Message-ID: <3C458059.44CF7601@usa.net>
Date: Wed, 16 Jan 2002 14:30:02 +0100
From: "Alberto di Bene" <dibene@usa.net>
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To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: G3YXM's Jason test sigs
References: <5.1.0.14.0.20020116102434.00a7a7f8@gemini.herts.ac.uk>
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James Moritz wrote:

>  If the centre frequency is
> F, and the spacing between tones is f, the possible tone frequencies are F
> +/- (n-0.5)*f where n is an integer from 1...16. Therefore there are 32
> possible equally-spaced tone frequencies from F-15.5f to F+15.5f. Is this
> correct?
>

Hi Jim and the group,

  yes, correct, that's how the information is encoded in Jason.
There is another possible format, which has pros and cons.
It has been also suggested by Stewart Nelson. I had initially,
when designing Jason, dismissed it, but now I am here asking
your collective opinion.

Presently only the absolute value of the frequency delta is used
to encode the information. If  I use also the sign, I have this results :

-Pros  The band occupied is nearly halved, from 32 slots, it goes
           down to 17 slots.

-Cons The system is no more sideband independent. Now it is
           immaterial whether the RX is set to LSB or USB.
           This would not be any more the case with the alternate scheme.

So, what would all you judge more important, sideband independence,
or bandwidth used ? Your vote will decide the final format for Jason.

73  Alberto  I2PHD