Why is there a maximum consecutive transmission time?

RE: Why is there a maximum consecutive transmission time?

Wojtek — Wed, 05 Apr 2017 13:38:02 GMT

Thanks Steve! Actually, I worked that out some time ago. The problem I had was with the custom board layout. One of the signals was routed under xtal and it caused clock phase jitter, resulting in broken transmissions. After fixing that, it worked continuously indeed :)

RE: Why is there a maximum consecutive transmission time?

Steve H — Wed, 05 Apr 2017 13:31:26 GMT

Wojtek, I know this is an old thread but I just found this blog entry which says:

On nRF51, TX mode was limited to a maximum of 16ms which was dependent on crystal accuracy.
On nRF52 TX mode can be used continuously without any limitations or need to switch it off.

RE: Why is there a maximum consecutive transmission time?

Wojtek — Fri, 21 Oct 2016 17:51:03 GMT

does that also apply to nRF52? there is nothing in product specification, so i assume not, but I am havving issues when transmitting for a long time without going to DISABLED state (but thay may be caused by something else)

RE: Why is there a maximum consecutive transmission time?

ovrebekk — Mon, 02 May 2016 11:11:10 GMT

There is no limit in RX mode, you can stay there as long as you like. If the RX is being disabled every 1ms it must be software controlled, unless it is the packet reception itself you are seeing.

RE: Why is there a maximum consecutive transmission time?

Scott — Mon, 07 Mar 2016 20:36:24 GMT

What about the RX channel? I am seeing a disable every 1 ms while in Rx mode.

RE: Why is there a maximum consecutive transmission time?

ovrebekk — Thu, 12 Nov 2015 09:19:08 GMT

Happy to help :)

RE: Why is there a maximum consecutive transmission time?

Tim — Tue, 10 Nov 2015 14:09:39 GMT

Makes perfect sense, thanks!

RE: Why is there a maximum consecutive transmission time?

ovrebekk — Tue, 10 Nov 2015 14:01:01 GMT

Hi Tim

The radio in the nRF51 runs in a so called "open loop" mode. This means that the carrier frequency is calibrated using the 16MHz clock at the start of the packet, but after that it is left to drift to save power. If the TX runs too long in open loop mode it might drift so far that the receiver can not receive the incoming packet. With a more accurate crystal the initial frequency is more accurate, and it takes more time for the frequency to drift outside the limits.
Yes.
At some point the link will break because the TX and RX frequencies are too far apart.

Best regards Torbjørn