Wednesday, 30 January 2013

Something to do with a GPS receiver - Geocaching

A GPS receiver can identify your position within a metre or so. So what do we do with this? Invent a new game called Geocaching. Geocaching involves finding a small container concealed in the middle of nowhere and recording the fact that you have found it. Fun? It is rather, particularly when trying to find the container when one arrives (roughly) at the right place. There are millions of Geocaches concealed round the world. will identify ones near a postcode or lat/log reference. There are 50 caches (yes, 50) within 2 miles of Little Hampden! 

Here’s a map of the caches round Great Hampden

Tuesday, 29 January 2013

Transistors - and Moore's Law

Back to science and engineering after a diversion to use of English yesterday – that’s a hostage to fortune so I’d better check this entry carefully!

Looking at GPS reminded me of the underlying technology and how that has changed. I can remember making radios with Red Spot transistors back in the ’50s. These were the first semiconductor devices available to hobbyists. They cost 10 shillings (50p) but that was a lot of money back then. Transistors were used as elements of construction – the original Transistor Radios had these soldered onto the circuit boards. I made one in the early sixties.

The Sixties brought the concept of integrated circuits where complete units – amplifiers or logic gates – were fabricated on a single integrated silicon chip. I can remember using nand gates which had four logic circuits built into a single unit. 

That was the start of an amazing escalation of components on a single chip. My mobile phone probably has nearly one billion (1,000,000,000) transistors! Moore’s law states that the transistor count in circuits doubles every two years. There’s a graph and list of transistor counts in various circuits on the Wikipedia page here.

Political content-free evasive English

Start the Week this morning was all about political writing referencing George Orwell’s essay ‘Politics and the English Language.’ I’m always amused – and sometimes frustrated – by the evasive language used particularly by politicians. I guess they are always afraid of having something quoted back at them later when things haven’t quite turned out as expected. So they duck the issue. Often the statements are process only – content-free. “We’ll learn the lessons and take these forward in a robust response” – what is actually going to happen?

I used to laugh at – and then try to fix – statements in Young Enterprise annual reports. We often had sections like this:

“We had a brainstorming session to think of ideas for products and services. We eliminated suggestions that we thought were impractical or unlikely to be successful. We created a short list and voted on the items” 

Good stuff – but what were the rejected ideas (or at least some of them)? What were on the short list? What criteria were used to decide? What was finally decided? 

Another pet annoyance of mine is neutral words. “Outcome” is one and “robust” another. They both sound positive (perhaps they sound robust) but they cover a range of possibilities. The use of “outcome” in the context of a medical intervention is OK but it is much weaker than “objective” or “achievement” which give some sense of direction.  There was a wonderful interview a while ago about a new appointment by the Cabinet Office: the holder of the appointment spoke excitedly and enthusiastically about the new role – but in all the answers there was nothing about what she was actually going to do!

Some advertisements are only a little better: the Trade Description Acts have made commercial organisations much more cautious – no more “Guinness is good for you”!  Just look out for the ads that don’t really mean anything. Coke is “the real thing” a TV ad I’ve just heard “reduces the appearance of wrinkles”

Orwell in his essay rewrites a section from Ecclesiastes:

I returned and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all.

Here’s his version rewritten in the then modern language:

Objective considerations of contemporary phenomena compel the conclusion that success or failure in competitive activities exhibits no tendency to be commensurate with innate capacity, but that a considerable element of the unpredictable must invariably be taken into account.

You can read the full essay here.

Sunday, 27 January 2013

Navigation – sextant and GPS

There was a man on the radio this week talking about his sextant – which was over 100 years old when he bought it some time ago. This was the only navigation instrument available to sailors for over a century. When searching for info for this entry I found a reference to Robin Knox Johnson’s circumnavigation of the globe 44 years ago – he had no radio, a barometer from a pub and a sextant. How things have changed! GPS, now on most mobile phones can locate your position to within a metre or so.

Sextants rely on the knowing the exact time to calculate the position in fact the British admiralty sponsored the development of the first accurate timepiece that could go to sea – pendulum clocks aren’t much use in a seaway! The balance wheel was the solution to this problem.

GPS rely on timing, too, but rather more precisely that a maritime chronometer. The basis for GPS is a series of satellites that orbit the earth – not in synchronous orbits like communications satellites – but with a period of just under 12 hours. These are equipped with extremely accurate atomic clocks. A GPS receiver will receive signals from at least four satellites and will calculate the distance from each based on the time take for the signal to reach the receiver from the satellite. It then calculates the position based on a mathematical principle called trilateration. This involved calculating the intersecton of the four or more spheres that are defined by the timings. Thinking of this in 3 dimensions is quite tricky (I always have to get an orange out when I try to think of the geometry of the earth!) In two dimensions, it’s a little simpler: here’s a local example. Suppose I’m 2.81 miles from Gt Missenden, 2.59 miles from Wendover and 3.33 miles from Princes Risborough. The first distance gives me a circle. 

