, contact services.didactic@festo.com. 3 Optional product training. Price provided on demand. For details and options, contact services.didactic@festo.com. 1 Optional product training. Price provided on demand. For details and options, contact services.didactic@festo.com. 4 Festo Didactic

5 Frequency Shift Keying (FSK) Binary Phase Shift Keying (BPSK) Optional instructional modules can be added to the Digital Communications Training System to study baseband data transmission. These instructional modules allow hands-on training in the following techniques: Time-Division Multiplexing (TDM) Serial data transmission over T1/CEPT links Line coding and decoding (duobinary, biphase, NRZ, RZ, AMI, CMI, B3ZS, and HDB3 codes) Clock recovery List of Equipment Qty Description Model number 1 Cables and Accessories - Digital Telecommunications Power Supply / Dual Audio Amplifier Dual Function Generator Frequency Counter True RMS Voltmeter / Power Meter Spectrum Analyzer RF/Noise Generator Enclosure / Supply Regulator Clock Generator Pseudo-Random Binary Sequence Generator Bit Error Rate Indicator Logic Analyzer DC Voltmeter / DC Source Low Pass Audio Filter Synchronous Audio Generator Signal Interruptor/Selector Noise Measurement Filters PAM/ASK Generator PAM/ASK Receiver PWM/PPM Generator PWM/PPM Receiver PCM Encoder PCM Decoder DPCM Encoder DPCM Decoder FSK Modem BPSK Modulator BPSK Demodulator Delta/CVSD Encoder Delta/CVSD Decoder Storage Cabinet Festo Didactic 5

6 List of Manuals Manual Description number Pulse Modulation and Sampling (Student Manual) Digital Communications (Instructor Guide) Digital Modulation (Student Manual) Modems and Data Transmission (Student Manual) Table of Contents of the Manual(s) Pulse Modulation and Sampling (Student Manual) ( ) 1-1 Time Characteristics of Pulses 1-2 Frequency Characteristics of Pulses 1-3 Band-Limiting 1-4 Noise and Signal Measurement 2-1 PAM Signals 2-2 Spectral Characteristics of PAM Signals 2-3 Aliasing and Nyquist Rate 2-4 Pre-filtering 3-1 PAM Signal Demodulation 3-2 Aliasing 3-3 PAM Signal Transmission in the Presence of Noise 4-1 PWM and PPM Signals 4-2 The Effects of Noise and Band-Limiting on Pulse-Time Modulated Signals 5-1 PWM and PPM Signal Demodulation 5-2 The Effects of Noise and Band-Limiting on PWM / PPM Signal Demodulation 6-1 Troubleshooting Techniques 6-2 Troubleshooting the PAM Receiver 6-3 Troubleshooting a PAM Communications System 6-4 Troubleshooting the PWM / PPM Generator 6-5 Troubleshooting the PWM / PPM Receiver 6-6 Troubleshooting a PWM / PPM Communications System Digital Modulation (Student Manual) ( ) 1-1 Binary and Hexadecimal Numbers 1-2 Analog-to-Digital Conversion 1-3 Digital-to-Analog Conversion 2-1 Distortion in PCM Systems 2-2 Characteristics of Quantization Noise 2-3 Quantization Noise Measurement 3-1 Information Transmission with a PCM System 3-2 Resistance of PCM to Noise and Distortion 3-3 Effect of μ-law Companding on the Performance of a PCM System 3-4 Effect of A-Law Companding on the Performance of a PCM System 4-1 Principles of a DPCM System 4-2 Dynamic Operation of a DPCM System 5-1 A Linear Delta Modulation (LDM) System 5-2 An Adaptive Delta Modulation (ADM) System 6 Festo Didactic

7 5-3 Signal-to-Noise Ratio in Delta Modulation 6-1 Troubleshooting a PCM Communications Systems 6-2 Troubleshooting a DPCM Communications Systems 6-3 Troubleshooting a DM Communications Systems Modems and Data Transmission (Student Manual) ( ) 1-1 Pseudo-Random Binary Sequences 1-2 Detection of NRZ Signals in Noise 2-1 Generation and Reception of ASK Signals 2-2 ASK Performance in Noise 3-1 FSK Principles 3-2 FSK Performance in Noise 4-1 CCITT V.21 and Bell 103 Modems (300 baud) 4-2 CCITT V.23 Mode 2 Modem (1200 baud) 4-3 Bell 202 Modem (1200 baud) 5-1 Generation and Demodulation of BPSK Signals 5-2 BPSK Performance in Noise 6-1 Troubleshooting an ASK Communications System 6-2 Troubleshooting a FSK Modem 6-3 Troubleshooting a BPSK Communication System System Power Requirement Space required per system 600 W kg (250.7 lb) 1.16 m² (12.5 ft²) Digital Communications Add-On The Digital Communications Add-On is an add-on to the Analog Communications Training System, Model that enables users to perform the exercises in the Digital Communications courseware. Since both the Digital Communications and Analog Communications Training Systems share the same basic equipment, this add-on is ideal to avoid any unnecessary duplication of equipment. List of Equipment Qty Description Model number 1 Cables and Accessories - Digital Communications Add-On Enclosure / Supply Regulator Clock Generator Pseudo-Random Binary Sequence Generator Bit Error Rate Indicator Festo Didactic 7

8 Qty Description Model number 1 Logic Analyzer DC Voltmeter / DC Source Low Pass Audio Filter Synchronous Audio Generator Signal Interruptor/Selector Noise Measurement Filters PAM/ASK Generator PAM/ASK Receiver PWM/PPM Generator PWM/PPM Receiver PCM Encoder PCM Decoder DPCM Encoder DPCM Decoder FSK Modem BPSK Modulator BPSK Demodulator Delta/CVSD Encoder Delta/CVSD Decoder Storage Cabinet List of Manuals Manual Description number Pulse Modulation and Sampling (Student Manual) Digital Communications (Instructor Guide) Digital Modulation (Student Manual) Modems and Data Transmission (Student Manual) Table of Contents of the Manual(s) Pulse Modulation and Sampling (Student Manual) ( ) 1-1 Time Characteristics of Pulses 1-2 Frequency Characteristics of Pulses 1-3 Band-Limiting 1-4 Noise and Signal Measurement 2-1 PAM Signals 2-2 Spectral Characteristics of PAM Signals 2-3 Aliasing and Nyquist Rate 2-4 Pre-filtering 3-1 PAM Signal Demodulation 3-2 Aliasing 3-3 PAM Signal Transmission in the Presence of Noise 4-1 PWM and PPM Signals 4-2 The Effects of Noise and Band-Limiting on Pulse-Time Modulated Signals 5-1 PWM and PPM Signal Demodulation 8 Festo Didactic

9 5-2 The Effects of Noise and Band-Limiting on PWM / PPM Signal Demodulation 6-1 Troubleshooting Techniques 6-2 Troubleshooting the PAM Receiver 6-3 Troubleshooting a PAM Communications System 6-4 Troubleshooting the PWM / PPM Generator 6-5 Troubleshooting the PWM / PPM Receiver 6-6 Troubleshooting a PWM / PPM Communications System Digital Modulation (Student Manual) ( ) 1-1 Binary and Hexadecimal Numbers 1-2 Analog-to-Digital Conversion 1-3 Digital-to-Analog Conversion 2-1 Distortion in PCM Systems 2-2 Characteristics of Quantization Noise 2-3 Quantization Noise Measurement 3-1 Information Transmission with a PCM System 3-2 Resistance of PCM to Noise and Distortion 3-3 Effect of μ-law Companding on the Performance of a PCM System 3-4 Effect of A-Law Companding on the Performance of a PCM System 4-1 Principles of a DPCM System 4-2 Dynamic Operation of a DPCM System 5-1 A Linear Delta Modulation (LDM) System 5-2 An Adaptive Delta Modulation (ADM) System 5-3 Signal-to-Noise Ratio in Delta Modulation 6-1 Troubleshooting a PCM Communications Systems 6-2 Troubleshooting a DPCM Communications Systems 6-3 Troubleshooting a DM Communications Systems Modems and Data Transmission (Student Manual) ( ) 1-1 Pseudo-Random Binary Sequences 1-2 Detection of NRZ Signals in Noise 2-1 Generation and Reception of ASK Signals 2-2 ASK Performance in Noise 3-1 FSK Principles 3-2 FSK Performance in Noise 4-1 CCITT V.21 and Bell 103 Modems (300 baud) 4-2 CCITT V.23 Mode 2 Modem (1200 baud) 4-3 Bell 202 Modem (1200 baud) 5-1 Generation and Demodulation of BPSK Signals 5-2 BPSK Performance in Noise 6-1 Troubleshooting an ASK Communications System 6-2 Troubleshooting a FSK Modem 6-3 Troubleshooting a BPSK Communication System Optional Equipment Festo Didactic 9

