First Meninos do Morimbi - Oldham gig

Today I played my first Samba gig with the Oldham branch of Meninos do Morumbi, as part of this year's Oldham Carnival. Meninos are a Brazilian group from São Paulo in Brazil, and at the moment three of their teachers, Eraldo, Sivuca and Adriana are over in the UK teaching a group in Oldham, set up by Leon and Ian, that I've been going to since the beginning of the year. Meninos do Morumbi in Brazil is a quite remarkable organization. Set up by Flavio Pimenta it 1996, it provides training in Samba and other styles of music to 4,000 kids between the ages of 7 and 18 in São Paulo, as well as a wide range of other activities. The association is largely run by the kids themselves, and provides over 1,000 meals a day for the kids, for example.

As well as switching bands I've also switched from playing Surdo (and hiding at the back of the group) to playing Tamborim (and being on display at the very front!), and I don't mind admitting it's proving to be a real stretch for me. Not only is the Tamborim played fast, it also has some fiendishly long and complicated patterns, plus we have to move around doing some dance steps and play the instrument everywhere from down by our knees to up over our heads - as we are at the front and have the smallest and lightest instruments we have to provide a bit of visual spectacle as well as volume ;-) It's taking me a while to get the hang of it, but I'm really enjoying the challenge. Anyway, here are a couple of photos of us playing in Oldham town centre - I'm second from the left in the red top.

Drummers Drummers

We are playing again tomorrow in Oldham - first taking part in a parade and later on we will be playing a set on our own. It should be a good day, as long as the weather stays fine! If anyone fancies having a go themselves, it's a really friendly crowd and everyone is welcome, especially kids - my youngest son Mark (8) has started going, as well as James, and there are lots of other kids there too. Not only is there percussion training, there's also dance, and best of all it is completely free! Rehearsals are at every Monday at 6:15pm in The Gallery in Oldham, next to Sainsbury's.

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Categories : Drumming

All you ever wanted to know about geodesy

If you've ever wondered what the difference between a coordinate system and a datum is, or what the difference between OSGB36 and WGS84 is, or what is the relationship between the ellipsoid and the geoid, or even what is the difference between a TRS and a TRF, then I recommend the excellent Ordnance Survey paper A guide to coordinate systems in Great Britain. It's an extremely well written explanation from first principles of the underpinnings of GPS - the coordinate and reference systems which are used to locate a point on the planet. Although the title suggests it is UK-centric, much of it is in fact globally applicable.

Categories : Peak District

Getting accurate height datums

My Garmin eTrex Summit has a built-in altimeter, and although it can auto-calibrate from the GPS fix, it isn't that accurate and it takes a while to do. The Ordnance Survey have been gradually removing the spot height and benchmark information from the 1:25,000 maps as mostly they aren't used for surveying any more. Both trig points and benchmarks need 'maintaining' by being resurveyed at intervals as they are subject to ground movement, so it is understandable that the OS isn't bothering if they don't use them any more. However they are still good enough for calibrating an altimeter which isn't accurate to less than a metre anyway, the problem is actually finding the information! I was browsing around the web looking for something else entirely and I found that The Planning Inspectorate provides a map facility that allows you to drill down on th the OS MasterMap maps which still have the height information on them. Go here and click on the "Select a Point" or "Select an Area" icons and keep drilling down to you see the individual property boundaries on the map. From that point on you will be able to see all the spot height and benchmark data, to the nearest centimetre, and there are a lot of them, so you should be able to find a convenient one to use for calibrating.

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Categories : Tech

Yet another eTrex Summit

As I documented at length earlier, I bought a Garmin eTrex Summit in October of last year, and had no end of problems with it powering itself off for no apparent reason. Garmin replaced it (twice) and the third unit was OK-ish but still tended to turn itself off occasionally. After an email exchange with Garmin I said I'd try to track down exactly what the problem was. I persevered, and the clincher was when I turned on the inbuilt magnetic compass and the unit immediately turned off - a fresh set of batteries, no low battery warning, it just turned off. Once this had happened a couple of times I felt I had enough information to send a detailed report to Garmin. I'd expected to be told it was a fimware issue and that I'd have to wait for a fix, but I was pleasantly surprised to be told that they were just releasing a new version of the Summit and that they would send me one. I was even more surprised when it turned up a day later! It appears that I've been sent a pre-release unit, as it has features that aren't mentioned yet on the Garmin product page for the Summit. It turns out that Garmin have made a whole bunch of improvements:

