458MHz (433MHz) UHF Narrow Band Radio Data Modules. CDP-TX-02A Transmitter, CDP-RX-02A Receiver. Operation Guide & Application Notes

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1 458MHz (433MHz) UHF Narrow Band Radio Data Modules CDP-TX-02A Transmitter, CDP-RX-02A Receiver Operation Guide & Application Notes Features Very small compact integrated device with PLL synthesiser and microcontroller. Type Approved to MPT1329 (UK) & ETS (Europe) standards. Frequency selection of 11 channels (UK) and 32 channels (Europe) by DIL switch. New integrated UHF SAW filter technology. Applications Radio remote control for cranes & machines Environmental Monitoring Security systems Telemetry systems General Description The CDP-TX-02A (transmitter) and CDP-RX-02A (receiver) are channel frequency selectable versions of the CDP-01 radio data modules. They are suitable for various applications such as wireless data communication, remote control, telemetry or wireless security systems and are easy to use and integrate into application systems. The CDP-02A has not only kept all the advantages of the CDP-01 but also has some new advantages. If you have used the CDP-01 you can upgrade your products by use of the CDP-02A. The CDP-02A is equipped with a frequency synthesiser system and microcontroller. The frequency range of the CDP-02A (UK) is from MHz to MHz in eleven channels that are selected by use of a four way DIL switch on the PCB. The frequency range of the European version is from MHz to MHz in thirty two channels. The small size, low operating voltage and frequency selectability of the CDP-02A make them ideal for applications where their interference rejection and range are far better than similar RF modules based on wide band SAW-resonator devices. Standard RS232 serial data and other digital data (TTL level), such as pulse width modulation signals and signals from standard encoder-decoder can be transmitted. CDP-TX-02A Transmitter Module The CDP-TX-02A is an UHF FM-narrow band transmitter with PLL synthesiser and microcontroller for high frequency stability and channel selectability. Modern SMT technology enable a small size - much smaller than a match box. Narrow band FM modulation (direct FSK) allows efficient use of the available RF spectrum. Modules can operate in a 25 khz channel spacing scheme unlike SAW resonator transmitters which use a very broad band of the frequency spectrum. Eleven channels can be easily selected by use of the DIL switch on the PCB. The CDP-TX-02A can transmit any 5-Volt digital signal within the specified bandwidth. The internal comparator digitises analogue signals. The transmitter power supply should be switched to avoid unnecessary power consumption. After power up the Phase Lock Loop (PLL) needs about 60mS to lock and data can be transmitted 70ms after the transmitter is powered up without any further control or synchronisation. The transmitter module can be connected to a flexible Lambda/4 (λ/4) antenna or a high gain antenna can also be used. The amount of radiated power and directional behaviour is influenced by the antenna surroundings. Installation in a large metal housing with the ground connected to the transmitter module ground with the transmitter antenna put in an upright position outside the metal housing will reduce the CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 1 of 11

