[App_rpt-users] radio tune rxnoise

[Ramesh Dhami]

Hi Guys:

One of my repeaters, using usbradio, is failing 'radio tune rxnoise'.

The raw discrim' output from the Bridgecom BCM220 RX is 100mV pk-pk.  In 
usbradio.conf, I have rxboost set to 1 (20dB attenuator removed).

The symptom that I am seeing (or hearing) is that the repeater has a 
hard time distinguishing a weak / noisy signal from "noise".

This is what I see in the asterisk CLI when attempting a 'radio tune 
rxnoise'

tune rxnoise maxtries=12, target=27000, tolerance=2750
tries=0, setting=2, meas=32767
tries=1, setting=2, meas=32767
tries=2, setting=2, meas=32767
tries=3, setting=2, meas=32767
tries=4, setting=1, meas=32767
tries=5, setting=1, meas=32767
tries=6, setting=1, meas=32767
tries=7, setting=1, meas=32767
tries=8, setting=1, meas=32767
tries=9, setting=1, meas=32767
tries=10, setting=1, meas=32767
tries=11, setting=1, meas=32767
DONE tries=12, setting=63, meas=32767, sqnoise=24631
ERROR: RX INPUT ADJUST FAILED.


Unless I am mistaken the above seems to suggest that the ADC is 
saturated, meaning too much signal??

I can try to set rxboost to 0 - but of course, this will mess up my 
rxvoice calibration (assuming that the rxnoise passes).  Is there a 
mathematical operation I can apply to the rxvoice setting in the 
radio_tune file to compensate for the 20dB attenuation? (the repeater is 
at a remote location, which I will not be returning to for another 2 
weeks or so).

My usbradio_tune file currently shows:

[usb_2424]
; name=usb_2424
; devicenum=2
devstr=1-1.3:1.0
rxmixerset=125
txmixaset=70
txmixbset=300
rxvoiceadj=0.316923
rxctcssadj=0.227263
txctcssadj=300
rxsquelchadj=400
fever=1

Cheers!

Ramesh.