10 Model Qty Description number 1 4 Data Acquisition and Management for Telecommunications (LVDAM-COM) System Power Requirement Space required per system 600 W kg (250.7 lb) 1.16 m² (12.5 ft²) Digital Communications Training System with LVDAM-COM 8085-B0 The Digital Communications Training System with LVDAM-COM provides modern and versatile equipment for measuring, observing, and analyzing signals in telecommunications systems. The LVDAM-COM system consists of a set of computer-based instruments running on an IBM - compatible personal computer under the Microsoft Windows operating environment. It can replace the Frequency Counter, True RMS Voltmeter / Power Meter, and Spectrum Analyzer. The LVDAM-COM system also includes a dual trace oscilloscope with a 40 MHz bandwidth. List of Equipment Qty Description Model number 1 Cables and Accessories - Digital Telecommunications Power Supply / Dual Audio Amplifier Dual Function Generator RF/Noise Generator Data Acquisition and Management for Telecommunications (LVDAM-COM) Enclosure / Supply Regulator Clock Generator Pseudo-Random Binary Sequence Generator Bit Error Rate Indicator Logic Analyzer DC Voltmeter / DC Source Low Pass Audio Filter Synchronous Audio Generator Signal Interruptor/Selector Noise Measurement Filters PAM/ASK Generator PAM/ASK Receiver PWM/PPM Generator PWM/PPM Receiver Allows the use of computer-based instrumentation to perform the exercises. 10 Festo Didactic

11 Qty Description Model number 1 PCM Encoder PCM Decoder DPCM Encoder DPCM Decoder FSK Modem BPSK Modulator BPSK Demodulator Delta/CVSD Encoder Delta/CVSD Decoder Storage Cabinet List of Manuals Manual Description number Pulse Modulation and Sampling (Student Manual) Digital Communications (Instructor Guide) Digital Modulation (Student Manual) Modems and Data Transmission (Student Manual) Data Acquisition and Management System (User Guide) E0 Virtual Test Equipment Interface (Instruction Manual) D0 Computer-Based Instruments (User Guide) E0 Table of Contents of the Manual(s) Pulse Modulation and Sampling (Student Manual) ( ) 1-1 Time Characteristics of Pulses 1-2 Frequency Characteristics of Pulses 1-3 Band-Limiting 1-4 Noise and Signal Measurement 2-1 PAM Signals 2-2 Spectral Characteristics of PAM Signals 2-3 Aliasing and Nyquist Rate 2-4 Pre-filtering 3-1 PAM Signal Demodulation 3-2 Aliasing 3-3 PAM Signal Transmission in the Presence of Noise 4-1 PWM and PPM Signals 4-2 The Effects of Noise and Band-Limiting on Pulse-Time Modulated Signals 5-1 PWM and PPM Signal Demodulation 5-2 The Effects of Noise and Band-Limiting on PWM / PPM Signal Demodulation 6-1 Troubleshooting Techniques 6-2 Troubleshooting the PAM Receiver 6-3 Troubleshooting a PAM Communications System 6-4 Troubleshooting the PWM / PPM Generator 6-5 Troubleshooting the PWM / PPM Receiver 6-6 Troubleshooting a PWM / PPM Communications System Festo Didactic 11

12 Digital Modulation (Student Manual) ( ) 1-1 Binary and Hexadecimal Numbers 1-2 Analog-to-Digital Conversion 1-3 Digital-to-Analog Conversion 2-1 Distortion in PCM Systems 2-2 Characteristics of Quantization Noise 2-3 Quantization Noise Measurement 3-1 Information Transmission with a PCM System 3-2 Resistance of PCM to Noise and Distortion 3-3 Effect of μ-law Companding on the Performance of a PCM System 3-4 Effect of A-Law Companding on the Performance of a PCM System 4-1 Principles of a DPCM System 4-2 Dynamic Operation of a DPCM System 5-1 A Linear Delta Modulation (LDM) System 5-2 An Adaptive Delta Modulation (ADM) System 5-3 Signal-to-Noise Ratio in Delta Modulation 6-1 Troubleshooting a PCM Communications Systems 6-2 Troubleshooting a DPCM Communications Systems 6-3 Troubleshooting a DM Communications Systems Modems and Data Transmission (Student Manual) ( ) 1-1 Pseudo-Random Binary Sequences 1-2 Detection of NRZ Signals in Noise 2-1 Generation and Reception of ASK Signals 2-2 ASK Performance in Noise 3-1 FSK Principles 3-2 FSK Performance in Noise 4-1 CCITT V.21 and Bell 103 Modems (300 baud) 4-2 CCITT V.23 Mode 2 Modem (1200 baud) 4-3 Bell 202 Modem (1200 baud) 5-1 Generation and Demodulation of BPSK Signals 5-2 BPSK Performance in Noise 6-1 Troubleshooting an ASK Communications System 6-2 Troubleshooting a FSK Modem 6-3 Troubleshooting a BPSK Communication System Computer-Based Instruments (User Guide) (36220-E0) 1 Familiarization with the True RMS Voltmeter and Frequency Counter 2 Familiarization with the Oscilloscope 3 Familiarization with the Spectrum Analyzer Additional Equipment Required to Perform the Exercises Model Qty Description number 1 5 Personal Computer System 5 Refer to the Computer Requirements in the System section of this datasheet if the computer is to be provided by the end-user. 12 Festo Didactic

13 Power Requirement Space required per system 600 W kg (250.7 lb) 1.16 m² (12.5 ft²) Equipment Description Cables and Accessories - Digital Telecommunications The Cables and Accessories - Digital Telecommunications set contains the various cables and accessories required to perform the exercises in the courseware. The accessories package contains the following parts: three different lengths of coaxial cables terminated with BNC connectors, whip, pigtail, and folded dipole antennas, BNC T-connectors, resistive loads with BNC connectors, headset. These accessories come in a convenient plastic storage case. Cables Coaxial BNC/BNC 30 cm (14), 75 cm (6), 120 cm (2) Multi-Conductor D9/D9 40 cm (5), 70 cm (2) Resistive Loads BNC Terminated 50 Ω (1), 620 Ω (1) Accessories BNC T-Connector 6 Stereo Headset 1 Cables and Accessories - Digital Communications Add-On The Cables and Accessories - Digital Communications Add-On set contains the various cables and accessories required to perform the exercises in the courseware. The accessories package contains the following parts: three different lengths of coaxial cables terminated with BNC connectors, whip, pigtail, and folded dipole antennas, BNC T-connectors, resistive loads with BNC connectors, headset. These accessories come in a convenient plastic storage case. Cables Coaxial BNC/BNC 30 cm (8) Multi-Conductor D9/D9 40 cm (5), 70 cm (2) Resistive Loads BNC Terminated 620 Ω (1) Accessories BNC T-Connector 2 Festo Didactic 13

14 Power Supply / Dual Audio Amplifier The Power Supply / Dual Audio Amplifier module forms the physical base for the analog and digital communications training systems, and can be used in several other training systems. It is double-width to accommodate two instructional modules or two instrument modules in a side-byside configuration. A two-channel audio amplifier with headphone jacks and speakers accommodates FM stereo and narrowband FM and AM receiver outputs. The power supply distributes power to the complete system and provides three regulated dc voltage outputs (15 V 0.5 A; -15 V 0.5 A; +5 V 1 A) on the faceplate. Also unregulated voltages are distributed to the system modules through a connector located on each module. These unregulated voltages are regulated within each module to provide the required voltages. Each regulated supply has an LED indicator that shuts off if the supply is overloaded due to equipment malfunction or if a faulty power connection is made to external equipment. Power Requirement Current Service Installation Power Outputs Unregulated Power Bus Regulated Front Panel Dual Audio Amplifier Rating Bandwidth Input Nominal Output Power Sensitivity (at nominal output power) Output (intermediate outputs) Maximum Output Level (open-circuit) Protection AC Line Input DC Regulated Outputs DC Unregulated Outputs 3.5 A Standard single-phase ac outlet ±25 V typ. 3 A max; -25 V typ. 3 A max.; +11 V typ. 5 A max. ±15 V 0.5 A; + 5 V 1 A 50 Hz to 15 khz 10 kω 250 mw 140 mw 1 kω 20 V p-p Circuit breaker Foldback current-limiting Circuit breaker 104 x 687 x 305 mm (4.1 x 27 x 12 in) 15.8 kg (34.8 lb) Dual Function Generator The Dual Function Generator consists of two independent function generators (A and B), each capable of generating a sine-wave signal, a square-wave signal, a triangular-wave signal, a sawtooth-wave signal, and a pulse signal with variable pulse-width. The signal frequency can be varied from 10 Hz to 100 khz through four ranges. A digital display is pushbutton-selectable between generators A and B to monitor the frequency of each 14 Festo Didactic

