[App_rpt] Problem tuning USB Radio Interface - resistor wring?

Stephen Rodgers hwstar at rodgers.sdcoxmail.com
Thu Feb 14 10:35:55 EST 2008

See below.


Anonymous wrote:
> I don't know if this may be the problem, since I do have audio into and 
> back out of the usb device, but I'm a bit confused about the wiring at 
> http://usbradio.org/usbfob.pdf for the resistors.

The rxnoise test shows zero audio.

1. Please post your usbradio.conf file to the list.

2. Can you measure the top of the voltage divider with a scope to see if
there is noise there during the time you are running the rxnoise adjustment?

> The written instructions say that the end of the resistors that are 
> twisted together get connected to the white wire and that the loose end 
> of 68k goes to ground and the loose end of 470k to pin 3 (I'm guessing 
> to RX Audio from radio)
> The picture shows the white wire (black in the picture) is connected to 
> the loose end of the 470k while the loose end of 68k is connected to 
> ground and the twisted end to pin 3.

The wiring in picture is incorrect, the wording and the xgematic are is
correct. You would still get audio with the incorrect wiring, it just
wouldn't be at the same level as when wired correctly.

> I don't know if this has been talked about before, I gave up searching 
> through the archived manually.  It would be a lot easier if this were on 
> a forum so that you could just search the forum for keywords.  Any help 
> on which one of these would be right would be greatly appreciated.
> Thanks,
> Jeff
> Jeff Lavoie wrote:
>> I seem to have a problem tuning the USB radio interface.  Here'e what I 
>> get in the CLI.
>> *CLI> radio tune
>> Active radio interface is [usb]
>> Output A is currently set to composite.
>> Output B is currently set to voice.
>> Tx Voice Level currently set to 500
>> Tx Tone Level currently set to 200
>> Rx Squelch currently set to 500
>> Device String is 3-2
>> Usage: radio tune <function>
>>        rxnoise
>>        rxvoice
>>        rxtone
>>        rxsquelch [newsetting]
>>        txvoice [newsetting]
>>        txtone [newsetting]
>>        auxvoice [newsetting]
>>        save (settings to tuning file)
>>        load (tuning settings from EEPROM)
>>        All [newsetting]'s are values 0-999
>> *CLI> radio tune rxnoise
>> tune rxnoise maxtries=12, target=23000, tolerance=2000
>> tries=0, setting=2, meas=1
>> tries=1, setting=16, meas=1
>> tries=2, setting=16, meas=1
>> tries=3, setting=16, meas=1
>> tries=4, setting=16, meas=1
>> tries=5, setting=16, meas=1
>> tries=6, setting=16, meas=1
>> tries=7, setting=16, meas=1
>> tries=8, setting=16, meas=1
>> tries=9, setting=16, meas=1
>> tries=10, setting=16, meas=1
>> tries=11, setting=16, meas=1
>> DONE tries=12, setting=1000, meas=1
>> *CLI>
>> I know I have audio going into the device.  When I made the 
>> modifications to the usb device, I decided not to remove the audio 
>> output jack so that I may use it for testing purposes.  So I plugged 
>> some speakers in, went into alsamixer, un-muted the microphone, turned 
>> it up a little, and I had sound from the radio without any problems.  So 
>> why can't asterisk hear the sound when tuning?  Have I forgotten to do 
>> something else before trying this?
>> Jeff
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