AD8302

[KingJL]

Has anyone considered using the Analog Devices AD8302 as the heart of a VLF detector? I am considering experimetation (as soon as I can conclude some other projects).

[homefire]

Pricey little suckers, Eaaa? Interesting Idea. http://www.newark.com/analog-devices...14_US%2Fsearch

[KingJL]

Pricey little suckers, Eaaa? Interesting Idea. http://www.newark.com/analog-devices...14_US%2Fsearch

A module on ebay can be had for as little as 6.75 us.

[KingJL]

A module on ebay can be had for as little as 6.75 us.

http://www.ebay.com/itm/182479637184...%3AMEBIDX%3AIT

[Davor]

It may be useful as a hart of a 2boxx device or something similar.
There are basically 2 problems here.
1st is the air signal that would obliterate any traces of a target after it is compressed with a log amp.
2nd is a phase detector that provides meaningful response only for the first and second quadrant. For 3rd and 4th you'd need to reverse it to make sense.

Problem with normal VLF is that target response is only a small fraction of a much larger air signal, and somewhat larger ground signal. Log amps will iron the signal so that only the strongest is represented, while the fine detail within it is lost.

[KingJL]

It may be useful as a hart of a 2boxx device or something similar.
There are basically 2 problems here.
1st is the air signal that would obliterate any traces of a target after it is compressed with a log amp.
2nd is a phase detector that provides meaningful response only for the first and second quadrant. For 3rd and 4th you'd need to reverse it to make sense.

Problem with normal VLF is that target response is only a small fraction of a much larger air signal, and somewhat larger ground signal. Log amps will iron the signal so that only the strongest is represented, while the fine detail within it is lost.

1st stated issue may be true, but I still see value in experimentation; 2nd stated issue, I foresaw, and can be overcome by using 2 modules in quadrature (inpb references 90 degrees apart). I planned on buying to in the 1st place. All 4 input filter caps can be set to a value CnF = 2/fMhz; 2 output Cflt caps =1 uF. This will allow operation at the frequencies that we would be interested in.

[Altra]

I ordered a couple to play with, not sure about metal detector applications? But for RF it seems pretty useful.

Also found this app note for low frequency use.

http://www.analog.com/media/en/techn...tes/AN-691.pdf

[KingJL]

But for RF it seems pretty useful.

That is what originally tweaked my interest... I also dabble and experiment with suppressed carrier, SSB and lock-in amps. Could even make a modern "Dicke Fix" rx circuit.

[Altra]

I was thinking of a "fox hunt" directional rf detector. Using two antennas where the magnitude would indicate a direction at the peak. I have used the AD8313 and AD8307 in the past for rf detectors and they are very sensitive. Thanks for posting.

[xix]

Hi Altra
I've puzzeling for some time now on using these devices for MD. Did you managed to progress on this?
Cheers

[Altra]

Hi

Not yet, it's coming from China on a slow boat. I'll post after I receive them.