BHX2

EW N Issue A, 03 April 2008 Radiometrix Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233 BHX2 NBFM MultiNBFM Multi-channel 500mW UHF Transceiver The BHX2 transceiver module offers a 500mW RF power output in the UK 458MHz band. This makes the BHX2 ideally suited to those low power applications where existing multichannel narrow band devices like TR2M have insufficient range. Figure 1: BHX2-458-5-SMA Features Conforms to EN 300 220-3 and EN 301 489-3 Any 5MHz band module from 420 - 480MHz available as factory tuned custom variant High performance double superhet, 128 channel PLL Synthesizer with TCXO Data rates up to 5 kbps for standard module Usable range over 5km Fully screened Feature-rich interface (RSSI, automatic noise squelch, analogue and digital baseband) Incorporates a 1200baud dumb modem User configurable via RS232 interface Low power requirements Applications Handheld terminals Heavy vehicle/machine remote controls EPOS equipment, barcode scanners Data loggers Industrial telemetry and telecommand In-building environmental monitoring and control High-end security and fire alarms Vehicle data up/download Technical Summary Operating frequency: 458.5-459.1MHz Custom variants from 420MHz to 480MHz on any 5MHz band 23 channels in 458MHz band (128 channels max.) Transmit power: +27dBm (500mW) nominal Supply range: 5.5V - 15V Current consumption: 350mA transmit, 30mA receive Data bit rate: 5kbps max. (standard module) Receiver sensitivity: -118dBm (for 12 dB SINAD) Size: 85 x 39 x 13 mm (RF pin version) Radiometrix Ltd BHX2 Data Sheet page 1 Radiometrix Ltd BHX2 Data Sheet Figure 2: BHX2 block diagram page 2 Figure 3: BHX2 Footprint (Top) view User Interface Pins Name 1 TXE 2 3 4 5 6 7 8 9 10 11 12 13 TXD AF in RSSI SQF AF out RXD +4.4V out 0V PGM P1 P2 P3 Function Transmitter Enable. Low = ON, Open = RX mode. Internal 10kΩ pull-up to 4V DC coupled digital data input for 3-12V CMOS logic. Leave open if unused 50mV - 2.5v p-p AC coupled input. Variable gain DC level between 0.5V and 2.5V. 60dB dynamic range Noise operated carrier detect. Open collector. ON/low = no signal 200mVpk-pk audio. DC coupled, approx 1V bias. Muted by squelch Open collector output of data slicer suitable for Biphase codes Regulated DC supply. 75mA max. drain. Present if unit is powered Ground Serial programming/configuration input at RS232 level Parallel frequency select inputs. Inverted logic, internal 10kΩ pullups to 4.4V Notes: 1. BHX2 transmitter section inverts sense of the baseband stream, so a logical inversion is present between input of TX and output on RX 2. Carrier detect mutes the AF and DATA outputs. It can be disabled by rotating the level set trimmer fully ACW. 3. There are no pullups on the open collector outputs. 4. The sofware incorporates a 1200baud dumb modem, compatible with that implemented in TX2M, RX2M, TR2M, SMX2 and UHX2 radios ( i1200 tones and format ). 5. RS232 input pins (10 and 11) tolerate true +/- levels. No buffering is required. 6. This unit actually consists of a TR2C RF board and an AFS2-458 amplifier module, combined with a 5v LDO 7. In future versions of the software, pin 13 will have a modem handshake function 8. The BHX2 has the same footprint/pinout/function as the TR2M (TR2B), but the case is longer, and the RF output is a coaxial connector. Compared to an TR2M, the minimum supply voltage is higher (5.5v vesus 4.5v). Radiometrix Ltd BHX2 Data Sheet page 3 TXE (MOD TX_ON) (1) TXD (2) AF in (3) RSSI (4) SQF (5) 1kΩ (7) BHX2 RXD (8) +4.4V out GND (9) PGM (10) P1(11) P2 (12) P3 (13) AF out (6) Carrier Detect Transmit Enable ADC Host Microcontroller Data Out 6 7 8 9 Data In 10kΩ 100nF VDD Parallel Channel Select 2 3 4 5 TXD SGD Figure 4: BHX2 interfaced to host microcontroller and serial port for configuration BHX2 can be directly interfaced to a host microcontroller which can generally be powered by the regulated +4.4V output on pin 8 of BHX2. Three I/O pins on the microcontroller port can be assigned to select the first 8 channels on frequency table