[arm-allstar] Receiver audio levels

[Cole Cunningham]

Thanks, Doug.  Yeah I found the rxboost and have played with it some.  But
in doing so I broke something else I now have to find and fix.  I also had
to discover you have to have COR active for tuning to work, too.  Always
something new to find.

 

What is the function of the duplex=1 in simpleusb?  Does it make the FOB
operate full duplex for audio or some other function?

 

I did notice an anomaly that I was curious about.  While testing with
simpleusb-tune-menu, at times after making a change to the TX audio setting
using option 3 or 4 it would transmit a tone at the new level for 5 seconds,
and at other times it wouldn't.  Is there something I can do to make that
happen every time and also to extend the transmit time so my station monitor
has time to respond?  The Flash option works fine but again, the Tx time is
too short for the test equipment to settle.

 

Cole

AA7RD

 

From: arm-allstar-bounces at hamvoip.org
[mailto:arm-allstar-bounces at hamvoip.org] On Behalf Of Doug Crompton
Sent: Tuesday, March 03, 2015 7:56 PM
To: BeagleBone Black ARM Allstar
Subject: Re: [arm-allstar] Receiver audio levels

 

Cole,

 Typically you want about 100mv p-p or so max but you can turn off rxboost
in simpleusb.conf  - rxboost=0   

It defaults at 1 or on. That might get you in the ball park but it looks
like you do need to drop the level down a bit also. I would suggest a 47 K
in series with a 10K to ground on the FOB side for starters. Then take the
47K up if it is still too high. Experiment until you can get the level value
reasonably close to mid scale (500). 

73 Doug
WA3DSP
http://www.crompton.com/hamradio



  _____  

From: colecaz at gmail.com
To: arm-allstar at hamvoip.org
Date: Tue, 3 Mar 2015 16:12:45 -0700
Subject: [arm-allstar] Receiver audio levels

I'm having trouble setting the receive audio input level to interface with a
Motorola Radius radio.

 

I'm using a USB FOB modified as shown on
http://www.crompton.com/hamradio/usb_fob_modification/ , and connecting to
the audio output of the radio on the rear connector I am unable to set the
proper level using simpleusb-tune-menu.  Even going all the way to 0 isn't
enough.  The peak to peak voltage out of the radio with 1kHz audio/3 kHz
deviation is 1.2 volts.  I have confirmed that it is truly sensing the audio
by shutting the modulation off and seeing the tune indicator line go to
about 500 Hz of noise.

 

What audio level directly into the FOB, after the voltage divider shown in
the mod, is correct for decent tuning range?

 

Cole Cunningham

AA7RD


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