ELF to VLF Equipment

[Dirk_SDR]

One question on your stationary "below LF equipment":
My problem living in the 3rd floor is having no good or no RF ground.
For HF and above there are DIY or ready to use virtual ground devices like the MFJ-931, which will possibly help a bit.

I didn't find a solution for a virtual ground or other DIY project for e.g. VLF.
What do you use for these low frequencies as RF ground?

 

[ko6jw_2]

My question would be: What do you expect to hear?

The Navy's Project ELF antenna array was 84 miles long. It is used for submarine communications. The bandwidth is so limited that it takes minutes to send a few characters. Fifteen minutes for a three letter cypher group. No voice and one-way only. The frequencies were 45 or 76 Hz. Yes hertz.

The ground? An array of 300 foot electrodes in boreholes.

Don't try this at home folks.

 

[Dirk_SDR]

You'r right, ELF is quite difficult to receive, there is only natural radio like the Schumann Resonance.
The navy transmitters you mention are in the SLF band.

Other submarine communication also can be found in the VLF band, at my location I can receive HWU, GQD, DHO38, etc.

Of course you don't need 300 foot electrodes in boreholes to be successful with these low frequencies (if you don't plan to build a large navy transmitter).

In my situation everything that improves reception can be helpful. Ideas about (artificial) RF ground for low frequencies?

 

[Dirk_SDR]

Just for a :
In another forum someone answered to my similar question:
"Fill your bath tub full with warm water, solve 5 kg salt in this water and hang your ground electrode into the tub."
Should I try? 😁

 

[dlwtrunked]

My question would be: What do you expect to hear?

The Navy's Project ELF antenna array was 84 miles long. It is used for submarine communications. The bandwidth is so limited that it takes minutes to send a few characters. Fifteen minutes for a three letter cypher group. No voice and one-way only. The frequencies were 45 or 76 Hz. Yes hertz.

The ground? An array of 300 foot electrodes in boreholes.

Don't try this at home folks.

Receiving antennas and transmitting antennas can be very different. Also, the Russians still transmit down there a (some have received those) and the Chinese reportedly are also recently doing it. Some of us are very interesting at receiving these at home and have.

 

[bearcatrp]

Are these transmissions your receiving encrypted or can you listen to a conversation? If encrypted, why waste the time?

 

[dlwtrunked]

Are these transmissions your receiving encrypted or can you listen to a conversation? If encrypted, why waste the time?

There is far more than listening to conversations--designing and experiementing with equipment, reception, and studying systems--for many of us, that if much more interesting than listening to "conversations".

 

[Dirk_SDR]

Like on other frequencies the challenge is to be able to setup the equipment as described e.g. here:

www.vlf.it - Reception of strange signals with a PC

... and possibly to decode the VLF navy transmissions up to the last bit:

🤽 👨🏼‍🏫 🛀🏻 Wie man Signale von der deutschen Marine mit einer Soundkarte empfängt oder Ultra-Niederfrequenz-Funksignale studiert 🌰 👼🏾 🏿

Hallo Habr. Das Thema des Empfangens und Analysierens von ultralangen Wellen ist sehr interessant, wird aber bei Habré selten erwähnt. Ver...

tech--de-netlify-app.translate.goog

... or decode time transmissions:

Time Signal Decoder

www.qsl.net

... or ...

 

[Dirk_SDR]

After a lot of testing I've come a bit closer to a solution for a good RF ground.
I followed this good article:

https://helpdesk.flexradio.com/hc/en-us/articles/204779159-Grounding-Systems-in-the-Ham-Shack-Paradigms-Facts-and-Fallacies

... and had to do it as shown in Fig. 5 (counterpoise), because I'm on the 3rd floor.
The problem stays of course, that I would have to use very very long floating wires for ELF-VLF, but I see, that already 10 to 40m (partly hanging out of a window) bring a lot.
I made a central grounding plate with a single connection to each hardware component. I also have the option, to connect the ground system of the cable TV (DVB-C) house installation to the central plate. Unsure, whether this is helpful, because noise level rises a bit then.

 

[cistercian]

Use a loop antenna. No ground required.
Lucky for you at vlf and elf frequencies the 3rd floor is an inconsequential length of wire to run down to a ground field.
The downside is it wont be a ground at MW and up.