[linrad] Linrad-02.35

[Leif Asbrink <sm5bsz.com; leif@xxxxxxxxxxxxxxxx>]

Hi All,

This new version is only available at the bottom of
the development page:
http://www.sm5bsz.com/linuxdsp/linroot.htm
and its mirrors. At "Linrad home page" the version
is still 02-34.

Linrad now has a speech processor, the first step
towards a transmit chain. The dsp side of it seems
to work fine, but the hardware (=Delta44) does 
not quite work as expected. Data sheets typically say 
that the D/A is better than the A/D, but in real
life it seems to be the other way around. So far I
have only tested un-modified soundcards and the next step
will be to see if there are any mods that might help.
Another possible improvement could be to use all four
D/A channels and send both I and Q in two opposite
phases so a differential amplifier could be used.
Interferences might be in the same phase and cancel out...

Other changes:

A wheel mouse can now be used to tune the Linrad frequency
in steps of the bin size in the main waterfall. By turning
the depressed wheel one can make the step size multiples
of the bin size.

The network now sends the time when a recording was made,
so now MAP65 should get the correct time stamps to decode 
automatically on "S-files"

Feedback wanted:

1) Is there anyone interested in using Linrad on old computers?
Things older than Pentium III. Linrad works OK on as old 
machines as Pentium 66 MHz for low bandwidths, but I have
a problem with too many computers around to be able to start
looking into tx hardware. I contemplate to get rid of Pentium I
and Pentium MMX but if several people have an interest I will
move them elsewhere to keep the possibillity to occasionally verify
that those old computers still are OK with Linrad.

2) There is a part in Linrad "voicelab" by which one can study
speech processors. I wrote it in a hope it would be possible
to find ways to improve differently for different voices.
As it turned out, the conclusion was that the only important
aspect when it comes to copyability under marginal conditions 
is the average to peak power. The new speech processor is designed
for that and Linrad will not use any part of voicelab any more. 
Is there any interest in voicelab? If not I will remove it.



I will be away for about a week, probably without E-mail,
leaving tomorrow (Friday) late evening. I look forward to
bug reports on return home :-)

73  

Leif / SM5BSZ


 


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