LR1110
User Manual
Rev.1.0
UM.LR1110.W.APP
March 2020
59 of 130
Semtech
8.3.7 GetPacketStatus
The command
GetPacketStatus( )
gets the status of the last received packet. Since the returned values are modem
dependent, the description hereafter is valid only for the LoRa® modem.
•
RssiPkt
defines the average RSSI over the last packet received. RSSI value in dBm is –RssiPkt/2.
•
SnrPkt
is an estimation of SNR on last packet received. Expressed in two’s complement format multiplied by 4. Actual
SNR in dB is SnrPkt/4
•
SignalRssiPkt
provides an estimation of RSSI of the LoRa® signal (after despreading) on last packet received. In two’s
complement format [negated, dBm, fixdt(0,8,1)]. Actual Rssi in dB is -SignalRssiPkt/2
Additional information on the RSSI can be found in section
Section 8.7 "RSSI Functionality" on page 69
.
8.4 (G)FSK Modem Description
8.4.1 (G)FSK Modulation Principle
The (G)FSK modem is able to perform transmission and reception of 2-FSK modulated packets over a range of data rates
ranging from 0.6 kbps to 300 kbps.
Both the bit rate (
Bitrate)
and frequency deviation (Fdev) are directly configured using the command
SetModulationParams()
.
Additionally, in transmission mode, several shaping filters can be applied to the signal in packet mode or in continuous
mode. In reception mode, the user needs to select the best reception bandwidth depending on its conditions. To ensure
correct demodulation, the following limit must be respected for the selection of the bandwidth:
Where the bandwidth BWF ranges from 4.8kHz to 467kHz.
The bandwidth must be chosen so that:
where the frequency error is two times the frequency error of the crystal oscillator used.
Table 8-15: GetPacketStatus Command
Byte
0
1
Data from Host
0x02
0x04
Data to Host
Stat1
Stat2
Table 8-16: GetPacketStatus Response
Byte
0
1
2
3
Data from Host
0x00
0x00
0x00
0x00
Data to Host
Stat1
RssiPkt
SnrPkt
SignalRssiPkt
2
Fdev BR
+
BWF
Bandwidth[DSB]
BR
2 frequency deviation frequency error
+
+
