Re: [K3] Spectrogram and the K3

Posted by Don Wilhelm-4 on Jul 09, 2012; 11:22pm
URL: http://elecraft.85.s1.nabble.com/K3-Spectrogram-and-the-K3-tp7558874p7558911.html

Great suggestions.

If you want to see the phase relationship, take a look with Audacity.

Audacity is an editor for audio files, but can be made to work in real
time too (see the help files).
It will show both channels like an oscilloscope.

There are other audio tools that can be either fun or useful in
analyzing many signals in the audio spectrum.  Spectrum Lab,
Spectrogram, Audacity, and Total Recorder are favorites of mine.
There are also Audio Signal Generators that are helpful at my workbench
(but also in the shack at times) - F-G Lite serves most of my purposes,
NCH Function Generator is better, but will only run for a while before
you have to purchase it.

73,
Don W3FPR

On 7/9/2012 6:47 PM, Al Lorona wrote:

> When you look at Delay1 through 5 in MONO mode in Spectrogram you see peaks and
> nulls in the frequency response. Spectrogram is only able to show the magnitude
> and not the phase of signals, so from what was learned from AFX = Bin we saw
> that the result of adding L + R as vectors can result in cancellation.
>
> Similarly in Delay1 through 5 we are seeing the L and R noise signals adding
> together and cancelling each other out at regular intervals -- resulting
> in nulls in the frequency response. The *spacing* between the nulls can tell us
> something. I measured the spacing as follows:
>
> Delay1 :  500 Hz
> Delay5 :  100 Hz
>
> The nulls are caused by two signals, L and R, at the same frequency but shifted
> in time, and as they combine their vector sum causes the nulls. The time delay
> between L and R is easy to calculate based on our measurements:
>
> Delay1 = 1/500 = 2 msec
>
> Delay5 = 1/100 = 10 msec
>
> That's my best guess as to the actual delay values.
>
>
> Al  W6LX
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