SR500 RECEIVER OPERATING INSTRUCTIONS 1892 1211 These operating instructions are intended to provide the user with sufficient information to install and operate the unit correctly. The Wood & Douglas SR500 UHF synthesized receiver is intended to fulfil numerous OEM applications by virtue of its highly flexible synthesized design approach, miniature size and cost-effective performance. The unit complies with MPT1329 and as such does not require an operating licence in the UK.
DIMENSIONS AND FIXING The unit is intended for PCB mounting within the customer’s equipment. Figure 1 - SR unit dimensions and connectors 2 1892 1211 - SR500 Receiver Operating Instructions - 2.
CONNECTION Connection to the unit is via PL1, PL2 and PL3 which plug directly into the user's own equipment. The location of these connectors is shown in Figure 1 and detailed in the following tables. PIN NAME 1 0V 2 FUNCTION 0 volts RF I/P RF input 3 0V 0 volts REMARKS common ground 50O input common ground Connector PL1 pin detail PIN NAME 1 +VIN 2 0V FUNCTION REMARKS positive supply +6.0V to +14.
OPERATING FREQUENCIES Each radio is made to order to cover a band (the switching bandwidth) of 5MHz within the range 400 - 470 MHz. Each radio is also manufactured to work within a particular channel width of 12.5kHz, 20kHz or 25kHz. Within the switching bandwidth, the unit can operate on any frequency provided it is a multiple of the channel width, and up to 128 frequencies can be stored as numbered channels.
STSRn00 Programmer v.1.0.21 Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan Chan 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 458.5 458.5125 458.525 458.5375 458.55 458.5625 458.575 458.5875 458.6 458.6125 458.625 458.6375 458.65 458.6625 458.675 458.6875 Start table 458.7 Max. Freq. 458.95 Table step 1 x 12.5 MHz << MHz MHz MHz MHz MHz MHz MHz MHz MHz MHz MHz MHZ MHz MHz MHz MHz MHz kHz Comparison freq. 12.5 kHz Ref. (TCXO) freq. 12.
PROGRAMMING THE UNIT Three steps are necessary: v v v Upload values from the unit Edit the values Download values to the unit Uploading Current Unit Settings (F5) First, you must read into the computer what is in the unit’s memory at present. To do this, press F5. The data replaces the default on the screen. v The program insists that you do this before allowing you to reprogram the unit to make it less likely that inappropriate values be entered.
Press then move the highlight to Table Step and type in the spacing between channels in multiples of the Comparison Frequency shown at the top right. For example, if the Comparison Frequency is 12.5kHz, enter 2 for a spacing of 25kHz. v Make sure that the Start and Maximum frequencies are within the switching bandwidth of your unit, as the software cannot prevent you from programming inappropriate values. Press .
Channel Selection Mode (F7 and F4) Having programmed frequencies into the channels, you can specify which channel to use (channels 0-127) or that the channel will be selected by parallel logic levels (channels 0-7 only). The unit defaults to serial channel selection whenever it has serial communications, which includes whenever the STSRn00.exe software communicates with it. To select serial control, and a channel from 0-127 (which will be used until further commands are received), press F7.
CHANNEL SELECTION DURING OPERATION There are three ways to select a channel during operation: v v v In hardware, using three logic lines to select channels 0-7 Using the STSRn00.exe software and a serial connection from a PC to the unit By sending a short serial data message to the unit from your own equipment. Parallel Channel Selection v The unit must have been left in parallel mode when it was programmed (F4).
Serial Channel Selection (own equipment) If you want to select a channel using serial mode from your own equipment rather than using the supplied software, then you must use this protocol: 1200 baud, RS232 levels, 1 start bit - 8 bit data - no parity - 1 stop bit and send the following data sequence to the RS232 input, allowing at least 5ms between the characters in the data stream: x40 (decimal 64) synchronising code Channel number in hex (decimal 0 to 127) (in bits 0-6, msb = 0) x95 (decimal 149) confirma
RANGE INFORMATION The following table gives an indication of the typical ranges to be expected between a transmitter and receiver that have simple end-fed dipole antennas.
TECHNICAL SPECIFICATION Frequency range Switching bandwidth Frequency stability Number of RF channels : : : : RF channel selection : Channel switching delay Channel spacing Modulation type Spurious emissions (conducted & radiated) Supply voltage Supply current at 7.
APPENDIX: TTL TO RS232 ADAPTOR Many PCs do not require true RS232, and will work with the simple adaptor of Figure 3. The transistor used must have a gain of at least 30. Figure 3 - Simple programming adaptor Figure 4 shows the circuit of an adaptor providing true RS232 for readback when programming a unit. Figure 4 - Programming adaptor (True RS232) 1892 1211 - SR500 Receiver Operating Instructions - 2.
A suitable inverting TTL to RS232 buffer circuit using the industry-standard MAX232 part is shown in Figure 5. Figure 5 - Suggested RS232 buffer circuit The MAX232 is obtainable from many component suppliers, e.g. RS Components stock no. 655-290. Wood & Douglas Ltd, Lattice House Baughurst, Tadley, Hants, RG26 5LP Tel:+44 (0)118 981 1444 Fax: +44 (0)118 981 1567 email: sales@woodanddouglas.co.uk website: www.woodanddouglas.co.
