ADS-B also solves the tracking issue for Amazon, as each drone wouldn't need to use a separate communications channel to notify its controller of where its is; Amazon could simply tap into existing ADS-B data streams.
The positional accuracy of ADS-B as currently implemented is often measured in hundreds of meters, and GPS has never been particularly good at accurate estimations of altitude. Are drones to have ground based radar ranging? Altimeters based on barometric pressure? Updated to current altimeter settings via what means?
Anyone touting ADS-B as a realistic solution for avoiding mid-air drone collisions in congested areas is severely naive in my opinion, at least based on current technology. My assumption is that those advocating for it in this context aren't actually familiar with its specs and how it works.
In aviation, separation between flying objects is usually measured in miles horizontally, and a thousand feet or more vertically, and the systems are based on that reality for the most part.
> The positional accuracy of ADS-B as currently implemented is often measured in hundreds of meters, and GPS has never been particularly good at accurate estimations of altitude. Are drones to have ground based radar ranging? Altimeters based on barometric pressure? Updated to current altimeter settings via what means?
Some consumer drones use a radar altimeter to determine altitude AGL. The hardware is inexpensive. GPS is accurate for altitude in the US using WAAS (extremely small cost to use WAAS over traditional GPS).
> Anyone touting ADS-B as a realistic solution for avoiding mid-air drone collisions in congested areas is severely naive in my opinion, at least based on current technology. My assumption is that those advocating for it in this context aren't actually familiar with its specs and how it works.
Disagree. ADS-B was designed specifically for this circumstance (traffic avoidance).
Disclaimer: I have electrical engineering experience, a private pilot license with an IFR endorsement, and have worked on projects using ADS-B in production environments.
ADS-B just doesn't seem like a sensible solution. The only traffic you'll have is VFR, and they don't even require ADS-B out if they don't fly in controlled airspace. It seems that having ADS-B out would just clutter up the system and not be terribly useful.
I think the only viable solution would be to have sensors on the drones themselves -- visual and perhaps low-power radar. That way they should be able to avoid other drones and helicopters. It might be necessary to limit operations to VMC, although that shouldn't be much of an issue at below 500ft (you're only really going to be shut down during fog).
ADS-B being a broadcast would also notify anyone else listening to ADS-B broadcasts allowing for the potential of a golden age of drone piracy. Which would be quite profitable if you could avoid being caught.
ADS-B broadcasts contain a unique ICAO code, 6 hexidecimal characters filled in by the Transponder. The collision avoidance logic is handled by the TCAS unit on aircraft.
While new collision avoidance logic is being developed for unmanned vehicles in order to allow them to legally fly in airspace once the FAA restrictions are changed from see and avoid to sense and avoid, when it is released implementing it on an air frame will not be cheap, or light so will be reserved for larger drones. Think about 100k and 20-30 lbs in equipment for an ACAS-Xu Unit, Transponder, and antenna.
And because ADS-B is an internationally used system, changes like the addition of new messages to provide any other information commercial entities wanted their drone to provide would be unlikely to happen quickly if at all, as they would have to go through committee review.
