DVB-T dongles based on the Realtek RTL2832U can be used as a cheap SDR, since the chip allows transferring the raw I/Q samples to the host, which is officially used for DAB/DAB+/FM demodulation. The possibility of this has been discovered by the V4L/DVB kernel developer Antti Palosaari.
The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, dongles that use the Elonics E4000 offer the widest possible range (64 – 1700 MHz with a gap from approx. 1100 – 1250 MHz). When used out-of-spec, a tuning range of approx. 50 MHz – 2.2 GHz is possible (with gap).
|Elonics E4000||52 – 2200 MHz with a gap from 1100 MHz to 1250 MHz (varies)|
|Rafael Micro R820T||24 – 1766 MHz|
|Fitipower FC0013||22 – 1100 MHz (FC0013B/C, FC0013G has a separate L-band input, which is unconnected on most sticks)|
|Fitipower FC0012||22 – 948.6 MHz|
|FCI FC2580||146 – 308 MHz and 438 – 924 MHz (gap in between)|
Coming soon more details.
Homepage and other references:
Osmocom SDR Wiki