NTR2 RADIOMETRIX [Radiometrix Ltd], NTR2 Datasheet - Page 5

• Manufacturer Part Number: NTR2
• Description: UHF Narrow Band FM Transceiver
• Manufacturer: RADIOMETRIX [Radiometrix Ltd]

Applications information
Power supply requirements
The NTR2 has built-in regulator which deliver a constant 2.8V to the module circuitry when the external
supply voltage is 2.9V or greater, with 40dB or more of supply ripple rejection. 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 >100mV
TX modulation requirements
The module is factory-set to produce the specified FM deviation with a TXD input to pin 9 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 9. TXD input resistance is 100kΩ to ground, giving
typical required resistor values as follows:
NTR2 Received Signal Strength Indicator (RSSI)
The NTR2 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 <0.5V with no signal, rising to 2V at maximum
indication.
Typical RSSI characteristic is as shown below:
Figure 3: RSSI response curve
Radiometrix Ltd.,
3.3V
Vcc
≤3V
5V
9V
Series resistor
220kΩ
10 kΩ
68kΩ
-
NTR2 transceiver data sheet
pk-pk
).
Page 5