[linrad] Re: Sometimes you feel like a nut!

[<leif@xxxxxxxxxx>]

> At last, after approximately 5 weeks I finally have a version of Linux
> running in a dual boot configuration with Win ME(Knoppix 3.7, HDD
> installation), and I can launch Linrad.  My goal was to get
> Linrad running and learn to use it, then build a dedicated machine
> for Linrad.  Great right?  Well no, not exactly.
>
> What do I do now?
It is like Alice in the Wonderland. What do you want to do?
Linrad is a quite general package that can be configured in
many ways and I have not put any prejudice in the code on what
a user might want to do.

First of all you are limited by your hardware. The frequency,
bandwidth sensitivity and dynamic range is determined by
analog hardware. Without knowing what you have and what
kind of signals you want to look for I just can not answer the first
question.

> How do I turn the noise blanker on?
There are many pages about that - admittedly not well structured
but you might find out how to proceed by use of the F1 help key.
(You may have to expand the EME window to avoid an error exit in
case the minimised window is close to the right side of the screen
(this is a bug that will be gone in 00.34)


> How do I know if it is running?
There are many tools that will give detailed information.
If you have man-made noise you should notice immediately
when the blanker is operating.

>  Will I be able to tell the difference in the sound output?
This depends on your situation. What bandwidth do you use,
what is the dynamic range of your hardware and so on.
With good hardware you will notice a dramatic improvement
in case you have impulse noise - even impulse noise that
conventional receivers can not reduce at all with their
conventional blankers.

In case you use 2 kHz bandwidth from the loudspeaker output
of a radio on which you can not turn off the AGC, Linrad can
not do the blanking particularly well. It then depends on
the repetition rate of the pulses and the AGC characteristics
of the analog receiver.



> Is it adjustable, and if so what do I do to adjust it?
There are several controls that affect the blanker operation.
Have a look here:
http://www.sm5bsz.com/linuxdsp/blanker/bldemo.htm


> Apparently I am far too Windows and GUI oriented,
I am sure this is not the problem. The MS Windows version
will behave exactly the same - at least to start with I think.

> or I don't understand what Linrad is supposed to do
You are in command. What do you want to do?
Do you want to do accurate measurements on RF signals,
do you want to monitor a frequency band over long
periods of time to see when openings occur,
do you want to eliminate some local qrm,
do you want to make contest operation more efficient or
do you want to copy really weak signals that you can not
copy without extremely narrow filters and perhaps coherent
processing? You may want all of it but it may take some time
until you can use Linrad in an optimum way for all these tasks.

If you have a specific question like this: "I want to work
mode xxx on the frequency band zzz and I currently have
the yyy qrm problems. I want to use the radio hardware
uuu I already have. How should I set up Linrad to be
able to copy stations that currently are too weak to
be copied?" Then I could give a specific answer:-)


> I am drowning in this stuff, and just about ready to
> throw in the towel.  Only rarely do I get something that might look like
> the baseband scope, and then it doesn't tell me anything I understand.
???????
There should be several spectra on the screen.
The first one to worry about is the full range spectrum
and the waterfall graph that belongs to it.
(This is the graph with the blue dB scale)
First of all you have to make sure that this graph
shows the spectrum of the signal you send into the
soundcard. You may have to adjust the signal levels or
set the soundcard controls to not overload the soundcard
input.

> Can someone please point me in the right direction, or at least
> tell me how to figure out where the right direction is?
I hope you have already taken some steps forward by help
of the information that Roger, W3SZ supplied.


The Linrad Home Page contains a large number of
sub-pages. Here you can (in principle) find the
answer to all questions about Linrad.
http://www.sm5bsz.com/linuxdsp/linrad.htm

The problem is that the number of pages is very large....

73

Leif / SM5BSZ


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