I’v got a cheap blue DVB-T+FM+DAB dongle to play with SDR.
The hardware
One chip on the PCB is marked RTL2832U.
The other one is marked R820T2. It matches what written on the case.
According to USB data it’s a RTL2838 but according to Osmocom wiki, RTL2838 chip do not exist.
Bus 003 Device 014: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 [unknown]
bDeviceSubClass 0 [unknown]
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0bda Realtek Semiconductor Corp.
idProduct 0x2838 RTL2838 DVB-T
bcdDevice 1.00
iManufacturer 1 Realtek
iProduct 2 RTL2838UHIDIR
iSerial 3 00000001
bNumConfigurations 1
The tuner is physically a Rafael Micro 820T2, which provides the frequency range of 24 MHz to 1766 MHz according to Oscom’s Wiki.
Getting it to work on Linux Mint 22
Some RTL SDR libs exist in the official repos. Let’s install them.
apt install rtl-sdr librtlsdr2 librtlsdr-dev
Osmocom software and GNU radio blocks are also there.
apt install osmo-sdr gnuradio gr-osmosdr
rtl_test output
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001
Using device 0: Generic RTL2832U OEM
Detached kernel driver
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
Checking for a known FM radio signal presence with osmocom_fft --samp-rate=2.554M --center-freq=100M --waterfall:
Testing FM reception with GNU Radio:
It works !