Now, lets try to listen to some radio. I choose 100.7 FM as this is a fair strong signal. Lets hook up some speakers to the Raspberry and let’s go :
pi@srv-rasp-01 ~ $ rtl_fm -f 100.7M -M wbfm -s 200000 -r 48000 | aplay -r 48k -f S16_LE Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000001 Using device 0: Generic RTL2832U OEM Found Rafael Micro R820T tuner Oversampling input by: 2x. Oversampling output by: 4x. Buffer size: 5.12ms Tuned to 101116000 Hz. Sampling at 1600000 Hz. Output at 48000 Hz. Tuner gain set to automatic. Playing raw data 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
And we have radio.!….let’s try if the Terratec dongle does any better 🙂 .. Let’s first run it through a rtl_test with the -t parameter designed to benchmark the E4000 tuner.
pi@srv-rasp-01 ~ $ rtl_test -t Found 1 device(s): 0: Terratec T Stick PLUS Using device 0: Terratec T Stick PLUS Found Elonics E4000 tuner Supported gain values (14): -1.0 1.5 4.0 6.5 9.0 11.5 14.0 16.5 19.0 21.5 24.0 29.0 34.0 42.0 Benchmarking E4000 PLL... [E4K] PLL not locked for 52000000 Hz! [E4K] PLL not locked for 2214000000 Hz! [E4K] PLL not locked for 1107000000 Hz! [E4K] PLL not locked for 1249000000 Hz! E4K range: 53 to 2213 MHz E4K L-band gap: 1107 to 1249 MHz
Good.. this seems to work. Now lets try the radio again…. same quality..Not better or worse. Though it have to be mentioned that I had to use a good antenna (outside) to get a noise-free signal while a portable radio could do the same with a small internal antenna. (Don’t mind my long antenna-adapter-conversion as I used what-ever I could find to hook it up to the IEC connector of the Dongle)
source : http://www.yellownote.nl/blog/index.php/2014/01/12/dvb-t-fun-raspberry-pi/