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

[Simonr]

Hi Dmitry

Sorry for the late reply, but it took some digging and asking around to find all the answers.

1. There is no IQ sampling during switching slots.

2. TSAMPLEOFFSET is one of the two start offsets for direction finding, and is the offset value in number of 16MHz clock cycles after the reference period (see figure 71 in product specification).

3. Energy detection is featured in the IEEE 802.15.4 operation, yes.

4. There is a correlator which can only operate on ADDR0.  It cannot work on 8 addresses in parallel.  Therefore only ADDR0 will be demodulated with a 3dB gain while the others will not.  Putting addresses in ADDR[1..7] does not degrade ADDR0 sensitivity. So sensitivity shouldn't drop when only filling it with 2 addresses.

Best regards,

Simon

[Dmitry]

Thanks Simon!