Do Becker DF's actually track the 406 signal???

[c172drv]

Had our regular meeting last night.  The topic was the Becker DF units.  Primarily this was a refresher/primer class on button pushing to get the desired result.  One area that came up was if the Becker Unit actually will track and give bearing info for a 406 only signal.  Reason this came up was that one of our CAP planes decided to pop off its ELT on 406 only.  Luckily being good Airmen it was registered and we got the call about it.

We reviewed the info regarding the 406 information screen, including the LAT/LON info and identifying info for the beacon but we can't determine if it can show a bearing to one that doesn't have LAT/LON to fly towards. 

Looking forward to info and commentary.

Regards,

John

[Eclipse]

No.

The 406 is a momentary data burst pretty much useless for DF'ing

The Beckers track 121.5.  If the ELT is not transmitting on that or 243, you're pretty much SOL.

[c172drv]

No.

The 406 is a momentary data burst pretty much useless for DF'ing

The Beckers track 121.5.  If the ELT is transmitting on that or 243, you're pretty much SOL.

Why do you say it is worthless on 243.  It is a selectable freq on the menu and if it is constant then it should work.  In regards to the burst nature, we were wondering if it would do it in a similar fashion to the "Wild Weasles" tracking momentary burst from radar.  I figure the major limitation is that it is not intergrated with the GPS and AHRS for position information to allow you to resolve a position.  Certainly would be a great project for the technically inclined out there.

John

[lordmonar]

Actually it will do a direct bearing on the 406 signal as well as the 243 signal according to the operating manual.

http://www.beckerusa.com/products/images/pdfs/SAR-DF-517%20Installation%20&%20Operation%20Manual.pdf

[Eclipse]

Typo.

Should say "If the ELT is not transmitting on that or 243, you're pretty much SOL."

[SarMaster]

I can confirm that the Becker will DF a 406.XXX only signal.  We did some extensive testing with ACR for beacons that got damaged and and only transmit 406.  The downfall is the databurst only happens every 50 seconds.  The Becker will hold the last direction bearing untill it hears a new one.  The good thing is the databurst on 406 is a full 5 watts.  Much more power output that the 200mw 121.5 homing beacon.  The beauty of Doppler DF!

[c172drv]

The SAR-DF 517 product is a general direction finder, developed for professional SAR (search
and rescue) purposes. This Direction Finder (DF) is a multiband type (118MHz...410MHz)
working with the physical Doppler-Effect.
It offers the possibility to bear and analyse traditional emergency frequencies in the UHF and
VHF band and the maritime radio band .The Cospas/Sarsat emergency signal is bearable,
despite its very short pulse length, too. It is also possible to decode and display the
Cospas/Sarsat message information.
The excellent bearing result become possible by the newly developed and patented antenna
concept (small, robust and wide-banded) and the sophisticated bearing analys is algorithms
(very complex hardware and software averaging), which deliver a quick, but nevertheless,
steady indication.
The direction finder is designed for working under rough conditions such as mobile uses on
helicopters, airplanes or vehicles.

Thanks to lordmonar for the link.  This is found in Section 1 of the manual.

JOhn

[Robborsari]

I can confirm that the Becker will DF a 406.XXX only signal.  We did some extensive testing with ACR for beacons that got damaged and and only transmit 406.  The downfall is the databurst only happens every 50 seconds.  The Becker will hold the last direction bearing untill it hears a new one.  The good thing is the databurst on 406 is a full 5 watts.  Much more power output that the 200mw 121.5 homing beacon.  The beauty of Doppler DF!

The ball on the becker will blink while it is holding the direction.  You can set the time it holds on the setup page.  I think it defaults to 10 seconds so you might want to increase it.

You also need to remember that the becker is not slaved and will continue to display the relative bearing off your nose at the time it received the signal.   We used it for a 406 beacon with no 121.5 by flying straight and level until the burst, figureing the new headding and then flying along the bearing listening for the 121.5 signal.  Never heard it but we narrowed it down by noting where it flipped to behind us.  Ground found it in a sporting goods store on the shelf.  They only heard the 121.5 when they were inside the building. 

Lesson learned:  If there is no registration data, check the stores