Based on the surface area of UK being only 3% of the USA, the later of which has substantial amount of mountains on the east coast and west, 17 stations should do an adequate job of providing UAT coverage for weather broadcasts thru out the entire UK. The weather products are already defined and implemented in numerous panel mount and ultra cheap portable receivers. It would make no sense to reinvent the wheel.
What is the power of the US transmitters?
NCYankee wrote:
17 stations should do an adequate job of providing UAT coverage for weather broadcasts thru out the entire UK.
This could be great not only for VFR pilots, but also for IMCr guys who fly in and out of clouds at 3-4000ft and will get a much better coverage.
Not sure how many watts, but the FAA gives a line of sight range of 150 miles.
https://www.faa.gov/nextgen/programs/adsb/faq/#i2
Obviously this depends on altitude and obstructions; if you look at the coverage maps for Colorado, Utah, and a few other places in the Rockies, there is substantial terrain masking.
https://www.faa.gov/nextgen/programs/adsb/
However, England is not so mountainous :) and you could probably get near perfect coverage if you stick the transmitter on an existing microwave or cell tower on a hill. Land’s End to John O’ Groats is 874 miles by road, so three or four transmitters would probably cover it in a straight line. Accounting for overlap and so on, I think NCYankees estimate of 17 is probably a bit high, unless he’s also including Northern Ireland, or wants very good low level coverage.
NB: This ICAO document doesn’t lay out a specific power level for ground transmitters, but sets a limit of +58dBm. Given that +54dBm is 250 watts, +58dBm should be in the range of 500 watts peak modulation, and an average draw of around maybe 100W?
http://www.ads-b.com/PDF/UAT%20SARP.pdf
ETA: Of course, this assumes that the FAA transmitters are at the max level output relative to the ICAO spec. Anyways, it doesn’t seem too onerous to set up a system.
This is from the uavionics.com website so they are using 25 watts output for the test sites……………
4. What is the expected range?
It depends (eek). The range depends on several factors including transmit power, line of sight (LOS), and receiver sensitivity. Our FIS-B stations transmit at 25W from an omnidirectional antenna. Theoretical calculations would say that signal should be receivable at 40+NM
That is from here
It’s interesting but there is a big difference between 25 watts and 250 watts (and on a tall tower) in terms of paying for it.
They are talking about getting a traffic feed but that is going to be really interesting, looking at how much NATS charge for that sort of thing.
Peter, this is being billed as a free service like in the US. Of course it would be challenging to do but shouldn’t we try to support it? Maybe they can get CAA/NATS support.
The biggest issue would be trying to get the rest of Europe to join in.
The biggest issue would be trying to get the rest of Europe to join in.
The 978MHz frequency is reserved for TACAN and DME use. So before that frequency could be used we would have to convince the CAA and the military in all European countries to let go of that frequency for their purposes. Technically that should be possible as there is no need for so many TACAN and DME channels anymore but the political effort sounds huge and I can not imagine to get that done in any realistic timeframe.
Then once the frequency is available a sender infrastructure would have to be deployed. A German FM radio station covering only a part of the country just complained they have annual broadcast costs of 2.5 million Euro to run their program from 37 sites. The Telekom EAN network for the airlines uses about 300 sites in Western Europe but it still needs a satellite to provide continuous service. I think this gives a very rough idea what kind of effort it would be to cover Western Europe with ADS-B UAT
I guess all in a satellite weather system is cheaper than a ground based system. As the FAA subsidises the ADS-B infrastructure for political reasons we get the impression this is a cheap solution. But if users would have to pay for it, the service would probably be not much cheaper than satellite based XM weather.
In fact the ADL devices which currently do individual downloads are also capable of receiving broadcast messages transmitted by Iridium. Currently the charges for a continuous broadcast would be much higher than the overall cost of the individual downloads so it is not used. But buying this broadcast would probably still be cheaper, easier and faster than the installation of ADS-B UAT ground infrastructure in Western Europe. So if anybody, public or private, feels like spending serious money call me ;-)
Let’s estimate how much FAA ADS-B would cost to the average US pilot.
Annual ADS-B cost : 130 million $
Number of private and commercial pilots : 195,650 +123,900 = 319550
Cost per pilot : 130M$ / 319K = 407 $ per year or 34$/month It would probably be much more, because all pilots would not subscribe.
XM satellite weather is 35$/month for a basic weather service and 55$ for a complete one, but with no traffic information.
Questions : would it make sense financially to build this on private money with the XM competition ?
To me, no way.
But the FAA probably wanted to prevent any unidentified airspace infringement so this itself has a cost (and a reward) I guess.
Edit : I just discovered XM sells its weather service to marine users and emergency services. This explains how they made it affordable.
Woult it be possble in Europe (business idea for Sebastian 
) ?
If we take a typical european example (France, UK, Germany) with Jacko’s figures :
Annual cost : 4 millions €
Potential members : 30K
Actual subscribers : 5K (most local-VFR pilots wouldn’t see its utility)
Cost would be between 133€ and 800€ per year depending on the number of subs.
So probably 67€ per month to get weather in one country.
An ADL box would be reimboursed in one year or two.
