[Premium-Rx] software based IF spectrum monitor/panadapter?

[Gary Geissinger]

Eugene,

Actually the A/D doesn't have to convert at all that high a rate if the
sample and hold (or track and hold) are of sufficient quality relative
to a 455 KHz IF.

For a 455 KHz I prefer a 20 KHz sample rate.  It is very handy, because
it places a 455 KHz input in the middle of the sampled spectrum.  With
frequency folding, the frequency input range is 460 KHz to 450 KHz;
i.e., the spectrum is inverted.

Of course the inverted spectrum can be easily fixed, just invert the
sign of every other A/D sample.

If you look on Ebay you will see National Instruments A/D converter
boards (other vendors have them too) that plug into either the PCI or
ISA bus.  They come with software drivers.  Some of these can handle the
20 KHz sampling with a 0 to 500 KHz input bandwidth.  At most you may
need to amplify the IF output in order to match the conversion range of
the board inputs.

Good luck.  This is a fun project.  Given that you can find FFT (and
other spectral analysis codes) on the web for free, the pain level is
pretty managable.

Intentional undersampling is cool!

Regards,

Gary WA0SPM 



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-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Eugene Hertz
Sent: Tuesday, October 05, 2004 8:16 AM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] software based IF spectrum monitor/panadapter?


This discussion got me ta thinkin...

Anyone know of a spectrum analyzer software with some kind of ADC board
(ie higher freq than audio board) that can be connected to the IF out on
a receiver (say 455)??  I guess short of buying an expensive
pc-o;scope/spectrum analyzer..something simpler, you know, poor man's
pc-panadapter

Eugene



>-----Original Message-----
>From: Alberto di Bene [mailto:dibene at usa.net]
>Sent: Tuesday, October 5, 2004 08:41 AM
>To: premium-rx at ml.skirrow.org
>Subject: [Premium-Rx] RE: Receiver Frequency Display Accuracy & 
>Calibration
>
>"Gary Mitchelson - N3JPU" <n3jpu at speakeasy.net> wrote:
> 
>> MixW will display 1HZ resolution. Now this all
>>relays on the soundcard to be fairly accurate, and the USB and LSB 
>>oscillators to be set the same. But if the USB and LSB tone is the
same on 
>>the spectrum display I think you have it close. Then you can calibrate
the 
>>display. 
>> 
>> 
> 
><shameless-plug>
>In case you need a better resolution than 1 Hz you can try Spectran, 
>found here : 
>http://www.weaksignals.com 
></shameless-plug> 
> 
>73 Alberto I2PHD
> 
> 
> 
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>



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