df517 and rt600 presentation

[starshippe]

   for those interested in direction finding techniques usable with the df517 and rt600 units,  i posted a presentation i made at the georgia wing conference this past april.

http://www.capga072.org/Pres1.ppt

   by the way, the squadron patch is modelled from the one actually used at the cap base that operated from st simons island during ww2.

   i can not provide audio from the presentation, so please let me explain what the point of the concentric circles is. since the early 80's, when satellites were first used for elts and epirbs, the prosecution of the mission has looked somewhat like a three layered upside down wedding cake. the satellite was the upper layer, having a very large radius of detection, and the ability to deliver a radius of resolution of, generally, from 5 to 30 miles. this "position baton" was then passed to an aircraft, which could further reduce the radius of resolution down to from 0.1 to 1 mile or so. finally the baton was passed to the ground team, who found the elt. 

   the 406 satellite system is claimed to provide a much smaller radius of resolution, which should be possible with the higher frequency. in addition, the beacon i.d. may have a current registration, which provides an owner and phone number. also, the beacon data may have embedded gps information. as you can see, there is less and less a need for either the aircraft or ground team.

   however, although much more infrequent as before, we still get tasking for elts, including 406 units. based on the theory behind the system, that the 406 data burst is much stronger than the 121.5 homing beacon. the airborne equipment is supposed to detect this strong burst, and put the aircraft on a course so that it can detect the much weaker homing beacon.  obviously, in order for all this to work, the aircrew needs to be thoroughly trained on the scanning function on the df unit.

   here are my concerns:

      the df517 can only receive the first pair of 406 frequencies. there are several more, of the seven possible, already being used. as mentioned, the premise is that the df equipment will detect this data burst. if the receiver can not receive that frequency, it will not detect the data burst. there are no plans to replace the current df517 units, unless it breaks. new aircraft are being supplied with the rt600. its scanning function is very different from the df517. 

      the scanning function is none too clear. if the aircrew misinterprets the operation of the df unit, it can fly over any number of elts, with no response whatsoever from the unit.

      practice on the scanning function and data bursts is very limited, at least for us. are there those of u out there who routinely use a practice 406 elt beacon during sarex's, and use scanning, and receive and come to bear on the 406 data burst? are there wings with several of these 406 practice beacons? if there are, maybe i don't need to be so concerned.

thanks for ur attention,

bill

     

   

[cap235629]

what about the recent news that CAP will no longer be putting a Becker in any aircraft?

[starshippe]

   do u mean a becker marketed unit, or the newer rho theta rt600 df? rho theta built the df517, which was then marketed by becker.

   if u mean no df unit at all, do u have a link to the story? this is certainly news to me.

thanks,
bill

[Spaceman3750]

   do u mean a becker marketed unit, or the newer rho theta rt600 df? rho theta built the df517, which was then marketed by becker.

   if u mean no df unit at all, do u have a link to the story? this is certainly news to me.

thanks,
bill

http://captalk.net/index.php?topic=12381.msg226188#msg226188

[sardak]

This was in the report I received from my wing commander after the Summer Boards: "In the Aircraft Maintenance Seminar the folks from National said that as the DFs become inop in our planes they would probably not replace them since our ELT searches have dropped off significantly and most of our missions are unrelated to SAR missions." My state director told me basically the same thing, but specifically said "Becker." They're too expensive. If this is really correct, it's criminal. Since 99% of CAP members don't know there are two 406 DF units in use, the 517 and 600, Becker is used as the generic term for 406 DF.   

Getting back to your presentation, not too bad. The biggest correction is to your repeated concerns in it and in your post at  http://captalk.net/index.php?topic=13931.0  that there are no 406 practice beacons. There are.   

CAP issued 406 practice beacons. Our wing beacon is a Seimac Model S1210 EPIRB received in 2006 along with the Seimac Pro-Find DF-500s and 121.775 practice beacons. It transmits on 406.028 and the "homing" signal is on 121.775. Your wing's should be listed in ORMS. The beacons are coded as test beacons so that they don't generate an alert in the Sarsat system. They are detected by the satellites and I've seen the information that ours transmits to the MCC. The beacon does not have an internal GPS or external GPS connection.

The other point, which has been discussed a number of times on CAP Talk, is the homing signal power. All beacons sold for use in the US are required to have the 121.5 homing signal, but the power requirement varies:

ELT (RTCA Standard DO-204A)
50 mW to 400 mW (technically, per the document - EIRP shall not be less than -13 dBW or greater than -4 dBW)

PLB (RTCM Standard 11010.2)
25 mW to 100 mW (the technical requirement -  25 mW -0/+6dB PEIRP)

EPIRB (RTCM Standard 11000.2)
same as PLB

Most beacons, particularly ELTs, have a spec power greater than the minimum.

Mike

[starshippe]

   thanks for the information.

   i know there are practice beacons. but, in this area, the one that georgia wing has, has been broken for some time. i have never seen it in operation. it is not available for training.
   i was asking how often these practice beacons were actually used in sarex's. specifically, how often is the mission pilot trained on how to use the scanning function of the unit?

   i had heard that the beckers would not be replaced (with a rho theta) unless they failed, but understood that new aircraft would be supplied with the rho thetas. that they might not was a surprise to rho theta usa.

   that the air force no longer looks at the cap aircraft as a search and rescue platform is simply disappointing. whiskey tango foxtrot also comes to mind. especially after nascar and archer. geeezzz. 

bill w