Standard - DIN 14610
     
Since at least 1978 a standard for acoustic warning systems is used in Germany and adapted in different rhythms of the new technology. Here is an overview of how the standard has developed.

The sound pressure level shall be at least 110db in the direction of maximum sound radiation at a distance of 3.5m in anechoic chamber for each of the two individual sounds.
     
  EL PM EG EK
  Electrically operated pneumatically operated pneumatic & electric blower electronic generation

1978-02 Bosch - SH HEN1 6 1 platzhalter    
         

1981-03 Bosch - SH HEN1 6 1 platzhalter Max B Martin - 2097GM Premier Hazard - PH7007 AT
         

2009-01 Bosch - SH HEN1 6 1 platzhalter Max B Martin - 2297GM Premier Hazard - PH7007 AT