Spectrogram - Linear or Log scale?

[Darwin, Keith]

I've read through the instructions for aligning filters using Spectrogram.  IIRC, they say to set the X axis to linear.  Shouldn't it be set to log?  I think the difference will be using Linear, you'll have your passband skewed a bit to the low side.
 
- Keith KD1E -
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[Alexandru Csete]

Keith,

I am not familiar with this particular case, but usually people only
want to use log scales when the data range spans over many decades. If
you take the logarithm of your data the decades become equidistant, in
other words, the "distance" between 1, 10, 100, 1000, ... will be the
same. Therfore, I don't see any reason why someone would want to have
log scale on the X axis in a signal strength vs. frequency graph. Your
frequency range spans 2 decades or so, if it is AF.

You may, on the other hand, want to try logarithmic scale on the Y
axis. The signal strength can indeed span several decades.

Taking the above into consideration I would also expect the passband
of a filter to be symmetric if you use linear X axis and skewed if you
use logarithmic X axis.

73
Alex OZ9AEC

On 3/10/06, Darwin, Keith <[hidden email]> wrote:
> I've read through the instructions for aligning filters using Spectrogram.  IIRC, they say to set the X axis to linear.  Shouldn't it be set to log?  I think the difference will be using Linear, you'll have your passband skewed a bit to the low side.
>
> - Keith KD1E -
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[Don Wilhelm-3]

Kieth,

I set the X axis (freauency scale) to linear because it is easier to read.
Yes, the passband will go off the right of the screen with the default scale
settings - I change the 'Band (Hz)' parameter in the right side of the setup
screen to show from 200 to 2956 Hz when aligning the 2.6 kHz wide filter and
it all shows on the screen.

73,
Don W3FPR

> -----Original Message-----

>
> I've read through the instructions for aligning filters using
> Spectrogram.  IIRC, they say to set the X axis to linear.
> Shouldn't it be set to log?  I think the difference will be using
> Linear, you'll have your passband skewed a bit to the low side.
>
> - Keith KD1E -
>

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