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Some questions on nRF52811 documentation

Dmitry

I'm studying nRF52811 manual, there are moments not clear to me:


1. Is I/Q sampling paused during SWITCHING slots? For example, if I configure 16 1-msec slots (8 switching + 8 sampling) with 125us sampling period, I'll get 64 or 128 samples?
2. TSAMPLEOFFSET is described as "Signed value offset before starting sampling in number of 16M cycles relative to the beginning of the REFERENCE state - 12 us after switching start". I'm completely lost... maybe you could describe this in other words to help me understand?
3. Can I use energy detection feature just for energy detection for custom 1-MBit protocol, not 802.15.4?
4. There is a note in radio electrical specification: "Typical sensitivity applies when ADDR0 is used for receiver address correlation. When ADDR[1...7] are used for receiver address correlation, the typical sensitivity for this mode is degraded by 3 dB". Is this because 1..7 are correlated sequentially? if so, can I be sure that sensitivity won't drop when I fill addresses 1..7 with the same value (I need only two addresses)?

Thanks

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  • +1

    Hi

    1. The range of I/Q samples depends on the AGC during the packet. It could be that the signal is so strong in this case that the gain is lowered a lot. Difficult to say from the description. One could separate the two devices and see if the I/Q sample range increases.
    2. The settings are very different to what we typically use for the BLE specification and I got confused about the switching slot/state. For the BLE spec typically SWITCHSPACING = SAMPLESPACING and then there is no sampling in switching slots. In general there is sampling in the Reference period and in the "Switching period" (i.e. switching and sample slots). We should probably have called it "Switching state" to align with the DFESTATUS register description. The 1us skip is expected, as it skips like that to ensure the switching period starts at the same place even with different sample settings.
    3. The documentation is a work in progress, and we will take your notes into account! For now, keep this value at 0 or 1, as these are the recommended values. Thanks for your input.

    Best regards,

    Simon

Reply
  • +1

    Hi

    1. The range of I/Q samples depends on the AGC during the packet. It could be that the signal is so strong in this case that the gain is lowered a lot. Difficult to say from the description. One could separate the two devices and see if the I/Q sample range increases.
    2. The settings are very different to what we typically use for the BLE specification and I got confused about the switching slot/state. For the BLE spec typically SWITCHSPACING = SAMPLESPACING and then there is no sampling in switching slots. In general there is sampling in the Reference period and in the "Switching period" (i.e. switching and sample slots). We should probably have called it "Switching state" to align with the DFESTATUS register description. The 1us skip is expected, as it skips like that to ensure the switching period starts at the same place even with different sample settings.
    3. The documentation is a work in progress, and we will take your notes into account! For now, keep this value at 0 or 1, as these are the recommended values. Thanks for your input.

    Best regards,

    Simon

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