Receiver section
pin
13
13
13
13
min.
typ.
-
300
1.0
1
max.
7.8
400
1.75
10
units
kHz
mV p-p
V
notes
-10 version
Note 5
Baseband bandwidth @ -3dB
AF output signal level
DC offset on AF output
Distortion on recovered AF
Ultimate (S+N)/N
0
200
0.3
-
-
-
Note 6
Note 7
-50dBm RF input
%
dB
pF
13
12, 13
40
-
-
Load capacitance, AF & RXD
100
Dynamic Timing
Rx power up with signal present
Power up to valid RSSI, tPU-RSSI
Power up to valid CD, tPU-CD
Power up to stable data, tPU-data
Power up to stable data, tPU-data
11
11
12
12
-
-
-
-
1
1.5
5
-
-
10
30
ms
ms
ms
ms
-64 version
-10 version
10
Signal applied with Rx on
RSSI response time (rise/fall)
Signal to stable data, tsig-data
Signal to stable data, tsig-data
11
12
12
-
-
-
100
5
5
-
10
30
µs
ms
ms
-64 version
-10 version
Allowable time between data
transitions
Allowable time between data
transitions
14
14
14
15.6
0.1
20
-
-
1500
15
µs
ms
%
-64 version
-10 version
Note 8
Averaged code mark:space
50
80
Note: 1. Increases at high RF input level (>-20dBm)
2. See page 6 for further details
3. For specified FM deviation
4. Tx select low > full RF output
5. ±30kHz FM deviation
6. Min/max at ±50kHz offset
7. Max at ±50kHz offset
8. Average, at max. data rate
Application Information
Modulation formats and range extension
The module will produce the specified FM deviation with a 2-level digital input to TXD which toggles
between 0V and 3V. Reducing the amplitude of the data input (to the TXD pin) from this value reduces
the transmitted FM deviation, typically to ±20-22kHz minimum at 2.7V. The receiver will cope with this
quite happily and no significant degradation of link performance should be observed.
TXD 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) should be DC-biased to 1.5V with the modulation AC-
coupled and limited to a maximum of 3V peak-to-peak. The instantaneous modulation voltage must not
swing below 0V or above 3V at any time if waveform distortion and excessive FM deviation is to be
avoided – use a resistive potential divider and/or level shifter to accomplish this if necessary. The
varactor modulator in the transmitter introduces some 2nd harmonic distortion which may be reduced if
necessary by predistortion of the analogue waveform.
At the other end of the link the AF output (pin 13) can be used to drive an external decoder directly.
Although the module baseband response extends down to DC, data formats containing a DC component
are unsuitable and should not be used. This is because frequency errors and drifts between the
transmitter and receiver occur in normal operation resulting in DC offset errors on the AF output.
Radiometrix Ltd, BiM2A Data Sheet
page 5
RADIOMETRIX [ RADIOMETRIX LTD ]
