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Satellites, Galileo, emergency location

Any source / evidence / quotes, perhaps?

I think this is complete BS, all that is required is that the phones can use at least Galileo to fix their position. Which, BTW, most of new phones do already, apple since the iPhone 8 and X, which was back in 2017.

It was on the android news feed. Don’t remember any source.

It’s not complete BS though. Google Galileo search and rescue and you will find info. I think the source was confusing smartphones and PLBs ? It works like this:

The PLB sends out a distress signal. It is picked up by Galileo or some other SAR satellite. The satellite sends a message to a ground station. Then a SAR mission is coordinated and a Galileo ground station sends return link signal to a Galileo satellite. The satellite sends this signal back to the PLB. The return signal typically include information that the signal has been received, and that help will be there in 29 minutes for instance.

Only Galileo satellites are able to send this return signal, and it works through the Galileo chip in the PLB (as far as I could tell).

Last Edited by LeSving at 24 Jan 11:37
ENVA ENOP ENMO, Norway

Here is a good document about the Galileo SAR capabilities. Very interesting also for GA, it works on ELT and PLB. In fact this system was used in a helicopter accident in Norway not that long ago.

Also found the smartphone thing. From 2022 all smartphones shall have the capability of sending “extended” positioning when doing emergency calls. At a minimum this shall include Galileo positioning (due to improved accuracy), but can also include wifi and GSM positioning. Of course most smartphones sold today have Galileo in any case, but this function of including Galileo positioning (specifically) in emergency calls is new.

ENVA ENOP ENMO, Norway

In the US, IIRC, the inclusion of GPS position has been mandatory for emergency calls for years.

It should work the same way in Europe, but limiting the position data to Galileo is bizarre.

Administrator
Shoreham EGKA, United Kingdom

From what I remember from the wording, it’s not limited to Galileo, but it has to include Galileo.

ENVA ENOP ENMO, Norway

That would make perfect sense. IOW the EU is mandating Galileo operation on consumer GPS products, which – like Russia’s – is a fairly logical move.

I could never get much from Galileo or Glonass with the Aera 660 but that’s another story…

406MHz detection has always been done with satellites. Normally these are geostationary but I guess it is totally feasible to do it with medium-orbit ones like the GPS constellations.

Administrator
Shoreham EGKA, United Kingdom

Originally, 406 satellite detection was lower earth orbit only, because then it was designed in the 70s the beacon transmissions were located using doppler effect from orbit. Transmission of location data by the beacon and the corresponding geostationary capability was added later, 10-15 years after initial launch, IIRC.

In any case, the 406 detection payloads are “piggyback” modules on other satellites, and more recently they have been installed on medium-orbit satellites, including GLONASS, GPS and Galileo.

At this point, there are 5 LEO, 9 geostationary and around 40 (And counting…) MEO payloads, which started to be operational about 4-5 years ago. About half of them are on GPS satellites

The only thing new or unique with Galileo is the return signal.

Biggin Hill

What does Galileo send to the ground device?

The receiver antenna is obviously small so that end will be S/N (Shannon) limited. Or the transmitter needs to push out a lot of power, briefly, given the unavoidably not great antenna gain. Thuraya and Iridium do it by having lots of beams, each coming out of a dedicated antenna. Thuraya use 128 beams, IIRC. And the phones are bulky, with no chance of that ever changing.

A PLB can have a bigger antenna…

Administrator
Shoreham EGKA, United Kingdom

The return signal is transmitted as part of the I/NAV navigation message, in the E1 band (around 1,575 GHz). It is 80-160 bit long, and the data rate is quite low at around 125 bit per seconds. Because it is embedded in the much bigger I/NAV message, it can take minutes.

The receiver needs to have a good Galileo signal for this to work.

So the satellite needs no additional capability but the ability to insert a data packed in a message transmitted anyway, and the receiver nothing more than the ability to extract it. All of this is software, not hardware capability.

Biggin Hill

Really interesting. I wonder how many downlink clients they can cope with.

I would expect Navstar to be doing the same thing, for ahem rather more classified purposes

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

406MHz detection has always been done with satellites. Normally these are geostationary but I guess it is totally feasible to do it with medium-orbit ones like the GPS constellations.

SARSAT uses LEO satellites to determine position via doppler. 406 MHz ELT don’t require GPS, but the service is better if it is available as a GEO satellite can pickup the ELT/PLB without requiring one or two orbital passes. In the US, 406 MHz ELT is not mandated and if one installs a 406 ELT, GPS is not mandated, We still can use 121.5 MHz ELT, they just don’t get detected by SARSAT. ELT’s have a very poor service record, regardless of frequency.

I am following a friend’s flight down in the Caribbean on FlightAware. What amazes me is how well they are tracked via ADS-B Out, often down to under 1000 MSL and I can even tell they are doing a specific approach. This is all accomplished by enthusiasts feeding ADS-B In data to FlightAware.

KUZA, United States
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