15 generator. Each generator output signal level is continuously variable and may be attenuated by push buttonselected switch attenuators. output signals are provided to synchronize external equipment, such as an oscilloscope. Generator A may be frequency-modulated by a signal from generator B or from an external source. The module is fully protected against short circuits and misconnections. Students use the instruments to make measurements in laboratory experiments performed on AM, FM, and digital communications systems. Power Requirement Generators (A & B) Rating Waveforms Pulse Duty Cycle 10 to 90 % Frequency Ranges Frequency Display (switchable between A & B) Output Output Level (open circuit) Attenuator Synchronization Outputs Frequency Modulation (Channel A only) Input Maximum Frequency Deviation Input Level for Maximum Deviation Frequency Counter ±25 V typ. 3 A max; -25 V typ. 3 A max.; +11 V typ. 5 A max. Sine, triangle, square, sawtooth, or pulse Hz, Hz, 1-10 khz, khz 4 digits 50 Ω 10 mv p-p to 10 V p-p 0, 20, or 40 db One for each channel (SYNC/) 100 kω 50 % of each side of the rest frequency 10 V p-p 162 x 330 x 300 mm (6.4 x 13 x 11.8 in) 4.4 kg (9.7 lb) The Frequency Counter is a directcounting frequency counter with an 8- digit display. The frequency counter has three functions: it determines the frequency of the input signal and displays the frequency in Hz, khz, or MHz, it determines the period of the input signal and displays the period in s or ms, and it works as an event counter when the counter function is selected. The frequency/period resolution is switch-selectable from 0.1 to 100 Hz (0.1 to 100 ns). As an event counter, each negative-going transition of the input signal adds one to the cumulative count displayed. The input signal may be attenuated by a switch attenuator. The module is fully protected against short circuits and misconnections. Students use the instruments to make measurements in laboratory experiments performed on AM, FM, and digital communications systems. Power Requirement Rating Input Frequency Range Input Period Range +25 V 425 ma; -25 V 325 ma 10 Hz - 10 MHz, 10 MHz MHz 0.1 s 4 µs (10 Hz-2.5 MHz) Count Range Input Sensitivity (Sine Wave RMS ) Attenuator Resolution 1 MΩ 10 Hz MHz: 25 mv; 100 MHz-200 MHz: 60 mv 0, 20 or 40 db 0.1, 1, 10, 100 Hz (ns) Festo Didactic 15

16 Frequency Display 8 digits 112 x 330 x 300 mm (4.4 x 13 x 11.8 in) 3.2 kg (7 lb) True RMS Voltmeter / Power Meter The True-RMS Voltmeter / Power Meter is a dual function instrument used to measure RMS voltage or signal power in communications systems. and power can be measured through four ranges on a 3½ digit panel display. The function is switch-selectable on the front panel. The input signal frequency range is 20 Hz to 12 MHz. An automatic zeroadjust function readjusts the meter s zero at regular time intervals. This feature provides precise measurements over a wide range of temperature. The module is fully protected against short circuits and misconnections. Students use the instruments to make measurements in laboratory experiments performed on AM, FM, and digital communications systems. Power Requirement Rating Measurement Bandwidth Input Ranges Power Ranges Accuracy (10 mv and 100 mv Ranges) Accuracy (1 V and 10 V Ranges) +25 V 125 ma; +11 V 350 ma; -25 V 75 ma 20 Hz to 12 MHz 1 MΩ 10 mv, 100 mv, 1 V, 10 V -27, -7, +13, +33, (50 Ω input) ±3 % (20 Hz to 12 MHz) ±5 % (20 Hz to 12 MHz) 112 x 330 x 300 mm (4.4 x 13 x 11.8 in) 3.0 kg (6.7 lb) Spectrum Analyzer The Spectrum Analyzer is used for signal observation of the communications system in the frequency domain. It is a frequencyselective instrument that allows the power level of each frequency component of a signal to be displayed on a regular oscilloscope: a dual trace oscilloscope or a single trace oscilloscope with an external sweep input having a sensitivity of 1 V/div. is required. The Spectrum Analyzer has two selectable input frequency ranges: dc to 30 MHz, and 85 to 115 MHz. The center frequency is indicated on a 3½ digit display. The Spectrum Analyzer has an output for use with the optional Dual Trace Oscilloscope, Model 797, or the X-Y Recorder, Model Festo Didactic

17 Two digital memories of 1024 horizontal points by 256 vertical levels provide a stable display at a refresh rate of 30 Hz. The frequency span is switch-selectable in five ranges from 2 khz to 1 MHz per volt. With the oscilloscope set at 1 V/div., total spans of 20 khz to 10 MHz are possible. The bandwidth resolution is automatically optimized between 100 Hz and 50 khz. Inputs to the spectrum analyzer may be attenuated by 40 db in five steps. The input impedance is switch-selectable between 50 Ω and 1 MΩ. The input signal may be displayed in linear or logarithmic form (10 db/v) up to a maximum display range of 60 db. The module is fully protected against short circuits and misconnections. Students use the instruments to make measurements in laboratory experiments performed on AM, FM, and digital communications systems. Power Requirements Power Requirements Rating Input Frequency Range Input Input Signal Level Maximum Input Signal Levels Frequency span (Oscilloscope/Plotter at 1 V/div.) Resolution Bandwidth (3 db) Frequency Markers Marker Frequency Stability Frequency Measurement Resolution Dynamic Range (input signal measurements +25 V 750 ma +11 V 600 ma -25 V 475 ma 0-30 MHz (500 Hz minimum) and MHz 50 Ω or 1 MΩ -70 to +30 dbm (50 Ω input) 7 V (peak AC + DC) at 50 Ω impedance 15 V (peak AC + DC) at 1 MΩ impedance 0 Hz; 2, 10, 50, 200 khz; 1 MHz/div. 100, 500 Hz; 2, 20, 50 khz (automatic selection) 10, 100 khz; 1, 10 MHz ±0.003 %/ C 1 khz (using 10 khz markers) 60 db Selectivity (60 db/3 db) Better than 13:1 Output Display Output Mode Output Scale Output Level Memories (A et B) Oscilloscope Outputs Plotter Outputs Input/Output Signal Connectors Accessories External oscilloscope set the X-Y mode at 1 V/div. and/or X-Y (oscilloscope and plotter not supplied) HOLD/LIVE Linear or Log (10 db/v) Variable up to 10 db from CAL position 1024 vertical points x 256 horizontal levels X: 0 to 10 V; Y: 0 to 6 V X: 0 to 10 V; Y: 0 to 6 V; ground BNC (except plotter output, which is 2 mm banana jacks) One 2 m (6.5 ft) plotter connection cable 162 x 330 x 315 mm (6.4 x 13 x 12.4 in) 5.6 kg (12.3 lb) RF/Noise Generator The RF/Noise Generator contains two independent generators capable of generating a tone signal in the frequency range from 100 khz to 32 MHz and a "white" noise signal in selected frequency bands from 0 to 11.2 MHz. The radio frequency (RF) generator produces a signal output in five frequency ranges to cover the Festo Didactic 17

18 frequencies in the analog communications system. This generator has FM and AM capabilities. The noise generator provides white noise in five independent frequency bands. The noise output may be used for measuring the frequency response of filters or the signal-to-noise ratio in any part of the system. The module is fully protected against short circuits and misconnections. Students use the instruments to make measurements in laboratory experiments performed on AM, FM, and digital communications systems. RF Generator Rating Frequency Ranges Output (across 50 Ω) Output impedance SYNC Output Level Amplitude Modulation Input Level Amplitude Modulation Input Frequency Modulation Input Level Frequency Modulation Input Noise Generator Rating Frequency Ranges Output (across 50 Ω) Output khz, MHz, 1-3 MHz, 3-10 MHz, MHz 100 mv p-p 50 Ω 1.5 V p-p min. 1 V p-p 10 kω 1 V p-p 10 kω Audio: 2 Hz - 20 khz Audio/RF: 0 Hz - 2 MHz AM IF Noise: khz SSB RF Noise: MHz FM IF Noise: MHz 0.5 V rms 50 Ω 162 x 330 x 300 mm (6.4 x 13 x 11.8 in) 4 kg (8.8 lb) Data Acquisition and Management for Telecommunications (LVDAM-COM) The Data Acquisition and Management for Telecommunications (LVDAM-COM) is a computer-based system for measuring, observing, and analyzing signals in telecommunications systems. It allows training in both analog and digital telecommunications systems using modern and versatile measuring instruments. A user manual provided with the LVDAM-COM system allows students to quickly familiarize with the instruments. The LVDAM-COM system consists of the Virtual Test Equipment Interface module and the Data Acquisition and Management for Telecommunications software (LVDAM-COM). The LVDAM-COM system is a standard feature in the Analog Communications Training System with LVDAM-COM, Model 8080-A, and Digital Communications Training System with LVDAM-COM, Model 8085-B. The LVDAM-COM system can replace the conventional instruments (Frequency Counter, Model 9403, True-RMS Voltmeter / Power Meter, Model 9404, and Spectrum Analyzer, Model 9405) in the Analog Communications Training System, Model 8080, and Digital Communications Training System, Model Festo Didactic

