Rpra - Google Earth - Loft Co-Ordinates

[Guest kdweb]

As many of you are aware, the RPRA is shortly to introduce the choice of using Google Earth for obtaining loft coordinates. However, you may not be aware they use the Ordnance Survey grid reference and Google Earth use the GPS WGS84 system, which means the RPRA then use software to convert the WGS84 to OS. The drawback is you then have no means to double check the acuracy, because when you input the OS co-ordinates, Google Earth being WGS84 will not display correctly.

 

I'm presently testing out software that will do both, in that it will convert GE to OS and OS to GE. However, Scotland Like Cornwall is on the outer area of OS and I'm seeking RPRA members living on Scotland who have access to Google Earth and their lofts can be seen when zoomed in (not all areas have recent satellite passes) and who would be prepared in the first instance to send me their RPRA co-ordinates, and then do a follow up loft Placemark in Google Earth using quite simple instructions.

 

If interested, email me at admin@kdwebsolutions.com and please double check your typing of the RPRA co-ordinates as it's easy to make a mistake.

[Guest Tooshy Boy]

?????? DONT THINK THAT SHOULD BE ALLOWED ??????

[Guest kdweb]

Tooshy Boy wrote:-

?????? DONT THINK THAT SHOULD BE ALLOWED ??????

 

Which, the testing of the software, or locating the co-ordinates by the use of Goggle Earth?

[Pompey Mick]

The RPRA are currently formulating the rule which will allow Google Earth to be used by Secretaries to obtain Loft Locations. This rule has been passed and will be in force following the March meeting.

The Google Earth co-ordinates will be forwarded to the RPRA who will then use their software to provide an Ordnance Survey reading which they will use to produce distances.

Mapping in the traditional way will still be used. Google Earth is optional.

[greenlands]

Sooner it's sorted the better,sticking pins in maps ?

Then again are they going to tell the transporter driver where to park up.X marks the spot.

[just ask me]

most are now using gps Google earth can be 100s of yards out as far as i know

 

 

 

surely gps should be the way forward

[dal2]

most are now using gps Google earth can be 100s of yards out as far as i know

 

 

 

surely gps should be the way forward

 

 

As Lindsay says Jam, you can measure anyway you want but the carpark,field or whatever at racepoint might be 500yds long????? compltely negating the measurement just taken???? pointless???

[just ask me]

As Lindsay says Jam, you can measure anyway you want but the carpark,field or whatever at racepoint might be 500yds long????? compltely negating the measurement just taken???? pointless???

 

 

 

wont be long till there something on a truck too

 

its the only way forward

 

 

all im saying is that Google is not accurate also there is areas in the uk where google earth dont zoom in right

 

 

and who collects the measurements for each loft

 

 

there is organisations now in the uk using gps

 

 

also states in Google that its coordinates are not correct it just seems like another mess to me

 

 

 

 

a few gps units bought and all lofts checked under the one system

 

 

 

under this ruling could you have one person using os to make there loft and another using a different formula

[dal2]

wont be long till there something on a truck too

 

its the only way forward

 

 

all im saying is that Google is not accurate also there is areas in the uk where google earth dont zoom in right

 

 

and who collects the measurements for each loft

 

 

there is organisations now in the uk using gps

 

 

also states in Google that its coordinates are not correct it just seems like another mess to me

 

 

 

 

a few gps units bought and all lofts checked under the one system

 

 

 

under this ruling could you have one person using os to make there loft and another using a different formula

 

Probably?

 

Solway fed will have every member measured from the lon/lat of race point to the front of loft using their new handheld GPS system so will let you know the differences that happen!

[just ask me]

there could be differences of 500 yards

[just ask me]

how will this Olympic race be calculated if all on different measurements

[Pompey Mick]

The RPRA will still be issuing Ordnance Survey Lat/Long. They are allowing the use of Google Earth as a Secretarial option, the readings obtained will be converted to Ordnance Survey by the use of a software package to calculate distances.

With the RPRA you don't get to pick and choose, once you have been remapped, that Loft Location is attached to your RPRA Loft No which is used by your Secretary whenever he applies for distances for you.