2 antenna impedance and increase the radiated power. For best performance in a user system the general rules of radio frequency technology should be taken into consideration. The same also applies to the receiver. CDP-RX-02A Receiver Module The CDP-RX-02A is an UHF receiver for FM-narrow band (NBFM) modulated signals. The receiver design is based on the double super-heterodyne principle with PLL synthesiser system and micro controller enabling high signal sensitivity, high selectivity, and high frequency stability not achieved by simple SAW resonator receivers or other low cost designs. The channel frequency can be easily selected to match the frequency of the transmitter. The method of frequency selection is the same as the CDP-TX-02A. Extensive filtering by a unique integrated SAW filter element enables operation in areas where interference may be expected. Steadily increasing use of the available frequency spectrum demands the application of narrow band systems for maximum operation reliability and fairness to other users of these bands. The CDP-RX-02A receiver module is designed to match the CDP-TX-02A transmitter module, though signals from other FM-narrow transmitters can be received as well. The CDP-RX-02A is designed for PCB mounting. It is allowed to install the CDP-RX-02A directly in to a system board which is designed for the CDP-RX-01S. A simple wire can be soldered to the antenna input or the antenna can be printed on the PC board. Better performance is attained with commercial antennas for the 458MHz ISM band. The receiver modules have an audio (AF) output, a digital output and a Received Signal Strength Indicator (RSSI) which indicates the power of the incoming RF signal. The AF output is the analogue output from the FM detector circuit. Voltage level, DC-offset and AF noise depend directly on the receiver input signal. This output can be connected to an MSK (Minimum Shift Key) decoder circuit if a transmitter with additional MSK encoder is used. For simple FSK modulation of digital data the DATA OUT terminal can be used. It contains a bandpass filter and comparator with digital output (open collector). With additional filtering, the sensitivity of the receiver is increased and the digital output signal can easily be connected to other digital circuits. To achieve the high signal sensitivity and short receiver response time no internal muting is applied and therefore digital white noise is present on the digital output in the absence of any RF carrier. Valid data signals can be detected by utilising the RSSI output in combination with an external comparator. Operation Instructions Please read these instructions before using the CDP-02A. The CDP-02A is designed as a module that will be integrated into a user system. It is not a ready-made product for end users. It can be regarded more like a special component for part of an electronic system. The user needs basic knowledge about electronics. Special knowledge about RF technology is helpful, but the most difficult parts are integrated into the modules to enable easy operation and use. Some additional information is given here: Supply voltage: The transmitter and receiver modules contain voltage regulators to guarantee stable performance within the given range of supply voltages. The design was made for operation with battery or regulated power sources. If the battery voltage drops under the minimum voltage given in the technical specifications, the transmitter output power will drop and the RF oscillator will stop. No data can be transmitted in this case. The receiver will continue to work down to a certain voltage but the performance will deteriorate. If the voltage connected to the Vcc (+) and Ground (-) terminal is beyond the maximum voltage given in the technical specification the internal voltage regulator will be permanently damaged. The result is an internal short-circuit or disconnection. The voltage of the data signal should be between 0V (Ground level) and Vcc. Because of the internal voltage regulator, it is recommended that the data high level be limited to 5 Volts. The data can be an analogue or digital signal. Analogue signals will be converted to a digital 1 or 0 inside the transmitter. CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 2 of 11

3 It is not necessary to synchronise the data signal of the transmitter, but the data signal should be fed to the transmitter 70ms after the transmitter power is on. As the CDP-TX-02A is a direct FSK modulation transmitter, without any data input the transmitter output frequency will be about 2KHz lower than the nominal F0. Data Format The digital data fed to the transmitter is passed through an internal low-pass filter to limit the bandwidth of the digital data. This is needed for efficient use of the available RF spectrum. At the receiver, a band-pass filter is used to recover the data signal from noise. Together the signal bandwidth is approximately 100 Hz to 2400 Hz. At the receiver, the signal is converted back into a digital signal for compatibility with succeeding digital systems. The type of digital data signals transmittable is limited because of the bandwidth of the system. DC signals or long consecutive sequences of HIGH or LOW bits should be avoided as following bits can be distorted in their bit length. If the sequence of HIGH or LOW bits is too long it is possible that the logic level of the data output will be changed. The best countermeasure is to use a digital-encoding scheme that guarantees that no low frequency components are included in the data signal. This can be achieved for example with Manchester encoding. A digital 1 is coded in a sequence of 10 and a digital 0 is encoded into a sequence of 01. In most cases it is also sufficient to transmit serial data by using start and stop bits of different logical level as it can be done according to the RS232 format. Each transmitted byte will be preceded by a 0 bit and succeeded by a 1 bit. The CDP-02A was tested with a number of standard encoder-decoder IC s for simple remote controls. For data speeds in the 300 to 4800 Baud range no trouble should occur. Because of the wide variety of data formats, data speeds and digital modulations techniques, it is best to set up a worst case situation and test the data transmission before the CDP-02A is used in a practical application. To enable a low minimum voltage no internal circuitry is used to prevent damage by incorrect polarity. If the transmitter CDP-TX-02A is connected incorrectly, it will be permanently damaged. If a higher supply voltage is available then a simple diode can be inserted in connection line to the Vcc terminal to prevent damage by incorrect polarity. The diode must be rated for the maximum supply current detailed in the technical specifications. Modules that have been connected to improper voltage sources should be sent back to the dealer for inspection. CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 3 of 11

