JimW
01-05-2007, 10:53
Hi
In order to kick off discussions on this Forum I am posting a synopsis of an Email discussion that has been going on regarding the competition.
Jim:cool:
Raymond Ruth
It has come to my attention that you are running a competition to develop a diver tracking system to enable the re-location of divers lost subsurface. Our company (RUCO Ltd) (w ww.ruco.co.uk )are the European distributor for an American acoustics developer called Sonotronics who make such a system already. The Sonotronics units are tried and tested over the last 30 years.
(Within your competition specification) you say the unit should preferable cost under £100, there is no way to know how much a unit will cost unless you know how many can be sold. The smallest tracking pinger Sonotronics make costs around £150 excluding VAT, import duty and freight but they make thousand per year and so can get the price down. Also they require a dedicated topside unit and it costs around £2000, using a general echosounder to locate a pinger has several disadvantages;
1. Not all echosounders work on the same frequency, so which frequency do you use?
2. There are digital and analogue echosounders out there all of which perform in a different manner.
3. It will be virtually impossible to know where the diver is using an echosounder, as there is not relational information in the echosounder to give you direction.
I believe the best way forward is for dive clubs, police or coastguards to own a topside unit and if any one gets into difficult then they can be called out to search for the lost diver.
It may be that Sonotronics could design a "sports" version of their pinger that could bring the price down but this would depend on quantities.
Diver response
These are certainly interesting points and the Sonotronics units would notionally do the task.
However if such systems are not routinely tested they can't be trusted. A batch of surface locator beacons (EPIRBs) failed in the field the year before last, these were only found when they were returned for routine maintenance at the end of the season. So the surface unit needs to be easily available and checked in the same routine manner as any safety equipment. It is correct that the operating frequency can vary but changing the beacon operating frequency (that the diver carries) will be a simple enough task once a suitable design is available. This would be done at a pre-production prototype stage in conjunction with a known echo sounder manufacturer. Most businesses are looking for market advantage in their field, being handed an opportunity like this would give a demonstrable technical advantage to any echo-sounder manufacturer.
Raymond Ruth Response
The report about faulty EPIRB's should not affect your concerns about the Sonotronics units;
The sonotronics products have been in production since the early 70' and have an excellent track record and very high MTBF (mean time between failure, an engineering term used to describe the frequency of failure of a unit). The comment about testing the pinger before use is valid but I am sure a small inexpensive tester could be developed to check the pinger before use but the dedicated topside would still be required, although a lower cost unit may be possible to develop for this application, and could be held by the police, coastguard or preferably the diving club.
Divers response
The problem is that each diver who uses one of these units needs to understand this is the case. I am sure that you have a very robust product however in fairness the EPIRB's are statistically very reliable. It happened to be one small group who bought 6 as a job lot and 3 were DOA at first service, unfortunately and I genuinely mean unfortunately many people see them as presenting a higher hazard than benefit. Any article of dive equipment needs to be capable of being tested for serviceability by the diver as a complete system to engender confidence in the system or risk being discarded.
Raymond Ruth
Some more technical point for consideration.
I would have to disagree with the response regarding frequency.
The only people I would be asking to over see this project is the NPL National Physics Laboratory as they are truly independent. Being able to change the transmit frequency of a pinger is not that easy, as for any given size of transducer there is only a certain range of frequencies it can be designed to use, effectively that is, and to make a pinger small enough to be manageable by a diver and low cost you would need to make the unit a fixed frequency as to make it selectable means either expensive software development or larger hardware, you can't have everything.
Diver Response
Sorry for the confusion I was not advocating utilising 1 pinger for a variety of frequencies the intent was to pick a suitable frequency pinger for the task. Once a frequency was picked to suit a prospective manufacturer's existing equipment the requirement to switch frequency is obviously redundant. Otherwise this would indeed be very expensive.
