Don brings to mind the observation that I have had over the years with
Speech Processors in general. I'd say that 99% of the time the speech
processor should be OFF position. The other 1% of the time perhaps the
radio should be off. Get my point. Speech Processors do not make for good
quality audio. They make for LOUD audio.
Frankly, I find that too many folks feel the urgent need to use speech
processing all of the time regardless of brand or model of radio and
regardless of band conditions. Frankly, I've never heard a processed
signal that sounded as good or better than an un-processed signal. Oh yes,
the speech processor makes the watt meter move higher because it compresses
the speech waveform and increases the average power and thus adds distortion
in the process of doing so. It may also modify the power in the spectrum
due to the selection of attack and release time constants. Behold, there's
a trade off, higher average power and poorer quality signal when a speech
processor is used. It doesn't work any other way.
Some say that they only run the speech processor just a "little bit". Well
you just introduced a "little bit" of distortion. Others say that they run
the speech processor to the max. That's why they are typically heard across
most of the band. But hey, their watt meter really moves up scale.
A properly designed speech processor will have four basic adjustments. (a)
attack time, (b) release time, (c) threshold and (d) compression ratio.
Without these 4 variables it is not likely that a single set of time and
level constants will fit every mike/voice characteristic. Some of the newer
microprocessor controlled digital processors have an adaptive feature that
automatically changes these values based on signal content but these aren't
found in radios. Did you ever wonder why TV commercials are always louder
than the program? Well it's because of the speech processing structure
which is designed to make them loud.
I've communicated with Don privately on several topics. I'm glad to see
that he found something strange with the Argo V and that it is as simple as
turning off the speech processor. Now if everybody would do just that on
their radios we'd have much cleaner signals on the bands.
Good going Don!
73
Bob, K4TAX
----- Original Message -----
From: "Don Rasmussen" <wb8yqj@yahoo.com>
To: <tentec@contesting.com>
Sent: Wednesday, January 25, 2006 10:33 AM
Subject: [TenTec] Argonaut V Transmit Audio on SSB
The latest and possibly last (hurray!) word on the
ARGO V transmit audio here is that that my new Argo
(from Jan 2006 with 1.08 firmware) seemingly sprang to
life after turning "OFF" the SP (speech processor)
that was set to "3" of 10.
After closely listening to the recordings, it is
obvious that the muted audio is not the result of
rolloff at the low end frequencies alone. The SP
function may have been coded and tested for the pre
1.08 hardware revisions or maybe the internal pot in
my unit is misalligned.
No value of speech processor setting would provide
good audio at any mic gain setting of the radio. But
the "OFF" position sounds reasonable, at least within
the 350hz rolloff TT suggests and much fuller at the
top.
So to the guys that reported their tx audio was doing
fine, I expect they were running previous to 1.08 of
the firmware or have 1.08 and leave the SP off.
This is a great small radio, and the absence of speech
processor, RF Gain, and selectable AGC which would
seem on paper to be deal killers for any desktop radio
really are not factors at this QTH. Overall a 9 of 10
I'd say - a keeper.
73,
de WB8YQJ/6
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|