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[TenTec] Enhanced SSB

To: <tentec@contesting.com>
Subject: [TenTec] Enhanced SSB
From: tongaloa@alltel.net (tongaloa)
Date: Fri Apr 18 16:23:19 2003
Just some reference points...re: the 3kHz spec.

Sitting in my lap, as I type, is a card from telco FDM radio gear.
The cover is off.
The Alpha crystal filter is labeled 3.2kHz.

I have in the warehouse a number of pieces of telco surplus test gear
that was designed for analyzing FDM systems. The bandpass for a voice
channel on the Wandel and Goltermann set is 3.1kHz, the HP is up on a
shelf but IIRC, it's close, if not the same.

Modern telephone is a mix. The digital stuff is 8bit samples taken at
a 8kHz rate. 4kHz is Nyquist and with reasonable filters, 3kHz is about
all you can squeeze through this. It's still a 3kHz voice channel!

Fact: Wideband SSB is tecnically inferior.
More power is required to overcome the higher noise power in the greater
bandwidth. It's an inefficient use of spectrum.

Opinion: Wideband FM is an allowed mode for UHF and is superior to SSB
for quality. There is plenty of spectrum for pushing the limits on
voice quality. It's just not HF spectrum.


w8au@sssnet.com wrote:

> Also, having been in the Telecom business for the last 40 years, I can
> also say that the typical freq division mux (ssb) systems allowed an audio
> bandpass of 3 khz....   (300 to 3300 Hz)   The channel width was 4 kHz

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