Hi Jacek,
Are you sure the x-axis label is correct?
In vtblank, you use -t1000, not -t100 ?
You need to determine the carrier S/N. I usually take an EbNaut message
having the same length, containing stars (*****), which is equivalent to
a carrier. Then the decoder tells me the carrier S/N.
So, try:
Am 02.01.2019 10:33, schrieb Jacek Lipkowski:
vtfilter -a th=5 -h hp,f=1750,poles=8 -h lp,f=4250,poles=8 | vtblank
-a25 -d0.005 -t1000
and then | vtmult -f2970.01 | vtresample -r240 | vtresample -r10 | vtraw
-oa | ebnaut -dp8K19A -r10 -c4 -S12 -N5 -k27 -v -f15 -f16 -M'*****'
There you need at least 14 dB S/N for a valid detection.
73, Stefan
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
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