The second ties the position down to two possible points

The third fixes me at Little Hampden

Now try to imagine this in three dimensions – intersections of spheres. The calculation to achieve a position is pretty complicated. GPS devices can also calculate the position in a number of formats including the GB OS grid reference. I’ve put a map on the waymark outside outside our house with a grid reference read from my GPS. Lots of walkers stop to look – but I’m not sure if the reference means anything to many of them!

Thursday, 17 January 2013

Amaryllis - flower or superyacht?

When looking at the Solent AIS display for Saturday’s blog, I noticed that the “Amaryllis” was moored at Gunwharf Keys, Portsmouth. We had seen this vessel moored in the Solent on one of our sails last summer. It is a large superyacht: we have an acronym for these in our family: FGP but this is really over the top. It’s available for charter – it has 6 cabins so can take 12 guests. I think it comes with a full crew of 23 and has five tenders including a Graf Ipanema wooden tender – quoted at $550,000 somewhere on the web. Charter rate? Starts at €770,000 per week. 

We also have an amaryllis at home – on our kitchen windowsill. Not quite the same league, although this has shot up at an alarming rate: the second flower which is half way up the stem in these pictures grew 1¾ inches in two days!

Oh, FGP? Floating Gin Palace

Wednesday, 16 January 2013

Snow, frost and some strange thawing

Winter has arrived at Little Hampden. Some wonderful frost this morning:

Monday’s snow had thawed in a rather strange way yesterday. We have a small square of concrete in the lawn – it’s where the clothes dryer plugs in. The snow above this had thawed completely:

Also the snow on the concrete parking area had virtually thawed but on the expansion joint between the two slabs, there was still snow. This joint has a small area of earth and moss – no more than one inch across:

I’ve been trying to work out why this has happened – but I’m having problems. If the ground – earth, grass and concrete – had all been cooled to about the same temperature before the snow fell – a reasonable assumption, I think – then the heat transfer to the snow would depend on the available heat in the material – concrete or earth. I don’t know the specific heat of the various materials but water is typically five to ten times larger than solids. This is why freezer bags – things one freezes then uses to keep things cold when there is no fridge – are filled with liquid rather than being solid. So the grass and earth in the lawn around the square, and the earth and moss between the concrete parking slabs would have more heat to give up to the snow, causing the snow above these to thaw more than that over the concrete. But the opposite actually happened. So what is the explanation?

Saturday, 12 January 2013

Technology that shows shipping movements – AIS

Writing about the Aaron Manby crossing the channel last week reminded me about another crossing I actually witnessed. I was in the cross-channel ferry last year following our crossing and other vessels we could see on AIS – Automatic Identification System. This system is designed to show a ship any vessels in its vicinity with speed and direction as an aid to avoiding collisions. However, there are several web sites, run by enthusiasts, that show the positions of ships. These rely on shore-based receiving stations so don’t give 100% coverage. However, the results are pretty good.

AIS operates by transmitting via a dedicated VHF radio the position of the vessel, taken from a GPS receiver, together with speed, direction and other information such as destination and call signal. On busy shipping lanes, this must be a big benefit.

While I was drafting this entry, I was watching the port of Calais on one of the web sites – there are links below. There was a pilot vessel heading out of Calais. It eventually met up with a chemical tanker, Christine, presumably to put a pilot on board. The Christine then headed for Calais, avoiding the ferry Pride of Kent which was sailing for Dover. Here are the images I captured of the movements.

You can see this slideshow larger here

The crossing I actually saw from the ferry last year was a team rowing across the channel. I first spotted on AIS a pleasure vessel that was clearly going to pass very close to us. When we eventually got within range, I could see the power boat but also a rowing boat nearby – the power boat was escorting the rowers. Whe I got home I looked up the boat – the Sea Satin – on the web and found a very interesting web site – this boat and several others offer to escort people rowing or swimming across the channel – and even rowing from London to Paris. You can see the web site here.

Here are some web sites on which you can watch live shipping movements around the UK. – this covers most of the UK and also allows you to find any ships about which it has info. Sea Satin is moored at Ramsgate tonight! shows shipping around the Isle of Wight. This shows on a Google map so can be zoomed and panned.

