Re: Controlling and reading a usb radio

[Deron <de...@pa...>]

On 5/12/12 10:57 PM, Hans de Goede wrote:
>
>> "radio" appears to get a little further along. It actual seems to 
>> enable the radio in so much as when it is running, I get what seems 
>> like real radio static as to the just near silence I get otherwise. 
>> But I don't get any change in the output no matter the frequency tuned.
>>
>
>
> Ok, good, looking in:
> drivers/media/radio/si470x/radio-si470x-common.c
>
> I see the following module parameters:
> /* Spacing (kHz) */
> /* 0: 200 kHz (USA, Australia) */
> /* 1: 100 kHz (Europe, Japan) */
> /* 2:  50 kHz */
> static unsigned short space = 2;
> module_param(space, ushort, 0444);
> MODULE_PARM_DESC(space, "Spacing: 0=200kHz 1=100kHz *2=50kHz*");
>
> /* Bottom of Band (MHz) */
> /* 0: 87.5 - 108 MHz (USA, Europe)*/
> /* 1: 76   - 108 MHz (Japan wide band) */
> /* 2: 76   -  90 MHz (Japan) */
> static unsigned short band = 1;
> module_param(band, ushort, 0444);
> MODULE_PARM_DESC(band, "Band: 0=87.5..108MHz *1=76..108MHz* 
> 2=76..90MHz");
>
> /* De-emphasis */
> /* 0: 75 us (USA) */
> /* 1: 50 us (Europe, Australia, Japan) */
> static unsigned short de = 1;
> module_param(de, ushort, 0444);
> MODULE_PARM_DESC(de, "De-emphasis: 0=75us *1=50us*");
>
> /* Tune timeout */
> static unsigned int tune_timeout = 3000;
> module_param(tune_timeout, uint, 0644);
> MODULE_PARM_DESC(tune_timeout, "Tune timeout: *3000*");
>
> /* Seek timeout */
> static unsigned int seek_timeout = 5000;
> module_param(seek_timeout, uint, 0644);
> MODULE_PARM_DESC(seek_timeout, "Seek timeout: *5000*");
>
> Especially the band parameter looks interesting, as
> according to your commented usb dumps your device has a
> bottom of 87.5 Mhz, were the driver defaults to 76 Mhz,
> so if you tuned to a known to work station in radio,
> you actually didn't because of this setting being wrong,
> edit /etc/modprobe.d/radio.conf
>
> And put the following there:
> options radio-usb-si470x band=0
>
> Then do:
> rmmod radio-usb-si470x
> modprobe radio-usb-si470x
>
> And redo the driver binding, now tune to a radio station
> you know to work (from testing in windows for example)
> using radio, and hopefully things will work then.
>


I was so hopeful! However, it made no difference. I even then tried 
setting space=0 and de=0, to no avail.

My attempts at a custom frequency changing program will generate pops in 
the audio output when changing the frequency, but the audio is silent. 
The radio program 
(http://www.cs.fsu.edu/~baker/devices/lxr/http/source/xawtv-3.95/console/radio.c) 
seems to enable the radio as when it is started the audio goes from 
silent to static, but I get the error "VIDIOCGAUDIO: Invalid argument" 
twice to console and changing the frequency does not generate any change 
in audio output. No pop, no change to static.


Thanks!

Deron