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5 years ago.
SX1276 Poor performance at 433 MHz band
We have a problem with SX1276MB1MAS and ST32F411RE Nucleo boards. The PingPong tests at 433 MHz band are very poor in range, compared to 868 MHz
With a spectrum analyzer we can detect a well formed FSK spectrum signal with power levels of -70 dBm near the receiver board. But the demodulator receives the frames with errors. The theoretical sensitivity is about -105 dBm. The band is a bit more noisy in 433MHz, but this not explain this diference in range compared to 868 MHz.
We have corrected some issues in SX1276PingPong mbed application. One of those is that in callback function "OnTxDone" from DIO0 isr, it needs a delay of 2 mseconds before sending the transceiver to sleep. If this wait is not implemented, the transmitter could be sleeping when is yet transmitting the CRC bytes and the receiver could detect a CRC error. This bug seems that is only affecting to 433MHz.
However, even with the improvements, behavior at 433 MHz remains worse than expected.
Is there any error in SX1276 transceiver at 433MHz that is not documented in the errata-sheet? Has anyone experimented this behaviour in 433MHz?
Question relating to:
5 years ago.
The SX1276 shield 433MHz output has been checked as well as the code. We are unable to reproduce the issue listed. A few items could be verified to get more information. These items are: 1. Measure the output level directly at the antenna? Is the antenna on the LF side? Are you using a 433MHz antenna? Does the issue occur on another type of Nucelo board? Have you tried a second SX1276 shield to remove the possibility of a board problem?