Radiometrix Ltd, TXM Data Sheet

page 5

The TXM-UHF transmitter requires only a data modulation input, supply, ground and an antenna.

Power supply requirements

• The module will operate over the range 6V to 9V and is typically powered by either 9 Volt 'PP3'.

• The module is not reverse polarity protected. Reverse supply voltages higher than 2V will cause

damage and must therefor be externally protected against.

Modulation requirements

• The TXM-UHF transmitter has a DC to 10kHz modulation bandwidth and will accept direct

analogue (AFSK) or digital data. A modulation low-pass filter (10kHz @ -6dB, 1st order) is use

internally.

• Although the modulation bandwidth of the transmitter extends down to DC as does the AF output of

the receivers, it is not possible to pass data with a DC component due to frequency errors & drifts

between the transmitter and receiver. Frequency differences between the transmitter and receiver

will produce a DC offset error which causes the data slicer in the receiver module to give errors on

long high or low pulses which exceed the maximum pulse width, see the receiver's data sheet for

more detailed information.

figure 4: TXM 10kbps version test circuit

figure 5: Typical performance curves