of the appropriate band for which the module is configured by pulling the P1-P3 pins low. Channel select pins of BHX2 have internal pull-up to 4V supply rail, hence channel selection operate on inverted logic. Channel 0 1 2 3 4 5 6 7 P3:P2:P1 111 110 101 100 011 010 001 000 458MHz band 458.525 458.550 458.575 458.600 458.625 458.650 458.675 458.700 Digital Received Data Output (RXD) pin is an open collector output, which should be pulledup to required voltage swing level (e.g. +4.4V or Vcc). BHX2 has an automatic noise squelching function which is activated when there is not any RF signal at detectable level on the channel or if the non-coherent noise like interference level is high enough to block any weak RF signal from being received. SQF is provided as an opencollector output for monitoring which should be pulled-up to required voltage swing level. SQF output will jump to pull-up voltage level if received RF signal level at the RF In/Out pin of the module is about 3dB below the level required to produce 12dB SINAD level on demodulated AF Output signal. SQF pin can be connected to an LED to act as a Carrier Detect indicator. Pull-up resistor value should be reduced (e.g. 1kΩ) according to the current requirement to produce satisfactory brightness on the LED used. BHX2 can be configured using any PC/Laptop/PDA having a serial port and modem/terminal program. TXD (pin 3) of DB9M connector can be directly wired to PGM (pin C10) of the BHX2 and SGN (pin 5) of DB9M connector should be either connected to common ground or pin C9 of the BHX2. The whole frequency/channel table is user reconfigurable to 128 channels within 5MHz band of supplied frequency subject to regulatory band limits. Serial Channel Selection via PGM pin gives access to the whole of regulatory band allocation for 458.525MHz-458.925MHz (23 channels). Radiometrix Ltd BHX2 Data Sheet page 4 PC serial port 1 Received Signal Strength 2.5 2.3 2.1 1.9 RSSI output (V) 1.7 1.5 1.3 1.1 0.9 0.7 0.5 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 RF Level (dBm) Figure 5: RSSI voltage variation with respect to RF level at BHX2 If the microcontroller has a built-in Analogue to Digital Converter (ADC), the Received Signal Strength Indicator (RSSI) output voltage level can be read by the microcontroller to estimate its distance from transmitting BHX2 unit or identify areas of weak signal reception. RSSI can also be used to make a decision to switch to the second antenna in fixed installations within building where the probability of null-spots are higher. Radiometrix Ltd BHX2 Data Sheet page 5 BHX2 serial configuration commands 2400 baud RS232. 8 bit data, no parity, 1 start bit, 1 or 2 stop bits, No flow control SINGLE nnnnn GOCHAN xx LOADMX xx Set value of N for single channel operation Serial select of channel xx (0 to 127) Set highest permitted (serial selected) channel xx (others default to ch0) LOAD aa nnnnn Set value of N for channel aa (channels 0 to 15) LOADTB nnnnn Set value of N for channel 16 (channels 17 to 127 then in sequence) RVALUE rrrr Enter value for R register SETPAR Channel selected by 3 bit parallel input (0 to 7). Disable modem SETSER Channel selected by most recent 'gochan' operation SETMOD Enable internal modem. Frequency selected by most recent 'gochan' or 'single' OFFSET Set receive frequency offset (for 25KHz this is 1800) GOTEST 250Hz test tone transmission Process entry / Clear all buffers xx = channel number from 00 to 127 aa = two digit channel number from 00 to 15 nnnnn = synthesizer N register value, (up to 65535) rrrr = synthesizer R register value, (up to 16383) N= f RF f Channelspacing = 458.525 MHz = 18341 25 kHz R= f TCXO f channelspacing = 13MHz , So R=520 25kHz On receive, the local oscillator operates at 45MHz (the first IF) below the carrier. An OFFSET value is subtracted from the channel's N value when the unit is switched into RX OFFSET = First IF / Fc, so, OFFSET = 45MHz / 25KHz = 1800 (usually) Notes: 1. A pause of at least 50ms must be allowed between command strings (EEPROM programming time) 2. SINGLE mode does not store the N value in EEPROM. Therefore the unit is inoperative after a power down until either another valid SINGLE command is received, or mode is changed by a GOCHAN, SETPAR or SETSER command. SINGLE mode is intended for frequency agile applications. 