GPS/satnav is 40 years old this month

[cdev]

Huzza huzza, it appears we're old timers now - those who remember the era before GPS. "Where will GPS be" in another 50 years?

http://gpsworld.com/first-gps-signal-received-40-years-ago-this-month/

This maybe should be a thread on GNSS systems and technology generally. I want to start it out by talking about new systems in the pipeline which will greatly increase the accuracy of non RTK (non differential) GPS, especially in tracking mobile devices.

The day is coming when these devices will be so accurate they will literally see if we are breathing or our hearts are beating.

This will be useful in disaster recovery.

[fourtytwo42]

I can remember when people could read maps and trucks didn't get stuck down tiny lanes!!

[BradC]

I remember being blown away by LORAN, so GPS was a whole new ball of wax.

I look at what my great grandmother saw in her 96 years from 1903. Boys used to pick her up in a horse and buggy, to man on the moon, to a 747 to the US for Disneyland on her 80th birthday to grandkids carrying phones around and being able to call them 24/7.

She's been gone a few years now, but tech just keeps charging along. I want to see what the next 40 years brings. Happy birthday GPS, you're only 3 years younger than me.

[cdev]

Arrgh...  Indeed fourtytwo42 That problem is definitely a darker side of GPS..

http://www.sacbee.com/entertainment/living/travel/article2573180.html

'Death by GPS' in desert  By Tom Knudson       January 30, 2011 12:00 AM
Five harrowing days after becoming stuck on a remote backcountry road in Death Valley National Park in August 2009, Alicia Sanchez lay down next to her Jeep Cherokee and prepared to die.
Then she heard a voice.
"I called as I approached, asking if she was okay," wrote Ranger Amber Nattrass in a park report. "She was waving frantically and screaming, 'My baby is dead, my baby is dead.' ....."

[G7PSK]

GPS might be 40 years old and so is my local hospital but my GPS device still claims that it is unreachable by road despite the hospital being just off a dual carriageway. GPS might be accurate to a few cm but the implementation in sat nav devices leaves a lot to be desired still as do some of the idiots using them and making turns without looking like the one who turned into a river and another who turned right straight up a railway line at a level crossing.

[georges80]

I remember buying my 1st Magellan 1000 ($2900 US) when they first came out in 1989. You would get spotty reception of 3 and 4 (for 3D fix) during a 24 hour period. The unit could calculate from your estimated location when you would have windows of reception to get a 2D fix (you entered approximate altitude) or a full 3D fix. It had a single multiplexed receiver, needed good view of the full sky and took several minutes to get a fix.

Was fantastic when out in the oz bush on 4wd trips - finally to know where you were. Of course it only provided lat/long so you had to transcribe that to paper maps to locate yourself. So paper maps, ruler, gps etc and some spare time to figure it out or wait a few hours for the next 2D or 3D coverage period.

What we have now is mind boggling versus those early days and Loran days. Now I have maps, topo, aerial photography etc all at my finger tips and location down to a handful of +/- metres. For anything more accurate (or for when a map that doesn't show the correct turnoff) I can use those even more amazing things call eyes in conjunction with some common sense... And bad maps etc, is not a fault of GPS - it only provides the lat/long/altitude info.

cheers,
george.

[BradC]

GPS might be 40 years old and so is my local hospital but my GPS device still claims that it is unreachable by road despite the hospital being just off a dual carriageway. GPS might be accurate to a few cm but the implementation in sat nav devices leaves a lot to be desired still as do some of the idiots using them and making turns without looking like the one who turned into a river and another who turned right straight up a railway line at a level crossing.

All the technology and disclaimers can't fix "stupid". I see boats hit the reefs in the bay's at Rottnest Island every Summer holiday with the general response from the skippers being "it wasn't on my GPS". Actually, they generally are, it's just there s no big red warning saying "here be dragons". Even if it was, the muppets would still ignore it. They are all clearly marked on all the paper charts too.

[brucehoult]

When GPS reception is mostly blocked by skyscrapers, and GSM signal is bounced many times by buildings, Google Maps still gives very bad location data, sometimes a few tens of meters away from the real location.

Tens of meters! The end of the world is nigh!

Where's that Louis Ck interview?

Ah, yes:

I didn't own a GPS until 1994. Not exactly an early adopter.

It was a Cambridge Aero Systems GPS-NAV Model 10 and was a black box about 15cm x 15cm x 10cm with an external antenna on a BNC connector. There were I think two LEDs on the box. And a great big lead/acid motorcycle battery inside the box.

You could use it just like that as a "secure flight recorder", recording your GPS position and some other parameters (raw pressure altitude, sound level (as an engine detector)) every four seconds for the last 12 hours. It was approved for glider flying tasks and records up to and including world record level.

You could sit at your PC, enter a flight you wanted to attempt, along with you name, date, aircraft registration and download it into the GPS. All digitally signed. You then attempted your flight. If you failed .. just wipe it. No need to tell anyone. But if you were successful then you could upload the flight "declaration" and GPS fixes to your PC (again, all digitally signed), put it on a floppy disk, send it to the FAI, and they would duly issue your world record. The only other thing you needed was someone to witness your landing and take the GPS out of the glider.

In addition, you could plug an instrument panel-mounted navigation display into the GPS with a serial cable and see your current position, bearing to the next waypoint, current track and speed, and a turn-left/turn-right graphical indicator.

It was a pretty cool box in 1994, for an amateur civilian sport.

[Voodoo 6]

I remember receiving some of the first military gps units at the time, and they basically threw them at us and said figure them out. Contacted Rockwell and they sent over the cables and and software. Still have both the cables and the software, made sure to back the data up since it was on floppy.

[cdev]

The antenna and its placement are really important for accuracy. I have a small GPS that I use for logging sometimes, and Ive found that it has to be in a specific pocket in my backpack with the antenna facing up to work even halfway well when I am walking around in big cities. Otherwise the location jumps around.

Its my understanding that new multi-constellation GPSs (which can include GPS L1/L2/GLONASS/Beidou/Galileo or QZSS) are much better than GPS L1 only receivers in avoiding "cycle slips".

The best accuracy is attainable using RTK-capable receivers. They can be very accurate but trees and big buildings still do cause them to lose accuracy fairly often. But they are much better than they were a few years ago and a lot cheaper too.


Quote from: blueskull on 2017-07-26, 20:47:22

GPS coverage and accuracy for non military use still sucks. Google Maps still depends heavily on GSM triangulation to pin point your location, plus a lot of guess work based on way points on their map.
When GPS reception is mostly blocked by skyscrapers, and GSM signal is bounced many times by buildings, Google Maps still gives very bad location data, sometimes a few tens of meters away from the real location.
In my experience, Google Maps doesn't work well in even outdoor parking lots due to the lack of way points, and it certainly sucks in NYC (for pedestrians, since you don't have the speed required to pass GSM beacons fast enough to allow Google Maps to calculate your direction, speed and location).