[linrad] Re: Knoppix CD audio

["Rein A. Smit" <rein0zn@xxxxxxxxxxxxx>]

   Hello Mike,

 From your email to Leif, I understand that you have access to a 2 meter 
Beacon. That is even
better than cw signals from some HF band. You know at least that the 
signal is always there,
though the local field strength may vary.

By tuning your 2 meter receiver, you should be able to get a nice beat 
note from the beacon,
A good value should be in the 500 to 1200 Hz range to start. Remember 
you are monitoring and watching
a narrow spectrum band. In the wide band mode the spectrum would be 10 
or 20 times wider.

I think it is more beneficial to learn to play Linrad in this mode than 
going wide band with a lot of other variable
some of them might be unknown when you start to use Linrad.

On the left side of your display, just by loading the W3SZ CD, you 
should have 2 windows.
The bottom is the wide freq display How wide depends among other 
parameters from your sampling
speed of the read sound card. For audio signals from a receiver you 
might as well match the audio spectrum,
probably given by the band width of the IF channel in your rx,  1.8 to 
2.7 kHz perhaps in SSB .

On the top of the other window you will see the lower and upper freqs 
limits of that spectrum. Bottom
window being the wide band , it shows freq. vs signal strength on a log 
scale as in a spectrum analyzer.
The top widow has the same freq. range as the wide band but the signal 
strength is given by the color
at any given time. With the 2 numbers of  the top window( right side) is 
it possible to set the average color level
I like to have  that level such that I see here and there a spot in the 
field for a constant noise level
from your receiver output level. As soon as signal above this noise 
level appears you will see a change
in color.. This needs some adjusting. AS you can set the detection level 
too high. In that case you will see
only the strongest signals,  On the other hand you can set it too 
sensitive and you will see the a screen
full of noise signal. It it is like the baseline and span on a recorder.

So now you have detected a signal in that 3 kHZ wide spectrum.

You got a window ( wide ) and now you are going to move another ( narrow 
window )
perhaps 100 Hz wide , depending on other settings and you place that 
narrow window where
the signal is . This is done by clicking with the mouse in either 
window. Now you feed
the desired signals to the later stages of the processing in Linrad.

This is like pass band tuning in the top of the line receivers. This 
only works a lot better

Once  you have selected the signal with the cursor, make sure that the 
wide squire marker is somewhere in the
middle of the filter window ( enter bottom ) of your computer display, 
If the spot is not in the middle Use the
slider perhaps hidden ( red line or bar on the right side of the white 
marker about 1/4 " ) drag the bar up or down
so that you see the white marker somewhere in the middle of that window 
( left side) By now you should be hearing
the signal or noise background.

If you hear the cw signal, you can use the "bfo" to let it sound the way 
you like it. Move red vertcal line 100,
10 and 1 time sweep.What you do here is design the audio part of the 
receiver. It keeps the differnce
beween the 2 cursors constant in terms of audio output. I.e., you can 
move the 1st in the wide
freq. spectrum and the 2 second will follow so that the beat not remains 
constant. A good measure
of band pass tuning.

 From here on you should start using the Linrad keys file,  And make 
copies of the QEX articles. They are
on Leif's web page. 

The best is just using the written articles and a known weak signal as 
that 2 meter beacon.  Learn what
effect the different parmeters have. The default settings are for the 3 
modes SSB, normal CW and weak-signal
cw.

This is my personal opinion. Linrad is a tool that one has to learn to 
play as a music instrument.
And that will take some doing or rather listening. It is not a black box 
with an on/off switch.
Because of the output presentations it is possible not only ot hear what 
the system is doing for
you, but also to see what is happening.

I like here in the evenings to monitor the IARU 20 meter beacons at 
14100 kHz . Are they there?
How many and which beacons? Wonderful. With the event of JT65 and the 
JT65 board you should be
able to see signals almost al the time when the moon is above the 
horizon. Do antenna testing, pre amp
work,  learn Linrad and so on and so on. Of coarse 6 meters is another 
world,  MS, airplane reflections
and many other applications

73 Rein W6/PA0ZN



Mike(W5UC) & Kathy(K5MWH) wrote:

