Good morning I agree that 1deg is overkill but I was simply extrapolating one extra decade from BOB kb8tq's "backing off a bit" comment where he got down to 10deg. :-)
10MHz is an obvious sample rate - sorry, that fell into a blind spot here! I think I will get distracted over Christmas sketching out some designs ... Thanks - John -----Original Message----- From: Poul-Henning Kamp [mailto:[email protected]] Sent: 4 December, 2018 11:03 PM To: Discussion of precise time and frequency measurement <[email protected]>; John Moran, Scawby Design <[email protected]> Subject: Re: [time-nuts] new WWVB BPSK dev board -------- In message <am0pr03mb4129fbd0922805fc14b8cefde4...@am0pr03mb4129.eurprd03.prod.outlook.com<mailto:am0pr03mb4129fbd0922805fc14b8cefde4...@am0pr03mb4129.eurprd03.prod.outlook.com>>, "John Moran, Scawby Design" writes: >However, fast A-Ds are not particularly cheap and you would need circa >50MHz sample rate to resolve 1deg of the carrier, and TVB has already >stated that there are no time benefits to BPSK, so this is all just an >interesting technical exercise, isn't it? I admit it would be interesting to do the allan variance on it, but measuring the carrier to 1 degree in every single cycle is waaaaay overkill. 1 MHz sampling rate is fine, but go for 5 or 10 MHz so you can drive the ADC directly from your house-standard. And BPSK *does* improve the timing, because you can very precisely measure when the change of phase happens, and it since it happens at a carrier zero-crossing you can filter it down to +/- sample. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [email protected]<mailto:[email protected]> | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
