[App_rpt-users] USB Radio Commands

Ken ke2n at cs.com
Wed Oct 10 04:55:51 EDT 2012

When you are injecting into a part of the audio chain that does not require
pre-emphasis, you might still want limiting.

In that case, you set




At one time several people reported they were getting pretty
horrible-sounding clipping when the URI was driven beyond full scale.


Subsequent to that I found the real problem was that when you use composite
audio the software will happily attempt to generate a number bigger than 16
bits when you use gain settings for voice and tone that total >1000.  The
restriction that these two numbers not add to more than 1000 (for composite
audio) *is* documented and is the real solution to that issue.


However, it's not inconceivable that somebody might want limiting without
pre-emphasis, if the limiting in the radio was inadequate.




From: app_rpt-users-bounces at ohnosec.org
[mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of Jim Duuuude
Sent: Tuesday, October 09, 2012 9:17 PM
To: w7ry at centurytel.net; app_rpt mailing list
Subject: Re: [App_rpt-users] USB Radio Commands


It is one of those 'it really has no good reason to ever be used' options,
and I have no idea why someone wanted it,
but it was harmless and utterly trivial to add, so I did. It, along with a
few others of those were never documented
to discourage their (quite questionable) use.



From: w7ry at centurytel.net
To: app_rpt-users at ohnosec.org
Date: Tue, 9 Oct 2012 18:05:25 -0700
Subject: [App_rpt-users] USB Radio Commands

So if this setting txprelim=no   is: 


TX audio processing. Options: (no,yes). Choosing yes turns on transmitter

preemphasis and peak limiting, along with a lowpass filter. The yes option

is used when driving an FM transmitter directly by injecting audio right

the modulator. The no option provides audio which should be injected into

the microphone input of the transmitter or at some point in the transmitter'

speech amplifier before preemphasis,

and limiting.



What is the setting? 



Nothing in the manual about it.


Thanks 73

Jim W7RY


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