RX packets overlap (SoftDevice is not used)

[Stanislav Silnitskiy]

Hi,

I have three beacons in my setup: One listening (R1) and two transmitting (T2, T3). T2 and T3 transmit packets with same length.

Say, T2 has started transmission of its packet and at R1 is now receiving it. A little bit later, T3 has started to transmit its packet and it is now suppressing the packet from T2.

here is a stack of questions I have:

1. Does RSSI will influence the outcome of receipt in R1?
2. if yes, in which situation R1 will receive CRC Error and CRC OK events and which packet will be received in case of CRC OK?
3. Will the length of packet influence the situation somehow?

Please also refer me to documentation, in the case it had been described somewhere.

[Hung Bui]

Hi Stanislav,

1. Yes, if the signal strength from T3 is strong enough to interfere with the signal from T2.

2. Most of the case R1 will receive CRC Error. It will receive CRC OK if by coincident the interfered packet managed to have the correct CRC. The more byte the CRC the smaller chance that R1 miss-detect the interference.

3. Yes, the shorter the packet length the bigger the chance the packet can get to R1 without being interfered.

[Stanislav Silnitskiy]

Hi Hung, If RSSI from T3 is stronger enough, does it mean, that RADIO will just "forget" address bits, etc. already received from T2? And if I "listen" to ADDRESS event, does it mean, that it will be triggered twice?

[Hung Bui]

When the radio is receiving the packet, the ADDRESS matched event will only occurs once. The radio works with a state machine, after the address is matched it will process to the payload. The receiver won't be able to detect the packet from T3, and simply gets an manipulated signals that it assumes coming from T2.

[Stanislav Silnitskiy]

OK. Its clear, Thank you!