Issue 2, 9 July 2014 NTX2B /NRX2B UHF Narrow Band FM Transmitter & Receiver The NTX2B transmitter and NRX2B receiver offer a low power, reliable data link in a Radiometrix SIL standard pin out and foot print. This makes the NTX2/NRX2B pair ideally suited to those low power applications where existing single frequency wideband UHF modules have insufficient range. Figure 1: NTX2B & NRX2B Conforms to ETSI EN 300 220-2 (radio) and EN 301 489-3 (EMC) Standard frequencies - 434.075MHz, 434.650MHz and 458.700MHz Factory programmable custom frequency (425 - 470MHz). No crystal lead-times User programmable custom frequencies on 433MHz (EU) and 458MHz (UK) bands Data rates up to 10kbps Usable range over 500m 12.5kHz / 20kHz / 25kHz Channel spacing (factory set) Feature-rich interface (true analogue and/or digital baseband) Longer range compared to Wide Band FM modules EPOS equipment, barcode scanners Data loggers Industrial telemetry and telecommand In-building environmental monitoring and control High-end security and fire alarms DGPS systems Vehicle data up/download. Technical Summary Transmitter – NTX2B       Fully integrated sigma-delta PLL synthesizer based design High stability TCXO reference Supply 2.9V - 15V @ 18mA (internal 3.0V LDO voltage regulator) Data bit rate: 10kbps max. Transmit power: +10dBm (10mW) Dimensions 43 x 15 x 5mm (fully screened) Receiver – NRX2B  Fully integrated sigma-delta PLL synthesizer based design  SAW front-end band pass filter, image rejection: >60dB  Supply range: 2.9V - 15V @ 17mA (internal 2.8V LDO voltage regulator)  Data bit rate: 10kbps max.  Receiver sensitivity: -118dBm (for 12dB SINAD) / -112dBm (for 1ppm BER)  Dimensions 47 x 17 x 8mm (fully screened) Evaluation platforms: Uni-Eval or NBEK + SIL

Functional description The NTX2B transmitter consists of a highly integrated sigma delta (fractional N) synthesizer based single chip RF device, configured over an SPI serial bus by an on-board microcontroller. The primary frequency reference for the transmitter is a 26MHz VC-TCXO. Modulation is applied directly to this reference via an AF baseband filter (rather than using the chip's internal modulator) to permit a wider range of baseband data rates and waveforms. Operation is controlled by the EN (Enable) line, the transmitter achieving full RF output typically within 5ms of this line being...

Absolute maximum ratings Exceeding the values given below may cause permanent damage to the module. Operating temperature Storage temperature Performance specifications: NTX2B transmitter (Vcc = 3.3V / temperature = 20C unless stated) General DC supply Supply voltage TX Supply current (10mW) Power down mode Antenna pin impedance RF RF centre frequency NTX2B-434.650-10 NTX2B-434.075-10 NTX2B-458.700-10 Channel spacing Number of channels RF power output (10mW) Spurious emissions Adjacent channel TX power Frequency accuracy Peak FM deviation (25kHz channel) Baseband Modulation type Modulation bandwidth...

NRX2B receiver The NRX2B receiver consists of a highly integrated sigma delta (fractional N) synthesizer based Local Oscillator (LO), configured over an SPI serial bus by an on-board microcontroller. The primary frequency reference for the LO is a 26MHz VC-TCXO. The RF input is filtered using SAW front-end filter to improve image rejection and blocking performance. SAW filter reduces user programmable frequency range to passband, but factory programmable frequency bands are determined by SAW filter availability. Title: EAGLE Drawing Y:/Products/NRX2B/NRX2B_bloc.sch Creator: EAGLE Preview: This...

Absolute maximum ratings Exceeding the values given below may cause permanent damage to the module. Operating temperature -20C to +70C Storage temperature -30C to +70C NRX2B Vcc, RXD (pins 7,9) En, RSSI, AF (pins 4,5,8) RF in (pin 1) Performance specifications: NRX2B receiver (Vcc = 3V / temperature = 20C unless stated) pin DC supply Supply voltage Supply current RF/IF RF centre frequency NRX2B-434.650-10 NRX2B-434.075-10 NRX2B-458.700-10 Frequency stability Number of channels RF sensitivity @ 12dB SINAD RF sensitivity @ 1ppm BER RSSI threshold RSSI range IF bandwidth Blocking Image rejection...

Channel Programming At the heart of the device is a fractional N synthesizer locked to a high stability VCXO. The minimum step size of this PLL is (approximately) 12.4Hz The data required by the PLL consists of two coefficients: the integer (INTE) and the fraction (FRAC). Output frequency relates to these values thus: FRAC  2  VCTCXO  Freq   INTE  19   Outdiv 2   NTX2B, NRX2B uses 26MHz VCTCXO and Output Divider (Outdiv) value for 425MHz-525MHz band is 8. For correct operation, the component (FRAC / 219) must have a value between 1 and 2 FRAC   Freq   INTE  19   6.5 2    ...

When programming the NTX2B/NRX2B, keep in mind that the unit maintains in SRAM the current values of all programmable values (frequency, band of operation, RF power and frequency offset adjustments values) and that toggling the NTX2B EN/PGM pin does NOT erase or corrupt them. These values are only loaded from EEPROM at cold start power-up (but not when the NTX2B EN/PGM pin is cycled) There is one "write all values to EEPROM" command. It is usually necessary to load the relevant current operating RAM value(s) and THEN issue a suitable command to write the RAM value to EEPROM. The NTX2B and NRX2B...

Serial interface commands NTX2B PGM serial interface consists of an 9600bps, 8 data bits, No Parity, 1 Stop bit, 0V-3V level Inverted RS232 (UART) datastream applied to the EN/PGM pin (the idle state of the interface will turn the transmitter on) NRX2B PGM serial interface consists of an 9600bps, 8 data bits, No Parity, 1 Stop bit, 0V-5V level RS232 (Inverted UART) datastream applied to the AF/PGM pin (if a PNP open collector drivers is used then the idle state of the interface will not affect the AF output levels) Every command string starts with the phrase "@PRG_" and terminated with Carriage...