SR450 RECEIVER OPERATING INSTRUCTIONS

Transcription

1 SR450 RECEIVER OPERATING INSTRUCTIONS These operating instructions are intended to provide the user with sufficient information to install and operate the module correctly. The Wood & Douglas SR450 receiver is intended to fulfil the numerous OEM applications by virtue of its highly flexible design approach, miniature size and costeffective performance. The unit complies with MPT1329 and as such does not require an operating licence in the UK. It is also approved to various EC specifications. VARIANTS FREQUENCY RANGE (MHZ) CHANNEL SPACING 12.5kHz 20kHz 25kHz The SR450 is available in two frequency bands and channel spacings as detailed in the table. The code designations form part of the product variant type given on the label fixed to the top screening cover of the module.

2 INSTALLATION The SR450 is intended to fit easily and with minimum space requirements into the user's own equipment housing. The complete module is housed within a tin-plated enclosure and is secured by means of four No 4 self-tapping screws which locate in the four corners through the lower screening cover. DO NOT overtighten these screws during assembly.

3 CONNECTIONS The radio antenna connects by means of a SMB miniature coaxial connector. All other connections to the SR450 receiver are made using a standard 9-way D type connector (PL1) or a 10 way header PL2 as detailed in the table below. D-TYPE PL1 10-WAY PL2 NAME FUNCTION REMARKS 1 1 0V supply 0 volts common ground 2 3 SQF 3 5 RSSI squelch output (open collector) S meter output (optional) 4 7 AUDIO audio output 50mA NPN to ground (ON under no signal conditions). Internal 10kS pull-up to 5V 5 9 +Vin + positive supply +6V to +15V nominal 6 2 CS0 channel select (LSB) 7 4 SQ DIS squelch disable 8 6 CS1 9 8 RXE channel select (MSB) receiver enable (active low) not connected - 0 to 3V output proportional to the received RF signal level. Rout =1kS 600mV p/p AC coupled Rout = 1kS Note: the output audio is inverted with respect to the ST450 (or similar Wood & Douglas product) audio input high >4V (or floating internal pull-up), low <0.8V, leave floating for normal operation 0V (or <0.5V) inhibits all squelch operation high >4V (or floating internal pull-up), low <0.8V RS232 level serial programming input Note: Inverted TTL level data can also be used. If not used, leave not connected or connect to 0V high >4V (or floating) Receiver OFF low <1V Receiver OPERATIONAL

4 CHANNEL SELECTION The SR450 offers one of 4 channels in parallel mode selection and one of 100 channels in serial mode selection. PARALLEL MODE In parallel mode, the channel is selected via the inputs applied to PL1 pin 6 and PL1 pin 8. The channel select inputs are a binary representation of the channel number as shown in the table. SERIAL MODE PIN 6 PIN 8 CHANNEL HIGH HIGH 1 LOW HIGH 2 HIGH LOW 3 LOW LOW 4 In serial mode the required channel is programmed using a serial input word (0 to 99 inclusive) at 9600 baud RS232 level applied via PL1 pin 8. Mode selection is also achieved through the serial port. Transmission of character 160 (decimal) selects parallel mode/reset and transmission of character 161 (decimal) characters three times, (to avoid accidental selection), selects serial mode/reset. Frequency assignment/channel numbering can be reprogrammed using the SPROG software (available separately).

5 OPERATING MODES To provide maximum flexibility, a number of options are available via links (as detailed in the figure and table below) which allow users to configure the SR450 according to their own requirements. Flat audio response Audio de-emphasis (-6dB per octave) Data output DC-coupled analogue output that bypasses squelch gate Disable mute (bypasses squelch gate) PL3 PL4 PL5 pin 1 pin 2 pin 1 pin 2 pin 3 pin 4 pin 5 pin 1 pin 2 pin 3 NOTE: The squelch flag remains operative when muting is disabled Figure 3 Link Positions

6 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. The following assumptions have been made in the calculations: line-of-sight between antennas 0dB gain for the transmitter and receiver antennas 0dB loss for connectors and cables between the antenna and the radio connector 20dB fade and environmental margin -100dBm received signal strength, allowing for digital and analogue signals Range versus TX power Frequency (MHz) Power (mw) Power (dbm) Range (km) mW mW mW mW

7 TECHNICAL SPECIFICATION Frequency range : 430 to 470MHz (contact Wood & Douglas for 350 to 500MHz operation) Number of RF channels : 4 maximum using two bit parallel input 100 channels programmed using asynchronous serial input Channel spacing : 12.5, 20kHz and 25kHz Modulation type : F1D/F2D/F3D Sensitivity : >-115dBm for 12dB SINAD (Flat audio response) Image rejection : >70dB Intermediate frequencies : 21.4MHz and 455kHz Conducted spurious : <2nW (-57dBm) at any frequency Recovered audio level : 600mV p/p (+/-20%) into 10k ohms Squelch type : Noise operated Squelch status : open collector NPN 50mA max output (on under no signal condition) RSSI option : output 0 to 3 volts (1kS) : dynamic range 50dB Supply voltage : +6 to +15 volts DC Supply current : 45mA Size : 113 x 57 x 22mm (l x w x h) Weight : 110g Operating temperature : -10 to +55E C Storage temperature : -30 to +70E C Wood and Douglas Ltd, Lattice House, Baughurst Road, Tadley, Hampshire RG26 5LP Tel: +44(0) Fax: +44(0) /February 2000