19 Virtual Test Equipment Interface The Virtual Test Equipment Interface (VTEI) module links the personal computer running the LVDAM-COM software with the Analog and Digital Training Systems. Data exchange between the VTEI module and the personal computer is made through a standard parallel port. The VTEI module is designed to meet the high frequency signal requirements for communications systems. It provides the necessary hardware to implement a dual trace oscilloscope, a Spectrum analyzer, a true-rms voltmeter, and a frequency counter. All inputs are fitted with BNC connectors and are fully protected against short circuits and misconnections made by the students. An instruction manual provides detailed information about the VTEI module. LVDAM-COM Software The LVDAM-COM software consists of a complete set of instruments. Each instrument appears as a window on the computer screen. Computer-based instruments provide instructors with the opportunity to clearly demonstrate concepts that are usually presented using traditional textbook methods and static drawings. They also enhance the overall presentation of course material with built-in capabilities for waveform observation, data storage, and graph plotting. The various instruments of the LVDAM-COM system are briefly described in the next section of this data sheet. The LVDAM-COM software can operate in either of the following modes: acquisition and simulation. In the acquisition mode, the input signals are measured by the VTEI module and then transmitted to the LVDAM-COM software through the computer s parallel port. In the simulation mode, input signals are generated by the computer using user-defined simulation parameters. When used in conjunction with the LVSIM -COM - Virtual Laboratory Equipment for Analog Communications, Model 9480, a third mode, referred to as virtuality, is available. In this mode, input signals are generated by the computer using simulation parameters that are produced by the LVSIM -COM software. See the data sheet of Model 9480 for additional information. The LVDAM-COM software configuration, the recorded data, and the user-defined simulation parameters can be saved to files. All display screens obtained with LVDAM-COM can be printed out or pasted in any document. Frequency Counter The Frequency Counter has three functions. It can measure the frequency of the input signal and display the frequency in Hz, khz, or MHz. It can determine the period of the input signal and displays the result in ns, μs, or ms. It can also be used as an event counter. The Frequency Counter resolution is software-selectable from 0.1 to 100 Hz. True RMS Voltmeter The True RMS Voltmeter is a dual function instrument that can measure the true RMS voltage or power of telecommunications signals. and power can be measured using any one of four software-selectable ranges (10 mv, 100 mv, 1 V, 10 V, and -27 dbm, -7 dbm, +13 dbm, +33 dbm). Festo Didactic 19

20 Spectrum Analyzer The Spectrum Analyzer is used for frequency-domain observation of telecommunications signals. It is a frequency-selective instrument that allows the power level of the frequency components in the input signal to be displayed on a graduated screen. The Spectrum Analyzer has two selectable frequency ranges: 0 to 30 MHz, and 85 to 115 MHz. The center frequency can be selected directly by typing the frequency on the keyboard or by using the special Seek function which locates the closest spectral component within the selected frequency range. The total frequency span of the main screen can be varied from 20 khz to 10 MHz. The Spectrum Analyzer includes a special window which allows the student to visualize all the spectral information contained in the selected frequency range. A portion of this spectral data can be zoomed in the main screen for precise analysis. The input impedance is selectable between 50 Ω and 1 MΩ. The input signal can be displayed using linear or logarithmic scales up to a maximum display range of 60 db. Oscilloscope The Oscilloscope is used for timedomain observation of telecommunications signals. It has two input channels and an external-trigger input. The Oscilloscope has the same features as a conventional oscilloscope (scales, time bases, trigger level, channel math, X & Y display), to which have been added digital properties such as auto scaling, cursors, waveforms memorization capabilities, and more. Data Table and Graph The Data Table window interacts with the four other computer-based instruments (Oscilloscope, Spectrum Analyzer, Frequency Counter, and True RMS Voltmeter) to record data in a table. Each of the four instruments contains a data area, and each cell in that data area can be linked to a column of the Data Table. With the press of a button, the data contained in the instrument is transferred into the Data Table. Once data is acquired, different graphs can be generated using the Graph Window. 20 Festo Didactic

21 List of Manuals Manual Description number Data Acquisition and Management System (User Guide) E0 Virtual Test Equipment Interface (Instruction Manual) D0 Computer-Based Instruments (User Guide) E0 Table of Contents of the Manual(s) Computer-Based Instruments (User Guide) (36220-E0) 1 Familiarization with the True RMS Voltmeter and Frequency Counter 2 Familiarization with the Oscilloscope 3 Familiarization with the Spectrum Analyzer Additional Equipment Required to Perform the Exercises Model Qty Description number 1 6 Personal Computer Power Requirements Current Service Installation Frequency Counter Input Frequency Range Input Period Range Count Range Input Sensitivity (Sine Wave RMS ) Attenuator Resolution True RMS Voltmeter Input Ranges 2 A Standard single-phase ac outlet 10 Hz MHz 5 ns s (28 bits) 1 MΩ 10 Hz to 140 MHz: 60 mv MHz: 200 mv 0, 20, or 40 db 0.1, 1, 10, 100 Hz 1 MΩ 10 mv, 100 mv, 1 V, 10 V Power Ranges -27 dbm, -7 dbm, +13 dbm, +33 dbm, (0 dbm = 1 mw in 50 Ω) Operating Range Accuracy 5% Crest Factor 5 Spectrum Analyzer Input Frequency Ranges Input Input Signal Level Maximum Input Signal Level Frequency Span Resolution Bandwidth (3 db) Dynamic Range (input signal measurements) 50 Hz - 12 MHz 0-30 MHz (500 Hz min.) and MHz 50 Ω or 1 MΩ (software selectable) -70 to +30 dbm (50 Ω input) 10 V peak 0 Hz/div; 2 khz/div - 1 MHz/div 100, 500 Hz; 2, 20, 50 khz (automatically selected) 60 db Selectivity (60 db/3 db) Better than 13:1 View Scale Oscilloscope Channels 1 & 2 Coupling Bandwidth (Channel 1) Bandwidth (Channel 2) AC Coupling (Lower Limit) Linear or Log 1 MΩ AC or DC 40 MHz 20 MHz 16 Hz 6 Refer to the Computer Requirements in the System section of this datasheet if the computer is to be provided by the end-user. Festo Didactic 21

22 Range Time base Oscilloscope Triggering Source Slope Oscilloscope External Trigger Ranges Coupling Bandwidth Oscilloscope A/D Conversion Resolution Maximum Sampling Rate (Channel 1) Maximum Sampling Rate (Channel 2) Computer Requirements Dimensions (H W D) 5 mv/div - 5 V/div 0.2 μs/div s/div Channel 1, Channel 2, External Positive or Negative 1 MΩ ±1 V and ±5 V AC or DC 40 MHz 10 bits 80 MSPS 40 MSPS A currently available personal computer with USB 2.0 ports and a parallel port, running under one of the following operating systems: Windows 7 or Windows x 205 x 580 mm (13.6 x 8.1 x 22.8 in) TBE Enclosure / Supply Regulator The Enclosure / Supply Regulator provides enough regulated power to supply four digital communications modules. It converts unregulated dc voltages from the Power Supply / Dual Audio Amplifier, Model 9401, into four regulated dc voltages accessed via backplane connectors. Built-in guides facilitate the insertion of modules into the enclosure, while a thumbscrew fastener secures each module in the enclosure. Each module is automatically powered through the backplane connectors installed inside the enclosure. Power Requirements Connection to the Power Supply / Dual Audio Amplifier, Model 9401 DC Regulated Outputs DC Regulated Outputs +15 V 1 A -15 V 1 A +5 V 1 A -5 V 0.5 A 215 x 675 x 320 mm (8.5 x 26.6 x 12.6 in) 5.3 kg (11.7 lb) 22 Festo Didactic

23 Clock Generator The Clock Generator provides a series of synchronized clock signals required for the clocking functions of the digital communications system. The module consists of a master clock driving a 10^n-frequency divider, which in turn drives eight divide-by-two cascadeconnected frequency dividers. Access to the output signals of each section is achieved through BNC connectors. In addition, a multi-pin connector provides the output signals from each of the divide-by-two frequency dividers. All frequency divider output signals have a 50% duty cycle. One of the following four master clocks can be selected through push buttons: variable frequency clock (1-10 MHz) crystal-controlled fixed-frequency clock (10 MHz) external clock manual clock (activated through a push-button switch) The frequency-division ratio of the 10^n-frequency divider is determined using a push button that selects an integer power n from 0 to 7. An LED display indicates the chosen frequency-division ratio. The Clock Generator can be stacked on top of the Power Supply / Dual Audio Amplifier, Model 9401, the Enclosure / Supply Regulator, Model 9420, the FSK Modem, Model 9449, or on top of any module of the Analog Communications Training System. Power is distributed through the self-aligning multi-pin connectors located on the top and bottom of the modules. Power Requirements Connection to the Power Supply / Dual Audio Amplifier, Model 9401 External Clock Input Maximal Frequency Clock Outputs Clock Outputs Output 10 MHz A (Master Clock) Complement of A B (Master Clock/[10^n]) (n=0 to 7, switch selectable) Complement of B B/[2^n] (n=1 to 8) Composite Clock (all eight B/[2^n] clock outputs on D-connector) 50 Ω (all BNC outputs) 3.3 kg (7.3 lb) 3.3 kg (7.3 lb) 112 x 330 x 300 mm (4.4 x 13.0 x 11.8 in) Festo Didactic 23