Raymond Ruth
Regarding the echosounder manufacturers, people own different sizes of vessel so they use different types and frequencies of echosounders for different uses and depths of water,
Diver Response
Amateur divers generally operate in the 0-60m range but that range is extending hence the high depth requirement. There are a small group of divers who regularly operate in the 100-130m range but these are extremely rare. Dive boats by their nature are operating in a restricted role so a transponder that is as 'limited' as a fish finder for example would fulfil the role.
Raymond Ruth
If a manufacturer is going to make a dedicated echosounder for this application then there is no difference in that and a dedicated surface unit. If an accident does occur do you really want to spend valuable time searching for a vessel that has a suitable echosounder?
Diver Response
As a diver I would not carry the tracking device unless the vessel I was diving from was actually carrying the surface transponder. Most divers would do likewise unless the device was matchbox size. Any extra equipment is a further hazard and no matter how small will is unlikely to utilised.
Raymond Ruth
You should also consider the search and find ability of an echosounder, if the echosounder is a narrow beam unit then the chances of it "hearing" the pinger are slim as you have to be directly over the pinger to hear it so your search pattern would have to be very high density, if the beam is wide then the echosounder can only locate a general area where the diver might be where as the Sonotronics unit can take you straight to the diver, even in zero visibility, thus saving valuable minutes of search time. If an echosounder is in 20m of water then the range of that unit is normally set to the depth +20% i.e. 24m, this is now the range of the search ability of the echosounder so to cover a large area will take a long time to do, the range on the Sonotronics system is model dependant but is a minimum of 1km so by rotating the receiver at a single point, possible even a pier, you can cover an area of 1km radius, again saving time.
Diver Response
That sounds very similar to the commercially available 3D echo sounders that I first saw 5 years ago. These were essentially scanning narrow beam units, but quite effective at 3-500m (from memory). Potentially there are other answers to this problem, of course this also covers specialist surface units but cost is a concern with this approach. The main attraction for me as an Engineer of using echo sounder technology and selling to a larger market is that there could be a synergy with the core technology and development costs can be amortised over a broader base and consequently reduce the selling price.
In order to kick off discussions on this Forum I am posting a synopsis of an Email discussion that has been going on regarding the competition.
Jim:cool:
Raymond Ruth
It has come to my attention that you are running a competition to develop a diver tracking system to enable the re-location of divers lost subsurface. Our company (RUCO Ltd) (w ww.ruco.co.uk )are the European distributor for an American acoustics developer called Sonotronics who make such a system already. The Sonotronics units are tried and tested over the last 30 years.
(Within your competition specification) you say the unit should preferable cost under £100, there is no way to know how much a unit will cost unless you know how many can be sold. The smallest tracking pinger Sonotronics make costs around £150 excluding VAT, import duty and freight but they make thousand per year and so can get the price down. Also they require a dedicated topside unit and it costs around £2000, using a general echosounder to locate a pinger has several disadvantages;
1. Not all echosounders work on the same frequency, so which frequency do you use?
2. There are digital and analogue echosounders out there all of which perform in a different manner.
3. It will be virtually impossible to know where the diver is using an echosounder, as there is not relational information in the echosounder to give you direction.
I believe the best way forward is for dive clubs, police or coastguards to own a topside unit and if any one gets into difficult then they can be called out to search for the lost diver.
It may be that Sonotronics could design a "sports" version of their pinger that could bring the price down but this would depend on quantities.
Diver response
These are certainly interesting points and the Sonotronics units would notionally do the task.
However if such systems are not routinely tested they can't be trusted. A batch of surface locator beacons (EPIRBs) failed in the field the year before last, these were only found when they were returned for routine maintenance at the end of the season. So the surface unit needs to be easily available and checked in the same routine manner as any safety equipment. It is correct that the operating frequency can vary but changing the beacon operating frequency (that the diver carries) will be a simple enough task once a suitable design is available. This would be done at a pre-production prototype stage in conjunction with a known echo sounder manufacturer. Most businesses are looking for market advantage in their field, being handed an opportunity like this would give a demonstrable technical advantage to any echo-sounder manufacturer.