3. /SETPAR command should be issued at the end of channel programming to put the module back into parallel frequency select mode 4. In 458MHz band, channel 12 (458.825MHz) and channel 15 (458.900MHz) are allocated specifically for fixed alarm and radio keys/vehicle paging applications respectively and should not be used for general purpose applications. 5. User can modify the frequency table of 128 channels to any desired frequency by changing N, R values of synthesizer within ±2.5MHz of factory set Channel 0 frequency subject to the Radio Regulatory Band Allocation in the country of intended use. 6. All other frequency, power, analogue input gain and automatic noise squelching adjustment will be treated as custom variants of the module to be set by factory. Radiometrix Ltd BHX2 Data Sheet page 6 Pin description of BHX2 with Modem mode selected The 'modem' mentioned is a 1200 baud RS232 semi-intelligent unit (Transmit keyed when valid serial data is present, so no separate TX control needed. Coding in the datastream also permits the receiver to ignore noise and only output valid serial data). This is a half duplex unit, so collisions between transmitted and received packets must be dealt with by the user. Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 Name MOD TX_ON MOD NC MOD NC RSSI MOD NC AF out NC +4.4V out 0V PGM MOD TXD MOD RXD MOD NC Function Open = normal modem operation. Low = constant TX (for test). 10k pullup to 4V Leave open Leave open DC level between 0.5V and 2.5V. 60dB dynamic range Leave open Modem tones or noise present Leave open Regulated DC supply. 75mA max. drain. Present if unit is powered Ground Serial programming/configuration input at RS232 level RS232 data input (true). 10k pullup to 4V Inverted RS232 data out (to inverting buffer like MAX232) Leave open BHX2s on both ends should be configured to required operating frequency using GOCHAN command before starting to use the internal 1200 baud modem, because the P1-P3 pins will be used as Modem Data pins and the modem will operate on the last serially selected channel after SETMOD command is used to enable the Modem. TXE (MOD TX_ON) (1) TXD (MOD NC) (2) AF in (MOD NC) (3) RSSI (4) SQF (MOD NC) (5) AF out (6) RXD (MOD NC) (7) Serial COM Port 6 SW1 VDD 7 8 9 1 2 3 4 5 SGD +4.4V out (8) GND (9) PGM (10) BHX2 RXD TXD P1 (MOD TXD) (11) P2 (MOD RXD) (12) P3 (MOD NC) (13) RS232 driver Note: Baud rate used for Modem is half that of used for serial configuration. Attached RS232 devices should be set with the following: 1200bps, 8 Data bits, No Parity, 1/2 stop bits, no flow control TXD (Pin 3) of a Serial Port can be switched from PGM (Pin C10) to MOD TXD (Pin C11) with no RS232 driver in between. However, MOD RXD (Pin C12) requires an RS232 line driver before it can be connected to RXD (pin 2) of a serial port. Some of the RS232 line drivers can be powered from the regulated +4.4V out (Pin C8). Radiometrix Ltd BHX2 Data Sheet page 7 Figure 6: BHX2 interfaced to PC serial port in modem mode Condensed specifications Frequency Frequency stability Channel spacing Number of channels Transmit Output power TX on switching time Modulation type TX modulation bandwidth Adjacent channel TX power Inputs Receive Sensitivity image / spurious blocking adjacent channel Outputs Spurious radiations Power on to valid audio Power on to valid audio Power on to stable data out (50:50 mark / space) Supply Voltage Current 458.5-459.1MHz (any 5MHz band from 420-480MHz) and any 3MHz band from 210 – 270MHz +/- 1.5kHz 25kHz (12.5kHz by special order) 128 channels controlled via RS232 interface (8 parallel selected) +27dBm (500mW) ±1dB 50 ms FM, FSK (F1D, F3D) DC – 3kHz -37dBm analogue, data (CMOS/TTL compatible) -118dBm for 12 dB SINAD -70dB -85dB