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NRF52833 - phase-based distance measurement feasible?

Our group is trying to use the NRF52833DK do phase-based distance estimation as described in the attached paper. To do this we want to transmit packets with constant tone extensions at different frequencies and look at the way the phase of received CTE waveforms varies with distance between transmitter/receiver. We have had trouble doing so and we think this is because each time we change the frequency, the radio must be disabled and re-enabled and the phase of carrier waveforms is not preserved.

Is it possible to transmit packets at different frequencies in such a way that for each packet the phase of the output of the transmitter either has a consistent offset some constant time before the beginning of a packet, or varies in a continuous way as the frequency is changed, i.e. for a sequence of increasing frequencies, the phase of the carrier waveform would look like a continuous piecewise linear function with a slope that increases each time the frequency increases?

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  • We have had trouble doing so and we think this is because each time we change the frequency, the radio must be disabled and re-enabled and the phase of carrier waveforms is not preserved.

    I can see this may be a problem yes, but unfortunately I am not aware of any other suggestion that try the different radio features in the datasheet: https://infocenter.nordicsemi.com/topic/ps_nrf52833/radio.html

    Maybe enabling shortcut between PHYEND event and START task can improve the situation? Since PHYEND is generated when the last bit is sent on air (or in case of RX: The last bit on air is received), while END event is related to byte received/fetched from RAM. You may also try Fast mode in MODECNF0 in case that is better (40us instead of 150us).

    Best regards,
    Kenneth

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  • We have had trouble doing so and we think this is because each time we change the frequency, the radio must be disabled and re-enabled and the phase of carrier waveforms is not preserved.

    I can see this may be a problem yes, but unfortunately I am not aware of any other suggestion that try the different radio features in the datasheet: https://infocenter.nordicsemi.com/topic/ps_nrf52833/radio.html

    Maybe enabling shortcut between PHYEND event and START task can improve the situation? Since PHYEND is generated when the last bit is sent on air (or in case of RX: The last bit on air is received), while END event is related to byte received/fetched from RAM. You may also try Fast mode in MODECNF0 in case that is better (40us instead of 150us).

    Best regards,
    Kenneth

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