Menu
What's new
Find's Treasure Forums

Welcome to Find's Treasure Forums, Guests!

You are viewing this forums as a guest which limits you to read only status.

Only registered members may post stories, questions, classifieds, reply to other posts, contact other members using built in messaging and use many other features found on these forums.

Why not register and join us today? It's free! (We don't share your email addresses with anyone.) We keep email addresses of our users to protect them and others from bad people posting things they shouldn't.

Click here to register!

Need Support Help?

Cannot log in?, click here to have new password emailed to you

Changed email? Forgot to update your account with new email address? Need assistance with something else?, click here to go to Find's Support Form and fill out the form.

SMF

P

Picketwire

Well-known member
I cannot understand how a one wire can transmit multiple frequencies at the exact same time. I can see them alternating quickly but not simultaneously. Can someone help me understand how this is possible.
 
Its voodoo…..
Couldnt resist, I do not have an answer for you, sorry.
Is it one wire or is it a cable with several wires? Interesting question……
 
If I remember correctly.
Most run like the old Explorers.
The frequencies come out in strings of pulses.
All frequencies come out one after the other.
Like
1,2,3,4,5 gap 1,2,3,4,5 gap and so on.
And the recieve is programmed to see each frequencies response in sequence.
Combining and computing the results for it's best guess for vdi and tones per the program.
You can see it on an oscilloscope.
 
Picketwire said:
I cannot understand how a one wire can transmit multiple frequencies at the exact same time. I can see them alternating quickly but not simultaneously. Can someone help me understand how this is possible.
Click to expand...
Do remember
Metal detectors are simply a transmitter and radio receiver.
With a lot of filtering.
They could possibly transmit hundreds of frequencies on one of the channels.
 
Legend has 8 pins
 
I was thinking maybe two separate receive and transmit coils but I would say odanscoils would know better than me. But if they only ran two frequencies together I could see how that might work simultaneously. Maybe Carl will come along and explain. I am pretty sure I remember him talking about using an oscilloscope on SMF detectors before.
 
Its hard to comprehend how many different frequencies can be put down and analysed at once......minelab advertised this when their multi frequency technology first emerged but we know that each frequency was put down seperately,although seperated by a very short delay.
I'm with Picketwire on this one......although i do not understand the technology to a great degree i still don't believe it is possible in my simple brain.......maybe detector manufacturers don't want anybody to dig to deep,into it.😊
 
Nauti said:
Its hard to comprehend how many different frequencies can be put down and analysed at once......minelab advertised this when their multi frequency technology first emerged but we know that each frequency was put down seperately,although seperated by a very short delay.
I'm with Picketwire on this one......although i do not understand the technology to a great degree i still don't believe it is possible in my simple brain.......maybe detector manufacturers don't want anybody to dig to deep,into it.😊
Click to expand...
Think about a radio station. Voice and music are thousands of frequencies being transmitted over a single frequency.
Received by millions of radios.
I think that's amazing.
Metal detectors are a radio wave transmitter.
With the receiver built into the same unit.
 
Good description.........but the radio transmitter doesn't recieve the signal back and have to anslyse the info in each frequency at the same time,surely to get the correct info from the return signal each frequency would have to be analysed seperately??
 
Picketwire said:
I cannot understand how a one wire can transmit multiple frequencies at the exact same time. I can see them alternating quickly but not simultaneously. Can someone help me understand how this is possible.
Click to expand...

The TX coil has 2 wires, just like a loudspeaker. And like a loudspeaker you can mix frequencies and send them at the same time. With sequential MF (Minelab BBS/FBS) the frequencies are sent one-at-a-time, rapidly alternating between 3.125kHz and 25kHz. With simultaneous MF (everything else) a TX waveform is constructed that has 2 or 3 frequencies mixed together.
 
But how are the return signals analysed......surely they have to be analysed seperately in which case an average fequency would be used from a combination of all of them meaning that the resulting analysis of the signal isn't really similtaneous mf at all.
I just dont see any improvement between the old minelabs and the newer technology on actual targets from comparisons done on the beaches although i havent compared signals on inland sites.Comparing my Sov GT to the newer minelabs on the beach,i will be sticking with my Sov.
 
Nauti said:
But how are the return signals analysed......surely they have to be analysed seperately in which case an average fequency would be used from a combination of all of them meaning that the resulting analysis of the signal isn't really similtaneous mf at all.
Click to expand...

The composite signal from the RX coil is split into the 2 or 3 individual frequency components using bandpass filters. Then each frequency is demodulated and processed. For sequential MF (BBS/FBS) the bandpass filters aren't needed, the frequencies are time-demodulated.
I suspect that the newer MF detectors will beat the Sov on low conductors like small jewelry while the Sov will excel in high conductors like silver coins. The new models will also win hands-down in target separation, though that's usually not an issue at the beach.
 
You must log in or register to reply here.
Top