4 Channel and Frequency Setting 458MHz Version The CDP-02A has 11 available channels (MPT1329) that can be selected by use of the four way DIL switch on the PCB according to the following channel plan. Ch. No. Fo Switch Position MHz Ch On On On On Ch Off On On On Ch On Off On On Ch Off Off On On Ch On On Off On Ch Off On Off On Ch On Off Off On Ch Off Off Off On Ch On On On Off Ch Off On On Off Ch On Off On Off Ch Off Off On Off Ch On On Off Off Ch Off On Off Off Ch On Off Off Off Ch Off Off Off Off View of switch for frequency setting ON N.B. Ch 12 & 15 same, Ch14 & 16 same. Frequency selection must be done before power ON CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 4 of 11

5 Channel & Frequency Settings 433MHz Version The CDP-02A has 32 available channels (ETS ) that can be selected by use of the four way DIL switch and jumper on the PCB according to the following channel plan. Group A Jumper ON Ch. No. Fo Switch Position LSB MSB MHz Ch. A On On On On Ch. A Off On On On Ch. A On Off On On Ch. A Off Off On On Ch. A On On Off On Ch. A Off On Off On Ch. A On Off Off On Ch. A Off Off Off On Ch. A On On On Off Ch. A Off On On Off Ch. A On Off On Off Ch. A Off Off On Off Ch. A On On Off Off Ch. A Off On Off Off Ch. A On Off Off Off Ch. A Off Off Off Off Group B Jumper OFF Ch. No. Fo Switch Position LSB MSB MHz Ch. B On On On On Ch. B Off On On On Ch. B On Off On On Ch. B Off Off On On Ch. B On On Off On Ch. B Off On Off On Ch. B On Off Off On Ch. B Off Off Off On Ch. B On On On Off Ch. B Off On On Off Ch. B On Off On Off Ch. B Off Off On Off Ch. B On On Off Off Ch. B Off On Off Off Ch. B On Off Off Off Ch. B Off Off Off Off View of switch for frequency setting ON Frequency selection must be done before power ON. Jumper selects which group is used. CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 5 of 11

6 Data Input The data input terminal is connected to a digital transistor compatible input. Data sources of high impedance can be used if the capacitive load of the data input is acceptable. Start-up After Vcc is connected to the transmitter the VCO and PLL will start up and, after about 60ms, the output frequency and power will reach their normal value. The receiver needs the same start-up time after it is switched on. Data transmission during these times is not possible. Therefore the input signal should be fed to the transmitter 70ms after TX power ON. The transmitter is active as long as the power supply is on. The power should be switched off immediately after the data transmission is finished in order to save valuable battery power and avoid unnecessary use of the RF spectrum. The receiver does not use the RF spectrum actively and it can therefore remain on as long as desired. Outputs On the receiver three output signals are available. AF is the direct analogue output of the FM receiver. This signal can be used for checking the receiver and where signals with additional analogue modulation are to be received. For example, it can be connected to an MSK decoder. The DATA output is a digital open collector output. An internal 10K Ohm pull-up resistor is applied to enable direct connection to CMOS compatible circuits. For other applications an additional external pull-up resistor should be used. The receiver has no internal mute circuit to avoid delays and achieve maximum sensitivity. The AF and DATA output will show noise on the output when no signal is being received. The third output is RSSI. It is an indicator of the received signal strength. It can be used to drive an external mute circuit id desired. Antennas Most important for reliable data transmission is a good antenna, and RF grounding, both for the transmitter and the receiver. Without an antenna it is impossible to transmit data over a long distance range. The antenna of the transmitter is a Lambda/4 wire, protected by a plastic cover. The transmitter antenna can be replaced with any other suitable antenna. The receiver has a simple antenna input pin. Any suitable UHF antenna can be connected to it. The easiest way to connect an antenna to the CDP-RX-02A is to solder a 17cm wire directly to the antenna input. If the receiving antenna is installed remotely from the receiver module, a 50 Ohm co-axial antenna wire can be used. The shielding of the antenna wire should be soldered to the case near the antenna input of the CDP- RX-02A. To find the best method of installation for the transmitter and receiver, many factors should be considered and tested. It is recommended that the user read specialised literature on antennas and radiation characteristics to gain a better understanding of these fields. A detailed explanation cannot be given here. In most cases the following basic rules will help you. Connect an antenna with 50 Ohm impedance designed for operation at 458MHz (or 433MHz.) The simplest construction is a wire of approximately 17cm length. Place the antenna vertically, straight up or down from the transmitter and receiver module. Do not cover the antenna with metal parts. The connection of the metal surface of the transmitter and receiver case to a larger metal part (ground plane) will increase radiation and reception efficiency. Such metal parts should not be placed near the antenna. Best range is achieved if the transmitter and receiver antenna have a direct visual connection. Any object in between the transmitter and receiver antenna, and metallic objects in particular, will decrease the range. CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 6 of 11