I don't what system the Continentals use for their Loft Locating, it doesn't seem to have been a problem up to now as regards International Racing.

Speaking personally I would like the RPRA to embrace Google Earth entirely, from my own observations Google Earth and GPS are very close (using a SatNav).

[Guest kdweb]

Google Earth is not 'Out' as some suggest. As I stated in my original post Google Earth uses the GPS WGS84 system, not OS which the RPRA uses.

 

Also there is no point in comparing hand held GPS co-ordinates with Google Earth unless the GPS unit uses WGS84 (not all do) and it gives the two decimal places if using Degrees, Minutes, Seconds, six decimal places if using Decimal Degrees, or three decimal places if using Degrees, Decimal Minutes and in all three cases you then need software to convert to OS if comparing to the RPRA co-ordinates.

[airdrie2]

?????? DONT THINK THAT SHOULD BE ALLOWED ??????

why not tooshy boy

[Guest Tooshy Boy]

[Walter swanston]

As has already been staed on this site the Solway will have every loft in the federation re-measured using GPS this winter in time for the 2013 season.I know nothing is perfect but its got to be better than sticking pins in maps.The time will surely come when the racepoints are similarly measured.Surely it is painfully obvious that the only way for the pigeon fancy to survive is to take advantage of every technological advance.

[Tony C]

http://irishhomingunion.com/page10.htm

 

In the sport of pigeon racing, knowing as accurately as possible what the latitude and longditude (location) of a pigeon loft is of paramount importance. With the location of the release point also known, the distance the pigeons fly can readily be computed.

 

With the boom in the Irish economy, new housing estates sprung up faster than the mapping system could keep pace with, and the fanciers moving into these estates were faced with a problem.The expert map-readers in the Irish Homing Union had no maps to read for these new fanciers.

 

THE NEED FOR A RELIABLE POSITIONING SYSTEM

 

Apart from the sport of pigeon-racing at all, trying to find out where exactly he is on the globe has been a problem for mankind since the dawn of history. Down the years, many systems have been tried, but each one has had its disadvantages.

 

The Cold War and the arms race that developed after World War II injected a real sense of urgency into solving this problem. The targeting of ICBMs (intercontinental balistic missiles) became so advances that these missiles could be expected to pinpoint targets thousands of miles away. The ability to take out your opponent's missiles had a profound effect on the balance of power.

 

But you could only knock out enemy missile silos (storage places) if you knew where exactly you were launching your attack missiles from. Most of the United States missiles were at sea on submarines, so the Americans had to come up with a system whereby a submarine could surface at sea and know within minutes its exact location. Fortunately for them, they had the kind of money ($12 billion!) to build such a world-wide system. Thus GPS was born.

 

HOW DOES GPS WORK?

 

The basis of GPS is "triangulation". In simple terms, triangulation is a method of calculating the relative positions of objects using the geometry of triangles. By very accurately measuring our distance from at least three (but preferably four) satellites high above the earth we can establish our position anywhere on the surface of the world. A GPS receiver measures distance using the travel time of radio signals. Knowing the distance from the satellite and where exactly it is, is the secret.

 

Lets look at a very simplified example, to see how it works. Suppose we know that we are exactly 10,000 miles from satellite 1. This narrows down the possible positions we could be in the whole universe to the surface of a sphere that has a radius of 10,000 miles centered on satellite 1. At the same time, if we also know that we are exactly 11,000 miles from satellite 2 ,we must be on a second sphere 11,000 miles from satellite 2. That means that we can only be in one of the positions where the two spheres intersect. When we bring in satellite 3 which is 12,000 miles above us and that sphere comes into play, there are only two possible positions where we can be, and one of those is deep in space and so can be ruled out. But by bringing in satellite 4, the position is established beyond doubt. Also, the fourth satellite is needed to synchronise your receiver's clock with a common time standard which is strictly adhered to by the clocks on board all the satellites. In general, the more satellites used, the greater the positioning accuracy. The Americans have twenty-four satellites up there, ensuring that a sufficient number are always in position to give information when needed.

 

WHERE ARE THE NAVIGATION SATELLITES?

