2024-01-18 04:43 AM - edited 2024-01-22 11:31 PM
Hello,
my setup consists of 2 NUCLEO-WL55JC1 boards and an adapted version of the example project SubGHz_Phy_Per with which I can recognize the number of bit errors, RSSI of the latest received packet and some interrupts (IRQ_RX_DONE, IRQ_PREAMBLE_DETECTED, ..) using Serial Wire Viewer and STMViewer.
Modulation is 2GFSK.
Tx-Node sends every 10 ms a packet with 80 bytes.
Overview of modulation and packet parameters:
My calculations of Rx BW and Tx Fdev refer to Semtech SX1261/2 RF Transceiver Datasheet (p.43, LoRa Connect Transceiver, SX1261, +15dBm for Global Coverage | Semtech).
(2*Fdev + BR) < BW
I am aware that the bit error rate depends on the SNR. I don't understand why numerous packet losses occur, even over short distances (indoor) and acceptable RSSI, screenshot from STMviewer:
Packet Loss increases for much too small or large BW, which is understandable.
What possible mistakes have I made?
If you need further information, I can of course add it.
2024-01-23 11:23 PM
Hello @altoleoi
The packet losses depend on a few characteristics (modulation, TX_OUTPUT_POWER...). Also, it can depend on different external characteristics such as the electromagnetic interference, the Antenna gain, ...
I suggest you try to use a direct line of sight (LOS) between both boards and increase the TX_OUTPUT_POWER to the max value.
Best Regards.
STTwo-32
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2024-01-24 07:43 AM
Hello @STTwo-32,
thank you for your reply.
The board is delivered with an omnidirectional compressed whip / stubby antenna with a gain of 2dBi (should be ANT-SS900), which "[...] is stuck to the SMA connector because of FCC constraints". "[...] the FCC implies that the antenna must be stuck to the board connector with epoxy glue" (UM2592 - Rev 2, p. 27), therefore there is no possibility to change the antenna to increase the receiver gain.
Due to regional regulations, the ERP is limited to a maximum of 14dBm (13.98dBm).
Unfortunately, the required application does not guarantee LOS.
Best Regards
altoleoi