> Rein, Good Morning and thanks for the input.
>
> I will go look at that today.  I think I understand the controls you 
> are speaking about, but will print this and take it to the shack with 
> me.  It will be a while before I can try it, as It is expected to rain 
> later in the day, and I have some Honey-do's to take care of before 
> that happens. If you are not familiar with Honey-do's,  that is when 
> your wife says, Honey do this, and Honey do that, etc.
>
> 73,
> Mike
>
>
> At 08:57 PM 5/13/2005 -0700, you wrote:
>
>>   Hi Mike,
>>
>> The first message went out by accident! Phone call broke u the 
>> internet here and it slipped through! Soory
>>
>> You must have a receiver there, Tune the receiver to a signal on 40 
>> or 80 and make sure you hear a cw
>> signal in your headphone or speaker.. Connect  the output audio of 
>> your receiver, headphone or what have
>> you and watch the cw signal  on the frequency display of linrad. You 
>> should see a  peak being modulated by the
>> signal ( 300 - whatever Hz  most likely 3000 Hz)  You might also see 
>> the pass band of your receiver or the xtal filter.
>> There  will be a higher noise level over limited width of the display (
>> 1.8 Khz or 500 Hz wide band.)
>> When you do this, set your sampling rate of your read card section to 
>> 6000 Hz or 8000 Hz., your output
>> card is probably running at 48 kHz. sampling rate.
>>
>> If you see this put the cursor on the center of this peak or on the top.
>>
>> A vertical line should be visible over the peak. Having made this 
>> selection your
>> audio. from the sound card should start if all is OK.
>>
>> Try a peak height of 10 scale Divs. above the noise , the base line.
>>
>> Look now at your filter display, middle of screen, in particular the 
>> left side
>> of that display. You might see a red line or block. This is a slider. 
>> Turn up
>> the slider with your cursor. On that side of the display should also 
>> be a little
>> white block, Turn the slider so that the white block is in the middle 
>> of the
>> display being moved by the audio. If you turn the slider too high , 
>> the spot will turn
>> red , overload.
>> If you see this white spot moving and the sound card is properly set, 
>> you should hear
>> audio ( cw or a constant tone for a carrier ). In that same window 
>> you should see a red
>> line straight or broken in 3 pieces. This is an oscillator ( BFO 
>> adjustment) Again move the bottom of the
>> middle section of that red line and change the beat frequency of the 
>> incoming signal. like a normal bfo
>> in a receiver ( boat ancker )
>>
>> Is easier to do this testing with a defined signal  from your 
>> receiver than from a HF mixer/LO
>> source at this point
>>
>> If you are lucky and 40 is open you might see other carriers or cw 
>> signals in the same display.
>> side by side
>>
>> In this mode you have a spectrum analyzer , sweeping 3 or 4 KHz  of 
>> audio
>>
>> In my first installation I had the white spot sittng at the bottom 
>> and no audio.!
>> Even after many questions answerd here
>>
>> If you listen to noise, again you should see that block moving with  
>> the noise signal at the point of your cursor
>> line in the spectrum
>>
>> I think even if you were to have a problem with the output of the 
>> sound card you should see the
>> white dot moving. If you see the audio signal on the display you have 
>> your own tool to bootstrap
>> to a operational system.
>>
>> If you know all this already, pse ignore this email. l
>>
>> 73 Rein W6/PA0ZN
>>
>>
>>
>>
>>
>>
>>
>>
>> Mike(W5UC) & Kathy(K5MWH) wrote:
>>
>>> At 12:40 AM 5/14/2005 +0200, you wrote:
>>>
>>>> > turned up in the Kmix pannel?
>>>> Maybe. You might make a screen dump by pressing 'G'
>>>> and send that to me off-list.
>>>
>>>
>>>
>>>
>>> I will run the experiments that you suggested. I went ahead and did 
>>> the screen dump. NOW, again I need help.  I don't have the foggiest 
>>> idea where the screen went, or where to look for it.  Once i find 
>>> it, I need to try to move it into this machine on the local network 
>>> so I can send it to you, If you, or anyone else has any idea where 
>>> the pic went, please let me know.  Is it a .gif ?  Meanwhile I will 
>>> try to run the experiments that you suggested.
>>>
>>> One other thing about the input to the Line-in port. I can see a 
>>> change in the level in the frame below the waterfall as I vary the 
>>> input, so I know there is something going into the software.  I just 
>>> can't see the carrier on the waterfall?
>>>
>>> Do the numbers above the waterfall represent the audio bandwidth 
>>> that the software is seeing?
>>>
>>> 73,
>>> Mike
>>>
>>>
>>>
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