Is It Worthwhile Writing A Noise Filter For Detectors?

[oldmancoyote1]

I might write an iPhone app to filter noisy metal detector signals.  Is this a big problem, or is the problem just my old GPX4500?  The basic idea is to repeatedly swing across an area, and the app would add all the signals together.  Random signals would cancel each other out, and a valid signal would be reinforced.  The oil companies call it "stacking", and it has been extremely successful.  Any other ideas for an app for nugget hunters would be very welcome.

[bklein]

If a VLF, you already know the good target ID, wouldn’t discriminating out the other IDs accomplish the same thing?  I guess if you have a pi it might work but it would also lock on real but unwanted targets.  Likely be a latency issue plus you’d need to have a consistent swing and sense end of swing with a sensor.

Perhaps go into detail how you think it would work.

 

[oldmancoyote1]

You're right about VLF not being practical.  Yes, for PI machines it would lock on real non-gold targets, but in that respect I don't think it would be that different from  what is normal for PI machines.  Syncing between swings would be difficult, but it would be doable if the user laid down a thin chain alongside the area to be searched.  Then, the beginning of each swing would be marked by a double peak signal.  I probably would discard the second (return) half of the signal.  A uniform swing wouldn't be that hard to maintain.  

How about wether there is enough noise with PI machines to make this worthwhile.  I have very little experience with PI machines.

[tboykin]

No, the last thing I want to do is be tethered to another screen while prospecting. The issue with using something like an FFT is that the human brain and ear are still more discerning than any machine. You would need to have a machine swing the detector, otherwise sweep speed, height, and coil control will skew the results. Could maybe work with some kind of automated detector.

A much better app would be a GPS coverage map so I know I have covered an area 100%, or where gaps remain that I have yet to scan. There would be limitations due to GPS accuracy but those may be minimized by using the accelerometer. This would also be useful for beach, relic, and coin detectors. You could potentially allow people to share their search grids and finds, but I would personally use it privately only. Maybe include the ability to meet other lonely detectorists in your area and call it DIGGR.

The issue with developing anything for our hobby is its small size, and the fact that it will continue to get smaller.

[klunker]

5 hours ago, oldmancoyote1 said:

or is the problem just my old GPX4500?

  The 4500 is a good detector but my experience with several of them was they were all a bit noisy. The 5000 was an improvement so developing an ap for the 4500 my not be justified. But the concept is interesting. 

[jasong]

6 hours ago, oldmancoyote1 said:

I might write an iPhone app to filter noisy metal detector signals.  Is this a big problem, or is the problem just my old GPX4500?  The basic idea is to repeatedly swing across an area, and the app would add all the signals together.  Random signals would cancel each other out, and a valid signal would be reinforced.  The oil companies call it "stacking", and it has been extremely successful.  Any other ideas for an app for nugget hunters would be very welcome.

When you say old, how old is your 4500? Did you get it right when they were first released?

I don't know how many units were affected but if you bought a first run 4500 (or bought a used unit from someone who bought a first run unit), then they needed main board replacements up to a certain serial # due to EMI/instability issues. No clue what the serial # range was though, mine was #0000007 so that doesn't help much.

[phrunt]

I can't remember exactly now as I was concerned my 4500 was one of them but it was only the first 100 or something so it'd have to be a VERY early one.

The 4500 is a noisy detector compared to the 5000 though, since I had both I was really able to see the difference.  I guess the newer 4500's with the 5000 PCB would be much quieter. 

I think if there was a good easy way to do a noise filter the detector itself would be offering it, not an App on a phone.  Great idea and I applaud you having a go but with the money detector manufacturers could make if they incorporated that sort of thing into a detector I would hope they'd already be doing it if it were viable.  Sometimes it just takes the right person with the brains to do it though and you might just be that person.

[jasong]

6 hours ago, oldmancoyote1 said:

How about wether there is enough noise with PI machines to make this worthwhile.  I have very little experience with PI machines.

Have you messed around with the Stabilizer much? Just mentioning it because you are new to PI's, and that control sorta disappeared on the GPZ (it was kinda dumbed down and renamed) and is absent altogether on the 6000, so there isn't much talk about it these days on forums and whatnot.

But it's simultaneously one of the most useful controls in terms of EMI, as well as one of the most misunderstood/misused, and is a good one to know about. 

[oldmancoyote1]

Thanks for all the info folks.

[oldmancoyote1]

I'm thinking about your suggestion.  It may take a while.  Thanks