[GreenKeys] SELCAL - auto start proposed
Eric Scace K3NA
[email protected]
Mon, 19 Apr 2004 10:48:10 -0400
Defining frequency based on the suppressed carrier frequency of a transmitter using AFSK to generate a signal encourages a great
deal of confusion:
-- there are both "high" and "low" pairs of audio frequencies used to produce AFSK.
-- one has to also understand whether the transmitter is running LSB or USB.
[To make matters worse, using AFSK introduces two variables into the frequency stability issue: the accuracy and stability of the
transmitter, and the accuracy and stability of the tone generator. Then there are the pitfalls associated with producing a good
quality AFSK signal, free of intermodulation products...]
I would encourage folks to identify frequencies based on the mark RF frequency.
I also support the suggestions by many to use 45.45 baud (60 wpm ITA-2 code). Because a SelCal frequency will be used at times
when propagation is less than ideal, the slower baud rates will help improve the accuracy of copy.
Have any proposals been made for the sequences to be used to start and stop the selective calling phase and to stop a
transmission, and for the actual selector codes?
-- Eric K3NA
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Roy Morgan
Sent: 2004 April 19 10:31
To: GreenKeys List
Subject: RE: [GreenKeys] SELCAL - auto start proposed
At 06:52 AM 4/18/2004 -0700, you wrote:
>The net I was on was 3620Khz with Keith,Irv etc.
Greenkeyers,
How is this frequency set:
- The MID point between mark and space?
- The mark frequency?
- That carrier frequency, which if present, would result in audio tones
of 2750 or the like for the mark tone?
Roy
- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254, Fax: 301-948-6213
[email protected] --
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