ACR Electronics aerofix 406 gps i p-elt User Manual

Y1-03-0175 Rev. E 

12

P-ELT is not registered, Search and Rescue (SAR) Authorities do not know who you are, or how to 
contact anyone who might know anything about your situation (Refer to section1). 

 
 Once 

the 

AeroFix™ 406 GPS signal (406 MHz) is relayed through the LEOSAR and/or GEOSAR 

network, SAR forces determine who is closest, and then track the signal using the 121.5 MHz homing 
frequency for intermediate and short-range location. 

 
7.2.1 The 

AeroFix™ 406 GPS transmits an encoded phase modulated radio signal to the satellite portion 

of the COSPAS-SARSAT System. The system was developed and implemented by the COSPAS-
SARSAT Partners (Russian Federation, Canada, France and the United States). 

 
7.2.2  COSPAS-SARSAT is an international system that uses Russian Federation and United States low 

altitude, near-polar orbiting satellites (LEOSAR) that assist in detecting and locating activated 
121.5/243 MHz P-ELTs and 406 MHz Satellite P-ELTs.  

 
7.2.3  COSPAS and SARSAT satellites receive distress signals from satellite P-ELTs transmitting on the 

frequency of 406 MHz. The COSPAS-SARSAT 406 MHz P-ELT signal consists of a transmission of 
non-modulated carriers followed by a digital message format that provides identification data. The 
406 MHz system uses Satellite-borne equipment to measure and store the Doppler-shifted frequency 
along with the P-ELT digital data message and time of measurement. This information is transmitted 
in real time to an earth station called the Local User Terminal (LUT), which may be within the view 
of the satellite, as well as being stored for later transmission to other LUTs. 

 
7.2.4  The LUT processes the Doppler-shifted signal from the LEOSAR and determines the location of the 

P-ELT; then the LUT relays the position of the distress to a Mission Control Center (MCC) where the 
distress alert and location information is immediately forwarded to an appropriate Rescue 
Coordination Center (RCC). The RCC dispatches Search and Rescue (SAR) forces. 

 
7.2.5  The COSPAS-SARSAT System includes 39 LEOSAR LUT stations, 9 GEOSAR LUT stations and 

over 19 Mission Control Centers that provide real-time as well as global-mode coverage for the 
Northern Hemisphere, while the Southern Hemisphere is presently served primarily by the global 
mode. Additional LUTs and MCCs are planned for installation in the near future both in the northern 
and southern hemispheres. 

 
 

The addition of the GEOSAR Satellite system greatly improves the reaction time for a SAR event.  
This satellite system has no Doppler capabilities at 406 MHz, but will relay the distress alert to any of 
the LUT stations.  When there is GPS data included in the distress message, SAR authorities instantly 
know your location to within 110 yards.  This speeds up the reaction time by not having to wait for 
one of the LEOSAR satellite to pass overhead.  

7.2.6  Because most of the search and rescue forces presently are not equipped to home in on the 406 MHz 

Satellite P-ELT signal, homing must be accomplished at 121.5 MHz.