Hi Steve,
yesterday I committed code for the Rafael Micro R820T
tuner to
librtlsdr.
That's great! The code Rafael supply doesn't look very neat, and I haven't
been able to get a register map out of them either, so great job on getting it
to work with librtlsdr.
Sticks with this combination (RTL2832 + R820T) are
relatively new on
the market. The main difference to all the other supported tuners so
far is that it uses a Low-IF (3.57 MHz) architecture instead of
Zero-IF. That means the tuner is only connected to the In-Phase ADC
input, and the internal downconverter of the RTL2832 is generating the
complex samples. This has the benefit of having no DC offset spike in
the middle of the spectrum.
If I have read the datasheets correctly, the E4000 is also able to use a
non-zero IF. Would doing this help reduce the spike in the middle of the
spectrum for sticks using the E4000?
The driver originally had a frequency limitation of 40
MHz to 900 MHz,
but tests showed that the PLL of my stick can achieve lock up to 1766
MHz, and indeed both ADS-B at 1090 MHz and L-Band DAB at 1463 MHz, as well as
GMR at 1556 MHz can be received just fine with the R820T.
Also, the PLL could lock again at 1850 MHz to 1860 MHz, and the
reception of a GSM 1800 BTS at 1854 MHz worked as well.
Wow, this sounds like a really good IC! I might have to go buy one now :-)
Cheers,
Adam.