[TenTec] WIDE BAND

[Adam Farson]

Hi Stuart,

The typical voice channel filter response in Bell System and ITU-T telephone
carrier systems is usually 300 to 3000 Hz at the -6 dB points.
Program-channel filters used for the transmission of radio or TV-sound
program material over FDM (analogue) telephone carrier systems are wider
(typically 6 kHz), but are not used for voice telephony.

ITU-R Recommendation M.1173 for HF-SSB transmitters in the maritime mobile
radio services specifies: "The transmitter audio-frequency band shall be 350
Hz to 2 700 Hz with a permitted amplitude variation of 6 dB." Some of the
clearest-sounding HF-SSB audio I have ever heard was from shipboard radio
installations.

Studies have shown that excessive transmitted energy below 250 Hz can
degrade articulation at the distant receiver. I find that when listening to
weak SSB signals, I frequently use Twin PBT to "slice away" everything below
300 Hz, for easier copying.

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: tentec-bounces at contesting.com
[mailto:tentec-bounces at contesting.com]On Behalf Of Stuart Rohre
Sent: Monday, February 16, 2004 16:14
To: PaganSilverDrgn at comcast.net; tentec at contesting.com
Subject: Re: [TenTec] WIDE BAND


Actually, SSB has its earliest history in telephone service where bandwidth
can be needed wider than minimum voice band.   The so called wideband SSB,
is full fidelity for better articulation, not excessively wide when compared
to AM.
Stuart
K5KVH


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