On which radio?
On a SoftRock the QSD mixer with a 48KHz sampling rate, it converts
a 48KHz window of RF centered on the clock frequency down to audio in
a +-24KHz range, the "IF" of the radio moves around as you listen to
different frequencies, it's not a fixed place. For example;
If your detector frequency (clock) is at 7.040KHz,
and your listening to 7.050MHz, your IF is 10 KHz
if you are listening to 7.060MHz your IF is 20 KHz
if you are listening to 7.030MH your IF is 10 KHz but you are
listening to the negative image.
If you want a bigger window, you would increase the sampling rate of
the audio card to 96KHz, then your window would then become +-48KHz
from the QSD oscillator frequency.
On a radio like the SDR-1000 it tries to keep the IF at approximately
11KHz by moving the clock frequency, but if the requested frequency
would generate a lot of spurs, it changes the DDS frequency a little
bit to get rid of the spurs and adjust the IF frequency slightly to
end up on the requested frequency.
At 08:57 AM 3/8/2006, you wrote:
>In order to double the bandwidth of an SDR, say from 20Khz ro 40Khz
>wouldn't you also have to double the IF from 12Khz up to 24Khz (or at
>least 22Khz)?
>
>JR
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>Yahoo! Groups Links
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Cecil Bayona
KD5NWA
www.qrpradio.com
I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time ...
[Non-text portions of this message have been removed]
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