Rx-Tx relationship

[Texasgopher]

I don't know much about the actual electronics of a MD and how they work other then the very basics. But I've been thinking about this some.

For a concentric coil.
The Tx coil is the big one and the Rx coil the small correct? Well I recently heard a person say that the Tx signal most likely goes down many feet in depth. It is the ability of the Rx coil to pick up the return signal that gives a detector it's max depth. Or is it more that the object can not produce a distinct enough return signal to be picked up by any Rx coil? If the problem is the first one, is there anyway to boost it's strength? Modify it's size, shape or configuration to the Tx coil? I know that the big name MD company's have probably spent a lot of time and money on the best concept for a coil and what is out there right now might be the best. But, I was wondering if maybe there are better ways of doing it that they don't use because of practicality in mass producing. If you could have to different dedicated power supplies for each coil (Rx and Tx) and had your computer match them to each other could this potentially go deeper and be more accurate even though it might make the machine really heavy? I have become more and more interested in the theory of it and would like to learn more. Specifically if there are any technologes that would perhaps work better than what is out there but for whatever reason (practicality, expense, etc...) the big names don't use it.

Do overlapping electrical fields of this nature strengthen each other? Would many Rx coils arranged just right strengthen the signal? Would you even be able to fit it all in side a coil housing of reasonable size after that?

I know these are all just random thoughts based on nothing at this point. But if anybody has the time to discuse I would be very interested.

TG

 

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[DGDancer]

Are you talking about a VLF detector or a PI detector? Pretty sure its a VLF your refering to~~
The relationship between the TX and RX coils is one of tuning and balance for the frequency the
detector operates at.
Sure the TX signal is large and the coil a bit larger thus can go deeper however the RX coil can be any size as long as its
tuned. Its the recieving circuitry that does most of the work. Coil size is relative to the area of maximum
sensitivity and ultimatly depth. Think of an onion and its layers, thats the field the TX coil sets up. RX coils
work inside this field.
VLF's work by measureing the distortion of the balance between the TX signal and the signal read by the RX coil
as the TX signal returns thru the center of the onion.
Packing more RX coils adds to the overall distortion inside the onion so there is a limit to how many you want inside
the field set up by the TX signal.
Overall accuracy, discrimination, sensitivity and what not is the work of the detectors electronics and/or programing.
Simply adding more RX coils is of limited use and generally degrades coil performance due to the need to
account for the additional metal inside the TX field.
My thoughts

 

[UncleVinnys]

I know the FCC puts a limit on the amount of power you can output to the coil.
A friend tried increasing the voltage in to see it that would add more depth, and it did
not work at all.
I would suggest just going to one of the newer DD coils, as they flatten the
wave form into a blade shape which goes deeper than the concentric coil.
And their techs have already worked out the waveform engineering.
I would not monkey with frequency or double coils, as the fields would interfere more than add to each other, unless you have an engineering degree and can synch the sine waves.