[Moon-net] Linrad for Windows

[Leif Asbrink]

Hello Lance,

> I have been starting to experiment with Linrad for Windows, using my 
> SDR-IQ receiver.  I have been waiting to see how it works on the new 
> computer I got for this purpose (AMD A64 X2 6000 3.0 G, running Windows 
> XP PRO and 2 GB of RAM) before I ask any questions.
Linrad should run happily on something slower.....

> My questions at this stage are:
> 
> 1) Linrad seems to freeze up and just quit working after some period of 
> time (which seems to vary).  I have disconnected my computer from the 
> internet, and it is not running anything but Linrad.  Is there some 
> special setting that needs to be made somewhere in Linrad to keep it 
> from shutting itself off?  I have disabled the screen-saver on my monitor.
This is new to me. It could be a bug that nobody reported before,
but more likely it is a problem with latency times under XP PRO.

The dll that has to be used under Windows will hang in case an error
occurs in the USB link (contrary to Linux where errors are properly
handled) In case this is the explanation you should try a bit smaller
bandwidth to reduce the latency time requirements for the USB link.
Try something like 100 kHz. If that fixes the problem, increase
the speed up to where problems start. In case this helped, you may
check the system monitor that shows all the programs Windows runs
when seemingly doing nothing. One of them (or more) is responsible
for holding the CPU too long for the USB not to be serviced in time.
I know very little about Windows - presumably there is a way to
use the dll better..... 

> 2) Is there a copy of starter setup files somewhere that I can download 
> that will help me get Linrad set up properly to receive SSB or CW and to 
> utilize the famous Linrad noise blanker?
What is right depends on the usage. Someone who uses SDR-IQ on
HF without pre-selector filters should set other parameters than
someone who wants maximum bandwidth for a VHF band. Linrad is not
for any particular hardware. I do not own an SDR-IQ and in 
particular I do not have the antennas and other hardwares 
for all the different bands. Note that Linrad allows you to
set up your AD6620 in many different ways so you can avoid
the shortcomings of this chip and place the spurious responses
that it suffers from at frequencies where they are harmless.
The compromise is in how much oversampled the output has to be.

I hope that people who actually operate SDR-IQ on various bands
upload information about what they found good control parameters
for the SDR-IQ (=AD6620) under different circumstances. This
information is not specific for Linrad. In case something is
favourable under Linrad, it will be equally favourable for
all softwares that uses the USB data from an SDR-IQ.

The parameters of Linrad itself is another story. It should
be ok to press enter and use the default everywhere.

I practically never get any feedback. In case there are situations
when it does not work it is just because I have not seen it
myself and nobody told me.

> I have saved my own SSB setup 
> files in order to be able to restore operation of the program because 
> the first time I tried it, I wound up making frequency range changes 
> that apparently were out of range, and nothing would work after that.
Oooh!

If you ever manage to do something like that again, please save
all the par files, put them in a zip file and send it all to me
with a short description what you did.

> I admit to not being at the top of the class when it comes to all this 
> technical and computer stuff, but I also realize the power available 
> through these new innovations, and am trying my best to take advantage 
> of these incredible innovations.  I would appreciate any suggestions or 
> guidance anybody might have ;-) 

Anything that does not work as you expect it to do is a problem.
It could be a bug, or it could simply be a problem in that the
dialog and help messages are too compact - or perhaps even
misleading.

Linrad is extremely flexible and allows almost anything including
things that may seem very silly and use all CPU resources for
nothing. There may be reasons for such things in special situations
but I want Linrad to always be well behaved and verbose enough to
make it reasonably easy to understand what is going on in such
cases. 

If you ask for more memory than available for example, Windows
will silently put some processing data on the hard disk. I do
not know how to detect that from inside Linrad so the user has to
find out with the system tools that Microsoft provides.
Processing data on the hard disk causes big problems.......
(But Linrad should be well behaved. Please inform me 
when you find cases where it is not.) Error that you might
do should never lead to freezes or crashes. Surely I am
aware it happens - but I try to fix everything that is
reproducible as soon as I know about it.

73

Leif  /  SM5BSZ