Info about Gigabyte GT-U7300

Tibor Zenis zenis at fmph.uniba.sk
Sat Jan 3 10:40:35 UTC 2015


Hello,
this device has the USB ID 1b80:d3a8, Fitipower FC0013 tuner. The
frequency range is out of specification on page
http://sdr.osmocom.org/trac/wiki/rtl-sdr .
It is 13.5 - 1897.2 Mhz with a hole 948.6 - 996.6 MHz. This device has
xtal_freq_div_2 = 14400000. For the hole, there is no valid PLL using
multi = 4 and non-stable operation using multi = 2 (see the recorded
samples for signal f + 50 kHz: GT-U7300_samples_996.43.png). The
frequencies in the hole can be covered using multi = 3. I'm not sure if
it is possible to set an odd number of the multi.

I tested a response of this device using a "software driven generator"
with output frequencies in the range 34.375 Mhz - 4.4 GHz. This
generator doesn't have calibrated output power. Some waves in the
frequency response can be created by both the generator also the tuner.
I found a sharp steps in the response at 300 and 862 MHz. Band filters
are changed at this frequencies: VHF for f < 300 MHz, UHF for 300 MHz <
f < 862 MHz, GPS for f > 862 MHz. I modified the tuner_fc0013.c file to
force the filter selection.
The GPS filter is useless at all, VHF is usable up to 300 MHz, UHF is
the best one for f > 250 MHz with no disadvantage for f > 35 MHz (lower
frequencies not tested).

This device using the UHF filter is usable up to 1.7-1.9 GHz.

Could you insert this device to the list of supported devices?

It should be fine to have a possibility to select the filters by
software. I can make the modification of the file tuner_fc0013.c (and
higher level files).

Concerning the file tuner_fc0013.c, function fc0013_set_params(). There
is a 64-bit variable f_vco, but a 32 value (f_vco = freq * multi) is
assigned to it. The 32-bit value is enough for my device. I don't see
any reason for using the 64-bit variable.

Cheers,
	Tibor

-- 
,..,.,..,.,..,.,..,.,..,.,..,
; Tibor Zenis               ;
: zenis @ fmph . uniba . sk :
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