# The Forester

1433

1. ## Distance measuring using GPS & Google Earth

For geocaching it is very important to stick to WGS84, but when you start getting down to metre-resolution calculation of distances things can start to get quite squirrelly quite quickly, regardless of which geodetic datum and spheroid you choose to use. It's a bit like asking "how far is it to the nearest good pub?". The answer needs an awful lot of detail to be added to the question. F'rinstance: do you intend to go via a motorway; do you intend to go by rail; do you intend to take the canal towpath; have you got a steeple chase class horse; a helicopter? etc etc. A geodesist will give you one answer, if you define the question well enough, but TomTom will give you a quite different answer.
2. ## I was wrong but.............

Sometimes a malicious (person) will post a "needs archived" notice on a cache which he hasn't actually visited. I've had that happen to one of my caches, once.
3. ## Can Etrex Models Average Coordinates?

You can average with the cheapest of yellow eTrex cheapos, but not in realtime. Set the logging interval to 1 second; log as many fixes as you can; stop logging; download the fixes to a spreadsheet and do the averaging there. Unlike with realtime averaging, you will be able to identify any rogue fixes by inspection and reject them before recalculating the mean.
4. ## Distance measuring using GPS & Google Earth

Neither of the two methods proposed will produce a correct distance, though for different reasons. Google Earth uses a peculiar inverse gnomonic projection which is good for producing eye-realistic imagery, but is geodetically unsound for accurate measurement of distances over wide areas. The Garmin method seems to me to be differently unsound, though I haven't explored it fully as the resolution is too coarse. Let's take a quantified example: the distance between Snowdon and Ben Nevis's trig pillars. A spheroidal calculation, assuming both points are on the WGS84 spheroid, shows a distance 419,274.66 metres between these two points, but is misleading as both of the points are actually located on tall mountains. Actually, the distance between the two trigs is 419,358.47 metres. Why the disparity? Consider this: The tops of the two towers of the Forth Road Bridge are a few centimetres further apart than their bases, despite the fact the two towers are perfectly vertical. That this is so is similar to measuring the distance between two spokes of a wheel: it depends how far from the centre of the wheel you make your measurement. The Nevis trig has an orthometric height of 1,346.911m, but is 1,407.736m above the WGS84 spheroid. The Snowdon trig has an orthometric height of 1,086.022m, but is 1,140.855m above the WGS84 spheroid. Forget about Mount Everest. The geodesy over such a huge distance is far too complicated for most people to calculate the co-ords of a geocache from. The geoid has vast undulations along a transect of that line and for most geocachers the geodetic task of back-calculating the true distance to a place in Essex would make their brains hurt. I'd suggest making the thing much simpler by omitting the height of the given points and just doing a simple spheroidal trig calc of the distances on the WGS spheroid. Spheroidal trigonometry is easypeasy for most people who can remember A-level maths. There are also several online calculators to assist that simple calc.
5. ## Galileo update

EGNOS is merely a local augmentation of the USAF global system. Back in the happy days when a US President switched off SA (the event which triggered geo stashes which eventually became commercialised and monopolised by the GC.com bureaucracy) the US guaranteed that their version of GPS, called NavStar, would not be switched off for civilian users without at least 7 years prior notice. In the dark years of the Bush43 regime, Shrub issued a decree which gave him and his successors the right to switch off GPS for civilian users at any time, either with prior notice or not. In effect, he was threatening to hold the world to ransom. Western civilisation has become hooked on the timing facilities of GPS. Even basic stuff such as the synchro of 50HZ power transmission systems and most upper frequencies of radio and microwave telecommunications gear is now dependent on GPS. That's a helluvan investment in the trustworthiness of the most warmongering country on the planet. Galileo will release us from having to stand under that sword of Damocles. The fact that Galileo will also be an improvement in accuracy over Glonass and NavStar is merely a fortuitous side-benefit.
6. ## Galileo update

Many many differences. The most important is that it will be available to all of mankind, not withdrawable at the whim of somebody like G.W.Bush (as he gave his own office the right to do). The monopolar world is over and the monopoly of "GPS" will have been broken. At a technical level, the major advantage will be that Galileo satallites will have atomic clocks which are at least an order of magnitude more accurate than the 1970s technology of the dinosaur clocks in the USAF satellites. As the fundamental operating priciple of these things is based on time, that's what 1066 and All That would call "a good thing". Another major advantage is that the Galileo system will allow seamless integration of all three constellations: NavStar; Glonass; Galileo. The US miltary fought tooth and claw against civilians being able to receive Glonass. Remember the furore when NorthWorstOrient equipped their 747s with Glonass receivers? In the bad old days the monopoly system was the USN Transit. Then along came Glonass, which was vastly better. Then SA was removed from NavStar and it beat Glonass into a cocked hat. Now Galileo will trounce NavStar like the dinosaur that it will soon be shown to have been. Whooppee! It'll be a civil system which is not controlled by military fingers. It'll be much better than the overpriced military stuff and it'll be beyond control of any "czar".
7. ## The All New All New Groundspeak UK Pub Quiz

Yup. the Willis Tower. It's renaming was a very low key affair, mostly to avoid the embrassment of the former owners.
8. ## The All New All New Groundspeak UK Pub Quiz

Recently the world's tallest building was renamed from Burj Dubai to Burj Khalifa in recognition of the fact that Dubai is skint and the sheikh's uncle Khalifa in neighboring Abu Dhabi has had to bail out the prodigal child. That's in the Eastern hemisphere. What is the name of the tallest building in the Western hemisphere?
9. ## Galileo update