Raymond Ruth Response
The report about faulty EPIRB's should not affect your concerns about the Sonotronics units;
The sonotronics products have been in production since the early 70' and have an excellent track record and very high MTBF (mean time between failure, an engineering term used to describe the frequency of failure of a unit). The comment about testing the pinger before use is valid but I am sure a small inexpensive tester could be developed to check the pinger before use but the dedicated topside would still be required, although a lower cost unit may be possible to develop for this application, and could be held by the police, coastguard or preferably the diving club.
Divers response
The problem is that each diver who uses one of these units needs to understand this is the case. I am sure that you have a very robust product however in fairness the EPIRB's are statistically very reliable. It happened to be one small group who bought 6 as a job lot and 3 were DOA at first service, unfortunately and I genuinely mean unfortunately many people see them as presenting a higher hazard than benefit. Any article of dive equipment needs to be capable of being tested for serviceability by the diver as a complete system to engender confidence in the system or risk being discarded.
Raymond Ruth
Some more technical point for consideration.
I would have to disagree with the response regarding frequency.
The only people I would be asking to over see this project is the NPL National Physics Laboratory as they are truly independent. Being able to change the transmit frequency of a pinger is not that easy, as for any given size of transducer there is only a certain range of frequencies it can be designed to use, effectively that is, and to make a pinger small enough to be manageable by a diver and low cost you would need to make the unit a fixed frequency as to make it selectable means either expensive software development or larger hardware, you can't have everything.
Diver Response
Sorry for the confusion I was not advocating utilising 1 pinger for a variety of frequencies the intent was to pick a suitable frequency pinger for the task. Once a frequency was picked to suit a prospective manufacturer's existing equipment the requirement to switch frequency is obviously redundant. Otherwise this would indeed be very expensive.
Raymond Ruth
Regarding the echosounder manufacturers, people own different sizes of vessel so they use different types and frequencies of echosounders for different uses and depths of water,
Diver Response
Amateur divers generally operate in the 0-60m range but that range is extending hence the high depth requirement. There are a small group of divers who regularly operate in the 100-130m range but these are extremely rare. Dive boats by their nature are operating in a restricted role so a transponder that is as 'limited' as a fish finder for example would fulfil the role.
Raymond Ruth
If a manufacturer is going to make a dedicated echosounder for this application then there is no difference in that and a dedicated surface unit. If an accident does occur do you really want to spend valuable time searching for a vessel that has a suitable echosounder?
Diver Response
As a diver I would not carry the tracking device unless the vessel I was diving from was actually carrying the surface transponder. Most divers would do likewise unless the device was matchbox size. Any extra equipment is a further hazard and no matter how small will is unlikely to utilised.
Raymond Ruth
You should also consider the search and find ability of an echosounder, if the echosounder is a narrow beam unit then the chances of it "hearing" the pinger are slim as you have to be directly over the pinger to hear it so your search pattern would have to be very high density, if the beam is wide then the echosounder can only locate a general area where the diver might be where as the Sonotronics unit can take you straight to the diver, even in zero visibility, thus saving valuable minutes of search time. If an echosounder is in 20m of water then the range of that unit is normally set to the depth +20% i.e. 24m, this is now the range of the search ability of the echosounder so to cover a large area will take a long time to do, the range on the Sonotronics system is model dependant but is a minimum of 1km so by rotating the receiver at a single point, possible even a pier, you can cover an area of 1km radius, again saving time.
Diver Response
That sounds very similar to the commercially available 3D echo sounders that I first saw 5 years ago. These were essentially scanning narrow beam units, but quite effective at 3-500m (from memory). Potentially there are other answers to this problem, of course this also covers specialist surface units but cost is a concern with this approach. The main attraction for me as an Engineer of using echo sounder technology and selling to a larger market is that there could be a synergy with the core technology and development costs can be amortised over a broader base and consequently reduce the selling price.