Update on 121.5 and 406 MHz Homing for Second Generation Beacons Mike McDonald Douglas County SAR Team (MRA) Colorado Wing Civil Air Patrol Colorado SAR Board Cospas-Sarsat Homing and Intelligent Transmit Scheduling Correspondence Working Group State Search and Rescue Coordinators Council Washington, DC February 27-28, 2018

Update on 121.5 and 406 MHz Homing Background A proposal to the Cospas-Sarsat Programme sought to eliminate the option of a 121.5 MHz homing signal on Second Generation Beacons (SGB) because This signal is the primary user of battery power, which is needed for other SGB functions Improved accuracy of beacon location due to MEOSAR and increasing number of beacons which transmit position from Global Navigation Satellite System (GNSS) receivers (e.g. GPS) reduces the need for a homing signal More search and rescue units (SRU) with capability to DF the 406 MHz beacon signal A homing signal is optional per C-S regs, but the 121.5 MHz homing signal is required by most administrations and international regulatory organizations

Update on 121.5 and 406 MHz Homing Background C-S members voted to keep the option because of the world-wide lack of 406 MHz DF equipment and cost to upgrade Need for a longer period to transition from 121.5 MHz to 406 MHz homing Look at ways to reduce the homing signal power consumption The Homing and Intelligent Transmit Scheduling (HITS) Correspondence Working Group was established to find solutions to the homing and power conflict HITS proposed a reduced duty cycle (intermittent) homing signal based on a note in the ELT technical spec (but with rare exceptions, not utilized in current ELTs) 0.75 second on, 1.5 seconds off, repeating

Update on 121.5 and 406 MHz Homing Background 121.5 MHz DF Units L-Tronics LL-16 Little L-Per $750 VK3YNG Mk 4 Sniffer $450 L-Tronics LH-16 Little L-Per L-Tronics closed last year after making DF units since the early 1970s. Photos courtesy CAP and Bob Miller Enterprises

Update on 121.5 and 406 MHz Homing Background 121.5 / 406 MHz Portable DF - $17,000 Rhotheta RT-500-Manpack Wideband RDF/Location System Production unit Prototype unit developed for USCG

Update on 121.5 and 406 MHz Homing Current Status The International Maritime Organization (IMO) requires EPIRBs to have a continuous homing signal It would consider changing its regulations if testing shows that existing DF units can locate a beacon with a reduced duty cycle signal Known testing to date Australian Maritime Safety Authority (AMSA) – land test success Colorado Search and Rescue Board (CSRB) – land/air test success Norwegian Maritime Authority (NMA) – maritime test success Report of a test in which the DF on an aircraft traveling 150 kts was reportedly not able to locate the intermittent signal

Update on 121.5 and 406 MHz Homing Current Status HITS is also studying the addition of a low-power, short interval 406 MHz homing signal for close-in or on-scene homing and locating The fundamental 406 MHz signal (5 watt data burst, ½ second long, every 50 seconds) is OK for long-range and enroute homing, but is difficult to use in-close Low power 406 MHz locating signal with an interval much less than the 50 seconds of the primary signal Intermittent low-power 121.5 MHz homing signal

Questions in the future? Questions now? Questions in the future? Mike McDonald mgmsar@comcast.net Cell: 303-792-5256 Work: 720-847-5003