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We're about to be hit with a solar storm... 4

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GregLocock said:
Quite why the lede photo is a sprayer when they are talking about planting is just one of those journo things.
Click to expand...

It's file footage, probably supplied but John Deere, which in reality, if the request was for this specific article, they should have done a better job.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without
 
Agricultural implements use the Russian version of GPS with multiple antennae places around the field. The USA version does not allow a high enough level of precision for row crop work.
 
USA gps will do real time accuracy in cm, if using the enhanced "multiple antenna system" probably just the same RTK (real time kinetics) equipment addition. Without RTK, nobody's system works better than a few meters, due mostly to differing atmospheric/space conditions from day to day.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
 
Most of the increase in accuracy features are differences not so much in the satellite equipment, but what has been set by each system operator as being within the free package vs what is available as extra paid or specially authorised user service level and the receiver's one uses. A dual band receiver is important.

Satellite-based augmentation system (SBAS) corresponds to the FAA's WAAS system, Wide Area Agumentation System, and US defense Dept WAGE system, European Geostationary Navigation Overlay Service (EGNOS), operated by the ESSP (on behalf of EU's GSA), The commercial StarFire navigation system, operated by John Deere and C-Nav Positioning Solutions (Oceaneering), plus others.

These are all wide-area differential GPS based positioning systems that enhance the basic raw satellite positioning capability.

A 3D fix is not a sufficient criterion of quality. The PDOP is an indicator of the precision of the GPS measure (Position Dilution of Precision). If it is higher than 6, you can consider that you do not have a good fix. Under 4, it is good enough for OSM tracking. Less than 2 means you have a very good fix. The quality of the DOP depends on the GPS capacity of correcting the satellite's signal, which usually depends on satellites being dispersed. You can have a good DOP with only a 2D fix.



--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
 
We use the SBAS for 3D approach guidance for GNSS approaches.

They were rolling a load of them out and getting rid of the ground systems such as ILS. The amount of GPS jamming going on these days I think they are rethinking this idea.
 
Alistair said:
They were rolling a load of them out and getting rid of the ground systems such as ILS. The amount of GPS jamming going on these days I think they are rethinking this idea.
Click to expand...

FAA is indeed starting to backtrack on their move away from ground systems. They are also making an effort to maintain and improve VOR/VORTAC system, presumably to protect against widespread GPS outage.
 
That might actually be a good idea. I still have my trusty, no batteries required, Pickett.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
 
DME/DME triangulation with INS is getting used alot these days.

Must admit I am keeping the GNSS page open during the cruise as soon as the sats drop below 4 it gets turned off.

The spoofing is a different issue and challenge to spot. I just watch for jumps in xtrax error to INS.

Unfortunately the pax maps in the back are linked to another GPS receiver. So an occasional PA of don't worry we are going to Germany not Iceland needs done.
 
I used to try the poor pilot's DME. DME from a VOR only.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
 
Galilaio has only been legal in the USA since 2018.

And alot of US products still don't have the chipsets for it.

They claim for the free version of it you can get 20cm horizontal and 40cm vertical resolution.

Certainly it seems my car sat nav is way more responsive and accurate using it than my Garmin GPS.

All cars in Europe need to have it these days as a lead up to being taxed by it I presume.
 
Oh come on. It's only for emergency location purposes. :)

When I'd get lost, I worked out that if you turn 90° off an inbound radial and fly until the radial changed by 10°, I could divide my airspeed by 10 and get a (no wind) DME within 5% of actual. That east Texas Big Piney Wood was huge. One pine tree looks just like the next one.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
 
its linked to so many safety systems and other things.

Sometimes the sensors get locked out with a corrupt almanac which needs a tech with a laptop to sort out after jamming a spoofing.

Hence my preference to turn them off before all the lights and whistles start going off.
 
And yes your old school method does work. So does looking out the window and a stop watch on a heading.
 
The multi antenna version of GPS (or GNSS if using more than 1 consellation) is most often used with one (sometimes more than one) fixed station(s) and any number of rovers (could be a tractor or dozer control, or a surveyors field unit). Usually when the fixed unit is within 10 km of the rover, cm accuracy from post processing is common.

Autonomous solution of the reference station moved around several feet during the storm. It is likely that under these conditions post processing solutions would be divergent due to signal travel path distortion.
 
Quad constellation GNSS receivers are claimed to have an accuracy of 2 cm.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
That's what the farmers are shooting for. 20 years ago they were using systems that could drive the tractor off and on the trailer.
 
Greg said:
Quad constellation GNSS receivers are claimed to have an accuracy of 2 cm.
Click to expand...

Our Trimble GNSS R8 rovers are good for about 0.03' (~1 cm) horizontal and 0.1' (~3 cm) vertical accuracy, depending on several factors.
 
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