Message-ID: <5C2C9BF1.2090609@posteo.de>
Date: Wed, 02 Jan 2019 12:09:37 +0100
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <976652757.10789891.1546166793929.ref@mail.yahoo.com> <976652757.10789891.1546166793929@mail.yahoo.com> <5C28AE1C.1020707@posteo.de> <alpine.DEB.2.11.1812302117390.1809@mailn.lipkowski.org> <5C293558.6010606@posteo.de> <alpine.DEB.2.11.1901021028190.1809@mailn.lipkowski.org>
In-Reply-To: <alpine.DEB.2.11.1901021028190.1809@mailn.lipkowski.org>
Subject: Re: ULF: Carrier on 2970.01 Hz
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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 <selberdenken@posteo.de>
>> Reply-To: rsgb_lf_group@blacksheep.org
>> To: rsgb_lf_group@blacksheep.org
>> 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 <selberdenken@posteo.de>
>>>> Reply-To: rsgb_lf_group@blacksheep.org
>>>> To: rsgb_lf_group@blacksheep.org
>>>> 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
>>>>
>>>
>>