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[linrad] RE: Bamboozled by bandwidth

Thanks Lief I can see that I will have a lot of fun with a narrow bandwidth first and no doubt will graduate from there.

Really appreciate all your work and responsiveness.

Hi Ron,

 Just getting going here and have read all the QEX articles with great
 interest. I am bewitched, bothered and bewildered over the question
 of bandwidth requirements.
 It would be useful to see a display of activity taking place in the
 frequency spectrum of interest for example my operation is almost
 exclusively in the low 25 kHz of the HF CW bands.  When in QSO I only
 need a 100 Hz or so and I note that Leif states that  large
 bandwidths are primarily required for noise reduction functions but
 that increases the problems of dealing with large in-band signals.
Absolutely. If you do not have local QRN at your QTH, then you should
use an ordinary SSB transceiver and run Linrad without the second fft.

 Given a high performance HF radio (mine is a Ten-tec Omni pro) with
 100 Hz  Xtal filtering, linrad DSP and a 16 bit sound card what's to
 be gained by more elaborate hardware measures that increase bandwidth
 ? What am I missing ?
You will miss what happens 10kHz away. The pattern on the waterfall
display when something interesting occurs (pileup) is very characteristic.
If you do not care - and if you do not need the blanker, use some 486
computer from the junk yard and run Linrad only for baseband processing.
(If you can figure out how to get Linux running on an old computer)


Leif  /  SM5BSZ