implement interface to RTL-SDR

[bvacaliuc]

Bent Pedersen sent a message using the contact form at
http://www.radio-astronomy.org/contact/Technical-Queries.

Hi Folks,
Have downloaded the viewer, thinking it could be a useful software to follow
a RTL dongle 'listening' on 1420 MHz.
But after a few hours of experimenting, it stood clear that the Dongle cannot
be used as receiver in connection with RASDR - correct ?
Best regards,
Bent, OZ6BP.

User would like to use the astronomy software with hardware other than RASDR. There are several challenges to this:

1. the UI is highly integrated with the Lime Microsystems C library distribution that preceded the LMS7002M software release.
2. normalization calculations are determined by the response of the ADC in the LMS6002D device

There have been discussions on a way forward, and some of them include using SoapySDR. To accomplish this, an LMS6002D device support for SoapySDR would need to be created, then SoapyRemote would be the interface that the rasdr software would interface with.

[bvacaliuc]

so between this ticket and #22 getting this feature requires:

1. Converting the UI to talk only to the Soapy SDR Client API
2. Creating a Soapy SDR Driver for the LMS6002D

So, let's make this ticket about supporting RTL-SDR via SoapyRTLSDR