[linrad] Major revision. Linrad-01.18

[Leif Åsbrink <leif.asbrink@xxxxxxxxxxxxxxxxxxxx]

Hi All,

Problems solved in Linrad-01.18:

After upgrading to Red Hat 9, PentiumIV and the latest
version of OSS there have been occasional overrun errors
on my system. The problem turned out to be the usleep(20000)
call which sometimes causes a delay above 0.1 second.
By placing a call to gettimeofday() immediately before 
the usleep() call and by making sure that the A/D buffer 
is nearly empty it has turned out to be possible to make 
the releasing of the processor not last more than the 
desired time.

Another problem with my new "fast" computer is that the 
graphics is very slow. The AFC graph can not be wider than
30% of the screen otherwise the time to redraw it becomes 
longer than the time it takes to fill the A/D buffer.
(Moving one pixel vertically takes 30 microseconds!!!!) 
The new computer has a nvidia gforce4 board, it is in a 
new and faster AGP slot into which my good old board 
does not fit. svgalib selects the VESA driver, maybe that
is the reason it is so very slow.
(or maybe the old sound driver had a much larger buffer
so I did not notice how long time it took to move
pixels around)

The actual dsp computations take very little time, the
graphics dominates. To make Linrad run smoothly on this 
kind of computer I have changed the graphical routines
to only update a fraction of the graph on each call. 
This means (of course) that many changes have been required
in the main receive loop that keeps track of the priorities 
of different things.

The oscilloscope functions are still useless on my new 
computer, but they are not needed to operate Linrad.
I will try to install svgalib-1.9.18, hopefully it
includes a properly working driver for the GeForce card.

Because of the large number of changes I have not put
Linrad-01.18 at the "Linrad Home Page", it is only 
available at the development page and its mirrors: 

http://antennspecialisten.se/~sm5bsz/linuxdsp/linroot.htm

http://g7rau.demon.co.uk/sm5bsz/linuxdsp/linroot.htm

http://nitehawk.com/sm5bsz/linuxdsp/linroot.htm


Please report any bugs!

Reports about differences in behaviour (if any) are also welcome.

73


Leif  /  SM5BSZ



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