RX1-151.300-10 RADIOMETRIX [Radiometrix Ltd], RX1-151.300-10 Datasheet - Page 5

• Manufacturer Part Number: RX1-151.300-10
• Description: VHF Narrow Band FM High Power TX
• Manufacturer: RADIOMETRIX [Radiometrix Ltd]

Power supply requirements
The TX1H has a built-in regulator which delivers a constant 3.5V to the transmitter circuitry when the
external supply voltage is 3.5V or greater. This ensures constant performance up to the maximum
permitted rail, and removes the need for external supply decoupling except in cases where the supply
rail is extremely poor (ripple/noise content >0.1V
TX modulation requirements
The module is factory-set to produce the specified FM deviation with a TXD input to pin 14 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 100k
giving typical required resistor values as follows:
Expected range
Predicting the range obtainable in any given situation is notoriously difficult since there are many
factors involved. The main ones to consider are as follows:
The following are typical examples – but range tests should always be performed before assuming that
a particular range can be achieved in a given situation:
Note:
The TX1H’s TXD input is normally driven directly by logic levels but will also accept analogue drive
(e.g. 2-tone signalling). In this case it is recommended that TXD (pin 14) be DC-biased to 1.2V approx.
with the modulation ac-coupled and limited to a maximum of 2V
The varactor modulator in the BiM1 introduces some 2
necessary by predistortion of the analogue waveform.
Although the modulation bandwidth of the TX1H extends down to DC it is not advisable to use data
containing a DC component. This is because frequency errors and drifts between the transmitter and
receiver occur in normal operation, resulting in DC offset errors on the receiver’s audio output.
Radiometrix Ltd.,
Type and location of antennas in use
Type of terrain and degree of obstruction of the link path
Sources of interference affecting the receiver
“Dead” spots caused by signal reflections from nearby conductive objects
Data rate and degree of filtering employed
Data rate
1.2kbps
10kbps
10kbps
10kbps
The figure for 1.2kbps assumes that the receiver bandwidth has been suitably reduced by
utilising an outboard sallen-key active audio filter and data slicer or similar arrangement.
Tx antenna
half-wave
half-wave
helical
helical
Applications information
Rx antenna
3.3V
Vcc
5V
9V
half-wave
half-wave
half-wave
3V
TX1H high power transmitter data sheet
helical
Series resistor
p-p
).
urban/obstructed
220k
10 k
68k
Environment
nd
in-building
rural/open
rural/open
-
harmonic distortion which may be reduced if
p-p
to minimise distortion over the link.
500m-1km
100-200m
10-15km
Range
3-4km
to ground,
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