[Icom] pro comp on or off

Fri, 03 May 2002 11:11:29 -0700

Tony,

On the Pro/Pro II, three transmitted occupied-bandwidth settings (NAR 2.2 kHz,
MID 2.4 kHz, WIDE 2.8 kHz) are available. (Refer to
http://www.qsl.net/ab4oj/icom/ic756pro_notes.html) The DSP filtering process
limits the maximum occupied bandwidth to 2.8 kHz at -6dB.  According to George,
W5YR's power response plots,  the radio reduces its power output rapidly with
frequency above 2.9 kHz, regardless of the COMP setting.

That's it, unless you want to rewrite the DSP firmware. Rotsa ruck in getting
hold of Icom's source code!

You can run 5 to 10 dB of compression on voice peaks (no more) to increase
average power output. As George, W5YR said, any apparent increase in occupied
bandwidth caused by excessive compression will consist largely of distortion
products.

Also, remember that the maritime HF radio services do just fine, sound great and
save many lives on the high seas with an SSB occupied bandwidth of 2.7 kHz (per
ITU regulations).

Best 73,
Adam, VA7OJ/AB4OJ
North Vancouver, BC, Canada
http://www.qsl.net/ab4oj/
Note new e-mail address:
mailto:[email protected]

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of anthony costa
Sent: Friday, May 03, 2002 09:16
To: ICOM Reflector
Subject: [Icom] pro comp on or off

ive heard from a respected ham that the only way you can aquire 2.9
transmitt bandwidth is to run the compressor on the pro.(wide on).wide off
will only give you 2.4k.I cannot see and difference what so ever.can
someone reply if this is true or false.thank's.

tony k2vi