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Lets kick this one around...
- Thread starter Dan-Pa.
- Start date
Like you, I use a moderately slow sweep with the stock but a little faster with the Platypus. With the X-12, I go REAL slow. Basically, I go as fast as my ears can process the tones. Depends on where I'm hunting...
I guess I'd like someone to explain (keeping in mind I'm not a techie):
Why a fast swing would go deeper than a slow swing? Even if it did go deeper, how would one hear a deeper, "iffy" target between other targets?
I guess I'd like someone to explain (keeping in mind I'm not a techie):
Why a fast swing would go deeper than a slow swing? Even if it did go deeper, how would one hear a deeper, "iffy" target between other targets?
I cant say 100 % this is the reason, but this is what I am thinking.
Just a few thoughts on this while lying in bed at 4 am unable to sleep
An electromagnetic field from the detector builds and then decays across an object In the soil. It is the collapse of the field that causes the induced field to be produced in the object. It is this induced field that the detector detects. I believe this is the basics of how all machines work. Sure I will be corrected if I am wrong.
Asssuming the above to be correct then
If you sweep faster, there is a greater change with respect to time of the EM field across the object. This would then induce a bigger response field. Bigger response field, therefore easier to detect. Think of an unregulated dynamo (or alternator)on a car. The faster it spins, the higher the voltage output. I know in that case the field coil windings are DC not an high AC output as from detector, but it explains my thoughts........I think.
I will probably re read this when I am fully awake in the morning, and realise I have been talking c**p but for now it sounds reasonable as a theory.
As for the truth of the matter, does it go deeper with a fast swing or not, I cant say I have ever noticed or tried. but will have alook at this next time I am out. Also the amount of aluminium/copper/brass trash in the fields that I hunt means a fast swing is totally out of the question.
Just a few thoughts on this while lying in bed at 4 am unable to sleep
An electromagnetic field from the detector builds and then decays across an object In the soil. It is the collapse of the field that causes the induced field to be produced in the object. It is this induced field that the detector detects. I believe this is the basics of how all machines work. Sure I will be corrected if I am wrong.
Asssuming the above to be correct then
If you sweep faster, there is a greater change with respect to time of the EM field across the object. This would then induce a bigger response field. Bigger response field, therefore easier to detect. Think of an unregulated dynamo (or alternator)on a car. The faster it spins, the higher the voltage output. I know in that case the field coil windings are DC not an high AC output as from detector, but it explains my thoughts........I think.
I will probably re read this when I am fully awake in the morning, and realise I have been talking c**p but for now it sounds reasonable as a theory.
As for the truth of the matter, does it go deeper with a fast swing or not, I cant say I have ever noticed or tried. but will have alook at this next time I am out. Also the amount of aluminium/copper/brass trash in the fields that I hunt means a fast swing is totally out of the question.
Chris(SoCenWI)
Well-known member
But.....
In trash can't do this. Response time of electronics negates this effect.
Chris
In trash can't do this. Response time of electronics negates this effect.
Chris
So if this theory was correct, this would therefore be true of any metal detector?
Again assuming the response time of the electronics/receiver on time did not have an effect.
So......If you were to buld a coil that only worked in one direction of sweep, you could have continious TX one side/receive on the other.....fitted to modified potato harvester........plastic belts and rollers.......tractor mounted......digging and sifting down to about 2 ft.......and then I woke up
Again assuming the response time of the electronics/receiver on time did not have an effect.
So......If you were to buld a coil that only worked in one direction of sweep, you could have continious TX one side/receive on the other.....fitted to modified potato harvester........plastic belts and rollers.......tractor mounted......digging and sifting down to about 2 ft.......and then I woke up
Captain Kirk
New member
Dan,
I have conducted experiments that showed the following as you vary sweep speed from extremely slow to extremely fast.
* At extremely slow speed the response is very poor.
* As you increase the speed, then the response improves.
* At some speed you reach a maximum response.
* As you continue to increase the speed beyond the maximum point, then the response falls off.
But, all of this is dependent upon the ground characteristics, the target and the orientation of the target.
My conclusion is that just using any one sweep speed all the time does not necessarily produce the optimal results.
HH,
Glenn
I have conducted experiments that showed the following as you vary sweep speed from extremely slow to extremely fast.
* At extremely slow speed the response is very poor.
* As you increase the speed, then the response improves.
* At some speed you reach a maximum response.
* As you continue to increase the speed beyond the maximum point, then the response falls off.
But, all of this is dependent upon the ground characteristics, the target and the orientation of the target.
My conclusion is that just using any one sweep speed all the time does not necessarily produce the optimal results.
