FlightAware Discussions

GNSS (GPS and Galileo) to get much better by late 2020

(I know there is also BeiDou/Compass, and Glonass plus the other SBAS augmentation systems, however, I am focusing on planned improvements to GPS and Galileo here).

Galileo to become fully production

This has been scheduled for 2020 for years. I am not sure if they will make 2020 or whether it will be pushed back to 2021.

I know that they have been in the news this month due to an outage.

21 satellites are working at the moment. Four were launched last year and became operational this year. More are scheduled to be launched some time in 2020. It could take several months, after launch, for them to be made operational.

They all seem to transmit dual band signals.

GPS to transmit L2C signal.

This is about 300Mhz from (lower than) the L1C/A signal so should provide a way to negate the effects of the ionosphere. 19 satellites are broadcasting the signal today. The two new Block 3 satellites should start broadcasting soon(within a year). They expect to have it fully operational in 2021.

GPS to transmit L5C signal. This one is supposed to be a protected service for “Safety of Life”

Again, ~400Mhz lower than the L1C/A signal so should provide another signal to negate the effects of the ionosphere. This is only available on Block 3 satellites. Two have been launched (I watch the launch of SV02 last Thursday, on NASA TV). Due date is 2024, however, that is only for just enough satellites for the system to work. It will take a few more years for every satellite to transmit L5C.

GPS to transmit L1C signal (not L1 C/A).

https://www.gps.gov/systems/gps/modernization/civilsignals/

The GPS satellites are being replaced. The new GPS III satellites will transmit a new L1C signal. Whilst this is a nice improvement, we have to wait until the end of the 2020s for this to be fully rolled out. At the moment there is one GPS satellite testing this signal.

SA or Selective Availability was turned off almost 20 years ago. It was a little pointless when WAAS and other SBAS systems were enabled. Also, the new Block 3 satellites don’t even have the facility to do it. The U.S. military has other options for to use to degrade GNSS services.

Glonass and BeiDou are also due for upgrades. They both have dual band transmitters, however, only about half of the satellites seem to be transmitting on both bands.

In my attic, I can “see” 20 to 30 satellites with a nice dual band, four constellation receiver(not cheap, at $US200 plus a $US50-100 antenna, however, the price will come down over time). I hope to move the antenna outside in the next week or so. I’ll post a Sky View when I move it.

Having four, or more, constellations available for navigation greatly improves availability and reliability. All should provide dual band signals by the end of the next decade.

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Screenshot_20190826-144549_GPS%20Test
I get 24 from my window at work, with my Galaxy S10 phone :yum:

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As the GPS satellites are being replaced, if you live in the UK or Denmark, be aware the launch vehicle passes over these places some 20 to 30 minutes after launch from the US.

They are best seen at latitudes very near to 55 degrees North and visible in the sky only if it passes over in the hour or two before sunrise or the hour or two after sunset.

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Only GPS: Accuracy 5 meters :slight_smile:

OK, let me go outside then :rofl:
4 meters, 30 satellites in view, 21 in use.

This app used to have flags above satellites. Now you have to use the “filter” function.
Now I “see” 5 Glasnost and 7 Galileo. Zero Beidou. Rest, of course, are GPS.

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By way speaking of measurement errors.
Height above sea level … on the coast of the sea :rofl:

That is due to the geoid correction that is applied by the software. Might not be that accurate for Crimea. Vertical location is hard to make accurate.
https://www.ngs.noaa.gov/GEOID/

image

Not too bad from my office window with big trees in front of it

Different view. Located in Germany, but no Galileo Satellites :smiley:

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Altitude is also the least accurate aspect of GPS positioning. It is much more dependent on constellation geometry, so some variation is to be expected, according to the arrangement of the satellites being received.

Yeah, the used geoid datum by that software is by default WGS84. Correction can be changed to something else or turned off.

I got an altitude of -10M. I am close to sea level and the std spheroid model, doesn’t work well here.

The GPS system has gone, or is going, from 24 to 31 satellites. This will help with PDOP and altitude accuracy. Dual band will help with accuracy, especially in locations without WAAS/SBAS or LAAS/GBAS.