RE: [linrad] Fw: Linrad-01.03

[Leif Åsbrink <leif.asbrink@xxxxxxxxxxxxxxxxxxxx]

Hi All,

> First, I am somewhat non-plussed at the trouble you had with RHL. 
>  Multiple versions
> of Linrad have worked with well here with versions of RHL from 
> 6.0 thru 8.0,
> including 7.x.  And I have used the Delta44 [along with various 
> soundblaster cards
> for the output] with each of these versions with good results.

It is not quite as easy...........

I spent a day trying to get Linrad running on a PIV machine
with a modern motherboard with integrated sound, video,
modem, ......

The machine had RedHat 7.3 already installed and I tried 
all possible combinations of everything but it was impossible
to get the Delta44 to work. The system crashed (reboot) every time
Linrad tried to open dsp2 in RDWR mode. Selecting dsp0 fixed did not
help, the system would just crasch at a later stage.

After too much time I decided there is no combineation of anything
selectable I did not try including several different oss versions
so I replaced RedHat 7.3 with Mandrake 8.1 which has always worked
perfectly on my PIII. No change whatsoever.

The next day I tried to boot the computer from another hard disk.
Suddenly everything worked beautifully!!!!!
The reason turned out to be that RedHat 8.0 is ok for this modern
motherboard while the older distributions are not.

I do not claim to understand anything of this, but I would
formulate it like this: "there is some incompatibility between
the OSS driver for Delta44 and elderly Linux kernels when a
system is run on modern motherboards"

Installing Linrad is not always trivial. I am sorry about that.
If you are lucky it IS easy:) Chances are good you will find that
everything works fine at the first attempt. If you run into problems, 
there is most probably a way out - but it may be hard to finbd it.....

>.
>.
>.
> You have full graphical control over the filter bandwidth with 
> Linrad.  You go to the
> baseband window and just pull the filter width to be what you 
> want with the mouse. 
But you are limited by the first mixer bandwidth reduction ratio.
It can be set by a fatcor whichnis a power of two.

If you ask for N=4 (the default value), the baseband is sampled
at 96/16 = 6kHz. When a 6kHz section is picked from the frequency
domain, a window function is used - the flat bandwidth is then
3kHz which would be the maximum bandwidth you can select in this 
case. There is another limitation as well. If you set the output 
sampling speed to 6kHz you will not be permitted to set the bandwidth
above 3kHz.


73

Leif / SM5BSZ



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