HH,
Glenn
Captain Kirk
New member
The induction effect does depend upon the time rate of change of the magnetic field. But, I think that most of the changing field comes from what is going on in the driving signal of the coil. The sweep speed is a factor, but not the dominant factor.
The effects are the same whether the field is building or collapsing. The Explorer II coil is driven from a rectangular bipolar voltage. Therefore the magnetic field is a bipolar triangular waveform (because the time rate of change of the magnetic field is proportional to the drive voltage). Both halves of the cycle are used to qualify the target.
HH,
Glenn
The effects are the same whether the field is building or collapsing. The Explorer II coil is driven from a rectangular bipolar voltage. Therefore the magnetic field is a bipolar triangular waveform (because the time rate of change of the magnetic field is proportional to the drive voltage). Both halves of the cycle are used to qualify the target.
HH,
Glenn
GraveDiggerMax-VaBch-Va
New member
n/t
Hi guys !
Reading the posts, and thought I'd try and get you back on the right track with regards to the incorrect lines of thinking regarding sweep speed etc.
IT HAS NOTHING TO DO WITH 'changing field's rate, etc.
Optimum 'Sweep Speed' is dictated PRIMARILY by the PASS BAND of the filters and/or the A.C. coupling of the signal amplifiers.
What YOU are doing by varying your sweep rate, is trying to match the target's 'response profile' ( in terms of its audio harmonic contents ), such that they best fit within the pass-band of your machine's signal amplifiers.
2 filters are generally the minimum found in any detector, that number is most tolerant of varying sweep speeds. Good in trash, but bad in fluctuating mineralization.
3 filters is a good compromise. 4 filters or more are more efficient in counteracting 'bad ground', but more constraining on sweep speed variability. You then have to determine more accurately what is the optimum sweep rate.
The average coin sized target produces a frequency spectrum of roughly 4 HZ to 20 or 30 Hz at sweep speeds of half to 1&1/2 metres per second.
The 'apparent' target size varies from its measured size, depending on its depth. So the same target at differing depths can require slightly different sweep speeds.
I have never subscribed to the myth regarding sweeping Minelabs very slowly.
As correctly stated in one of the posts..'he sweeps much faster, yet still finds as much'.......
You do your thing, but don't be shackled by the so called 'Minelab experts'. 99% of them are just 'swingers' and no more than that.
Be your own man...keep experimenting and discover by practicing, what suits you, in your situation.
That is the most important advice to follow.
You can't simply copy someone else's set up and use that regardlessly.
There is more bad advise bandied around on forums than most detectorists are aware off.
Be more enquiring and discerning about what you read. ..........MattR.UK
Reading the posts, and thought I'd try and get you back on the right track with regards to the incorrect lines of thinking regarding sweep speed etc.
IT HAS NOTHING TO DO WITH 'changing field's rate, etc.
Optimum 'Sweep Speed' is dictated PRIMARILY by the PASS BAND of the filters and/or the A.C. coupling of the signal amplifiers.
What YOU are doing by varying your sweep rate, is trying to match the target's 'response profile' ( in terms of its audio harmonic contents ), such that they best fit within the pass-band of your machine's signal amplifiers.
2 filters are generally the minimum found in any detector, that number is most tolerant of varying sweep speeds. Good in trash, but bad in fluctuating mineralization.
3 filters is a good compromise. 4 filters or more are more efficient in counteracting 'bad ground', but more constraining on sweep speed variability. You then have to determine more accurately what is the optimum sweep rate.
The average coin sized target produces a frequency spectrum of roughly 4 HZ to 20 or 30 Hz at sweep speeds of half to 1&1/2 metres per second.
The 'apparent' target size varies from its measured size, depending on its depth. So the same target at differing depths can require slightly different sweep speeds.
I have never subscribed to the myth regarding sweeping Minelabs very slowly.
As correctly stated in one of the posts..'he sweeps much faster, yet still finds as much'.......
You do your thing, but don't be shackled by the so called 'Minelab experts'. 99% of them are just 'swingers' and no more than that.
Be your own man...keep experimenting and discover by practicing, what suits you, in your situation.
That is the most important advice to follow.
You can't simply copy someone else's set up and use that regardlessly.
There is more bad advise bandied around on forums than most detectorists are aware off.
