Audio Test TG - VU multi-segment Meter and Level
Most us of do not
have a $42,000 AeroFlex 3920 DMR
optioned Radio Test Set sitting on
the kitchen table. So here's a
cheaper method you can try.
Very helpful if you have a spare
radio and can dedicate a VU-Meter to
monitor your favorite repeater.
A few members of
PNW DMR do have this VU Meter, just
ask for a test on by calling on WA 1
or 2, ask for a test, then move to
Audio Test 2 to give it a go.
any yellows with 1 red or all green
TO TEST: Always use your
normal voice, normal position, under
normal conditions. Sounds easy
but it is not. Ask if a meter
reader is listening on Audio Test to
like, "This is K6HOT, VU Audio Test 1, 2, 3, 4, 5".
To "exercise" your audio, you might say "4" several times; long and sustained.
This approach provides a better view of the bars and tends to
be the hottest audio in the number string, as well
as providing some averaging rather
than instantaneous changes.
After a test
sequence a VU meter owner will
comments on what he sees. You
may listen also to the
stream (~ 1 minutes delay)
The 20 segment LED VU bar meter
shown on the left provides an objective
view of the range of talkgroup
audio levels. The
target range is the
6 yellow bars but
1 red square is
acceptable on peaks. The 50 segment works
the same way but with better annunciation via the
additional 30 segments.
The meter is
adjusted so that reasonable audio (no piercing audio, no
distortion and breath puffs minimized) is likely when
your average audio falls within the yellow range.
This set-up provides a more complete "picture" of all
audio conditions. The actual dB values is less
important in this context. The peak audio level is held for 1
second and then falls away.
0dB = 3 reds
(HOT HOT) // -3dB =
1 red (HOT) //
-8 dB = 3
yellows (Perfect) // -12dB = 0-1 Yellow //
-15db = 3 greens
The responsive range of this
meter is 4-20 though the audio level input is can be
lower than 4 and higher than 20.
The VU meter is calibrated to a
baseline of all yellow and green bars plus one red
just flashing on the edge of illuminating while
pressing Touchtone number 5 on a MotoTRBO XPR-6500
HT keypad as it sends out roughly 1,000hz (dual)
tone. The D878UV may also be used as the TT
levels are fixed (set to LED 48 to just flicker on
while pressing TT #5). Calibration provides the dB levels vs
LED segments as measured by my
Sinadder 3 (More
To test with this resource,
always use your normal voice, normal
position, under normal conditions. Sounds easy
but it is not. Think about how other people
use cell phones, they talk louder when unaware of
the distraction they are causing. Most
people will speak softer when they are aware of the noise
they are creating or in this case when the OTA level
may be offensive. Most users will again, speak softer
when advised of their hot audio but it will creep
back up when they forget about it later. So try to
resist that temporary reaction. You could have your friends monitor your
audio at random times and report back to you later as to
where your audio falls when you are not thinking
about your audio levels. Most users tend to be
offended, even if they don't indicate it. So
try to be gentle and diplomatic. But a
temporary solution by saying that you will talk
softer or further from the mic IS NOT THE ANSWER.
You must reprogram for your voice and style or you
will fall back into that old method of speaking to
your radio and continue to violate acceptable levels
of audio as well as the clarity of your speech.
This human tendency cannot be emphasized enough!
The radio must be adjusted and likely the user will
need to modify the way they position the radio.
This is has been amazingly difficult to get users to
do. They don't need to listen to their own
audio but we do!
Most us of do not have a digital test test,
so some other method that provides a way for
us to quantify our (average) levels at a
cost that a typical ham is able to afford is
needed. This approach outlined below costs
$25 -$50 and works well for the end goal of
having effective and pleasant audio. A
spare radio HT dedicated to the project is a
Radio that provided earphone level audio
output or speaker output massaged to reduce
the levels so you have mid-range volume pot
to be approximate level to drive into the
segment 3 color LED VU module (30 segment
green/yellow/red for Amazon, ~$40)
segment 3 color LED VU meter (32 segment
green/red sample from: Ebay,
am having issues with this Ebay 32 segment,
FYI at this time only]
audio level on the HT's volume control is
set, mark it and then leave it alone.
can leave the 580 in the charger 7/24 or
use a battery eliminator pack.
radio in digital monitor mode, single or
dual slot so that you can "see" all
We hope that you will become
"Audio Active" in that you will try to generate good
audio over the PNW DMR network as well as help
others to so. If you hear poor audio, let the
user know and over to assist them with your VU
meter. You don't need to be the "Audio Police"
but you can make a difference if you make the effort
on behalf of all members of our network.