Andy Smith
MIne-action specialist

Comment: HSTAMIDS


HSTAMIDS is a combined metal-detector and Ground Penetrating Radar produced for US Army CECOM NVESD with encouragement from some field demining groups. However, (in 2004) it is a classified technology designed primarily for military use.

The first HSTAMID accident (I know of) occurred in Afghanistan in 2003, when a serving soldier with an HSTAMID in his hand lost his foot. Despite several requests for more information about how the accident occurred, I have received no details. I have received an assurance that the HSTAMID was not at fault. There may have already been other accidents with serving soldiers.

HSTAMIDS

Following my skepticism about the HSTAMID system, I was invited to Newcastle, UK, for an informal viewing in 2003 - this new detector is still "restricted" and may not be available to the public for a couple of years. (Field trials with HALO Trust are reported to be starting in 2005.) While it is sort of "classified", the guys did not put any restraints on my freedom to comment.

HSTAMID combines a hand-held GPR and a metal-detector - an approach that is also being worked on elsewhere (two programmes in UK, for example). What makes it "different" is that it is already (2003) being used by US soldiers in Afghanistan - so is considered to be already field-deployable.

I took some targets and hoped to be able to place a few on the riverbank outside the Pearson factory where the brief meeting took place. Pearson have a "nice" lawn, but I was only going to use the mowed dandelions on the riverbank strip. The Pearson people would not let me dig there even when I promised to lift "turf" carefully and return it so that no one would know. So the targets had to be placed above ground.

Surprisingly, I could still learn some useful stuff from that. The system is heavy, but lighter than anticipated with a small search-head - that means an advance in small increments. It has a sexy foldable design - far more robust than the mini-Schiebel but with a few design bugs (wimpy looking head-hinge, exposed wire to the head, low-volume - but nothing that could not be addressed). Also, thickness of the head-plastic may need to be increased to prevent it wearing through. It is designed to work below water (as a metal-detector only) so is presumably well sealed against moisture.

Early models had the metal-detector and GPR separately operated - but on this model you could not turn-on the GPR on its own. When the MineLab F3 metal detector signals, the volume of the GPR signal instantly kicks in unless you have turned the GPR off (which can be done if you want to use it as a stand-alone and rather cumbersome metal-detector). If the GPR "finds" an object under the ground and around/under above the metal reading, the GPR gives an audio-signal that is very different from the metal-detector indication. So the user-interface is by interpreting varying sounds only. The difference in sound is easy to hear. In its current configuration, it cannot be used to find mines with no metal content - but they are more myth than reality in any case.

It is power-hungry - and the battery is worn on your belt. All MineLabs are battery guzzlers and I guess the GPR is also a bit of a glutton. The manufacturers assure me that battery types can be varied (a US military battery is used currently).

The operator said that, with experience, you can begin to tell (very crudely) the size and shape of the GPR detection - partly from the speed of the signal and partly by moving the search-head towards it from all sides as you would with a metal-detector. There was a different GPR audio-signal when passing over a [surrogate filled] PMN and a GYATA-64, reflecting the different cavities inside these mines (both have a very similar outward appearance). However, he said that normal use would be that any GPR signal accompanying a metal-detection should always be investigated.

Ground compensation and set-up are computerised, with a female voice announcing when the detector is ready to use. Cute, but a trifle toe-curling.

Above surface, the metal-detector and GPR combination worked well - with the GPR kicking in on everything with bulk that the metal-detector "found". It even kicked in on an MUV fuze - with cavities inside the metal - while staying silent when the metal was a solid lump of frag, etc.

Sounds very simple - and it is. I was thrown a little by the 40hrs training time recommended, but that is apparently to break existing habits and reinforce new ones. Still seems a little excessive.

The questions over reliability in real contexts could not begin to be addressed. With an hour to play under Pearson restrictions, I could not begin to assess how reliable it was when the object was buried in soil, among stones, roots, on dry, 30-50% wet ground, flush with surface or at varying depths - all of which are critical questions and should be assessed with a range of targets. I could not begin to assess how deep the metal-detector was capable of searching - or how similar its performance was to the stand alone model of the Minelab F3.

If the GPR element is reliable - or if it is easy to tell in what conditions is may not be reliable (this may be what takes so long in training) I can think of places where it would be useful. I can also think of many where it would never be any more useful than a metal-detector on its own - such as a typical Afghan hillside of stones (stones would make the GPR signal). The ability to turn off the GPR would allow the detector to still be used there (if nothing smaller was available).

If the GPR and operator are less than 100% reliable at either identifying a mine-like object or indicating that they cannot determine whether a mine-like object is there - the system reduces "safety" over the use of the MineLab on its own (when all metal indications would be investigated as potential mines). ["Safety" in Humanitarian demining refers to the "safety" of the operator/deminer and (crucially) the "safety" of the eventual end-users of the cleared land.]

In all detection systems there are three typical false-alarms:

1) False indication - where nothing is present.
2) False-positive - where the article present is not an ERW item.
3) False-negative - where an item of ERW is present but the detection system fails to indicate this.

Of these, the False-indication and False-positive result in extra work, but do not have a direct impact on safety. If they make the operator "careless", they may have an indirect impact on safety but this can be controlled by adequate procedures and supervision. A False-negative is a major safety issue, with missed items resulting in deminer and civilian injury. This already happens (rarely) and any new technology should not be allowed to risk increasing the number of these incidents.

Because safety is supposed to be the prime concern in HD, concerns to limit "False-positives" must start with a requirement that "False-negatives" be reduced to zero (or as close to zero as is possible). With existing equipment, this often comes down to devising and enforcing safe operating procedures - and that would be the same for HSTAMIDS.

I should stress that, even assuming that the HSTAMIDS system (with operator) could ever be 100% effective (no False-negatives), the addition of the GPR to the MineLab F3 does not increase the thoroughness of current methods of mine detection using metal-detectors. In other words, it does not increase "safety" by finding more than a metal-detector would on its own. It is not intended to. It is intended to add increased speed - but if that is achieved at the expense of thoroughness (safety), it is not an appropriate tool outside a military context (where speed may be more important than occasional False-negatives and missed devices).

Before putting this on the market in HD, I recommend that the following should be field evaluated using genuinely experienced actual deminers under the supervision of suitably skeptical independent assessors:

a) The level of operator training, base intelligence and experience that is realistically required for the user to confidently discriminate signals.

b) The ability of the GPR to give meaningful signals on irregular dry or wet ground with mixed soils, and ways for the user to assess the parameters where its use may be unsafe in the field.

c) Realistic assessment of detection depth - and how to do this in-and-for each area of use.

d) Realistic assessment of the likelihood of false-negative indications.

e) Field durability and reliability.

f) Cost-benefit analysis over current methods.

The eventual unit cost of this system has been variously estimated to be at 12 -50 thousand US dollars. Those sources closest to the actual programme have expressed the lowest figure. At a price that may be around six times the cost of existing metal-detectors with good GC capabilities, the system would have to have real speed advantages over solo metal-detectors to be cost-effective. If what I have been told about it proved to be true, it could achieve this in some mined areas - so we may see it being added to the toolbox when it is made available in a couple of years.

Sexy? Yes. Potential? Perhaps. As NVESD put it - "the best thing since sliced bread"? Well no, I cannot agree with that. I prefer to slice my own bread. However, if well-organised and real field-testing proved its ability while addressing the safety concerns, the technology could replace the solo metal-detector in some areas. It would never increase the thoroughness of clearance over that achieved using existing procedures and metal detectors, so whether it will ever be useful enough to justify the cost of developing it is doubtful (at best).