[Linrad] Re: Linrad/SDR-IQ Notes

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

Hello Dave,

> I am still using LINRAD 2.41. I was able to get it 
> running with your help and also help from Leif many months ago. I am 
> wondering if it is worth the effort to go to a later version. Is the 
> sensitivity improved in the later versions of LINRAD? 

Sensitivity ??

In linear modes, ordinary CW and SSB, the sensitivity is determined 
by your hardware and the bandwidth that you select. There is no 
difference whether you use Linrad, Winrad or an analog radio as 
long as your system is "correct" in the sense that nearly all the 
noise you hear originates in the antenna or preamplifier. Switch the
preamplifier on/off to verify.

Now, in case you have man made interference it could be different.
The noise blanker and the spur removal develop (slowly) over time
and there is a small chance that you could notice a difference.
Some bug in the calibration routine is corrected but it is not 
very likely it would matter. (You did not report it so I guess
it did not happen - or maybe you did not need to calibrate.)

Recent Linrad versions have better timing. You can make the
delay from antenna to loudspeaker shorter. In case you do not
need it, there is no advantage for you with it.....

Non-linear modes, coherent CW and AM are affected by recent changes.
Things like placing the baseband filter non-symmetric with respect
to the carrier is useful in AM detection and perhaps also in
coherent CW if there is interference on one side of the carrier only.


There is another thing however. As you may know, Linrad-02.47 is
"Latest stable" while current version is 03.02. (Soon 03.03) This
is creating problems now because various new features are needed
for e.g. MAP65-IQ or Perseus. The reason I have not made a more 
recent version "Latest stable" is the lack of feedback. If too 
many operators decide they do not need to install the latest 
version I do not get the feedback I need:-(
There are still bugs that could make Linrad crasch when the memory
is reconfigured after e.g. a filter change in the baseband. I
have not been able to reproduce, but I have seen it myself although
very seldomly. Reports about it in 03.03 (if it is still there)
would be helpful.

Installing a new version should be VERY easy. Just save all files 
of the old installation somewhere and copy the new files on top of 
the old ones. At the new place or the old one according to your 
preferences. In case it does not work as well as (or better) than
your old version, please post a message with your observations on
this reflector and make sure to save the entire new installation
before you go back and continue to use the old one.

73

Leif / SM5BSZ


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