Latest Minelab Patent - 11th Feb 2016

[kt315]

The Minelab multifrequency technology that began with the Sovereign is not pulse induction

this is FULL-bridge TX driver of Sovereign XS. in your logic it is not PI, but HALF-bridge driver in firsher impulse is PI.
nonsense, Dave....

[kt315]

pulse induction signal

I reminder WHAT is THE pulse signal.

[kt315]

ok. let me look on tx o-scope pics from the fisher on a coil i could REALLY see what you mean. if there is the "delta pulse" - you win.

anotherway - satisfaction.

[Dave J.]

kt315, the Impulse is pulse induction. The CZ is IB VLF technology.
I know what they are. I designed them and my name is on the patent which describes both technologies. The Impulse circuit is posted in the schematics forum, and I think the CZ circuit is as well.

I also designed the circuit (but not the software) for the White's DFX and Surfmaster. Also IB VLF technology. And, the MXT (circuit and software) which is sinusoidal single-frequency.

The Minelab multifrequency technology that began with the Sovereign is not pulse induction, it is induction balance sequential multiple frequency.

[kt315]

Like all PI's,
---
Fisher Impulse is not PI. it has halfbridge TX driver like you can see it in CZ5/6. if fisher impulse is PI then CZ5, MXT, DFX,
Elite::GT, Explorer, Vision v3, etc are too PI, but they all are not PI.

[Dave J.]

The CZ operates in the frequency domain, not time domain like PI's. It's a type of induction balance VLF technology, operating at 2 frequencies simultaneously. Introduced in 1991 and still in production virtually unchanged.

The Fisher Impulse (no longer in production) was fully static (i.e. not "motion" or "autotune") and air tested on US coins out to about 10-12 inches (25-30 cm) as I recall. Sensitivity to low conductors was high enough that it did "see" salt water more than just a little bit, but of course a lot less than a regular VLF. No use for gold prospecting since it wasn't ground balanced. Like all PI's, it was rather vulnerable to electrical interference. Didn't like power lines at all. And in Los Banos we were able to detect some kind of U.S. Navy VLF transmitter somewhere up in the Suisin Bay area well over 100 miles (160 km) away (we RDF'ed it by triangulating from Santa Cruz) but holding the searchcoil plane horizontal nulled the H-field so it wasn't really a problem.

[WM6]

i wonder if the fisher CZ range is a type of discriminating pulse cause i think my friend once said that the CZ6 transmitted a square wave and the depth was very close to the earlier pulse machines.

If so, then purpose of square wave is probably to get better harmonic spectrum, to work with n-th harmonic. Despite of that, it still remain in field of VLF/IB technology. Known solution with some Minelab CW patents and detectors too.

[Teleno]

There are couple ideas around - I forgot patentee (not under those exact term, so I wrote "recuperation").

On widely available 8x1.5V AA alkaline batteries, Fisher Impulse work easy more than 100 hours.
For some nowadays PI, even 10 hours and using heavy lead acid accu appear to be dream score.

Most PI's strive for a fast flyback for detecting short time constants. This costs energy and is mostly wasted anyway because most of PI's have sampling delays above 15us.

Instead, Fisher Impulse allows the coil to be discharged through diodes into the power supply's capacitors. This causes a slow flyback but it conserves energy. Targets with tau longer than 15-20us are just as detectable as they are with conventional PI's. I bet Fisher Impulse fails miserably at smaller taus though (confirmation requested), but then again that's not its purpose.

[moodz]

There are couple ideas around - I forgot patentee (not under those exact term, so I wrote "recuperation").

On widely available 8x1.5V AA alkaline batteries, Fisher Impulse work easy more than 100 hours.
For some nowadays PI, even 10 hours and using heavy lead acid accu appear to be dream score.

SPECIFICATIONS 1Length 2 ......... Extended .................................................. .................... 50" Collapsed .................................................. .................... 31"Weight 2 ........ Complete (with Headset) .................. 5.2 lbs. 5.5 lbs.Handle and Search Coil...................... 2.3 lbs. 2.6 lbs.Control Housing ..................................... 2.4 lbs. 2.4 lbs.Transmit Frequency ........................................ 5,333 pulses per second crystal controlledAudio Target Response (Headset) ................................................VC O 3Visual Target Response.......................................... ........................1. LED 4 2. LCD bar graph 5Headset .................................................. ....... Waterproof, Piezo ElectricInterchangeable .................................................. ........ NoGround Balance Required .................................................. ............... NoSearch Motion Required .................................................. ................... NoDetachable Control Housing for Hipmounting................................YesSalt Water/Fresh Water Operation......................................... ...........YesLand Operation .................................................. ..................................YesSubmersible.. .................................................. .......................... to 250 feetSearch Coil Type .............Dual Spider coil, (Non-inductive balance) Diameter.................................... 8" or 10 1/2" Shielding ........................................ 100% ESI 6 Interchangeable .................................... NoBatteries .................................................. ............ (1.5-Volt, AA penlightBattery Life 2 ............. Carbon Zinc ....................................... 40-50 hours Alkaline .............................................. 100+ hours Nicads ............................................... 20-25 hoursAutomatic Battery Check .................................................. .................YesOperating Temperature....................................... ...................... 32-120°F

That is very good ... and the PRF is 5.333 Khz .... amazing. Any idea of the coil inductance or average depth ?

Answered myself .... one review seems OK here ...https://www.losttreasure.com/Home/FieldTestDetail/6124

[daverave]

i wonder if the fisher CZ range is a type of discriminating pulse cause i think my friend once said that the CZ6 transmitted a square wave and the depth was very close to the earlier pulse machines.

[WM6]

Which recuperation patents?

There are couple ideas around - I forgot patentee (not under those exact term, so I wrote "recuperation").

On widely available 8x1.5V AA alkaline batteries, Fisher Impulse work easy more than 100 hours.
For some nowadays PI, even 10 hours and using heavy lead acid accu appear to be dream score.

[daverave]

I built a target ID PI back about 1988 that came close to going into production. It was unveiled for the distributors who however said it was too quirky to be marketable (I'd told the boss the same thing but he was in love with the machine and I couldn't dissuade him.) After 2 weeks of deep funk the boss scrapped the project and we went on to do the CZ platform which had already been in the works before we got distracted by target ID PI.

did your pulse ID discrimination work down to full depth or only a few inches like some of the modern pulse based machines ????

[moodz]

Which recuperation patents?

[WM6]

, the basic core of the thing morphed into the underwater Impulse.

Funny thing, that 20-years old and relative complex Impulse PI, is still not comparable, not to say exceeded, by nowadays design, regarding power consumption. Despite new energy "recuperation" patents. Why some things should go worse?

[Dave J.]

What a pity your project got shelved, maybe you could get somebody interested in today's environment.

It wasn't shelved, it was buried. It worked, but that didn't make it a good idea. With features like ground balancing, discrimination, and target ID yanked, the basic core of the thing morphed into the underwater Impulse.