ADS-B Again

[David Z]

Looks like NavCanada is at this again:
https://www.navcanada.ca/en/air-traf...uirements.aspx

About a year to equip if you want to fly in class A or B airspace. The non-oxygen equipped planes (class B) have a few more years.

They seem pretty clear that we need a diversity antenna:
"The aircraft system will require an antenna able to broadcast out toward space-based ADS-B receivers emitting 1090 MHz Extended Squitter. This requirement can be met either through antenna diversity (the use of a top and bottom antenna) or with a single antenna that is capable of transmitting both towards the ground and up towards satellites. Bottom mount transponders alone are insufficient.".

Now if only NavCanada could staff the surveillance capabilities they already possess. Not sure how they plan to provide ADDITIONAL coverage.

[Weefle]

So it begs the question that I asked last year at this time on avionics......I’m getting ready to spec stuff out for a Garmin package so what makes sense? Go with the GTX 335 or the 335D which is diversity and will meet compliance in 4 years ...if this timeline stays as is?

The cost difference is about 4 k....not chump change. Maybe in 4 years my whole panel will need an upgrade the way technology is changing.

Keith

[jliltd]

And don't think that if you don't live in Canada you don't need a diversity ADS-B out antenna. If you fly to/from the lower 48 to Alaska and penetrate Canadian ADS-B mandated airspace you will need to be equipped with 1090ES diversity ADS-B. This could be avoided by staying in Canadian Class G airspace below 12.500 feet using uncontrolled airports with Class G for stops. That could limit IFR operations in IMC.

This is also applicable to any aircraft of any country of registration....

"US and European aircraft that plan to fly in Canadian mandated airspace will have to meet the earlier-described antenna performance requirements"

[Snowflake]

Near as I can tell, the tailBeaconX is still the cheapest option. Single antenna that broadcasts both up and down.

[Thermos]

A question from the cheap seats down south - does NAV CANADA get to dictate aircraft equipage requirements and standards to Transport Canada?

Just curious...

Dave

[David Z]

Short answer: No.

Long answer: Sort-of. NavCanada decides on airspace classification, meaning they can decide if airspace is controlled or uncontrolled, transponder airspace or otherwise. NavCanada can't change the regulations dictating aircraft equipment requirements in existing airspace. In this case, being ADS-B requirements in the different classifications of airspace. However, this press release appears as though Transport Canada and NavCanada are cooperating this time.

[Thermos]

Originally Posted by David Z

Short answer: No.

Long answer: Sort-of.

Thank you David!

I really like the idea of space-based ADS-B and I understand why it's so desirable in Canada and in remote environments. I hope there's eventually some time-limited accommodation for those of us who want to visit Canada without spending serious ducats on diversity ADS-B Out or a tail unit.

Dave

[dpansier]

Originally Posted by David Z

They seem pretty clear that we need a diversity antenna:
"The aircraft system will require an antenna able to broadcast out toward space-based ADS-B receivers emitting 1090 MHz Extended Squitter. This requirement can be met either through antenna diversity (the use of a top and bottom antenna) or with a single antenna that is capable of transmitting both towards the ground and up towards satellites. Bottom mount transponders alone are insufficient.".

I recall a post on VAF from someone involved with the satellite testing reporting they can receive adequate mode S signals from the lower mounted antennas but I can not locate it at this time. (Was in the last few years)

If a top and bottom is required, another option may be to mount an additional Transponder antenna on the top of the fuselage and use a 50 ohm 2 port power divider. This would allow the use of a standard mode S Transponder.
The coax from each antenna to the power divider would have to be the same electrical length to keep the antennas in phase.
I have constructed them for both 144 and 432 MHz and they perform well. http://www.pnwvhfs.org/conference/20...r-dividers.pdf

[Andy612]

Anyone know if something like this Archer Model 5 antenna mounted with proper vertical polarization in a wing tip might satisfy Nav Canada/Transport Canada's requirements for ADS-B? It seems to me that if it was mounted in a wing tip it would transmit both "towards the ground and up towards the satellites".

[Thermos]

Originally Posted by dpansier

I recall a post on VAF from someone involved with the satellite testing reporting they can receive adequate mode S signals from the lower mounted antennas but I can not locate it at this time.

That might have been me. I sat on an ARINC executive committee before I retired from my first job and Aireon presented some test results at one of our conferences that showed good reception of ADS-B from non-diversity GA airplanes. I have a hazy memory of posting something about it on VAF.

It would be neat to test a combiner. I think you'd have to be careful about where the top and bottom antennas go even if the electrical lengths are perfectly matched. You'd essentially be making a phased array and there could be some areas around the airplane where the antennas cancel each other out.

Dave

ps - apologies for the thread creep!