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Re: VLF: Back on 5.17 kHz / 58 km...

To: [email protected]
Subject: Re: VLF: Back on 5.17 kHz / 58 km...
From: DK7FC <[email protected]>
Date: Fri, 13 Jan 2017 00:50:58 +0100
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Hello Paul,

Thanks, that's great, just 3 days of about 8 hours each, for a 20 character message. But what was the message? I need to know it so i can see it as a valid detection.
The daily transmissions are a good choice and i have my LF and MF receivers available for receptions in the evening and night and early morning.

Tomorrow and during the weekend i have no time to play on the roof so let's use these days for a longer transmission.
Since we are already doing crazy things which are not possible (most HF or even GHz guys would think like that), let's keep it that way and try the following:

f = 5170.000000 Hz
Start time: 13.Jan.2017   08:00:00 UTC  (daily repetition)
Symbol period: 6 s
Characters: 100 (!)
CRC bits: 8
Coding 8K19A
Duration: 8h, 20m, 48s
Antenna current: ~ 225 mA

After the 75 character message you said that 0 CRC bits would have been a better choice. So i'm reducing the CRC bits here to 8, i can't go lower with the current EbNaut-tx version.

73, Stefan

Am 12.01.2017 19:47, schrieb Paul Nicholson:

Stefan wrote:

> f = 5170.000000 Hz
> Start time: 10.Jan.2017   08:00:00 UTC
> Symbol period: 24 s
> Characters: 20
> CRC bits: 16
> Coding 8K19A

Decoded after stacking three of the daily transmissions.

Eb/N0 = -0.7dB BER 34.7% at rank 71540 with constant
reference phase.

S/N (three days combined) 20.00 dB in 33.8 uHz.

Each day:

 10th -5.8 dB  phase 24.5   -63.9dB in 2500Hz
 11th -5.3 dB  phase 22.8   -63.5dB in 2500Hz
 12th -4.9 dB  phase 16.8   -63.0dB in 2500Hz

Paul Nicholson

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