From: Arno Verhoeven <pe1icq@sharon.esrac.ele.tue.nl>
To: Dave Platt <dplatt@radagast.org>
Cc: Linux-hams List <linux-hams@vger.kernel.org>
Subject: Re: Which tone comes first?
Date: Sun, 11 Jun 2006 21:41:30 +0200 [thread overview]
Message-ID: <448C71EA.60007@sharon.esrac.ele.tue.nl> (raw)
In-Reply-To: <courier.448C6F3D.0000325B@radagast.org>
On 2006-06-11 21:30, Dave Platt wrote:
>> With 1200bd AFSK NRZI a logical 1 is transmitted as a constant tone, and
>> a logical 0 as a change in tone.
>> I'm wondering which tone comes first when we start a sequence. Should it
>> start with 1200 Hz or start with 2200 Hz? Or doesn't it make any difference?
>>
>
> It really doesn't matter. Use whichever you wish, or switch
> deterministically or randomly on each individual packet transmssion.
> At the receiving end, all "knowledge" of the actual tone being
> transmitted is wiped out by the first stage of the NRZI detector,
> which simply compares current-tone to previous-tone via an XOR
> arrangement.
>
Thanks. That's what I thought. But I'm having some problems with a
particular setup using a PIC to genrate the tones. I will have to play
with it some more...
--
73, PE1ICQ Arno Verhoeven
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next prev parent reply other threads:[~2006-06-11 19:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-11 19:23 Which tone comes first? Arno Verhoeven
2006-06-11 19:30 ` Dave Platt
2006-06-11 19:41 ` Arno Verhoeven [this message]
2006-06-12 5:08 ` Kevin Dawson
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