Need for Anticipatory Time Offset

2 posts / 0 new
Last post
N7AIG
Offline
Last seen: 7 months 3 weeks ago
Joined: 2010/06/17 - 08:10
Need for Anticipatory Time Offset

Hi,

Using a Flex-3K here, with seemingly high latency through the sound-card interface. That latency is needed to keep the system running properly in the face of sometimes long (e.g., 7 ms) interrupt handling delays in Win/7 on the laptop.

As a result, I'm sensing that my reported DT values, and those reported on me, are systematically longer by the unknown latency. My clock is updated every 15 minutes and sync'd to the Naval Observatory clock, so I know my system clock is within 25-30 ms of being correct. But my DT values tend to average around 0.1-0.3 s.

[BTW, running WSJT7 in parallel with WSPR, and listening to my own monitor signal from the Flex-3K during transmissions, WSJT7 is reporting my DT to myself as 0.0 - 0.7 s. That should represent two trips of the audio through the buffer latency. Not sure why it reports 0.0 (rarely) but most often about 0.3 s]

Hence, in order to compensate for these latency delays, we need to have some kind of anticipatory time offset in the WSPR program so that it will start transmitting and recieving just a few hundred ms before the clock time says "go".

de N7AIG