Version List
Version List
Version List
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Transceiver module TRX433-10C2 / TRX868-10C2 (Vers. 1.0E) 17<br />
RSSI (Received Signal Strength Indicator)<br />
There is a voltage on pin 8 (RSSI) which is directly proportional to the RF - field strength. The transceiver<br />
scans the field strength every 3ms and outputs the RSSI-value as analogue voltage to pin 8.<br />
The voltage on the RSSI-pin follows this equation:<br />
Urssi<br />
1.5 * 3.3V<br />
PRF [dBm] = − 128 + * 127<br />
Zero-point by -128 dBm, Slope: 25.7dB/V, Measurement range -120…-60 dBm<br />
The RSSI-pin shows an internal resistance of ca. 10kΩ<br />
RSSI characteristic<br />
-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0<br />
Phf [dBm]<br />
Figure 16 Tension on RSSI-pin<br />
PRF can be read out digitally as a RSSI value with the command “READ RSSI current”, whereat the value is<br />
output directly in the twos complement in the unit dBm<br />
Examples: PRF = -128 dBm makes a RSSI of 128dec respectively 080H (under the noise floor)<br />
PRF = -120 dBm makes a RSSI of 136dec respectively 088H<br />
PRF = -110 dBm makes a RSSI of 146dec respectively 092H<br />
PRF = -100 dBm makes a RSSI of 156dec respectively 09CH<br />
PRF = -60 dBm makes a RSSI of 196dec respectively 0C4H (saturation limit)<br />
The maximal value of the RSSI will be saved by the transceiver (peak hold) and can be read out as well with<br />
the command “READ RSSI peak” as well. Every read operation of the RSSI peak initializes thereby the<br />
maximal value so that the maximal value represents the period between two read operations. The RSSI<br />
peak is initialized right after a sleep as well.<br />
The RSSI current and the RSSI peak go back to -128dBm during transmission<br />
3.50<br />
3.00<br />
2.50<br />
2.00<br />
1.50<br />
1.00<br />
0.50<br />
0.00
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