[time-nuts] EFC tracking
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
> POB 93167
> Southlake, TX 76092 (Near DFW Airport)
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
More information about the time-nuts