24 Pseudo-Random Binary Sequence Generator The Pseudo-Random Binary Sequence (PRBS) Generator designed to be used with the Bit Error Rate Indicator, Model 9423, to measure the reliability (error rate) of different digital transmission systems. Using an external clock, the PRBS Generator produces a pseudo-random sequence of bits. The bit rate can be varied from 100 bps to 5.44 Mbps. The length of the pseudo-random sequence of bits is selected through a switch and is indicated on the front panel of the module. Sixteen sequence lengths are available between 1 and 65,535 bits. One of the sequences is 511 bits long, thus meeting with recommendation V.52 of the CCITT. The generated pseudo-random bit sequence recurs indefinitely. The generator produces a synchronization signal for oscilloscope observation of the PRBS. A delayed PRBS is required when assessing the reliability of a digital transmission system. The delay of the PRBS must match that caused by the digital transmission system under test. For this purpose, the PRBS can be delayed by a fraction of a bit (fraction of a clock period) or by a whole number of bits (whole clock periods) using controls located in the DELAY block of the module. Clock Input Frequency PRBS Delayed PRBS (0 to 45 clock periods) Delayed Clock Sync. PRBS Length 5.44 MHz maximum PRBS Delayed PRBS (0 to 45 clock periods) Delayed Clock Sync. 1 bit to [2^16]-1 (= 65,535 bits) 1 kg (2.2 lb) Bit Error Rate Indicator The Bit Error Rate Indicator is designed to be used with the Pseudo- Random Binary Sequence Generator, Model 9422, to measure the transmission error rate on a bit stream within a communication system, in order to assess the reliability of the communication path. The module compares two data streams and counts, for a specific 24 Festo Didactic

25 period of time, the number of non-identical bits. Three test durations can be selected: 1 s, 10 s or 100 s. Error rates can be measured within a range of 0.01 error per second to 9999 errors per second. At the end of each test period, the error rate appears in errors per second on a 4-digit display. The display will blink in case of overflow. The counting cycle is automatically reset when another test duration is selected. Each new reading can be announced by a tone, which is useful for long test periods. This feature can be disabled at any time. The tone generator cannot be used for a test period of 1 s. Clock Input Frequency Auxiliary Output Frequency Display 5.44 MHz maximum 3.57 MHz maximum 4 digits 0.8 kg (1.8 lb) Logic Analyzer The Logic Analyzer is designed to observe successive bytes (8-bit words) on any 8-bit bus. The Logic Analyzer operation is divided into two distinct parts: data acquisition and data display. The data acquisition is controlled using a push button and can be triggered by an internal or external signal. During data acquisition incoming, 8-bit words are stored in the Logic Analyzer's memory until full. The memory capacity is bit words. A clock signal is required to carry out the data acquisition. The data in memory is stored until a new data acquisition is carried out or until the power is turned off. Once data acquisition is completed, the Logic Analyzer automatically proceeds with data display. The Logic Analyzer produces X-Y signals which allow observation on an oscilloscope screen of a group of 8-bit words stored in its memory. Each group or memory segment contains sixteen 8-bit words. The memory segment observed is selected through the use of push buttons. The number of the selected segment can be displayed on a 2-digit hexadecimal display. This display can also be used to obtain the hexadecimal representation of the 8- bit word present at the data input of the Logic Analyzer. The display on the oscilloscope screen consists of 8 horizontal traces. Each of these traces represent 1 bit of the 8-bit words. The lower trace represents the least significant bit (LSB) whereas the upper trace represents the most significant bit (MSB). Clock Input Frequency Data Input Memory 1 MHz maximum 8-bit parallel 2K x 8-bit Festo Didactic 25

26 X and Y Outputs Hexadecimal Display Indicators Indicators Trigger Ready 8-level multiple signal to oscilloscope 2-digit Acquiring data Trigger ready 0.9 kg (2 lb) DC Voltmeter / DC Source and of digital-to-analog conversions. The DC Voltmeter / DC Source combines a high-impedance digital dc voltmeter and a low-current dc source. The dc Source is designed to supply a user-adjustable reference voltage. The digital display of the dc voltmeter provides accurate voltage readings. The module is used mainly in the study of analog-to-digital conversions The dc source voltage is adjustable through a ten turn potentiometer. Its value can be read from the voltage display by pressing a push button on the front panel of the module. The dc voltmeter can be used on one of two ranges selected through a push button. The measured voltage is indicated on a 3½ digit display. The high input impedance of the dc voltmeter allows for a precise reading without disturbing the circuits being tested. DC Voltmeter Input Ranges Resolution DC Source Output Display 1 MΩ ±2 V, ±20 V 1 mv on ±2 V range 10 mv on ±20 V range -2 V to +2 V, 25 ma maximum 3½ digit 0.7 kg (1.5 lb) 26 Festo Didactic

27 Low Pass Audio Filter The Low Pass Audio Filter provides a second- or fourth-order filter with variable cutoff frequency. It is used before sampling and after decoding in digital communications systems to provide band-limited signals. The module is normally ac coupled, but dc coupling may be selected so that a digital signal can be band-limited for noise measurement purposes. Audio Input 2 V p-p input 600 Ω Audio Output 2 V p-p with 2 V p-p input (gain control at CAL position) 600 Ω Cutoff Frequency (3dB) 300 Hz to 8 khz 0.7 kg (1.5 lb) Synchronous Audio Generator level as frequency is varied. The Synchronous Audio Generator provides a triangle-wave audio signal that is synchronized to the system clock and enables PAM, PWM, PPM, and PCM signals throughout the system to be observed easily. The audio signal is derived from the clock input signal using a frequency divider and an integrator. An automatic gain control circuit ensures a stable output Clock Input Maximal Frequency 500 khz Frequency Division 10 (3 khz to 50 khz) 100 (30 khz to 500 khz) Audio Output Nominal 2 V p-p (gain control at CAL position) Maximal 10 V p-p 600 Ω Festo Didactic 27

28 0.7 kg (1.5 lb) Signal Interruptor/Selector The Signal Interruptor/Selector performs two functions in the system. It allows selective interruption of one or more lines on an 8-bit data bus to demonstrate the effect of losing bits in data transmission. The relative importance of each bit can also be demonstrated, e.g., the effect of interrupting the MSB line compared with interrupting the LSB line. Furthermore, the Signal Interruptor/ Selector is an interface for the test points, which are accessible via D-type connectors on the front panels of the instructional modules. Any two test points can be selected independently and are made available at two BNC connectors on the front panel of the Signal Interruptor/Selector, for observation on a dual channel oscilloscope. LEDs indicate which signal has been selected. Inputs Outputs Outputs 8-bit parallel 8-bit parallel 2 x Signal Outputs (BNC) 0.8 kg (1.8 lb) Noise Measurement Filters The Noise Measurement Filters measure the noise content of various signals in the system by separating noise from signals using filtering techniques. They can also be used to measure quantization and intermodulation noise, as well as noise on voice channels. The module contains a selectable frequency low-pass filter, a band-pass filter, and a notch filter. The low-pass filter simulates transmission channels of different bandwidths. It is preceded by a summing amplifier allowing the addition of a noise signal to simulate a "noisy" transmission 28 Festo Didactic

29 channel. The notch filter and the band-pass filter have the same center frequency in order to measure signal-tonoise (S/N) ratios. The band-pass filter can be used for cleaning up a signal or for Gaussian noise generation. All Inputs All Outputs Band-Pass Filter Center Frequency Notch Filter Center Frequency Low Pass Filters Cutoff Frequency 2 V p-p 600 Ω 2 V p-p 600 Ω 100 Hz, 300 Hz, 1 khz 100 Hz, 300 Hz, 1 khz 20, 40, 80, 160 khz 0.7 kg (1.5 lb) PAM/ASK Generator The PAM/ASK Generator converts analog input signals to Pulse Amplitude Modulated (PAM) output signals or digital data to Amplitude Shift Keyed (ASK) output signals. In PAM, an analog input signal is sampled using either natural or flattop sampling, and a pulse with a height proportional to the input signal amplitude is generated at each sample point. In ASK, a tone is output for a "1" and no tone is will be the output for a "0" at the input. PAM and ASK are not true digital signals, since both convey information as modified analog signals rather than as a digital code. Using the PAM/ASK Generator, students gain an understanding of the principles of PAM and ASK generation. The relationship between the sampling rate and highest frequency present in the modulating signal, and the effects of bandwidth and pulse duration are also investigated. Sampling Modes Audio/Carrier Input Maximal Frequency Clock/Data Input Maximal Frequency PAM / ASK Output Nominal Natural, Flat Top 2 V p-p 600 Ω 50 khz 100 khz 2 V p-p with 2 V p-p input (gain control at CAL position) Festo Didactic 29

