Message-ID: <5C5BE905.2010904@posteo.de>
Date: Thu, 07 Feb 2019 09:15:01 +0100
From: DK7FC <selberdenken@posteo.de>
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References: <168c41b89f6.marcocadeddu@tin.it> <CAKvcm2eoZZOrjQ6zZ6Tx3zxHfahEL6eJ2jrcHELgsVdecfLA2g@mail.gmail.com>
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Subject: Re: VLF: in VK?
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Hi Dimitris,

Interesting, theat LIPD class. So you could even try higher frequencies 
than 8.3 kHz. Here we are not allowed to transmit above 8.3 kHz.
However, i have a special licence to transmit arround 17.47 kHz, with 5 
mW ERP. On that frequency i have been received by Edgar and we 
transferred a 3 character message successfully some months ago. A 5 
character message almost decoded but in the end we failed.

Why is there is a  gap between 19.95...20.05 kHz? No idea but i would 
have expected a gap arround 19.8 kHz, because of NWC 
https://en.wikipedia.org/wiki/Naval_Communication_Station_Harold_E._Holt

200 uW on 8.27 kHz is a good signal but with the space you have, you 
could get up to 20 dB more so it is a pity. But anyway, many people 
could detect you at 200 uW, at least in a radius a few 1000 km.

73, Stefan


Am 07.02.2019 01:52, schrieb Dimitrios Tsifakis:
> Ciao Marco,
>
> yes, the grass is indeed greener on the other side but I am not
> complaining about that! If there is no time now, perhaps there will be
> later! More things to do when I retire, there is nothing worse that
> people that retire and do nothing...By the way I do look at the legal
> aspects. We are lucky in Australia our local spectrum authority has
> made it clear how much we can radiate in the various parts of the
> spectrum. There is a class licence known as LIPD (low interference
> potential devices) which tell you how many microwatts you can radiate
> on VLF and below and it is very generous I think. Here is what we are
> allowed to do:
>
> 0 kHz to 14 kHz        200 uW EIRP
> 14 kHz to 19.95 kHz   50 uW EIRP
> 20.05 kHz to 70 kHz  7.5 uW EIRP
>
> (note I cannot transmit between 19.95 kHz and 20.05 kHz, not sure why
> there is that gap)
>
> I can live with that!
>
> 73, Dimitris VK2COW
>
>
> Στις Πέμ, 7 Φεβ 2019 στις 5:46 π.μ., ο/η marcocadeddu@tin.it
> <marcocadeddu@tin.it>  έγραψε:
>    
>> Hi Stefan, Dimitris,
>>
>> room is sure a thing that is not missing in VK :-)
>> I remember a vacation I had there some years ago ... a lot of km between "adiacent places".. so ideal place for LF, VLF and even close to DC frequencies!
>> During my travel, just for fate, I drove close to Holt Navy Base sporting an antenna just a bit larger than your loop ;-)
>> Anyway you know the grass of the neighbor is more green...
>> Dimitris has room but not a lot of time..
>> I have more time but less room
>> somebody else has room and time but no money...
>> What an hard life!
>> But... we all have fun!
>>
>> 73 Marco IK1HSS
>>
>> P.S. who's looking the legal aspects?? ;-)
>>
>> ----Messaggio originale----
>> Da: selberdenken@posteo.de
>> Data: 5-feb-2019 23.40
>> A:<rsgb_lf_group@blacksheep.org>
>> Ogg: Re: VLF: in VK?
>>
>> Dimitris,
>>
>> Am 05.02.2019 21:14, schrieb Dimitrios Tsifakis:
>>
>> G'day Stefan and Edgar,
>>
>> My house is on QF44OX00OR and the property extends to QF44NX (50 acres
>> or 200,000 m^2). I do have permission from some neighbours to lay
>> wires into their properties, so an extra large (over 1km) ground wire
>> is entirely doable but not at this point in time.
>>
>> Wow, i'm envious and happy that you have such possibilities!!!!!!!!!!!!!!
>> Not at this time, ok. I would suggest to start in small steps anyway, then you can be happy about many improvements, not just a single big one :-)
>> I often imagine to live in Canada or Australia and do such experiments exactly!
>>
>> The reference loop
>> is from the shed, about 100 metres south of the house, to the tractor
>> shed.
>>
>> 100m is very close, the far field begins at about 5.7 km distance at 8.27 kHz. A RX in that distance is only useful to check and observe the signal stability and compare levels. A feedback monitor like my tree which is 3.5 km distant from my INV-L antenna in the city. From my ground loop antenna in JN39WI it is 57.6 km distant, which is already an interesting distance and can be challenging below 3 kHz.
>>
>>   I have mains in the shed and I also have a 200 W audio linear
>> amplifier to get things started.
>>
>> Excellent, just excellent! Your signal could be the stongest of the radio amateurs! 200W is just fine for the first steps. But be careful with those audio amplifiers, they do not seem to like to much reactive power.
>> For tuning the antenna you will only need a capacitor in series. For my portable VLF system i built a current transformer to produce a small voltage that goes to the soundcard. Then, using SpecLab, i can calculate the antenna current directly and even keep the phase of the current stable, even if there should be a soundcard glitch. For the signal generation i also use SpecLab and a cheap GPS module. It all works very reliable, there were no problems so far.
>> With a house at one of the ends of the antenna you are in a very comfortable situation! You may already have a ground system there, so the effort is at one end only.
