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[Linrad] Re: Question : tune the band with the mouse wheel
- Subject: [Linrad] Re: Question : tune the band with the mouse wheel
- From: Leif Asbrink <sm5bsz.com; leif@xxxxxxxxxxxxxxxx>
- Date: Mon, 6 Apr 2009 11:03:37 +0200
> In fact I believe we need a complete redesign of the way the center
> frequency and span setting are done under Linrad , in my opinion , it is
> very rougth way to manage frequency , changing span to zoom around a QRG is
> too long with the arrows and recating counter intuitive also the window
> changing width when tuning is annoying..
It seems I failed to explain how Linrad is intended to be used.
You are NOT supposed to change either zoom or frequency range in the
main spectrum while using Linrad as a receiver. Those controls
are intended to be set to fit the hardware you are using. The main
spectrum should normally show the full bandwidth of your system.
Use the hardware frequency control to select what frequency range to show.
Supported hardwares (WSE, SDR-14, SDR-IQ and Perseus) can be controlled
with the frequency control box. Add what is needed to control other
hardwares in users_hwaredriver.c
Tune like this:
1) Click near the desired signal in the main waterfall or main spectrum.
2) Fine tune by clicking the signal you want in the high resolution
spectrum which immediately becomes zoomed around the point where you
have clicked the main spectrum. The zoom width is set by the fft2
bandwidth for the current receive mode.
For CW that is all. Normal CW would use a bandwidth where finer tuning
would not make a difference, weak CW would use AFC and tune better
than you could do manually.
In SSB it is different. Set a suitable step size and use the mouse wheel
or the arrows. There are three tuning modes: BFO, frequency and passband.
> Why not adopt the same than others
> SDR softwares : You enter span and center QRG , and click on teh QRG U want
> to get AF from?
The main spectrum is there because the operator is supposed to want
to know that the blanker works properly and to generally have information
about strong signals that enter his passband and that might cause problems.
The colouring (red points) in the main spectrum conveys important information
and it is a bad idea to zoom the main spectrum so you would not know.
I think the two-step point and click of Linrad is much faster and more
accurate than procedures used in other softwares. Set a suitable averaging
for fft2 and note that the spectrum is based on the average when you release
the button after a click in the main spectrum. It means that when you see
a SSB signal in the main waterfall you click near its center. On release
the high resoultion graph will immediately show the averaged power spectrum
in a suitable scale (something like 3 cm wide on the screen) and it is
then easy to click the center to get a good enough tuning.
In the time it takes to move the mouse from the main spectrum to the
high resolution graph you should already have heard enough to know
in which direction you want to go, and roughly by how much. That information
tells you on what side of the center line in the high resolution graph
to click - and roughly by how many Hz away from it. It may be a good idea
to be a bit conservative here, if you click 100 Hz from the center line
the frequency will shift by 100 Hz. Clicking once more will shift another
100 Hz. Clicking either side of the center line is another way of doing
> Of course , mouse support with wheels would be good addition.
The mouse wheel tuning rate (step size) can be changed with plus or
minus. The same step size is used for the arrow keys. The step
size is displayed in the upper right corner of the baseband graph.
Another way to change the step size is to turn the wheel while it
It would be possible to make the initial adjustment of the main spectrum
easier (much easier) but it is not trivial so I would need a couple
of voices and a better motivation why zooming the main spectrum
would be useful during receiving.
Leif / SM5BSZ
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