30 Maximal 10 V p-p 600 Ω Maximal ASK Data Rate 9600 Bd Fault-Insertion Switches 8 Test Points kg (1.8 lb) PAM/ASK Receiver The PAM/ASK Receiver demodulates PAM or ASK signals from the PAM/ASK Generator to recover the original analog signals or data. Using the PAM/ ASK Receiver, students become familiar with techniques used in the demodulation of PAM and ASK signals. PAM / ASK Inputs 2 V p-p 600 Ω Maximal ASK Data Rate 1200 Bd Audio Output Nominal 2 V p-p with 2 V p-p input (gain control at CAL position) Maximal 10 V p-p 600 Ω Frequency 3.4 khz Data Output Fault-Insertion Switches 8 Test Points kg (1.5 lb) 30 Festo Didactic

31 PWM/PPM Generator The PWM/PPM Generator converts analog input signals to Pulse Width Modulated (PWM) or Pulse Position Modulated (PPM) output signals. In PWM, an analog input signal is sampled, and a pulse whose width (duration) is proportional to the input signal amplitude is generated at each sample point. In PPM, an analog input signal is sampled an a pulse whose position is proportional to the input signal amplitude is generated at each sample point. Both PWM and PPM signals are of constant height (amplitude), and the pulses in PPM signals are of constant width. Although PWM and PPM are more complex forms of message processing than PAM, they still are not considered true digital signals. Using the PWM/PPM Generator, students can gain an understanding of how PWM and PPM signals are generated. The noise resistance characteristics of PWM/PPM signals can be studied also. Audio Input Frequency Range Ramp Input Maximal Frequency PWM / PPM Outputs PPM Pulse Duration Fault-Insertion Switches 8 Test Points 6 2 V p-p 600 Ω 300 Hz to 5 khz 2.2 V p-p 600 Ω 20 khz 5 V, (gain control at CAL position) 0-5 V variable 3 µs to 1 ms 0.7 kg (1.5 lb) PWM/PPM Receiver The PWM/PPM Receiver is part of the 13 digital communications instructional modules that offer superior training in Telecommunications technology. It demodulates PWM or PPM signals from the PWM/PPM Generator to reconstruct the original analog signal. Using the PWM/PPM Receiver, Festo Didactic 31

32 students become familiar with the PWM / PPM decoding process. The relationship between PWM and PPM is easily demonstrated. PWM / PPM Inputs Clock Input Maximal Frequency Audio Output Nominal Maximal Frequency Range Fault-Insertion Switches 8 Test Points 6 20 khz 2 V p-p (gain control at CAL position) 10 V p-p 600 Ω 300 Hz to 3.4 khz 0.8 kg (1.8 lb) PCM Encoder serial PCM outputs are provided for experimental work. The PCM Encoder converts an analog input signal to a digitally-coded output signal (pulse to PAM, PWM, and PPM), since the PCM output is in binary code. In PCM, an analog input signal is sampled and an 8-bit code is generated representing the input signal amplitude at each sample point. A bar graph indicator for the test bus shows the logic states of the 8-bit A/D converter output. Both parallel and Using the PCM Encoder, students become familiar with the basics of A/D conversion and PCM signal generation. Other important concepts, such as quantization error and volume compression are studied as well. Audio Input Frequency Range Clock Input Maximal Frequency Outputs Output Compression Modes Compression Modes 2 V p-p 600 Ω 300 Hz to 5 khz 40 khz Serial-bit parallel end of conversion (A/D converter) 4 Bell µ-type laws 3 CCIT A-type laws Direct (no compression) 32 Festo Didactic

33 Fault-Insertion Switches 8 Test Bus kg (2.0 lb) PCM Decoder The PCM Decoder is used to demodulate a serial PCM signal generated by the PCM Encoder, or a parallel PCM signal generated by either the PCM Encoder or the DPCM Decoder, and to recover the original analog signal. A bar graph indicator for the test bus shows the logic states of the 8-bit D/A converter input. Using the PCM Decoder, students gain familiarity with PCM decoding and D/A conversion processes. The effects of compression and expansion on weak and strong signals can be investigated also. PCM Input Input Codes Input Codes Audio Output Nominal Maximal Frequency Range Fault-Insertion Switches 8 Test Bus 1 Offset Binary Sign Offset µ2-type Expansion A1-Type Expansion 2 V p-p (gain control at CAL position) 10 V p-p 600 Ω 300 Hz to 5 khz 0.8 kg (1.8 lb) Festo Didactic 33

34 DPCM Encoder The DPCM Encoder accepts parallel PCM signals from the PCM Encoder and produces a parallel Differential Pulse Code Modulated (DPCM) signal. A DPCM signal results when consecutive PCM signals are subtracted, so that only the difference between the signals is transmitted. DPCM offers advantages over PCM for voice signals, such as lower sampling rates and the ability to multiplex more channels on the same transmission link. DPCM requires fewer bits to encode the analog information and suffers less from noise degradation than PCM. Using the DPCM Encoder, students gain an understanding of the processes used to obtain DPCM signals, the differences between PCM and DPCM, and the advantages and disadvantages of each. Inputs Outputs Input/Output s Fault-Insertion Switches 8 Test Busses 6 8-bit parallel PCM end of conversion (from PCM Encoder) Less than 8-bit parallel DPCM 0.9 kg (2.0 lb) DPCM Decoder The DPCM Decoder is converts the less than 8-bit parallel DPCM signals from the DPCM Decoder to an 8-bit PCM signal. This PCM signal is then fed to the parallel input of the PCM Decoder to recover the original analog signal. Using the DPCM Decoder, students gain an understanding of the more complex processes involved in DPCM decoding and the effects of noise on DPCM transmissions. Inputs Less than 8-bit parallel DPCM end of conversion (from PCM Encoder) 34 Festo Didactic

35 Output Input/Output s Fault-Insertion Switches 8 Test Busses 5 FSK Modem bit parallel PCM 0.9 kg (2.0 lb) The FSK Modem converts of RS-232C data to Frequency Shift Keyed (FSK) audio signals which are compatible with a telephone line. The FSK Modem also converts FSK audio signals to or RS-232C data. Fullduplex and half-duplex operation is possible. FSK is the most popular method of low- and medium-speed data transmission. Using the FSK Modem, students gain an understanding of FSK generation, logic compatibility, data transmission speeds, and standards used in FSK communications. Power Requirements Connection to the Power Supply / Dual Audio Amplifier, Model 9401 Analog Input/Output Digital Input/Output Modes of Operation Modes of Operation Bell 103 Fault-Insertion Switches 10 Test Points or 4-wire through 600 Ω balancing transformer or RS-232C data Originate/Answer, full-duplex, half-duplex (2- or 4-wire) Bell 202 Bell 202 Equalized (V o/a, F/D; V.23.. Mode 2; V Mode 2 Equalized half-duplex Digital and analog loopback 112 x 330 x 300 mm (4.4 x 13.0 x 11.8 in) 3.9 kg (8.6 lb) BPSK Modulator The BPSK Modulator converts data to Binary Phase Shift Keyed (BPSK) signals. BPSK is used extensively in high-speed data transmission. Using the BPSK Modulator, students gain an understanding of the BPSK modulation process, as well as data rate limitations of a BPSK system. Festo Didactic 35

36 Data Input Maximal Data Rate 9600 Bd Clock Input Maximal Frequency 1 MHz Outputs Phase Modulator BPSK BPSK Output Maximal 2 V p-p 600 Ω Fault-Insertion Switches 8 Test Points kg (1.5 lb) BPSK Demodulator measurement. The BPSK Demodulator demodulates the BPSK signals from the BPSK Modulator and recovers the original data signal. The module employs demodulation techniques with the Costas Loop. Using the BPSK Demodulator, students gain an understanding of BPSK demodulation techniques, as well as phase ambiguity and bit error rate BPSK Input 2 V p-p 600 Ω Data Output Maximal Data Rate 2400 Bd Fault-Insertion Switches 8 Test Points kg (1.5 lb) 36 Festo Didactic

37 Delta/CVSD Encoder The Delta/CVSD Encoder converts audio input signals to Delta Modulated or Continuously Variable Slope Delta (CVSD) modulated output signals. Delta Modulation uses a more direct encoding process than PCM. In Delta Modulation, an analog signal is sampled and either a "1" or a "0" is transmitted at each sample point, depending on whether the sample size is larger or smaller than the previous sample size. The use of CVSD considerably increases the dynamic range of the audio input signals that can be used. Using the Delta/CVSD Encoder, students gain an understanding of the Delta Modulation encoding process. The difference between Delta Modulation and CVSD can be studied, together with their performance at different rates. Audio Input Frequency Range Clock Input Maximal Frequency Delta / CVSD Output Fault-Insertion Switches 7 Test Points 7 Delta/CVSD Decoder V p-p 600 Ω 300 Hz to 5 khz 40 khz 0.7 kg (1.5 lb) The Delta/CVSD Decoder is demodulates the Delta or CVSD modulated signal from the Delta / CVSD Generator and recovers the original analog signal. Using the Delta/CVSD Decoder, students gain an understanding of Delta / CVSD demodulation techniques. Distortion of the modulated signal due to slope overload or weak and noisy signals can be studied, as well as the effects of noise on the transmitted signals. Festo Didactic 37

