This is the best i can do so far. Using vlfrx-tools 0.9f and
vtfilter -a th=5 -h hp,f=1750,poles=8 -h lp,f=4250,poles=8 | vtblank -a25
-d0.005 -t1000
Does that count as a reception?
VY 73 es HNY
Jacek / SQ5BPF
On Sun, 30 Dec 2018, DK7FC wrote:
Date: Sun, 30 Dec 2018 22:15:04 +0100
From: DK7FC <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: ULF: Carrier on 2970.01 Hz
Hello Jacek,
Did you just look into a spectrogram or did you try to produce a spectrum
peak from your data storage?
Do you use the -a th=x function in vtfilter.
I think i have the latest version of vlfrx-tools. It is worth to upgrade.
Instead of the band pass filter i'm using a low pass and a high pass. After a
lot of trials i tend to use this setting as a standard:
vtread -T2018-12-30,11:17,+2h /database | vtcat -p | vtfilter -a th=5 -h
hp,f=1750,poles=8 -h lp,4250,poles=8 | vtblank -a25 -d0.0005 -t100 | vtmult
-f2970.01 | vtresample -r240 | vtresample -r10 | vtraw -oa | ebnaut -dp8K19A
-c4 -r10 -v -f15 -f16 -N5 -M'*****' -k27 -S12
The ebnaut message is just a dummy for a 2 hour long carrier transmission.
The output of that command line will show the S/N of the spectrum peak in its
bandwidth (1/duration).
The autonotch filter is important in that frequency range and can decide
between failed and success!
I would be interested in the result on your side.
73, Stefan
Am 30.12.2018 21:45, schrieb Jacek Lipkowski:
Ufortunately i didn't receive anything here. Not very exciting but i
believe that negative results should also be reported.
The spectrograms:
https://klubnl.pl/grabber/grabber_sq5bpf_2970.png
https://klubnl.pl/grabber/grabber_sq5bpf_2970_avg.png
Right now i use the same settings as on my 5170Hz grabber: a 3kHz wide
filter centered on 2970Hz, followed by vtblank -a1.4 -d0 -t100 (vtblank
from old vlfrx-tools). I would be grateful for any suggestions how to
improve this, maybe the filter is too wide (and lets too many 50Hz
harmonics through. which upset the blanker).
The antenna isn't optimised for ULF.
VY 73
Jacek / SQ5BPF
On Sun, 30 Dec 2018, DK7FC wrote:
Date: Sun, 30 Dec 2018 12:38:04 +0100
From: DK7FC <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: ULF: Carrier on 2970.01 Hz
Hi ULF,
The accu is fully recharged and i am on the hill again, transmitting on
the ground loop antenna. This time, the accu has even more power. The TX
power is 520 W (!), the DC measurement tells i need just 64 V for 1 A, and
now, at 2970.01 Hz i am getting a record antenna current of 2.75 A!!
The carrier ison the air since 11:17 UTC and i intend to run it for 2
hours again, like yesterday.
Reports are welcome :-)
73, Stefan
dk7fc_2970.png
Description: PNG image
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