[time-nuts] Performance verification for time counters
kb8tq at n1k.org
Thu Nov 30 09:39:59 EST 2017
Sweep the transfer function from 100 Hz down to 0.001 Hz at 50 points per decade.
Spend enough time at each point to get to 0.001 db sort of accuracy. The first decade
goes pretty fast. That last decade ( 0.01 Hz period to 0.001 Hz) …. not so much. The
request always has both the silly frequency and the nonsense db fraction in it ….
> On Nov 30, 2017, at 3:29 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> In message <42A2F881-1631-402C-8ED6-2C863F6FEE71 at n1k.org>, Bob kb8tq writes:
>>>> Needless to say *demonstrating* this 0.001 db sort of gain flatness on a repeater
>>>> out to crazy low frequencies is a bit involved. It *is* a great gig if you happen to be
>>>> a consultant …
>>> demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) precision in *any* application is a bit involved. That's 0.03%
>> Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. great way to waste a lot of time.
> Sorry, I don't see the challenge: HP3458A in sampling mode, careful cabling, done.
> At RF frequencies where you have to think about impedance however...
> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG | TCP/IP since RFC 956
> FreeBSD committer | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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