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Topics - Hugh Westacott

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Satnav (GPS GLONASS COMPASS Galileo) / Deleted topic
« on: August 24, 2015, 11:40:46 AM »
Sorry, chaps! In my cackhanded way I've accidentally deleted this topic. Can anyone restore it, please? This is the message I was trying to post:

Thanks, LS!

I have to admit that I have struggled with this chapter because it is one of the aspects of walking about which I know very little.

Also, it is the one subject that is dynamic and constantly developing and thus does not readily lend itself to book format. So all I can do is to discuss the subject in general terms. I’m glad that Ian pointed out that I was being too prescriptive and I’m pleased that it now seems about right.

I’ve contacted CP but I guess he’s on holiday in some exotic location.

Best wishes


Satnav (GPS GLONASS COMPASS Galileo) / Handheld satnavs and GNSS
« on: August 22, 2015, 05:52:45 AM »
The first printing of my book The Walker's Handbook; Everything you Need to Know about Walking in the British Isles has almost sold out. for the 2nd impression, I'm taking the opportunity to correct one major factual and elementary error, and a couple of typos.

In his helpful and perceptive review on this forum, Ianj37 queried whether it was possible for handheld satnavs to receive signals from GLONASS. Here is the relevant passage which I should be most grateful if some of the experts on this forum would comment and correct (some of the formatting has been lost in cutting and pasting). I've highlighted in red what I believe may be incorrect but I'd welcome additional corrections.

Definition of terms
2 The terms used in connection with satellite navigation systems have not yet been standardized and are sometimes confusing and self-contradictory. Those used in this book are defined here:
   .   a)  The Global Navigation Satellite System (GNSS) refers to the system of circulating satellites and the signals that they transmit. They are transmitted from the satellites of

• the Global Positioning System (GPS) operated by the United States
• GALILEO operated by the European Space Agency

• the Global Navigation System (GLONASS) operated by the Russian 

• BDS (formerly known as Compass and Beidou-2) operated by the 
Chinese authorities
Note that signals from all four systems are compatible and can be received by most satnavs, smartphones etc. Other countries are also developing navi- gation satellite systems.
Description of the Global Navigation Satellite System
3 The satellites of the four organizations, the Global Positioning System (GPS), GALILEO, GLONASS and BDS that make up the Global Navigation Satellite System transmit signals that can be picked up by a handheld satnav that converts the information into geographical coordinates. These will, depending on the sophistication of your handheld satnav, enable you to:
   .   a)  Establish your position anywhere on the earth’s surface to within 5 metres.
   .   b)  Establish a series of coordinates from a map,and in put them into a hand- held satnav and then navigate to each one in turn.
   .   c)  Record a route you are walking, and then to save it and use it again later.
   .   d)  Plot the route on a computer mapping system to see where you have been.
   .   e)  Share routes with others via computers.
   .   f)  Download maps from a computer into your handheld satnav and follow a route in real time.
4  The accuracy of the signals picked up by handheld satnavs used by walkers is generally 5 metres or better for 95 per cent of the time.

5  There are two supplementary systems that receive satellite signals and improve their accuracy for use in civilian handheld satnavs. These Satellite-Based Aug- mentation Systems (SBAS) use a network of ground-based stations in fixed locations to calculate the locally-received errors. Corrections are transmitted to the satellites which then broadcast the corrected signals to handheld satnavs
   •   WAAS (Wide Area Augmentation System) which covers the United States and Canada
   •   EGNOS (European Geostationary Navigation Overlay Service) which covers Europe and the British Isles and extends for hundreds of miles into the Atlantic and as far north as Greenland
6  WAAS, EGNOS, GLONASS and BDS are compatible systems. Providing that your handheld satnav is either WAAS or EGNOS-enabled then accuracy is likely to be as good as 1·5 metres for 99 per cent of the time. Note that most handheld satnavs are manufactured by American companies which means that when setting one up for the first time you can normally only specify WAAS in the menu option. However, when specifying WAAS in European countries you will automatically be tuned to EGNOS.

Maps / Fascinating Soviet maps
« on: July 20, 2015, 08:34:10 AM »
Here is a fascination and alarming article about the scope of maps made by the soviet Union


Maps / Major changes to Explorer maps
« on: March 14, 2015, 09:19:16 AM »
The Ordnance Survey has announced major changes to the numbering system and the method of indicating the date and extent of the revision of each edition of the Explorer series. Full details are at

I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S.Eliot

Maps / Ordnance Survey announcement on Open Data
« on: February 24, 2015, 11:10:27 AM »
Yet another interesting press release from the Ordnance Survey.



To coincide with International Open Data Day, when countries across the globe will show their support for open data policies, Ordnance Survey (OS) announce plans to launch a world-leading digital map as open data and the creation of an engagement hub in London.

