How does SenTAG work?

The SenTAG wristband has considerable processing power within that continually monitors depth relative to the surface and several characteristics of motion.  There inputs are used within a number of interlocking ‘rules’ and related to time.  It can be very complex but for example  “too deep for too long” can raise an alarm; If we also consider ‘motion’ characteristics we can then do things like reduce or lengthen the time ‘allowed’ at any particular depth or even consider situations like ‘the bather is face down on the surface’.  Any breaking of the rules first alerts the wearer by sound and high intensity LED’s.  If they do not return to a ‘safer’ situation within a few seconds the unit transmits either an ultrasound and’ or radio frequency alert to the pool supervisor and beyond.

How did you arrive at the concept and design?

Scuba diver monitoring and similar alarm systems have used similar concepts for decades but these would have been impractical for regular bathers due to size and cost etc.   

This is not to say that very considerable volume of original development was not required to produce the SenTAG system.   Some of these critical enabling developments are subject to patent application.

As importantly we talked with pool operators including a ‘think tank’ of owners representatives plus other industry organisations and a couple of specialist university departments to develop the specification from the bottom upwards.  In other words what problems did they want to tackle, what did they really want, and what was technically and economically possible.   

What are the advantages over camera-based/other detection systems?

SenTAG works is a very wide range of real world scenarios, shallow and deep water, small and large pools, crowded and ‘empty’ ones, and in any visual conditions however complex.   It does so with exceptionally high detection certainty, without any ‘line of sight’ requirements or complex or expensive servicing needs.   In fact the specification called for the highest possible ‘certainty’ irrespective of cost and the technological route eventually selected was chosen upon purely technical lines.    We can detect bathers in possible distress very early in the course or any incident, even before they ‘arrive’ at the bottom or pool surface, even before any ‘struggling’ necessarily ceases.   The system architecture was also specifically designed to accommodate retrofitting to existing pools in a quick and economic manner and to fit in with standard operator and supervisory procedures.

How does the system cope with radio/sound wave interference?

All wireless systems whether relying on visual, radio or acoustic information can suffer from interference that could affect normal operation.  SenTAG uses both radio and ultrasound to relay information from the individual to the ‘poolside’.  We employ highly sophisticated analytical signal processing techniques in our receivers plus we employ multiple frequencies to ensure these pathways are viable and that alerts can be received at all times. SenTAG also constantly tests and assess ‘transmissibility’ conditions of all wireless links.  If any ‘media’ is ultimately determined to have fallen below acceptable limits the system will immediately advise the pool staff who can react accordingly.   When conditions return to normal the system will then inform staff that it is again available on-line.   These are extremely unusual events but we believe that any system should be able to indicate conditions when its performance may be compromised.    We are unaware of any comparable capability with alternatives

How do you stop ‘customers’ removing wristbands from site ?

SenTAG wristbands constantly transmit a low power RF identification and status.   Signals are detected by a system retention unit  (STU).  These units can be placed in doorways or can cover larger general entrance areas raising an alert whenever a wristband is bought within range.  See the menu choice ‘Wristband Retention’ for more details.

How much does it cost:

Many SenTAG installations are supplied under an 'all in' leasing arrangement over a 3 to 5 year period. This covers supply and installation plus service.

Maintenance costs: depends upon standard selecte but typically 10 - 15% of purchase price

How quickly can a pool be up and running?

Basic installation can be completed in a single day.  We generally leave system elements to ‘monitor’ pool characteristics for 7 to 10 days before final commissioning and handover.  No interruption to normal operation is required and certainly no drain down or serious builders work is required.  Specific elements for retrofit installation are available to reduce cost and complexity of installation.

How is the lifeguard alerted?

The pool hall SenTAG wall unit has integral sound and alert light outputs.  In addition it has three sets of additional electrical contacts available to allow the system to be linked to existing or additional remote sounders and lights or to trigger existing operator pagers/radios.  The SenTAG system also includes portable pager type supervisor units which are carried by them.  This relays any alert directly to them and they can also be used to remotely acknowledge or cancel alerts.  

In addition it can be linked to standard IT elements such as PC’s via hardwire or wireless links.  Alerts can therefore be forwarded anywhere and the system can provide management information covering usage patterns, historical analysis and even the fully detailed information relating to any alert or whole incident.

Is it suitable for informally supervised pools?

Yes.  Where dedicated poolside supervision is not the option SenTAG can provide very valuable automatic cover greatly increasing the inherent level of bather protection. 

How does the system know that all the wristbands are operational?

All wristbands run a comprehensive self-diagnostic test every time they are used.  If any unit were to ‘fail’ at any time they send a wireless signal to the ‘central’ system as well as giving local indication.   Furthermore the system can be configured to log all issues of wristbands centrally.

What happens if a wristband is removed or falls off in the pool?

Wristbands that are removed and end up on the bottom of the pool will transmit a wireless alert and an advisory will be raised.  They can also be configured to provide an advisory if removed and left off for a predetermined period of time even when outside of the water.

Who is SenTAG and how is the company funded?

SenTAG Limited was created to develop, manufacture, distribute, licence and promote the SenTAG standard and technology worldwide.  It is owned by a syndicate of professional 'business angel' investors based in the south and south east of England

Are there plans to incorporate other functions in the wristband and if so, which?

Yes.  The SenTAG architecture easily permits changes and enhancements in functionality and it is already being applied beyond basic bather protection.  For example it can easily be integrated with sports club locker and other 'site access' systems, provide site/guest services including electronic 'cash' and can also carry location, training and personal information where this is desired through out the site.