2011/6/20 Antti Palosaari <crope@xxxxxx>:
> On 06/20/2011 11:55 PM, Rune Evjen wrote:
>>
>> 2011/6/20 Markus Rechberger<mrechberger@xxxxxxxxx>:
>>>
>>> to tell the difference the amplifier is for DVB-T2, DVB-C is disabled
>>> in windows because it's not reliable.
>>> Technically the chip supports it but the LNA decreases the quality.
>>> There are already some other PCI boards
>>> out there with that chip which do not use that LNA which should have a
>>> better performance with that Sony chip.
>>
>> Is it possible to work around this by disabling the lna or is the
>> quality decreased permanently as part of the hardware design,
>> independently of whether the lna is enabled or not ?
>>
>> I searched the linux-media list and it seems that an lna option was
>> discussed as a module parameter, but modinfo for the module I use [1]
>> (using the media_build git repository) doesn't show a lna parameter.
>> Can the lna be disabled in another way ?
>
> LNA is controlled by demod GPIO line. I don't remember if it is on or off
> for DVB-C currently. Look em28xx-dvb.c file, you can disable or enable it
> from there (needs re-compiling driver).
>
> I also saw BER counter running some muxes during development, but I think
> all channels I have are still working. And I didn't even have time to
> optimal parameters for tuner / demod. I will try to examine those later...
>
Thank you Antti,
I will test with lna disabled in the em28xx-dvb module
In line 349 of the code, I see this:
/* enable LNA for DVB-T2 and DVB-C */
.gpio_dvbt2[0] = CXD2820R_GPIO_E | CXD2820R_GPIO_O | CXD2820R_GPIO_L,
.gpio_dvbc[0] = CXD2820R_GPIO_E | CXD2820R_GPIO_O | CXD2820R_GPIO_L,
I suspect I should modify line 351, what should it be changed to ?
Best regards,
Rune
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