Hi all,

The RTL-SDR Blog V4 model is based on the R828D chip, which is no longer in production, and the stockpile we were using is now running low. 

But we found a bunch of stockpiled R828S chips, which I intend to use for a "V4 Lite" model that will allow a similar V4-like architecture to continue being sold for at least another year (and hopefully at a slightly lower price, too). To support the R828S chip a driver update is needed.

It's a little confusing as the R828S chip presents itself on I2C as an R820T/R860. Like the Blog V4 patch, the code looks for the "RTLSDRBlog" and "V4L" strings in the EEPROM manufacturer/product strings to know what it's dealing with. 

The R828S also has only two inputs, so there are some switching changes, and hence the 'lite' designation, as it doesn't have the additional VHF/UHF split filtering that we could do with the three inputs on the R828D.

I also added a small mod to disable the tracking filter when in HF upconversion mode for both the V4 and V4L, as this seems to help sensitivity a bit.

Please consider this patch. And if anyone at Osmocom wants to try a V4L, please let me know. An initial run of the V4L models should be ready in about 1-2 months.