38 Delta / CVSD Input Clock Input Maximal Frequency 40 khz Audio Output 2 V p-p 600 Ω Frequency Range 300 Hz to 5 khz Fault-Insertion Switches 6 Test Points kg (1.5 lb) Storage Cabinet The Storage Cabinet contains six shelves and can hold 24 modules from the Digital Communications Training Systems, Series The Storage Cabinet requires assembly. A diagram is provided to facilitate assembly. Capacity 24 modules from the Digital Communications Training Systems, Series 8085 Material Hard wood TBE TBE 38 Festo Didactic

39 Optional Equipment Description Dual Trace Oscilloscope (Optional) The Dual Trace Oscilloscope is an economical and highly reliable solidstate instrument, ideal for generalpurpose use in laboratory and training applications. Students can measure phase difference between waveforms using the X-Y operation mode, and video signals can be measured quickly with the special TV sync separation circuit. The Dual Trace Oscilloscope includes CH 1, CH 2, CHOP, and ALT display modes. An operating instruction manual, one fuse, one line cord, and two low-capacitance probes are provided with the oscilloscope. Features & Benefits 15 cm (6 inch) width, high luminance CRT with internal graticule, 8 x 10 divisions Wide dynamic range even at high frequencies of 3 db Fast rise time with low overshoot Flat frequency response up to half of 3 db frequency Alternate and chopping display Polarity inversion and algebraic sum of CH1 and CH2 Maximum sweep rates of 20 ns/div. Variable scale illumination Delayed sweep function with minimum delay time jitter of 1/20,000 or less Jitterless and superb trigger sensitivity TV sync separation and hold-off circuit useful for video signal observation Brightness modulation available with Z-axis input Low drift with compensation circuitry Signal delay with delay line useful for observation of signal leading edge X-Y phase difference measurement up to 50 khz Power Requirements Current Service Installation CRT Display Type Effective Area Acceleration Potential Vertical Deflection 0.4 A Standard single-phase ac outlet cm (6 in) rectangular, internal graticule, scale illumination 8 x 10 div (1 div = 1 cm) 12 kv Sensitivity 5 mv/div to 5 V/div in 10 calibrated steps ±3% Bandwidth Rise Time Maximum Input Input Coupling 1 mv/div to 1 V/div ±5% when using x5 magnifier Uncalibrated continuous control between steps 1:<2.5 DC to 40 MHz (-3 db); dc to 7 MHz (-3 db) when using x5 magnifier Less than 8.8 ns 300 V (dc + ac peak) or 500 V p-p ac at 1 khz or less AC, GND, DC Festo Didactic 39

40 Input 1 meg in parallel with 25 pf Operating Modes CH1, CH2 (INVERT), ADD, DUAL (CHOP: Time/div sw 0.2 s - 5 ms; ALT: Time/div sw 2 ms - 0.2µs) X-Y Operation CH1: X-axis, CH2: Y-axis Horizontal Deflection Display A, A int B, B, B triggered, X-Y Time Base A 0.2 µs/div to 0.2 s/div in 19 calibrated steps ±3% uncalibrated continuous control between steps at least 1:<2.5 Time Base B 0.2 µs/div to 20 µs/div in 7 calibrated steps ±3% Trigger Modes Auto, Norm, TV-V, TV-H Coupling AC Sources CH 1, CH 2, LINE, EXT Sensitivity (Internal Source) 0.5 div (20 Hz to 2 MHz), 1.5 div (2 MHz to 40 MHz) Sensitivity (External Source) 200 mv (20 Hz to 2 MHz), 800 mv (2 MHz to 20 MHz) Slope + or - TV Sync Polarity: TV (-) Calibrator 1 khz, square wave, 0.5 ±3%, duty cycle: 50% Accessories Power cable, fuse, operation manual, 2 probes 140 x 320 x 430 mm (5.5 x 12.6 x 16.9 in) 5.7 kg (12.57 lb) Personal Computer (Optional) The Personal Computer consists of a desktop computer running under Windows 10. A monitor, keyboard, and mouse are included. Power Requirements Current Service Installation 2 A Standard single-phase ac outlet 40 Festo Didactic

41 FM/PM Receiver (Optional) The FM/PM Receiver offers training in multiplex and wideband FM (covering commercial broadcast techniques), narrowband FM (widely used in commercial and military communications systems), and PM reception. PM reception is used in such applications as satellite communications, data communications, over narrowband communications systems, telephone lines, microwave communications lines and links. When the FM/PM Receiver is connected with the Direct FM Multiplex Generator, a complete commercial FM system is established. Students can readily see the effects of stereo signal generation, multiplexing techniques, and modulation. When the FM/PM Receiver is connected to the Indirect FM/PM Generator, a narrowband FM communications link is established, allowing the student to explore the generation and reception of narrowband FM and PM signals. RF inputs to the receiver are between 88 and 108 MHz for stereo and wideband FM, and 10.7 MHz for narrowband FM and PM. A demodulated audio signal is available at the NBFM audio output when a signal is injected at the RF input. When the output of the crystal discriminator is connected to the input of the integrator, a demodulated audio signal is available at the PM audio output. The WBFM section is equipped with two 50 Ω RF inputs, a balanced 300 Ω RF input for an external antenna connection, and an RF tuning knob which allows tuning across the 88- to 108-MHz band. A 3-LED tuning indicator and a 10-LED bar graph display (indicating received signal level) facilitate accurate tuning. The presence of the 19 khz pilot signal illuminates an LED also. A 2½ digit display can show the frequency deviation of the received WBFM or NBFM signals. These meters are often used on modern communications receivers. Receiver outputs for FM left and right stereophonic channels, monophonic FM, NBFM, and PM are provided, as well as an SCA channel audio output, often used for background music programming. Power Requirements Power Requirements WBFM Section Input +25 V dc ma +11 V dc ma -25 V dc ma 2 inputs at 50 Ω, 1 input at 300 Ω (balanced) 50 Ω Input Sensitivity 55 µv (typical for both inputs for 10 db S/N at baseband output) 300 kω Input Sensitivity 15 µv ( typical for 10 db S/N at baseband output) AUX IF Input Control RF Tuning Range Intermediate Outputs Indicator PM/NBFM Section Input Frequency Input Input Level Sensitivity Audio Outputs 50 Ω RF tuning 88 to 108 MHz IF (10.7 MHz), baseband Deviation (switchable between WBFM and NBFM) 10.7 MHz 2 inputs at 50 Ω 3 mv (typical for 100 mv p-p at NBFM audio output) Festo Didactic 41

42 L, R, L + R Bandwidth 50 Hz to 15 khz SCA, NBFM, PM Bandwidth 200 Hz to 3 khz 1 kω (all outputs) Fault-Insertion Switches 12 Test Points 35 Indicators Center tuning, signal level, pilot (19 khz), deviation display (2½ digits), Power ON 162 x 330 x 300 mm (6.4 x 13.0 x 11.8 in) 4.7 kg (10.3 lb) Baseband Channel / Brickwall Filter (Optional) and the Line Decoder, Model The Baseband Channel / Brickwall Filter is designed for use with the Time-Division Multiplexer, Model 9460, the Time-Division Demultiplexer, Model 9461, and the T1/CEPT PCM Transceiver, Model Other modules that can be used with the Baseband Channel / Brickwall Filter are the Line Coder, Model 9464, The Baseband Channel section of the module provides the frequency characteristics of a twisted pair of wires. The line length simulated is selectable between 0.15, 0.30, 1, and 2 kilometers. An auxiliary noise input is provided for noise injection. Input and output impedances are 120 S and coupling is either DC or AC (10 khz). When AC coupling is selected, both the input and output connectors have a balanced (ungrounded) characteristic. The Brickwall Filter creates heavy intersymbol interference (ISI) conditions. The filter has a very sharp low-pass characteristic that cuts off at 60 db per decade. Again, input and output impedances are 120 Ω and can be either DC or AC (balanced) coupled. Baseband Channel Maximal Input Input Noise Input Maximal Output Frequency Range DC Coupling AC Coupling Maximal Frequency Range Brickwall Filter Maximal Input 3 V p-p 120 Ω 3 V p-p with 120 Ω load 0-15 MHz with 0.15 km line length 0-9 MHz with 0.30 km line length 0-1 MHz with 1.0 km line length khz with 2.0 km line length 10 khz to 15 MHz with 0.15 km line length 10 khz to 9 MHz with 0.30 km line length 10 khz to 1 MHz with 1.0 km line length 10 khz to 100 khz with 2.0 km line length 2 V p-p 500 Ω 0-15 MHz 3 V p-p 42 Festo Didactic