  • The biggest change is the addition of support for WAAS (USA) / EGNOS (Europe). This is a satellite-based differential GPS system - basically a network of accurately surveyed ground stations watch the GPS signals, calculate the difference from where the signals says they are and where they really are, send the correction back up to some other satellites which then rebroadcast it so that WAAS/EGNOS-enabled GPS units can use the correction to improve their accuracy. At the moment the European system isn't fully deployed, but when it is it should give a 10x improvement in accuracy - indications are that the accuracy will be around 1 metre.
  • New 'Trip Computer' page which allows you to select 5 fields from a list of 31 to display. The list is very comprehensive - just about every parameter I can think of is covered.
  • When navigating to a waypoint the map page can display a line from where you are now to the destination (as per the older model) or a line from your starting point to the destination. This is the way the GPS12XL works, and it's much more useful as it allows you to easily see if you are wandering left or right from your course.
  • The compass can be turned off as well as on by holding down the PAGE button - on the older model you could only turn it on.
  • The track log can be turned off, and the point collection mode can be set to one of three modes:
    • 'Auto' which has 5 different resolution settings.
    • 'Distance' which allows you to specify the distance between sucessive points.
    • 'Time' which allows you to specify the time between sucessive points.
  • More internal memory, which means the following changes:
    • Waypoints per route up from 50 to 125.
    • Track log points up from 3,000 to 10,000.
    • Points on saved tracks up from 500 per track to 750.
  • The fairly useless Hunt/Fish page found on some of the other eTrex models is now available.
There are a few other minor changes - you can view pressure in hPascals, and they've modified the 'Units' setup screen so that if you select 'British Grid' as the position format you can only have 'Ord Survy GB' as the datum - a common mistake that people make is to set the position format but not select the correct datum, which causes all grid references to be several hundred metres out. The one thing they haven't fixed is that you still can't move an existing waypoint to your current position - this was a very useful feature on the GPS12XL - when EGNOS is deployed I expect to find that many of my waypoints will be inaccurate, and there is no easy way to correct them other than reentering them.

Overall Garmin have made an already impressive and useful GPS even better, and despite my best efforts I haven't managed to get the new one to power itself off, so it looks like they've fixed that problem too. Yay Garmin!

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Categories : Tech

Spooky game

The old game of 20 Questions, also known as "Animal, Vegetable or Mineral" was always a favourite way of passing long car journeys when I was a kid, and my kids in turn play it, although rather than being in the car it's usually whilst waiting for food to arrive in a pub or restaurant. Josh Simons points to an online version where the computer guesses and you provide the answers, and it's pretty spooky. Sometimes you can see the chain of questions zeroing in on the answer, but quite often it asks a series of seemingly random questions before startling you with the correct guess. Needless to say there is a neural net behind it which learns from previous sessions. Seemingly the online version has been around since 1995, so I'm not quite sure how I missed it. Kevin Kelly provides a history of the program, and what is really neat is you can buy a tennis-ball sized version for less than a tenner - I'm sorely tempted!

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Categories : Personal, Tech

The Snake and the Somme

I hadn't been back along the footpath through Snake Woodland, which had been badly damaged by floods in 2002 for over a year, but this evening I went back with the family for a walk, thinking it must have been fixed up by now. How wrong could I be, it's even worse:

Snake woodland

Apologies for the poor quality of the photo, but it was so dark and gloomy under the trees that's the best I could do. Now I don't expect there to be no muddy patches at all, but this is a wayposted path close to a main road, so it's reasonable to expect that not all visitors are going to be equipped to deal with conditions more akin to those of the trenches of the Somme. Apart from a few desultory patches of gravel that have been put down near the entrance, virtually nothing has been done to the path, despite it being three years since the floods. What's even worse is that there is no clear signage at the entrance that the bridge across Lady Clough is still in severe danger of collapsing into the river, and you are 30 minutes round the walk before you get to the bridge.

Snake woodland

The sign is rather amusing:

Warning Foot-path closed
Bridge due for repair

It's a miracle it is still standing - "due for repair" when? Forestry Commission, this is unforgivable - as it is now three years after the damage there really is no excuse for the repairs not being completed. Bah.