Be more enquiring and discerning about what you read. ..........MattR.UK
the response of EX is slow compared to other machines, and if you are swinging fast by the time it sounds off on good signal - it is moving over bad signal and trying to combine the two. If your ears can pick these signals out - more power to you. But this is not a detector you want to swing like a White's IMO.
and I'm not an arm-chair expert or a DFX user/expert posing as a Minelab guy - I actually own the machine and use it!
blaze away - i like finding what you missed
and I'm not an arm-chair expert or a DFX user/expert posing as a Minelab guy - I actually own the machine and use it!
blaze away - i like finding what you missed
halfdollar
New member
n/t
Mike Hillis
Well-known member
Yes in trash you have to slow down so you can separate. In this case you are not so concerned about the ground signal. Besides, the trash itself limits achievable signal depth.
But if you are not in the trash and you are after depth, then sweep speed is about managing the ground signal. You are trying to cause weak signals to respond above the ground signal. Sweep speed is about causing a faster rate of change in the metal target than you get from the ground response itself.
Couldn't resist adding my corroded, half dissolved zincs to the conversation.
HH
But if you are not in the trash and you are after depth, then sweep speed is about managing the ground signal. You are trying to cause weak signals to respond above the ground signal. Sweep speed is about causing a faster rate of change in the metal target than you get from the ground response itself.
Couldn't resist adding my corroded, half dissolved zincs to the conversation.
HH
Hello Mike.
I was just passing by this old topic, and noticed your comment.
QUOTE:-
You are trying to cause weak signals to respond above the ground signal. Sweep speed is about causing a faster rate of change in the metal target than you get from the ground response itself.
If I am interpreting your comments correctly then you are implying that you can some how make the target response rate of change faster without doing the same for the ground signal...????
I feel that the statement is not sufficiently explicit.
Here are some facts:-
If you 'quicken' your target response, then you also PROPORTIONATELY quicken your ground response (All other factors being kept equal)
For example:-
Let's say your ground's fundamental frequency signature is one hertz, and your target's fundamental is six hertz.
Now let's double our sweep speed.
Our ground signature will be Two hertz and our target's will be Twelve hertz.........
The point being, that the RATIO of target to ground fundamental frequencies will CONSTANT. i.e. ONE:SIX.
Trebling your sweep speed means the ground will be 3 hertz and the target 18 hertz.
The basic trick is to get the fastest sweep-speed that puts the target's response within your detector's filter-pass-band, whilst keeping the ground's response BELOW that pass-band, and so be attenuated.
The average detector has fixed filter pass-bands, (Minelabs),
whereas the White's DFX has 5 adjustable filters.
They are not only adjustable in bandwidth, but also in their center-frequency.
That is just a snippet of the complexities involved in understanding the fundamental variables associated with metal detecting.
I have contemplated writing a book on the more technical realities of the hobby, but I then wonder if the average detectorist is interested in knowing the facts of his detector, and its functionalities......MattR.UK.
I was just passing by this old topic, and noticed your comment.
QUOTE:-
You are trying to cause weak signals to respond above the ground signal. Sweep speed is about causing a faster rate of change in the metal target than you get from the ground response itself.
If I am interpreting your comments correctly then you are implying that you can some how make the target response rate of change faster without doing the same for the ground signal...????
I feel that the statement is not sufficiently explicit.
Here are some facts:-
If you 'quicken' your target response, then you also PROPORTIONATELY quicken your ground response (All other factors being kept equal)
For example:-
Let's say your ground's fundamental frequency signature is one hertz, and your target's fundamental is six hertz.
Now let's double our sweep speed.
Our ground signature will be Two hertz and our target's will be Twelve hertz.........
The point being, that the RATIO of target to ground fundamental frequencies will CONSTANT. i.e. ONE:SIX.
Trebling your sweep speed means the ground will be 3 hertz and the target 18 hertz.
The basic trick is to get the fastest sweep-speed that puts the target's response within your detector's filter-pass-band, whilst keeping the ground's response BELOW that pass-band, and so be attenuated.
The average detector has fixed filter pass-bands, (Minelabs),
whereas the White's DFX has 5 adjustable filters.
They are not only adjustable in bandwidth, but also in their center-frequency.
That is just a snippet of the complexities involved in understanding the fundamental variables associated with metal detecting.
I have contemplated writing a book on the more technical realities of the hobby, but I then wonder if the average detectorist is interested in knowing the facts of his detector, and its functionalities......MattR.UK.
Mike Hillis
Well-known member
n/t
Personally I feel swinging my Explorer fairly slow ( don't want to get into seconds per swing and such) works well for me but this young fellow swings fast with good results....You sure dial in a lot of facets but all detectorists differ, some have better hearing or perhaps hear tones better and more clearer than others, now dial in type of headphones and settings and your facets are plausible but surely not equal..Just my thoughts on a super hot day...