43 Input Slope Maximal Output Output 120 Ω 60 db/decade 3 V p-p with 120 Ω load 120 Ω 0.9 kg (2 lb) Time Division Multiplexer (Optional) also interesting and informative to transmit sampled analog signals. The Time-Division Multiplexer provides training in the principles of time-division multiplexing (TDM). This technique, commonly used in telephone systems because of the ease with which multiplexed signals can be switched, sequentially combines separate signals for transmission in a common channel. Although TDM techniques are generally used for digital signals, it is The Time-Division Multiplexer has inputs for 4 signals. The signals can be either analog or digital. An internal digital data generator can be used to produce 8 bits of data on each of the 4 channels. The bit sequences are set by 4 banks of 8 DIP switches located on the module printed circuit board (pcb). The internal generator bit rate can be adjusted over a frequency range of 0 to 200 khz. The TDM rate can also be any frequency up to 200 khz. It is selected by an external clock. Both the bit rate and TDM rate clocks are independent. A set of eight test points is provided for more in-depth study. Eight fault-insertion switches are also located on the pcb. All inputs and outputs are fully protected against erroneous connections. Channel Inputs Clock Inputs Maximal Frequency Clock Output Maximal Frequency Channel Source Fault-Insertion Switches 8 Test Points 8 ±5 V or 10 kω 200 khz 200 khz Internal or external 0.9 kg (2 lb) Festo Didactic 43

44 Time Division Demultiplexer (Optional) The Time-Division Demultiplexer provides training in the technique of recovering time-division multiplexed signals. This technique separates a TDM signal into a certain number of signals available at different output channels. The Time-Division Demultiplexer can be interconnected with the Model 9460 Time-Division Multiplexer. The module has inputs for the TDM signal as well as for the TDM clock. Internal sample-and-hold circuits allow demultiplexing with minimum filtering at each of the 4 outputs. TDM Input Clock Input Maximal Frequency Channel Outputs Maximal Frequency Fault-Insertion Switches 6 Test Points 16 ±5 V 10 kω 200 khz ±5 V 600 Ω 200 khz 0.7 kg (1.5 lb) T1/CEPT PCM Transceiver (Optional) Europe. The T1/CEPT PCM Transceiver provides training in PCM-TDM techniques. The most common forms of timedivision multiplexing used by telephone systems are T1 (also known as DS1) in North America and Japan, and CEPT (also known as PCM-30) in In the North American system, 24 channels of 64 kbits/s sampled audio signals are multiplexed. The bit stream produced is at a rate of Mbits/s, which includes one bit that is added to each frame (group of 24 channels) for synchronization purposes. In the European system, 30 channels of 64 kbits/s sampled audio signals are multiplexed. Including 2 eight bit framing and control channels, the bit stream thus produced is at a rate of Mbits/s. 44 Festo Didactic

45 The T1/CEPT PCM Transceiver can be set to operate in either T1 (DS1) or CEPT mode. The transmitter section provides an input connector for use with the Model 9444 PCM Encoder. This singlechannel input signal can be inserted in any one of the 24 (T1) or 30 (CEPT) channels. The other channel signals are generated internally by a built-in data generator. Outputs are provided for frame, channel, and bit clocks. All framing, signaling, and alarm functions are handled internally by the module. Internal DIP switches are used to configure these options. The T1/CEPT output signal is normally connected to the T1/CEPT input on the receiver section, as is the clock signal. The T1/CEPT signal can also be looped to the Model 9463 Clock Recovery module so as to produce an independent clock signal for use in the receiver. This technique is more realistic and provides training in clock recovery techniques. Power Requirement Connection to the Power Supply / Dual Audio Amplifier, Model 9401 External Input Clock Input Frequency (T1/CEPT) T1/CEPT Input Maximal Mux Output Clock Outputs Frame Frequency Channel Frequency (T1/CEPT) Bit Rate (T1/CEPT) Transmitter/Receiver Monitor Outputs Reset Output T1/CEPT Output Receiver Output One-Channel Data Output Trigger Output Frequency Modes of Operation Modes of Operation Multiplexer Operation Description External Mode Internal Mode (selectable with the internal switch) Demultiplexer Operation Fault-Insertion Switches 12 External Test Points 8 Internal Test Points /2.048 MHz 5 V rms 120 Ω balanced TTl 8 khz 192/256 khz 1.544/2.048 MHz 8 V p-p 120 Ω balanced 8 khz T1 with bit 7 stuffing T1 with B8ZS coding CEPT with HDB3 coding Multiplexes 23/29 (T1/CEPT) channels with 1 selectable external or internal channel All channels fed by external data input signals Data pattern of the internal data generator is selectable with internal switches Circuit samples one channel signal of 24/30 (T1/CEPT) channels and feeds it to the one channel data output 162 x 330 x 300 mm (6.4 x 13.0 x 11.8 in) Festo Didactic 45

46 5 kg (11 lb) 5 kg (11 lb) Clock Recovery (Optional) The Clock Recovery provides training in the technique of recovering clock (or bit timing) signals from baseband data signals. The Clock Recovery module provides a recovered clock signal for the Model 9462 T1/CEPT PCM Transceiver. The module has two modes of operation. The analog mode permits recovery of a clock signal at a fixed frequency of MHz. It uses a band-pass filter with a very sharp frequency response. The digital mode of operation is based on a digital PLL. A local clock oscillator drives a digital divider that resets to zero whenever a transition occurs in the input data. The frequency of operation of this circuit is variable between 0.2 and 20 MHz. The digital divider division ratio can be adjusted to 8, 16, 32 or 64 counts. This feature allows the reduction of jitter to be observed as the number of counts is increased. The module has an input for the data signal and outputs for the local and recovered clocks. Seven test points and eight fault insertion switches are also provided on the module. All inputs and outputs are fully protected against erroneous connections. Data Input Maximal Data Rate Local Clock Output Frequency Range Mode of Operation Mode of Operation Recovered Clock Output Operating Frequency Analog Mode Digital Mode Fault-Insertion Switches 8 Test Points MBd in digital mode 200 khz to 20 MHz 50 Ω Analog Digital with selectable dividers: 8, 16, 32, Ω MHz 3 khz to 2.5 MHz 0.9 kg (2.0 lb) 46 Festo Didactic

47 Line Coder (Optional) Coder provides the following line codes: The Line Coder provides training in the principles of line coding. Line codes maintain timing information in baseband signals. Line coding techniques facilitate timing recovery in data transmission systems. Different line codes facilitate the synchronization of signals but may require larger bandwidths. The Line Polar (positive and negative) RZ (Return to zero) Biphase (Manchester) CMI (Coded Mark Inversion) AMI (Alternate Mark Inversion) B3ZS (Bit 3 Zero Suppression) HDB3 (High Density Bipolar 3) Duobinary (Partial Response Signaling) The Line Coder is also provided with a data scrambler. This scrambler is normally used to introduce a minimum number of transitions in given data streams. The scrambler can be turned on or off. The module has inputs for data and clock signals and an output for the coded data. All inputs and outputs are fully protected against erroneous connections. The line coding modules (Models 9464 and 9465) are intended for use with the Baseband Channel / Brickwall Filter, Model NRZ Data Input Maximal Data Rate Clock Input Maximal Frequency Scrambler Output Codes Provided Coded Data Output Nominal Fault-Insertion Switches 8 Test Points 7 2 MBd 2 MHz 50 Ω Polar, RZ, Biphase, CMI, AMI, B3ZS, HDB3, Duobinary 3 V p-p with 120 Ω load 120 Ω 0.9 kg (2 lb) Festo Didactic 47

48 Line Decoder (Optional) The Line Decoder is provides training in the techniques of line decoding. This module is normally used with the Line Coder, Model The line codes accepted are the same as those generated by the Line Coder. A data descrambler can also be placed in-circuit. The module has inputs for coded data and for a clock signal. Decoded and descrambled (if selected) outputs are also available on the module. Coded Data Input Maximal Maximal Data Rate Clock Input Maximal Frequency Input Codes Decoded Data Output NRZ Data Output Fault-Insertion Switches 8 Test Points 7 10 V p-p 2 MBd 120 Ω 2 MHz Polar, RZ, Biphase, CMI, AMI, B3ZS, HDB3, Duobinary 50 Ω 50 Ω 0.9 kg (2 lb) Dust Cover (Modules) (Optional) The Dust Cover is a flexible fabric cover specially designed to protect the modules of the Digital Communications Training Systems, Series 8085, against the accumulation of dust during extended storage periods. Dust Cover (Module Rack) (Optional) The Dust Cover is a flexible fabric cover specially designed to protect a module rack of the Digital Communications Training Systems, Series 8085, against the accumulation of dust during extended storage periods. 48 Festo Didactic