 

The satellites are located in what is referred to as 'Medium Earth Orbits (MEOs) at an altitude of about 20,000 kilometres. MEOs are the orbits of choice for a number of reasons: their stability enables exact orbit predictions; the satellites travel relatively slowly and so can be observed over several hours, and the satellites can be arranged in a constellation so that at least four are visible from any point on the earth's surface at any time.

 

As stated above, the distance to each of the satellites is established by multiplying a signal's travel time by the speed of light. That sounds great, but, unfortunately, there are problems!

 

THE PROBLEMS

 

Firstly, the US millitary, understandably, I suppose, could not be expected to leave their system available to people who could use it against them, so they introduced Selective Ability (SA). This changed the time signals enough to bring in inaccuracies of up to 100m in the locations computed by anyone other than themselves.

 

Secondly, the speed of light is only constant in a vacuum, and the GPS signals get slowed down a bit on their way from space. For example, the Ionosphere, the layer of atmosphere ranging in altitude from 50 to 500km consists largely of ionized particles which can exert a perturbing effect on GPS signals. The troposphere, the lower part of the atmosphere that encompasses our weather, is full of watervapour and varies in temperature and pressure.

 

Thirdly, as the Americans controlled the entire system, they could turn it off or on as they thought fit.

 

SA on its own, regardless of the atmospheric problems, meant that GPS could not be considered for use in loft location, as the built-in inaccuracy was too great.

 

But then came Differential Global Positioning System (DGPS)

 

DIFFERENTIAL GLOBAL POSITIONING SYSTEM (DGPS)

 

The idea is quite simple. With GPS, a receiver takes in timing signals from at least four satellites to establish where it is. But if you put in a land-based reference receiver on a point that has been very accurately surveyed and keep it fixed there, it already knows where exactly it is! Instead of using the timing signals from GPS to calculate its position, it figures out what the travel time of the GPS signals should be, and compares it with what they actually are. The difference is an "error correction" factor, This error information is passed on so as to give more accurate measurements.

 

MARINE DGPS

 

When the Irish Homing Union learned at the turn of the century that as an aid to shipping, the authorities ( General Lighthouse Authorities) had established numerous land-based, fixed reference receivers around the coast of Great Britain and Ireland, giving an accuracy of up to 5m, it decided to adopt the Marine DGPS. The equipment used required two separate aerials - one to receive the GPS signal, and the other for the correction factor from the fixed reference receiver. Depending on where it was calculating loft locations, the IHu used signals from Tory Island (north coast), Loop Head (west coast), Mizen Head(south coast), Nash Point(south Wales) or Point Lynas (north Wales).

 

WAAS, EGNOS, MSAS and GLONASS

 

The rest of the world were not going to let the Americans have it all their own way, and so other systems were developed around the world.

 

In answer to the US military, the Russian military established their GLONASS system (Global Orbiting Navigation Satellite System)

 

As an aid to navigation, non-military systems were also developed, which correct the errors of the military systems.

 

WAAS (Wide Area Augumentation System) is maintained by North America.

 

MSAS (Multifunctional Satellite Augumentation System) is developed by Japan and other Asiatic countries.

 

EGNOS European Geostationary Navigation Overlay Service is maintained by the European Commission, the European Space Agency and the European Organisation for the Safety of Air Navigation.

 

In principle, all systems are the same and even more astinishing, the systems are compatible to each other.

 

For obvious reasons, EGNOS is of more interest to us in this part of the world, and it entered its pre-operational phase in 2006. It is Europe's first activity in the field of global navigation satellite system, and is a precursor to Galileo, the full global navigation system under development in Europe. Consisting of three geostationary satellites and a network of ground stations, EGNOS achieves its aim by transmitting a signal containing information on the reliability and accuracy of the positioning signals sent out by the American GPS system and the Russian GLOSNASS system. It allows users in Europe and beyond to determine their position to within 2 metres.

 

By the way, with all the error correction satellites going up, there seemed little sense in the Americans continuing their 'Selective Ability' built in error, so as of 1st May, 2000, it was discontinued, and the GPS error now ranges around the 20 metre mark.

 

We are glad to report that the Irish Homing Union Differential GPS system in operation uses EGNOS, and we believe our calculations to be accurate to a metre of even less.