Categories : Peak District

Mount Skip stamp

Letterbox stamp

As I was googling around to find the information for my last post on Bob and Len's letterbox, I noticed that all the sites mentioned something along these lines:

These boxes normally contain a visitors' book and a rubber stamp. On finding the box, hunters use the stamp to record the find in their own books or on a series of cards, and then mark the visitors' book in the box with their own personal stamps.

There are many letterboxes placed on Dartmoor, the majority of which are hard to find. Collecting letterbox stamp impressions is an enjoyable and challenging pastime.

Bob and Len's box is sadly lacking in the rubber stamp department, so I set about making one. There are bazillions of references on the web on how to do this, the basic technique is to carve a plastic pencil eraser with the design of your choice. I'm not particularly artistic so I decided a simple place name would be the best - the letterbox isn't particularly near anywhere, so I chose 'Mount Skip' as it is reasonably close, and it has the fewest letters to carve ;-) The easiest way to do the design is to edit it on a PC, then print it on a laserprinter, or photocopy it. You then put the paper face down on an eraser and with a cool iron, press the paper for a few seconds. Let it go cold, and gently peel the paper off - hey presto! the toner has transferred to the eraser. You then set about hacking away everything but the design from the eraser - in my case 'hack' was the operative word! I used a scalpel, and a set of jewellers screwdrivers for small details, e.g. the center of the 'o' and the 'p' - you can twizzle them around and drill out small details - you can see the final result above. I carved a cavity the size of the eraser into a bit of wood and glued the eraser in to make it easier to hold and to give it a bit of protection - it's my first effort so I'm not sure how robust it will be, but I can easily make another. If I was doing this on a regular basis I'd certainly consider get hold of a stand-mounted magnifying glass and some linoleum cutters, which seems to be the standard recommended toolkit for eraser carving.

I popped up to the letterbox this afternoon and put the stamp in the box, so I'm now eagerly awaiting the first visitor to use it - if it's you add a comment below to let me know!

Categories : Peak District

Bob and Len's Dark Peak letter box

Ages ago, Bob asked me to put some information on my blog about his and Len's letterbox and I've been very laggardly in doing so - sorry Bob! By letterbox I don't mean one of these or even one of these! For those of you who are now thoroughly confused, letterboxing started on Dartmoor in 1854, and involves hiding a box containing a logbook somewhere (moderately!) accessible and challenging people to find it. There's a far newer form of this activity called geocaching that gives you a GPS coordinate to walk to, which is quite a bit easier to do, whereas letterboxing requires a fair degree of navigational expertise.

Bob's letterbox is on Mount Skip in the Dark Peak, and I've reproduced his map below:

Letterbox map

And here are his instructions:

  • Map: The Peak District Outdoor Leisure Map No. 1. Scale: 1:25000.
  • Bearings: All bearings are magnetic.
  • Area: Rough moorland and should only be attempted by experienced hill walkers.
  • Letter Box: Maintained by Bob and Len. Please leave the box covered as in photo, thank you.
  • Clue: A small isolated peat hag.

The photos referred to above are these ones below:

letterbox letterbox

And if you are wondering what Bob and Len look like, you'll have to visit their letterbox to find out, there's a photo of the dodgy duo inside ;-)

Categories : Peak District, Friends

Useful directory of online maps for the UK

While I was looking for the format of links to the OS GetAMap service for my last post I came across this useful list of online maps for the UK, which it seems has been lifted straight from Wikipedia - why they didn't just link to the Wikipedia page I have no idea. I particularly liked the content of the Magic website, which as Wikipedia says "is a web-based interactive map intended to bring together information on key environmental schemes and designations in one place", although the presentation is a bit clunky when compared to something as slick as Google maps, although Google in turn suffers from not being based on the OS mapping, so it's pretty useless outside of urban areas.

And by the way, if you do want to link to somewhere on the OS's GetAMap service, the format of the URL is
http://getamap.ordnancesurvey.co.uk/getamap/frames.htm?mapAction=gaz&gazName=g&gazString=
with the normal OS grid reference appended onto it, e.g. http://getamap.ordnancesurvey.co.uk/getamap/frames.htm?mapAction=gaz&gazName=g&gazString=TQ302795

Categories : Peak District