cave pinger loan?

[jlillest]

Ken uses his pingers in the Nullarbor, and the overburden is 100m, and the water up to 30m deep.. It is pretty dry, though. Brian uses air core, or ferrite, Ken uses mu metal. Have you seen one of Ken's pingers? They are much more compact that any of Brian's.

Sure I understand expensive magnets make for better pingers, but i also don't drive the car that I wish I did. At ~four times the cost, I'd rather look at the economical versions. Brian has made some good radio-locaters that can do 100m, but testing will tell whether we can make something work for a broad application. Most of what I want to do is less strenuous than the Nullabor, as is most of Florida (and the Carribean).

-Jon

[Dave]

I just returned from a week of surveying using Kens (prototype) pingers. I was amazed at the ease and accuracy of the data collection. We were getting clear and concise data over 30m of karst and 10m of water. Its a very nice system.

[Paulmal]

Just wondering, as I have no idea but how much does a pinger cost to buy/ build.

[FW]

Just wondering, as I have no idea but how much does a pinger cost to buy/ build.

At the moment, nobody "sells" one outright. Ken Smith's plans are here: https://sites.google.com/site/kendiver/pinger
Materials are a few hundred, if you can find them.

[aa3jy]

Not knowing the circuitry of this system..but is it that same principal of current day SONAR which generally works in the 214hz range..?

Note the diver using a hand held version..

http://en.wikipedia.org/wiki/Sonar

This interests me

[apitkin]

Not knowing the circuitry of this system..but is it that same principal of current day SONAR which generally works in the 214hz range..?

Note the diver using a hand held version..

http://en.wikipedia.org/wiki/Sonar

Sonar uses sound waves, which will not penetrate far in solid rock. All of the cave radiolocation devices use electromagnetic ("radio") waves.

[aa3jy]

Sonar uses sound waves, which will not penetrate far in solid rock. All of the cave radiolocation devices use electromagnetic ("radio") waves.

Again not knowing the circuitry design I would assume the RF wave length must be in the ELF range

http://en.wikipedia.org/wiki/Extremely_low_frequency

and 1/4 wave lenght or even 1/8 wave and the antenna length would be extremely large.

We used these freqs as redundant communications in re constitutional conditions

http://en.wikipedia.org/wiki/Surviva...cations_System

for our submarine,bomber and missile forces

Again I find all this interesting..

[FW]

It is, and at the low end at that. Like apitkin said, it is radio, not audio. IIRC, the frequency is in the audio range, but still electromagnetic. The receiver is very simple, and just converts the radio wave to audio, with no decoding necessary. The antenna would be large, but it is coiled up. Ken's system fits into a 2" PVC pipe about 18" long. There is another system with a flat, wide coil, that is about 3' in diameter, and only an inch or so thick. Either system has to be level to work. It sends the signal perpendicular to the earths surface, so when you get the best signal, you know you are right over it. They actually use a null, to be more accurate, once over the strongest signal.

Again not knowing the circuitry design I would assume the RF wave length must be in the ELF range

http://en.wikipedia.org/wiki/Extremely_low_frequency

and 1/4 wave lenght or even 1/8 wave and the antenna length would be extremely large.

We used these freqs as redundant communications in re constitutional conditions

http://en.wikipedia.org/wiki/Surviva...cations_System

for our submarine,bomber and missile forces

Again I find all this interesting..

[aa3jy]

It is, and at the low end at that. Like apitkin said, it is radio, not audio. IIRC, the frequency is in the audio range, but still electromagnetic. The receiver is very simple, and just converts the radio wave to audio, with no decoding necessary. The antenna would be large, but it is coiled up. Ken's system fits into a 2" PVC pipe about 18" long. There is another system with a flat, wide coil, that is about 3' in diameter, and only an inch or so thick. Either system has to be level to work. It sends the signal perpendicular to the earths surface, so when you get the best signal, you know you are right over it. They actually use a null, to be more accurate, once over the strongest signal.

Basic math..

http://www.cis.rit.edu/class/simg303...ntoEMWaves.pdf

[FW]

Basic math..

http://www.cis.rit.edu/class/simg303...ntoEMWaves.pdf

Nice, but has no relation to pingers, as they aren't moving.