[time-nuts] EFC tracking

Steve Rooke sar10538 at gmail.com
Sat Jun 26 14:00:24 UTC 2010


On 27 June 2010 01:49, Oz-in-DFW <lists at ozindfw.net> wrote:

> Soundcards have inputs and outputs.  You can feed the output with a
> series of samples that represent your control waveform.  The PC becomes
> the oscillator and you know it's frequency and relative phase track.


> Chopping is used to cancel DC offsets in imperfect amplifiers, it adds
> no gain. If there is a DC component and you filter with a cutoff
> frequency below the chop rate, the offsets of the amplifier can be
> effectively canceled.

OK, I understand that. I'm not so sure this is the original problem I
would have but thinking about it now I wonder if the chopped signal
would end up being symmetrical with my original proposal as there is
likely to be some small offsets thinking about it now. I could resolve
this in software by sampling over a full cycle period of the chopper
and then do averaging of the RMS readings.


> --
> mailto:oz at ozindfw.net
> Oz
> POB 93167
> Southlake, TX 76092 (Near DFW Airport)
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Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein

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