RE: nRF905 Tx to Rx Delay and Jitter

Max — Wed, 21 Jun 2017 16:33:39 GMT

It would be possible to shorten the delay by timestamping the CD(Carrier Detect) event. And then validating the time when DR is asserted. That way you could say "this packet arrived n us ago"

However a better approach would be to use a synchronization protocol. Something similar to what is done with NTP(Network Time Protocol).

RE: nRF905 Tx to Rx Delay and Jitter

Jon Gunnar — Mon, 28 Oct 2013 11:48:03 GMT

I think you have misunderstood the way the nRF905 works. The data you clock in on the TX SPI as a packet payload will be buffered inside the radio until you initiate the transmission by pulling TRX_CE high. On the RX end, you will be notified by the DR (data ready) signal when a valid packet is received completely.

The time it takes from you pull TRX_CE high on the TX side until you get a DR on the RX side is dependent on your packet length since the whole packet has to be received by the RX before you get DR high. Chapter 10 in the nRF905 Product Specification gives you the details on how to calculate this. For a packet with 4 bytes address, 1 byte CRC and 1 byte payload, the time is 650us + 200 us + ((4+1+1)*8)/50000b/s =1810us. The variation of this time can be as high as +/-20us.