This consolidates the UK’s reputation as the most advanced country in the world on open data, as recognised by World Wide Web inventor Sir Tim Berners-Lee last month. It will generate opportunities for enterprise, drive innovation in the digital economy, increase demand for new apps and services and help data-driven businesses to grow.

OS OpenMap, which will be released at the end of March, has been designed to work with the latest mobile and web platforms and will allow developers to build new products incorporating some of the most sophisticated mapping data in the world. It will also enhance the wide range of existing apps that use geospatial data. Targeted at both public sector and commercial users, the map provides an enhanced level of building detail, extended naming of roads and identifies sites such as hospitals and schools – all in a customisable and easy to style format.

Today’s announcements from OS are underpinned by a more liberalised approach to licensing designed to maximise the benefits of the UK’s most valuable data.

This weekend OS will support the UK’s first ever Open Data Camp in Hampshire. Two hundred developers, innovators and entrepreneurs will have a first chance to trial some of the new data to create fresh insights and innovative products and services.
Vince Cable, Secretary of State for Business, Innovation and Skills said:
“Access to open data will open up job opportunities. Britain is already a world-leader at designing and making innovative products. But we need to keep investing and supporting our technology businesses to stay ahead.
“Making this data more accessible means more small and medium companies will be able to use Ordnance Survey’s world-leading maps, combining geographical data from multiple sources and visualising them at a high level of detail.
I am sure this will inspire a number of companies to create sophisticated new products.”
The Geospatial Innovation Hub will provide a space for OS to meet face-to-face with developers and to support the creation of new products and services. The Hub builds on OS’s experience of working with start-ups through their successful GeoVation programme, allowing developers to benefit from expert OS advice.

Matthew Hancock, Business Minister at the Department for Business, Innovation and Skills, said:
“Ordnance Survey has world-beating data and its expertise means that the UK has access to the best and most comprehensive mapping data in the world. I announced earlier this year that Ordnance Survey would move to a Government Company to ensure that it could operate in an increasingly agile and flexible manner in the fast changing geospatial market, and today’s announcement goes hand in hand with that change.
“Ordnance Survey data is already being used by a range of businesses and these developments will enable its open data, as well as its commercial activity, to continue to support growth and innovation in this country.”

Francis Maude, Minister for the Cabinet Office, said:
"As part of this Government's long-term plan for the economy, we are driving an ambitious transparency programme. Open data is a new raw material and today's Ordnance Survey announcement builds on the progress which has seen us recognised as the world's most transparent government. Transparency is an idea whose time has come and we must keep challenging ourselves to do more."

Neil Ackroyd, Ordnance Survey’s Acting Director General and Chief Executive, said:
“Over the last five years Ordnance Survey has been committed to supporting the open data programme in a sustainable way. I am confident these new open data developments will be welcomed across the public and private sector and that it may inspire a new wave of developers and entrepreneurs to work with OS data.
We are delighted to be releasing a new range of open data products, and I am particularly keen to see the new street level product being used across mobile and online services and applications, as it provides an unmatched level of detail at the national level. At Ordnance Survey we believe that open data releases are best supported by additional resources and we have explored ways to improve and modify our licenses and provide supporting initiatives to aid further innovation.”

The announcement today includes:
A significant enhancement to Ordnance Survey’s portfolio of Open Data products:
OS OpenMap – a new ‘street level’ vector dataset designed to be the most detailed open data mapping product available, providing a backdrop for integrating and visualising analytical data. The new product will provide an enhanced level of detail for buildings including the specific identification of functional sites such as hospitals and schools, extended naming of roads and an extensive set of cartographic names optimised for digital styling and presentation.
A new Open Water Network – a generalised network product covering Great Britain’s rivers which will deliver a national view of our watercourses.

A new and improved Gazetteer – for use by people who need the most up to date place names, road names, road numbers and postcodes for use in location searches for both mobile and online uses.
Supporting the release of UPRNs:
Enhanced support for developers and innovators:
A new Geospatial Innovation Hub; and
Improved licences for developers.

Today’s announcement also builds on statements earlier this week from Ordnance Survey around how it would be making it easier, and more effective, for public sector users of OS data to publish their own open data.


This press release may be of interest.

I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S.Eliot

Please pass on details of this week-long residential course I shall be tutoring to anyone interested in learning the skills necessary for navigating through lowland countryside in England and Wales. Go to for more information.

Marlborough College, Wiltshire, one of England’s leading public schools, is set in a charming small town amidst lovely countryside and its annual summer school attract visitors from round the world. The spectacular school chapel is a masterpiece of high victorian gothic architecture with murals and stained glass windows by pre-raphaelite artists. An organ recital in the chapel is alone worth the course fee!

I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S.Eliot

General navigational Kit / Altimeters
« on: November 12, 2014, 03:13:23 PM »
I've been considering the practicalities of employing altimeters when navigating in mountainous areas. Yes, I know that handheld satnavs will do the job much better, but there must still be a few walkers who rely on them.

