Kannad ELT Internal GPS Reception Test

[Andy]

I contacted Orolia (manufacturer of Kannad ELT) with these questions: (edit to correct Oralia to Orolia)

"How can I verify that the internal GPS of this ELT is receiving a GPS signal, has a GPS position lock, and is able to report my position? Will self test fail if no GPS position is being received?"

I received this answer:

"Unfortunately, there is no easy way to check the proper functioning of the internal GPS receiver.

Self-test will fail if the GPS module is found defective (loss of communication between GPS module and microprocessor) but self-test will pass even if no valid GPS position is received.

Indeed, to acquire a valid GPS signal, the ELT must be switched ON more than one minute, which would transmit a FALSE ALERT DISTRESS MESSAGE. It is strongly required to avoid such situation.

If you have got a 406 MHz beacon tester (IFR4000, BT100, BT200) AND IF you are familiar with it, you can connect it directly to the output of the ELT BNC connector to avoid transmission through antenna. This test would be done under your responsibility.

If you have a doubt about the serviceability of your ELT, you can have it tested by a Kannad Approved Repair & Warranty Center.

Mid-Continent Instruments and Avionics - Wichita, KS
Pacific Southwest Instruments - Corona, CA
SC Accessories (Southern Cross) - Fort Lauderdale, FL
Thales Avionics USA - Piscataway, NJ"

This confirms what I had suspected and leaves me wondering if the EX/FX ELT installation will work as intended. One test I had intended to perform was to disconnect the GDU 465 GPS antenna and place a substitute antenna under the seat close to the ELT. The GDU 465 has good GPS reception monitoring and should give an indication of how well the antenna works under the pilot seat as compared to the standard location on the fuselage bracket above the passenger seat.

I don't remember why I didn't complete this test but it's back on my list of things to do.

[PBY Catalina]

Thanks Andy !

Keep us informed !

[ceslaw]

Good information Andy. One wonders why Cubcrafters moved the ELT from the rear location in the baggage area to under the pilot’s butt. I am considering moving it back for several reasons:

1. No need to worry about the GPS signal getting past the grounded carbon fiber box it is setting within under the seat.

2. In the rear location the ELT is covered with only fabric, so the GPS signal is no longer an issue.

3. The length of the transmission line is significantly shortened, reducing line losses.

5. It opens up a nice storage area under the seat for one’s billfold, cell phone or Glock.

6. The Kannad can be mounted upside down, as long as the front-end points forward. Since the mounting holes don’t align with the existing bracket, a simple fiberglass panel could be easily fabricated to attach the Kannad bracket.

IMG_1823.jpg

The remote switch that comes with the Kannad would be mounted on the wing root panel on the door side where it can be easily accessed as one exits the plane in an emergency, yet is out of the way and not cluttering up the instrument panel

IMG_1801 (2).jpg

Am I missing something here?

[Andy]

6. The Kannad can be mounted upside down, as long as the front-end points forward.

Can it? I had assumed the internal GPS antenna should face upwards but I'd need to re-check the installation manual to be sure.

[ceslaw]

Can it? I had assumed the internal GPS antenna should face upwards but I'd need to re-check the installation manual to be sure.

Per the manual, page 9, it must be mounted
-“with “Flight direction” arrow towards the front of the aircraft;
- in any position parrallel to the roll axis.”

I read that as upside down is okay.

Wonder if the GPS antenna sits in the aft end?

Sure is tough getting hardcore data on this French device!

[Andy]

Sure is tough getting hardcore data on this French device!

I sent them another message asking about orientation for GPS view of the sky. The older GPS receivers used to be sensitive to antenna orientation but I'm amazed at how well the GPS in my Android phone works almost anywhere regardless of orientation.

[ceslaw]

With a tiny bit of trimming on the tray the Kannad could be mounted in its “up position” which would probabaly make the most sense.

it is impressive how devices can receive GPS signals in different positions and even indoors

[Pete D]

One wonders why Cubcrafters moved the ELT from the rear location in the baggage area to under the pilot’s butt. I am considering moving it back for several reasons:



Am I missing something here?

The hardpoint in the upper/fwd area of the baggage area is for the AmSafe Airbag option brainbox. The factory location for the ELT has always been under the front seat in the molded composite seat base.

[Andy]

One test I had intended to perform was to disconnect the GDU 465 GPS antenna and place a substitute antenna under the seat close to the ELT. The GDU 465 has good GPS reception monitoring and should give an indication of how well the antenna works under the pilot seat as compared to the standard location on the fuselage bracket above the passenger seat.

I don't remember why I didn't complete this test but it's back on my list of things to do.

I ran this test this morning. I'll write a report later but it is very obvious that GPS signal reception is significantly degraded by the seat. While the under seat location may have been good for an ELT receiving GPS over a serial data bus it is not a good place for an ELT that uses an internal GPS and antenna.

[Andy]

I plan to write a more complete report but these two screen shots tell most of the story. Aircraft was outside hangar and an amplified GPS antenna puck was connected to GDU 465 instead of the factory installed antenna. Antenna was placed on ELT under the pilot seat for screen capture 2218 and on top of the seat squab for screen capture 2304. The only difference between these antenna positions was the thickness of the carbon seat shell, foam, and fabric. I was not in the seat.

Under seat (crop of 2218.png)
under seat.PNG

On top of seat (crop of 2304.png)
on top of seat.PNG