Bridge board V1 vs V2

[Wadoadi]

So apart from the layout of the board so it fits the Stratux cases, I was wondering what other differences there are between the two bridge boards, that is if it isn't secret?

different chipset?
support for the Artificial horizon?
...

[Keithvinning]

Dont worry its just part of the PilotAware journey towards the target of developing the anti gravity machine.

[Wadoadi]

cool, I look forward to floating without the aid of any "substances"!

[Keithvinning]

Yes building an anti-gravity machine may be easier than fitting everyone using ADSB on 1090MHz using Pulse Position Modulation into the available bandwidth. We look forward to the authorities paper on this.

[Ian Melville]

To Right Keith, that is the elephant in the room for me and I have to bite my tongue when I hear the 'everything must be ADSB' supporters banging on about it.

Adi, I'm not in the 'know', but I don't think there is a secret, but the new board supports an alternative fused power input. Don't think there are any other feature or functionality changes, otherwise they may end up doing the CE mark testing again.

[Wadoadi]

Cheers Ian

[Keithvinning]

Too Right Keith, that is the elephant in the room for me and I have to bite my tongue when I hear the 'everything must be ADSB' supporters banging on about it.

Time to stop the tongue biting and asking the authorities when they are going to stop wasting money on ineffective projects such as Gains and undertaking a serious study proving that 1090MHz using PPM has the bandwidth to be the technology of choice. The US didn't think so. Thats why they use 978MHz or UAT for GA and why EASA are not jumping on the 1090MHz or CAP1391 bandwagon despite high level lobbying from the CAA NATS and AOPA.

Does Physics now work differently in the UK now we are leaving the EU?

[tnowak]

Keith,

In semi-non techical terms, what is the issue you are referring to?
Is it the potential to saturate the ADS-B out frequency when many aircraft are simultaneously transmitting ADS-B out data?

Tony

[exfirepro]

Tony,

In non-technical terms...... Yes, basically. 

Best Regards

Peter

[Ian Melville]

At the Light Aircraft Design Conference last year the man from the CAA Stated that the consultant had used 1000 simulated aircraft without issue. I have two issues with this. Simulated is unlikly to represent real life transmissions and 1000 is way too low.

Last year I tried a new design of ADSB antenna, nothing special, just a properly designed dipole mounted on the front screen. At 3000' over middle England, I was able to track a Harvard doing circuits in Holand! I was unable to count how many ADSB contacts I had on screen as the screen refresh stopped me scrolling to the bottom. SkyDemon also gave up trying to display them all, failing to display close contacts that I know we're outputting ADSB. Hence I pushed Lee for range filters. Before Lee asks I don't think I have the log file.😒

Scroll forward to a time when all aircraft, para motors, drones, balloons etc have ADSB. I think there may be issues wit transmissions being stepped on, and becoming corrupted.

[buzz53]

For that matter, has a channel capacity analysis been done for Pilotaware? I'm also a wee bit curious about the effect of having a large number of airborne relatively high powered transmitters in a rather unique section of an ISM band and wonder if any impact assessment of that has been done, or are we just relying on compliance with the standard access rules taking care of everything?

Alan

[exfirepro]

Alan,

You're talking about 500 milliWatts maximum output for PAW as against up to 500 Watts for ADSB, so a factor of up to 1000 times the power output. That makes it a totally different ballpark for starters.

Regards

Peter

[buzz53]

Peter, yes but as you know in the ISM bands 10 or 25mW is a more typical power so 500mW is high power, all the more so when the emitter is airborne. I was always surprised that airborne use with that power level was permitted but indeed it is there in black and white (by accident or design)? I wondered if the practical implications had been considered at all? An issue that is obviously closely related to the channel utilisation question.

Alan

[Admin]

The issues are not directly related to power levels
The issue is around the modulation technique

ADSB/1090 uses PPM also called OOK
This is analogous to morse code

Pilotaware/flarm/uat all use FSK

The problem is that OOK uses periods of silence, and if another transmitter overlays during the silence, the data is corrupted
FSK has no silent periods and constantly transmits 1 of 2 ‘tones’, so most powerful broadcast wins when 2 transmissions overlayed, a bit like your FM radio when driving between stations on the same frequency
Fortunately the most powerful is usually the closest (inverse square law), which is what we are interested in receiving

Thx
Lee