7 The transmission is influenced by reflections of the transmitter signal on metallic surfaces. By overlaying the direct and reflected signal with a 180 degree phase shift the signal can nearly fade out. Such reflections and fade-outs can result in data dropouts in mobile applications. The human body can have similar effects like metal objects. Pocket transmitters should be taken in the hand and put in a position away from the body and pointed in the direction of the receiver. Specifications Transmitter Transmitter type RF output power Spurious emission Modulation Deviation Input frequency Data input level Supply voltage Supply current Size & weight Antenna FSK modulation, PLL synthesiser 10mW + 0-3db at 50 ohm <-60dbm (at output terminal) FM narrow band 2KHz 10Hz to 2.4KHz CMOS or TTL 5v 3V to 12V DC <30mA (typical) 36 x 26 x 11mm, 11gms L/4 whip antenna Receiver Receiver type Sensitivity Selectivity Demodulation Distortion S/N ratio Data output level Other outputs Supply voltage Supply current Size & weight Double superheterodyne, PLL synthesised -120dBm (12dB/sinad, CCIT filter) khz at -6 db point FM narrow Less than 5% at 1 khz 35 db overall (AF output) Open collector (digital) RSSI (field power), AF (analogue output) 3.5 to 12V DC <30mA (typical) 50 x 30 x 7 mm, 18 gms Common Frequencies Baud rate Frequency stability MHz to MHz in 11 channels MHz to MHz in 32 channels 300 to 4800 baud FSK 5ppm (-10 to +55 c) CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 7 of 11

8 CDP-TX-02A Pin Description (Bottom View) Data In Antenna Vcc CDP-RX-02A Pin Description (Bottom View) AF Output Data Out RSSI Vcc Antenna Approvals Country Technical Guideline Approval No Frequency United Kingdom MPT MHz Germany BAPT 222 ZV 125 G G 434MHz Switzerland SR 784,103,12/1.19 BAKOM 96,0107,K,P 434MHz Sweden I-ETS Ue MHz Norway I-ETS NO R & 106R 434MHz CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 8 of 11

9 Application Notes Additional filters for optimum range performance For optimum range performance it is recommended that the supply and signal lines of the CDP-02 transmitter and receiver modules are de-coupled by low pass filters. This prevents any noise on these lines from entering the modules and ensures that digital or RF signals generated by the modules is not radiated by these lines. The CDP-02 modules employ high speed digital synthesisers that can generate such signals if the supply and signal lines are not well de-coupled from the surrounding circuitry. If not suppressed these signals can cause degradation in the very high performance that can be attained from these modules. Simple low pass pi filters offer greatly improved performance in attenuating such signals over mere capacitive de-coupling. They can be implemented either with ready built filter blocks or with discrete components for lowest cost. L CDP-02 C C In selecting component values consideration must be given to both attenuation and frequency response. Whilst the supply lines are not critical the signal lines should take into account the bandwidth of the signals. These are generally no greater than 5KHz. Surface mount inductors and capacitors provide can provide compact low cost filters whilst a commercial signal line noise filter that has been tried with success is the Murata NFV510-65STA106 available from Rapid Electronics. The filter circuitry should be mounted as close as possible to the module pins CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 9 of 11