I have two altimeters which I used for my experiments in the Chiltern Hills. My Garmin Foretrex 401 incorporates a barometric altimeter with a claimed accuracy of ±1 metre. The barometric altimeter in my Suunto Vector wrist computer has a barometric altitude mode with a claimed accuracy of ±5 metres.

Over the past few weeks, I've kept a record of the elevation data recorded on both instruments with some surprising results. In both cases, I never walked more than a kilometre before recalibrating against a known height. The Foretrex was often spot on and never more than 3 metres out, but the Suunto was often as much as 15 metres out and I should not care to rely on it in poor visibility in the mountains.

Factors that can affect the accuracy of altimeters include the calibration interval of the instrument; fluctuations in air pressure (which can be considerable in the UK); the humidity of the atmosphere (air with a high water content is heavier than dry air); the temperature. Also, spot heights and contours are subject to minor inaccuracies. Further information can be found at

Altimeters can sometimes be used to establish your position. This technique can only be used when climbing or descending steeply otherwise the distance on the ground between contours is too great to be of much use. If the altimeter is accurate to ±5 metres on a 10° slope angle (18% gradient) your position could be off by up to 29 metres in either direction. On a 20° slope angle (36% gradient) you could be off by up to 15 metres in either direction. On a 22° slope angle (40% gradient) you could be off by up to 13 metres in either direction.

If the altimeter is accurate to ±1 metre, on a 10° slope angle (18% gradient) your position could be off by up to 6 metres in either direction; on a 20° slope angle (36% gradient) you could be off by up to 2.9 metres in either direction; on a 22° slope angle (40% gradient) you could be off by up to 2.7 metres in either direction.

When relying on an altimeter as a navigational aid in poor visibility it is essential to fix your position against known heights as frequently as possible. This can be done at the contour nearest to any feature that can readily be identified on a map such as trig points (these are few and far between); summits; bodies of water (lakes, lochs, tarns and loughs); footbridges; junctions of paths, walls when following a path; junctions of walls when in pathless terrain.

When relying on pacing and/or timing as an aid to navigtion, you have to take into account  the forshortening effect of depicting steep slopes on maps. On a map showing a slope angle of 27°, for every 100 metres measured on the map, the distance on the ground is actually 112 metres. Over a distance of 500 metres this discrepancy is significant and has to be taken into consideration. A credit card-sized calculator for measuring the slope angle on 1:25,000 and 1:50,000 maps, and calculating the extra distance, can be obtained from

I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S.Eliot

Maps / Public right of way symbol on OS Explorer maps
« on: October 14, 2014, 01:21:40 PM »
I'd like to know the exact width of the symbol for public rights of way on Ordnance Survey 1:25,000 maps. Unfortunately, my eyesight is so poor these days (operation for cataract scheduled for next week) that I can't measure it accurately myself. I could ask the staff of the OS but I question them about so many matters that I don't want to overburden them.


This is a copy of  a post on the website of the Charles Close Society for the Study of Ordnance Survey maps. Richard Oliver of Exeter University is generally recognized to be the leading authority on OS maps.

The following has been sent out by Ordnance Survey. In its original form the e-mail includes an attached document, with illustrations, explaining about grids and datums, which would be difficult to forward, and from which I have extracted the following important passage:

"To support the increasing usage of GPS devices, OS are considering options that could help bring digital navigation devices and paper maps closer together and work more in harmony. Such an option could be the changing of the overlay on paper maps from Airy 1830 to WGS84.

It’s important for us to stress that this is NOT a change in the base map datum or the National Grid, which remains the Transverse Mercator Projection on the Airy 1830 ellipsoid, but it would result in a change in the datum of the latitude/longitude overlay only, adjusting where the latitude/longitude markers fall on the OS paper maps. For OS Landranger Maps, this movement may be as little as 2mm."

The e-mail originating from OS is as follows:


Proposed changes to the depiction of latitude and longitude representation on paper maps – tell us your thoughts

Ordnance Survey GB is considering changing the overlay showing latitude and longitude markers on Ordnance Survey paper maps. This would mean moving towards the overlay showing latitude and longitude used on GPS devices, to help bring digital navigation devices and paper maps closer together and work more in harmony. We believe this would have little impact on the majority of users of our paper maps; however, we would like your opinions on this change to ensure we fully consider all options and impacts before we make a final decision.
We’d like you to read the information below, and, if you would like to share your thoughts on how this would affect you, complete our short survey by Friday 3 October.
or respond directly to the Ordnance Survey product manager:
Please reply to our Product Manager:
Nicola Johnson
Product Manager - Consumer
Ordnance Survey
L1F3, Explorer House
Adanac Drive
SO16 0AS
Tel:         023 8005 5514
Mob:    07825 024176<>

The slight shift in L & L in the margin and on the map face will no doubt be a little irritating for those of us who like visual consistency, but the proposal does not affect the National Grid - a most important consideration for those of us who have large archives of NG references, which would require conversion were WGS84 to be adopted as the basis of the grid. Indeed, I believe that OS did toy with changing the grid to WGS84 about 20 years ago, but took it no further.