At last, the EU Commission has awarded the Billion Euro contracts for the production of the first 14 Galileo satellites. Sure, the project is four years late and four billion Euros over budget. No surprises there then. Sure, the Murricanes threw a hissy fit and tossed their rattle out of the pram when they realised that the US military chokehold on the GPS monopoly was not only being broken but is to be broken by a vastly superior quality product. No surprises there then. Sure, the Russians are miffed that their Glonass, which was massively better that the US NavStar GPS in the 1980s, is now decrepit and failed to make the transition from the 20th to the 21st century. Sure it'll take four years from now for the Galileo system to be up and running. Sure, they said the same thing four years ago. The really big news is that the contracts have now been awarded and the technocrats are in the driving seat. That's good news for all GPS users, all over the world.
10. ## The All New All New Groundspeak UK Pub Quiz

Yes, but we're Scottish. We can take it. The only small problem is that you need to put a quarter pint of gin into a glass of orange juice to stop it from freezing.
11. ## The All New All New Groundspeak UK Pub Quiz

A Cassowary is an ostrich or an emu which lost its passport in a tattoo parlour.
12. ## The All New All New Groundspeak UK Pub Quiz

I remember Hanson in the mid-1980s boasting that they were "doing rather well over there" while I was living in New York. A local explained to me why there were so many harrumpphs about a Brit company using that name with that slogan. The first President's name was John Hanson.
13. ## The All New All New Groundspeak UK Pub Quiz

For the sake of saving an unmaintained cache, let's give The Birdman of Alcotraz a Ding. He got them all right: Aurora Borealis Ali Baba Anaeroid Barometer Atom Bomb Anne Boleyn Let's agree to move the game on and give Birdman the chair for the next question. It's a good cache, so let's nurture it while the GC.com bureaucrats ain't botherin'.
14. ## Freedom of Information report

The Royal Parks bureaucrats are no more reasonable than the GC.com bureaucrats. They have power and they wield that power without reason, simply because they can. Just as the GC.com bureaucrcats have four or five thousand words of rules to "justify" their injustice, so too the Royal Parks bureaucrats have theirs.
15. ## The All New All New Groundspeak UK Pub Quiz

D&V got it right first. The Nore mutiny followed extremely quickly after the Spithead one, and my hero was affected, through no fault of his own, in both. The Oz mutiny most certainly was a mutiny, despite being on land, just as was the unrelated Sepoy Mutiny. Bligh was completely exonerated after the "Rum" muntiny, as he was at his Court Martial following the Bounty mutiny. In fact after the "Rum" mutiny he was promoted, twice: first to Rear Admiral and then to Vice Admiral. Did I mention that he was also a brilliant hydrographer? Did I mention that he learned part of his craft under Captain Cook? Did I mention that he engineered one of Nelson's victories?
16. ## The All New All New Groundspeak UK Pub Quiz

OK, my turn. One of my all time heroes is the much maligned "Captain"(sic) William Bligh. He was a brilliant mariner and a superb navigator. Never mind the pop culture crap which resulted from a string of idiotic movies about Bounty. He wasn't the cruel figure that he was portrayed in those movies, which had conflated the genuinely cruel master of HMS Pandora (the ship which brought the mutineers to Justice) into the persona of Lieutenant (he wasn't a "Captain" then) Bligh. Decades, or even centuries, ahead of his time, he implemepted a regime of what today we would call aerobic exercise. He also was one of the first masters to insist on anti-scorbutics (we call it Vitamin C) being admin/istered compulsorily to his men. His crews had the lowest death rate in the Fleet as a result of his far-sightedness. Now, to the question. Bligh suffered a total of four mutinies in his career. Two in the Northern hemisphere and two in the Southern hemisphere. Leaving aside Bounty, name one mutiny in each hemisphere.
17. ## The All New All New Groundspeak UK Pub Quiz

3 Kids have an innate ability to recognise simple shapes. To a kid those numbers have a commonly recurring shape, ie a round thing in the numeral. Adding up the number of round things is, err, kid's stuff. And for my next lesson: I'll tell you how an ATM recognises your PIN without knowing what your PIN number actually is.
18. ## WAAS reception

You only need to receive one WAAS satellite to receive the WAAS data. What was the question?
19. ## London Royal Parks - Geocaching refused

Methink I shoulda renamed Forester Towers as Bushy Park!
20. ## puzzle caches

A comment like that can get you severely banned by the GC.com bureaucrats!
21. ## A Pictoral Mapping Quiz

Yup. You got it. Just as John o' Groats is often wrongly thought to be the most Northerly part of Britain, while Duncansby Head is actually there, so too North Cape is often wrongly thought to be the most Northerly part of Norway, while Knivskjelodden is actually almost a mile further North.
22. ## A Pictoral Mapping Quiz

Go North. Really!
23. ## London Royal Parks - Geocaching refused

Yes, but think of the poor sad suckers for whom parks in London are their only greenspace. Let them too enjoy the great outdoors and do a bit of geocaching outwith the ghastly urban canyons of London. The carbon footprint of yer averager Londoner, yearning to breathe free and see a bit of countryside, is horrendous. Let the blighters have a bit of exercise in a bit of greenspace and do a bit of geocaching too. You never know. The poor sods might actually begin to feel that they have a life.
24. ## London Royal Parks - Geocaching refused

It seems to me that what we have here is a clash of bureaucracies. The English Royal Parks bureaucracy insists that caches in their parks insists that caches in their parks must be Virtual caches. The GC.com bureaucracy demands that they must be physical caches instead. It seems to me that the ideal win-win solution would be for the GC.com bureaucracy to relent and to allow Virts to exist in English Royal Parks and elsewhere. As for petitioning an intransigent bureaucracy, don't be so silly. You might as well petition the GC.com bureaucracy, for all the good it would do.
25. ## A Pictoral Mapping Quiz

Time for a clue. Think North. Think Duncansby Head. Then think North again.
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