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  • Case ID: 330059
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Unable to perform IQ sampling normally

honghuahh

SW version :2.4.0
HW revision: nRF52833 development board, PCA20054 Direction Finding Antenna Board 1_0_0
I use the routine director_finding_central  and  director_finding_periopheral for IQ sampling, and can obtain IQ sampling data.
When I put the original
static const uint8_t ant_patterns[] = { 0x2, 0x0, 0x5, 0x6, 0x1, 0x4,
0xC, 0x9, 0xE, 0xD, 0x8, 0xA };
Change to
static const uint8_t ant_patterns[] = { 0xC, 0x9, 0xE, 0xD, 0x8, 0xA,
0x2, 0x0, 0x5, 0x6, 0x1, 0x4 };
The Bluetooth connection will disconnect, making it impossible to perform normal IQ sampling.
May I ask why this situation has occurred?


Below is the serial port output

  • 0

    I did some tests.

    When static const uint8_t ant_patterns[] = {0xC, 0x9, 0xE, 0xD, 0x8, 0xA,
    0x2, 0x0, 0x5, 0x6, 0x1, 0x4 };

    The position of the two boards is shown below. The central can collect some IQ data, and the packet CRC ERROR often occurs. After a period of time, the connection will be disconnected


    Then move the central position to the position shown in the figure, and the connection will immediately disconnect,

    and IQ data cannot be collected

     

    But when I used the original

    static const uint8_t ant_patterns[] = { 0x2, 0x0, 0x5, 0x6, 0x1, 0x4,
    0xC, 0x9, 0xE, 0xD, 0x8, 0xA };

    central is in the top two positions, the connection and IQ sampling are normal, this phenomenon is very strange, why the connection is related to the order of antenna switching

  • 0 in reply to honghuahh

    Hi,

    We have received your query, and the ticket will be assigned to one of our engineers. Please bear that it may take few days to get an answer as we have high load during this time.

    Apologies for inconveniences.

    Regards,

    Naeem

  • 0 in reply to Naeem Maroof

    I use this  ant_patterns and  gpio，it cannot establish a connection

    But when I change the order of gpio, it works  well

    It's possible that gpio28 and gpio29 have different features compared to gpio3 and gpio4, or pcb design issues

    Have you made any progress on this issue now?

  • 0

    Hi

    Have you set this custom antenna pattern on both sides of the connection or just on the central side? How have you connected the antenna array to the nRF52833 DK on your end? The different antennas are connected to specific antenna switches, so they need to match in order to switch correctly. So when you change the antenna pattern without changing the switch pattern they won't match and likely cause these CRC errors. Is there a specific reason you're playing around with the antenna switching patterns here?

    Best regards,

    Simon

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