NTX2

EW N Issue B, 17 March 2005 Radiometrix Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233 NTX2/NRX2 UHF UHF Narrow Band FM TX & RX RX The NTX2 transmitter and NRX2 receiver offer a low power, reliable data link in a Radiometrix SIL standard pin out and foot print. This makes the NTX2/NRX2 pair ideally suited to those low power applications where existing single frequency wideband UHF modules have insufficient range. Figure 1: NRX2-434.650-10 NTX2-434.650-10 Features • • • • • • • Conforms to ETSI EN 300 220-3 (radio) and EN 301 489-3 (EMC) Standard frequencies: 434.075MHz, 434.650MHz and 458.700MHz Custom frequencies available in 433MHz (EU) and 458MHz (UK) band Data rates up to 10kbps Usable range over 500m 25kHz Channel spacing Longer range compared to Wide Band FM modules Available for licence-exempt operation in the 433MHz (EU) and 458MHz (UK) bands, the NTX2 & NRX2 modules combine effective screening with internal filtering to minimise spurious radiation and susceptibility thereby ensuring EMC compliance. They can be used in existing low data rate (100mVpk-pk). The Enable pin allows the TX module to be turned on or off under 3V logic control with a constant DC supply to the Vcc pin. The module current in power-down mode is less than 1µA. The Enable pin should be tied directly to the Vcc pin if this facility is not required. TX modulation requirements The module is factory-set to produce the specified FM deviation with a TXD input to pin 7 of 3V amplitude, i.e. 0V “low”, 3V “high If the data input level is greater than 3V, a resistor must be added in series with the TXD input to limit the modulating input voltage to a maximum of 3V on pin 7. TXD input resistance is 100kΩ to ground, giving typical required resistor values as follows: Vcc ≤3V 3.3V 5V 9V Series resistor 10 kΩ 68kΩ 220kΩ NRX2 Received Signal Strength Indicator (RSSI) The NRX2 receiver incorporates a wide range RSSI which measures the strength of an incoming signal over a range of 55dB or more. This allows assessment of link quality and available margin and is useful when performing range tests. The output on pin 3 of the module has a standing DC bias of