>>
>>   I can build a class-E kilowatt if
>> necessary later. I like the roughly north-south loop configuration as
>> it favours many large cities (Melbourne, Sydney, Brisbane and Tassie)
>> and most importantly Canberra which is only 30 km to the South. I will
>> try to get some signals received in Canberra before I start asking
>> people further away to have a listen.
>>
>> Yes, this is a very good distance to observe your own signal. If you have internet access there and can leave a small PC/notebook/tablet ... then you could build up a webpage and run a grabber from there like i do from my tree (still under maintenance). That would be ideal and it just feels good to see the own signal very clearly on a real RX in a short distance. You are then independent.
>>
>>
>>   I currently have assembled an XO
>> clocked DDS controlled by an arduino to do the initial tests but later
>> when I decide to go QRSSSSSI can dig out and use the old rubidium
>> clock as a reference for extra stability. For receiving I use a 24
>> bit, 192 kHz USB sound card and spectrum lab (thanks Wolf!). The
>> antenna I will use for receive is one of those monster ferrite rods.
>> Amplification may not even be necessary, the signals I get when the
>> antenna is tuned seem to be already quite good. Once I have a decent
>> RX antenna I think I will start gifting these rods (I have a few) to
>> interested amateurs in the region and help them get started with
>> receiving on VLF. Make a small army of receivers, that would make life
>> much easier when evaluating antennas!
>>
>>
>> Oh yes! Fortunately there are a few arround here. These days this is (sorted by distance to my VLF loop): DK7FC, DF6NM, DL0AO, DL4YHF, IK1QFK, Paul Nicholson, SQ5BPF and RN3AUS. Oh and W1VD, K3SIW and Edgar J.T. This is about the complete VLF group worldwide, at least those who prooved to detect narrow band (sub mHz) signals close to the limits, in the last 3 years until now.
>>
>> Hey, you should document your experiments even if it is a summary of
>> the activities and nothing more. The list is great but perhaps we are
>> missing out on many other potentially interested people that may have
>> not discovered the list.
>>
>> Yes, you are right. I had the same thought sometimes. Certainly there are many amateurs who would feel like having a new life when starting at VLF, It is an unknown spectrum for 99.9 % of the amateurs. Actually it is not even amateur radio because it is not a spectrum allocated to amateur radio. So everyone could operate there.
>> But there is a risk, you know. There are those people who do not simply start to transmit/receive there and feel good. There are those who prefer to ask if this is legal at all. And then they ask here and there, as long as they find someone who triggers their fears and phobs, and then they do nothing at all! Beware of such people, they are contaminating your free mind. Concentrate on ideas and wishes, like for example detecting your own signal in Canberra. And then the question "Will this also work on lower frequencies", for example.
>> When writing an article in a radio magazine, what will be the result? Will it actually lead to more active people on the band, who transmit and/or receive for a longer time, say at least 5 to 10 years? Or will it rise a short interest only, dominated by people telling it is not legal and so on... I'm not sure about that. It could be even better to stay in a smaller group who can do what it wants instead causing a decision / regulation by an 'authority'.
>>
>>   You are clearly not lazy having achieved so
>> much on MF and below :-)
>>
>>
>> Thanks but i'm lazy into a certain spectrum. On the other side, there are people who write many articles over the years but it is simply impossible for them to even imagine to wind a coil which has more than 100 turns. Maybe it is good that there is a variety of people, the article writers and the coil winders and something inbetween :-) Oh, and the programmers! Very important. Without Wolfgang and Paul and Markus we would do nothing at all!
>> Oh BTW maybe i'll transmit on my loop again the next weekend. I can't await it, it is more than 2 weeks ago, a very long time!!
>>
>> I have played with ground loops before and had some good results in
>> LF.
>>
>> On VLF it should work much better (relative to a vertical E field antenna). The idea is that the current runs back in a deep layer (skin depth), depending on the ground conductivity. So it should work better on poor conducting ground.
>>
>>   Once I establish a reference system, I can compare antennas
>> including ground loops. Unlike Europe where you have plenty of people
>> around you, I have to do both the TXing and the RXing and that
>> requires effort and time. The latter is a very scarce resource!
>>
>> Anyway, looks like a nice day today to do some more outdoor work. We
>> had lightning storms and plenty of rain the past few days, so I
>> haven't made any progress.
>>
>>
>> RR, good luck and fun with the new challenges.
>> Looking forward to your next steps and reports.
>>
>> 73, Stefan
>>
>>
>>
>> 73, Dimitris VK2COW
>>
>>
>>
>>
>>      
>