Richard Oliver


I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S. Eliot

General Discussion / Preventing water bottles freezing in winter
« on: August 05, 2014, 04:29:12 PM »
It is well-known that water in a water bottle buried in snow does not freeze. Why should this be?

I'm aware that the temperature of water cannot be raised above 100°C in normal atmospheric conditions. Is it the case that the temperature of snow cannot be lowered below 0°C in normal atmospheric conditions, irrespective of the air temperature? And because snow is a good insulator, is that the reason why the water in the bottle will not freeze?

Just idle curiosity...


Satnav (GPS GLONASS COMPASS Galileo) / GNSS signal multipathing
« on: July 28, 2014, 07:58:09 AM »
I've just returned form a three-day backpacking trip during which I explored Savernake Forest near Marlborough in Wiltshire. (For the benefit of our overseas members I should explain that an English forest, unless a plantation of conifers, does not usually have a dense tree canopy and there are numerous small open glades of grass.

I believe that, with the exception of mountain navigation in poor visibility, woodland poses the most difficult map-reading problems especially when contours are few and far between, so I was taking the opportunity of honing my map-reading skills. I came across a thoughtfully placed picnic table on the edge of a glade and decided to take a break. I knew exactly where I was on the map but switched on my Foretrex to record the location for future reference. I was looking at the map and realized that the location indicated on the satnav was at variance by a considerable margin from my estimated position. I could not believe that I had been so careless but could not work out where I had gone wrong.

Then light suddenly dawned; could it be my first experience of signal multipath? So I moved a few metres into the open glade and tried again and an entirely different grid reference appeared on the screen. I then returned to the picnic table, tried again and the correct location appeared. So the first grid reference was a multipath error and by the time I made the second attempt I imagine that the satellites had moved on and the signal was no longer bouncing off a tree.

I was aware of the possibility of satnav error caused by signal multipath but there is nothing like experiencing it to ram the message home!


I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S. Eliot

General Discussion / Fraudulent emails
« on: July 13, 2014, 06:30:55 AM »
I have been subjected to a phishing attack and at least one member of another forum has received a scam email purporting to come from me.


 Hugh Westacott

General Discussion / Dogs and some of their irresponsible owners
« on: July 07, 2014, 09:27:28 AM »
At the risk of of upsetting some of the responsible dog-owners on this forum, I have to admit to a great aversion to all dogs. I find too many of them to be smelly, ill-behaved, noisy, threatening, unhygienic and altogether unpleasant. I can see the value of working dogs for herding, search and rescue, and for the blind, but why anyone would want one in their home is beyond me.

Last Saturday I walked eight miles on the borders of Wiltshire and Dorset and had three unpleasant encounters with dogs:
1   I was walking across a field and saw a middle-aged couple with two dogs coming towards me. The dogs ran to me jumping up and licking my legs. I asked their owners to call them off, which they did, and assured me that ’They were only being friendly’ to which I replied that all my friends are human and none of the jump all over, me, sniff my private parts or cover my legs with disgusting slobber. They walked off in a huff.

2   I walked past a house on a bridleway and a very tall dog came out of an open gate and followed me for at least a hundred metres barking furiously. I was frightened and felt that I was in serious danger of attack.

3   I climbed a stile leading into a paddock and two dogs, one wearing a muzzle, rushed towards me and tried to jump up at me whilst I was standing on the step. Their owner saw what was happening but at first took no action even when I asked him to call them off. Eventually he did and as I passed him I heard him say in a singsong voice ‘That silly, nasty man doesn’t like you does he?’

Could someone explain why so many dog-owners seem to think that everyone loves dogs and welcomes their attentions? If I encountered a couple of strangers, danced round them, ran my hands over them, and licked them, I should be arrested for assault, but some dog-owners seem to think that such behaviour is acceptable in their pets

If a dog really is a man’s (or a woman's) best friend, then I can only feel sorry their impoverished emotional lives.

I’m considering getting a humane dog repeller such as [url]]. Does anyone have any practical experience of using such a device?


I grow old…I grow old, I shall wear the bottom of my trousers rolled. T.S. Eliot


General Discussion / Notification of posts
« on: June 28, 2014, 07:30:14 AM »

It is the nature of specialized forums like this one that posts are relatively infrequent which means that members often check fruitlessly. Would it be possible for an automatic notification be sent to all members whenever a new post appears?


I grow old...I grow old, I shall wear the bottom of my trousers rolled. T.S. Eliot.

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