QUISK and linrad

[John C. Peterson]

On Thu, Sep 22, 2016 at 03:16:55AM +0200, Leif Asbrink wrote:
> Hello John,
> > I was curious if the LimeSDR is on your radar for possible
> > LinRad support?? It won't be shipping until late November, but it has
> > some interesting specifications (for one, it's a transceiver, not just
> > a receiver). 
> > https://www.crowdsupply.com/lime-micro/limesdr
> > http://www.limemicro.com/

Hello Leif,

Work has kept me busy lately and I have not had a chance to reply
until now.  I did find some time to do more reading on the LimeSDR over
the weekend. Here is what I found.

> I find no information about the tuner chip. It seems to me
> that this product is intended to do all processing in the on-board
> fpga. [... snip ...]

You are right. It is like the newest generation of SDRs (e.g. FlexRadio)
where the FPGA does everything to provide a stand alone radio. I agree,
that does take most of the fun out of it for those of us that like to
"tinker". However, there appears to be some hope. I found this blog post
about using the LimeSDR with gqrx;

https://myriadrf.org/blog/first-tests-limesdr-gqrx/

> In case someone else develops fpga code that makes a decent
> SDR out of the LimeSDR with an appropriate library with an
> API that can reasonably easily be called from a C program
> I might become interested. I am not going to write fpga
> code myself - and also not a library to provide an API.

It looked to me like this "piece of the puzzle" does exist, it's a
"middleware" framework called SoapySDR.  The blog post above made some
comments to the effect that not everything has been implemented just yet
(tuning for HF frequencies was mentioned).  Then again, the article is
dated May 2016, so things might have improved since then??? More on
SoapySDR;

https://github.com/pothosware/SoapySDR/wiki
https://myriadrf.org/blog/limesuite-driver-architecture/

Getting Linrad to work with SoapySDR would require some effort for sure,
but another benefit is a common API interface to other devices like the
Realtek dongles, etc. (SoapySDR already supports a number of other
popular devices).

Some other threads on the LimeSDR for amateur radio applications:

https://amsat-uk.org/2016/03/14/listen-iss-raspberry-pi-3-limesdr/
https://discourse.myriadrf.org/t/limesdr-as-a-amateur-radio-transciever/450

Skol! de KD6EKQ

-- 
John C. Peterson, KD6EKQ
mailto:jcp at eskimo.com
San Diego, CA U.S.A