I started to do the testing per below. A -63 in sig would cause overrun error  and speed warning. At -62 the Hi Res Spec would go crazy. It appeared that the overrun errors were a function of time not SIG level. Even with no input the overrun error would appear in time. Big SIG would possibly make Overrun error ;;or.
I disabled the 2nd fft and afc. The crazy jumping stopped and all started looking good. -13 in gives me A/D .1 and s meter of 132.4 on an unmodified Delta44.
The overrun still comes in time and with or without SIG present. The size of the graph was made larger or smaller in both Vert and Horiz and seemed to have no impact on warnings or errors.
73, Stan, KA1ZE
In a message dated 4/14/2004 5:30:48 AM Eastern Daylight Time, leif.asbrink@xxxxxxxxxxxxxxxx writes:
> I wanted to let you know I statr getting speed errors and
> overrun errors as soon as the sig generator puts in a signal
> of -65Dbm. I am using Linrad-01.18 and svgalib-1.4.3.
Please do the following.
1) Find out what is the strongest signal that does not give
2) Find out by how much you have to increase the level
to get these problems frequently.
3) Set the level to what you found under 1) and change the
scale of the Linrad windows so the signal peak is at least
as high above the noise floor on the screen as it was in 2)
Do this for all windows on which you see the signal as a
two-dimensional curve. The waterfall graph timing is independent
of the signals.
4) If you get the problems back, the problem is slow graphics.
If this is the case, please run your computer as in 1) for
a few seconds, then press "F", "T" and "G" to make a gif file.
Send the gif to me and I will make some changes that I would
like you to test. On a fast computer, Linrad should run with
a very slow graphic card (except for oscilloscope functions).
Linrad-01.18 writes to the screen in blocks of 64 points.
(screen width/16). Writing smaller blocks will cost too much
overhead on slow computers with fast graphics such as my old
computers with Pentium 166 and a S3 card.
If Linrad runs on your computer with a smaller block size I
can make it a parameter that the user can set to meet his needs.
(Some day Linrad could find out by itself....)
Leif / SM5BSZ