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Re: VLF: 300 mA on 6470 Hz

To: [email protected]
Subject: Re: VLF: 300 mA on 6470 Hz
From: DK7FC <[email protected]>
Date: Wed, 04 Oct 2017 11:50:40 +0200
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Hi Paul,

Am 04.10.2017 11:07, schrieb Paul Nicholson:
You may as well use 8K19A or even 4K15A.

If you look at the big table at the end of

 http://abelian.org/ebnaut/ops.shtml

you can see there's no further improvement in success
rate for 6 bit payloads (1 char plus zero CRC = 6 bits).

The reason appears to be the payload is simply not long
enough to make full use of the longer constraint lengths.

OK, so i'm changing to:

f = 6470.005000 Hz
Start time: 04.October.2017  17:00:00 UTC
Symbol period: 240 s
Characters: 1
CRC bits: 0
Coding 8K19A
Duration: 12h48min
Antenna current: 300 mA



For some reason, the signal last night was about 6dB weaker.
Interesting. And for some reason, the signal was much stronger last night at SQ5BPF. Did you see it? What could be the reason? Just the noise blanker / background QRN?
The message will give you/us and 3rd impression about SNR and phase. A 10 deg phase variation between last night and the night before seems already to be quite high, relative to what we observed at 8270. Maybe we will learn a bit about propagation by that.
The 1 char message is for Jacek mainly. The chance for a decode will be high i think. Then i thought i try another (daily) 12 char message for Jacek before we can try the 100 char message. We've already done quite much on that 46 km band, so i wouldn't spend to much time there, 2 weeks maybe. Then QSY to 58 km where we can stretch the record list a bit by transferring 100 chars to you Paul.

73, Stefan


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