10 Power Save Circuits for Battery Operation As both transmitter and receiver modules typically draw 30mA during continuous operation the power consumption of these devices can, in some cases, be a consideration for portable or hand-held applications. In the case of the transmitter power is applied to the module only during transmission time - typically 1-2 seconds. A typical usage of 20 transmissions per hour will then give a lifetime in excess of 9,000 hours, when using a Lithium PP3 cell. The receiver circuit must however be constantly powered, listening for data. This gives a battery lifetime of hours in a typical application, when a lithium PP3 cell is used. To improve this lifetime, the following power save circuit for the receiver is recommended: This circuit pulses the power supply to the receiver module, and then monitors the RSSI (Received Signal Strength Input) line to check for the presence of an RF carrier. If a carrier is present, the power supply to the module will lock on while the carrier is present. If there is not a carrier present, then the power to the module will be immediately switched off. The values shown above give a power duty cycle to the module of 1:16 (100mS ON, 1.6 S OFF) representing a significant battery life improvement. Due to the power up settling time of the receiver module, the minimum power on pulse length must be 90 ms. Using the above circuit, the transmit pulse must be set to a minimum duration of 1.8 seconds, to allow reception of the signal at any time. If a longer transmit pulse can be tolerated, then the duty cycle of the above circuit can be altered to match the transmit pulse length, giving a further improvement of battery lifetime. Care should be taken when selecting components for the power save circuitry, as these components are a constant drain on the battery. The 555 timer, ICM7555 used above (Harris) consumes only 60µA typically. The TS3V3V3 comparator (SGS-Thomson) has been specifically designed for use in battery powered applications, and will typically consume only 20µA. It should be noted that a reduction in receiver sensitivity will occur as a result of implementing this circuit. The sensitivity will reduce by at least 42%. However, field trials have proven that ranges in excess of 1.2kilometres are achievable with the power save circuit implemented. The current consumption of these devices can, in some cases, yield shorter than acceptable battery lifetimes for portable, hand-held applications. The transmitter module typically draws 18mA, while the receiver draws 10mA. CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 10 of 11

11 Evaluation kits An evaluation kit is available for these modules. This allows users to evaluate performance and suitability for purpose. Please contact the sales office for details. Product Order Codes Description CDP-TX-02A 458MHz Transmitter CDP-RX-02A 458MHz Receiver CDP-TX-02A 433MHz Transmitter CDP-RX-02A 433MHz Receiver Order Code LC-TX458F-SF LC-RX458F-SF LC-TX433F-SF LC-RX433F-SF Document History Issue Date Revision 1.0 Oct 1995 Preliminary 1.1 Jan 1996 LPRS version 1.2 Mar 1996 Module Pin out corrected 1.3 Apr MHz version only 1.4 Jul 1998 Updated. Application notes added Copyright The information contained in this data sheet is the property of Circuit Design Inc and copyright is vested in them with all rights reserved. Under copyright law this documentation may not be copied, photocopied, reproduced, translated or reduced to any electronic medium or machine readable form in whole or in part without the written consent of Circuit Design Inc. The circuitry and design of the modules is also protected by copyright law. Disclaimer LPRS has an on going policy to improve the performance and reliability of their products, we therefore reserve the right to make changes without notice. The information contained in this data sheet is believed to be accurate however we do not assume any responsibility for errors nor any liability arising from the application or use of any product or circuit described herein. This data sheet neither states nor implies warranty of any kind, including fitness for any particular application. For further information or technical assistance please contact: Low Power Radio Solutions A Division of The Quantelec Group Ltd. A MEMBER OF THE Two Rivers Industrial Estate Station Lane Tel: +44 (0) Witney Fax: +44 (0) Oxon. LOW POWER RADIO ASSOCIATION Web: info@lprs.co.uk OX8 6BH England. CDP-02 Operation Guide.doc Issue 1.4 LPRS Sep-98 Page 11 of 11