Saturday, 5 January 2013

The First Iron Ship

Researching the Horseley Iron Works for the canal bridges, I discovered that they were responsible for one of the first ships with an iron hull. Named after the owner of the works, the Aaron Manby was designed by Charles, later Admiral Napier. He took the design to Manby at the works – at Tipton in the Black Country. As one reference says, it’s difficult to think of anywhere further from the sea. Anyway, the ship was built in Tipton, then dismantled and transported to Rotherhithe on the Thames where it was reassembled and had engines fitted. After successful trials in 1822, the Aaron Manby sailed to Le Havre under the command of Napier. This trip seems to have been the first sea voyage ever of a vessel with an iron hull. The Aaron Manby sailed on the Seine for 10 years. 

The Aaron Manby when operating on the Seine

Napier went on to build several more steamships but his venture was not commercially viable: it went bankrupt in 1827. His naval career was more successful however.

Incidentally, one of the places in the UK that I’ve heard claims to be the furthest from the sea is Amersham. However, Guardian readers don’t agree – in fact they don’t agree that any place holds this prize -,5753,-63924,00.html

Thursday, 3 January 2013

Cast iron bridges

After yesterday’s high-tech achievement, let’s look at something which in its day was equally advanced: the wonderful Horseley cast iron bridges on the canals. These occur in many places – either as simple bridges spanning the canal – often at junctions where a brick bridge would be difficult – or more elaborate constructions. Here are some examples.

A Horseley Bridge on the Birmingham Canals

The date of the bridge
Another Horseley bridge over a branch near Rugby
One of a pair of bridges over the junction at Braunston

There are two more substantial and beautiful bridges on the Birmingham Canal system. One is actually an aqueduct taking a branch from the upper or old main line across Telford’s new main line.

The Engine House bridge

The other is the Galton Bridge, designed by Telford and cast by Horseley which used to take the road across the canal. This listed building is now only used by pedestrians

Galton Brdge

Wednesday, 2 January 2013

Fibre optics network... along the canals!

Who owns a strip of land that runs all the way from London through Birmingham to Manchester? Why, the Canal and River Trust does (this is what was British Waterways is now called) They own the towpath (and the waterway, of course) and they took advantage of this ten years or so ago when they installed a fibre optic network along the major routes, thus providing a high-tech high-speed network. This network is used today by many carriers.

I found it difficult to locate any detailed information about this network until I found a detailed map – you can see it here. If you are familiar with the routes of the Grand Union canal from London to Birmingham, you’ll recognise it on this map. Altogether there is over 650km of fibre optics are buried along the towpaths. This is on a rather different scale from yesterday nanophotonics but the technology is substantially the same!

Tuesday, 1 January 2013

Now for something completely different

After a month of poems, I’m going to switch to science and engineering again – but I’ll try to be a little more regular than last autumn. 

Two things have triggered this. Firstly, I did some practice interviews at The Misbourne in December. The students were in their GCSE year and were looking at opportunities for further education. Some were hoping to continue in school to do A-levels, others were looking at colleges. One of the questions I asked the students was “what is your favourite subject?” Rather surprisingly (perhaps) a large proportion answered “Maths”! Wow isn't that great? I think they have a new inspirational Maths teacher – just shows what good teaching does. At least one of my interviewees was thinking about engineering as a career.

The other prompt is an announcement from my old company: IBM Research has announced that they have developed Silicon Integrated Nanophotonics technology to the stage that these chips can be manufactured by the standard semiconductor fabrication methods. Nanophotonics is basically using optical transmission of signals (like fibre optics) within and between integrated circuit elements. As with long-distance communications, where fibre optics have transformed reliability and speed of connections, this technology is faster and more reliable than electrical connections. Incidentally, on the former, have you noticed that the delays in transatlantic and similar long-distance communications, which were a regular occurrence in radio and TV interviews a few years ago, have now virtually disappeared? The delays were caused by transmission times using geosynchronous orbit satellites. Presumably these links now use fibre optic cables.

Cross-sectional view of an IBM Silicon Nanophotonics chip combining optical and electrical circuits

The nanophotonics connections allow a data rate that exceeds 25Gbps – that’s 10,000 times faster than our broadband connection here in Little Hampden. The other big advantage of fibre optics – and of nanophotonics – is that a single connection can carry multiple signals by using different wavelengths to carry each one. I don’t think we’ll be seeing these chips on our PCs or tablets – but who knows? Technology is always advancing at an increasing rate.

There’s more information on the IBM web site – click here.