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Re: VLF: 300 mA on 5170 Hz

To: [email protected]
Subject: Re: VLF: 300 mA on 5170 Hz
From: DK7FC <[email protected]>
Date: Fri, 03 Nov 2017 12:07:45 +0100
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Hello Paul, VLF,

What a great result again! Many thanks for the decode and detailed informations. As expected, we needed 5 days. That's still quite fast i find. But we see it begins to become harder on the way down to DC.
Quite a difference between the SNR of H and E on your side. It becomes
higher the lower we go in frequency. About 5 dB difference on a good
day, and more than 5 dB on a noisy day.
It seems to show that propagation on 2970 Hz between us was not as bad
as concluded, it rather was the missing sensitivity. So now it makes
hope to get much better results already with the new E field RX and it
is worth to optimise the H field, as you say.
For the next step downwards i would like to operate in the range between
4...4.47 kHz, i.e. somewhere near 70 km wavelengh. We already got a
carrier detection there, between us, but that was with the old E field
RX, right?
What next? I will move to 8270 Hz again for some time to attempt to
leave a trace at RC4HAA. That's the plan for the weekend. After that, i
go back to 5170 Hz, trying to transfer 12 characters (or more) to
RN3AUS. The move to the range near 4 kHz is planned for the end of December.
73, Stefan

Am 03.11.2017 10:34, schrieb Paul Nicholson:
Stefan wrote:

> f = 5170.1000 Hz
> Start time: 26.October.2017  18:00:00 UTC (daily)
> Symbol period: 8 s
> Characters: 100
> CRC bits: 16
> Coding 8K21A

> The transmission starts as announced, just a day late.

> On the 29th and today, the 30th, there was no transmission.
> The safety function triggered again.

Copied "I LIKE THE 58 KM BAND, WHAT A GREAT PLAYING FIELD!!!
        ANOTHER STEP DOWN ON THE WAY TO DC. 73 DE DK7FC"

after 5 transmissions stacked.  BER 32.7%, Eb/N0 -0.2 dB, with
constant reference phase, list rank 312678.  Used combined
H-field and (new) E-field receivers.

That's a record number of characters for this band.

Individual days and receivers:

        H-field                    (new) E-field
 27/28  -13.2 dB 178 deg         -8.5 dB 156 deg
 28/29  -12.8 dB 168 deg         -7.4 dB 171 deg

 31/01  -15.5 dB 170 deg         -8.7 dB 167 deg
 01/02  -12.8 dB 180 deg         -7.3 dB 168 deg
 02/03  -16.9 dB 180 deg         -7.4 dB 166 deg

Pretty stable phase and S/N from night to night.
Consistently better performance from the new E-field rx.

--
Paul Nicholson
--





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