A DSP Based Alarm for the Deaf and Blind
Microelectronics Simplifies the Design of the 'Silent Alert' Pager
Technologies used

    Digital Signal Processor (DSP)

Industrial sector (PRODCOM code)
    15 Manufacturing of Food Products - Image Processing/Inspection
    17 Finishing of Textiles - Image Processing
    22 Reproduction of Sound Recording
    30 Computers and Other Information Processing Equipment
    322 Radio and Electronic Goods
    331 Medical Equipment
    332 Precision Instruments for Measuring, Testing, Checking

Clofield Limited design, manufacture and sell a silent radio paging system called 'Silent Alert'. This product is designed to alert deaf people to a variety of sound related events around their home and workplace. 'Silent Alert' is marketed to private individuals, sheltered housing associations and local health authorities.

The company employs six people and has an annual turnover of approximately 600kECU. The industrial sector within which Clofield operates is precision instruments.

The current system consists essentially of a transmitter unit which is physically connected to an audible sound source such as a doorbell, telephone, smoke detector, car alarm, burglar alarm or baby alarm, and a receiver unit, which when activated, sends a radio signal to a body worn receiver unit (the pager unit) which has a vibrating pad fitted. When a signal is received from the transmitter the pager vibrates and illuminates the corresponding symbol on the display screen. The system is reliable and is not prone to false alarms.

The system is based on analogue device technology and is limited because it requires a dedicated transmitter for each sound source being monitored. This makes the system expensive. Furthermore each transmitter has to be physically connected to the sound source which adds further cost. Due to these reasons the sales of the units is being restricted. Furthermore, since this product has set the standard for this type of product the market leadership currently enjoyed by Clofield may be lost to competitors if the system is not enhanced.

The objective of this Application Experiment was to enhance the company's product range by producing a technically advanced version that was both cheaper to produce, allowing for a lower selling price and make it more user friendly.

The AE enabled the company to develop a sound recognition system using DSP technology. The main advantages achieved by using this technology were as follows :

· One single transmitter replaces the six different transmitters previously required
· One dedicated DSP detector 'listens' and discriminates between each sound
· Up to 5 sound samples can be programmed into the DSP detector
· The pager unit worn by the wearer is unchanged, hence no re-training is required for the deaf user.

The project cost 76kECUs was based around a workprogramme of 9 months duration. The experiment commenced on the 1st July 1997 and was completed on the 31st July 1998 giving a total duration of 13 months. The reason for this was to carry out additional evaluation and modification work on the prototype product, to ascertain that the false alarm rates and mis-detection rates were acceptable. A period of extended testing has been scheduled as part of the industrialisation phase in order to confirm the detection and discrimination performance over a sufficiently long period of time.

The benefits of the AE include a reduction in build costs by an estimated 40%, with an estimated annual growth of sales of 10-15%. The return on investment is predicted to be 250% over the product's 5 year lifetime. The payback period on the prototype development costs of 82 kECU is estimated at 2 years.

The main lessons learned include:

· The use of new technologies can provide a significant commercial advantage over your competitors.
· The need to manage both sub contractors and budgets closely.
· Activities undertaken in the workplan were generally underestimated.
· Project management and reporting can take a significant amount of time, and this is an activity that small companies often neglect.
· Stage payments to subcontractors and suppliers must be specified in order to maintain a healthy cash flow.


    Clofield Ltd
    St John's Road
    S41 8DB UK
    United Kingdom

Detailed information

You can also benefit from microelectronics

DSP technology provided Clofield Ltd. with the means of improving its products and enhancing its market position. You can also achieve significant benefits by acquiring the right microelectronics technology and utilising it in your product or manufacturing process. You can get help from FUSE to realise this.

FUSE is a technology transfer programme, funded by the European Commission to stimulate the wider use of microelectronics technologies by European enterprises to increase their competitiveness and enhance their economic growth. The demonstrator described here is one of many examples in the public FUSE portfolio covering the whole spectrum of microelectronics technologies and spanning a wide range of applications and industry sectors.

FUSE provides you with:

  • Best practice in acquiring specific microelectronics technologies and conducting full development projects through the FUSE portfolio of real life demonstrator documents.
  • Local training and expert support to plan your innovation realistically and help you conduct your project successfully.

Further information and support relating to this and other demonstrators can be obtained from the addresses below.

Further information   Guiding Technology Transfer Node
For further information and support regarding this case study, please contact a Technology Transfer Node (TTN) in your region.
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