I was reading about the Thanet offshore windfarm, the largest in the UK and read one of those classic unhelpful statements, "The Thanet offshore wind farm will create enough renewable energy to power 240,000 homes."
The problem with that statement is it doesn't say 1) Whether this takes into account the fact that wind turbines might only run at about 10% installed capacity (a 2GW turbine only produces an average 200MW over a year) 2) Whether it is the best case scenario i.e. at 100% of operating output (I doubt it, that wouldn't sound very impressive) and 3) what other allowances it might take into account such as the number of turbines that might be disabled for maintenance at any one point.
The sad fact is 240,000 homes is not a great number, it is only a 3rd of Kent's homes (assuming they are 'average' in size) and bearing in mind that, particularly in winter, the farm could produce nothing for days at a time, the 40 year lifespan and the £780M cost, it is hard to determine whether this is really value for money.
Sadly these things all sound great, they are "renewable" but we must look beyond the warm feeling we get by not burning fuel and consider the inconvenience of variable output electrical plants and work out the real economics. I for one would not like to see electricity increase by 10 times the price just to pay for these "green" energies when compared to other methods.
Thursday 23 September 2010
Wednesday 15 September 2010
The weakness with statistics
I was wondering the other day whether statistics have any real value other than providing points of arguing. For instance you could claim that the government should invest more in X than Y since your survey says that twice as many people like X than Y, case proven! I have already blogged about the problem with the lack of ability to say "no" in surveys. In the example of the Olympics, saying that 500,000 people signed a petition asking for the Olympics is impressive unless you have the chance to report that 45 million didn't want it.
Another thing that has come up recently however is the weakness of survey questions. An article I read on the BBC news site was talking about how the "don't knows" might not be people who don't care as much as people who can't answer the question because they are not sure quite what it means.
Consider the question, "Do you regard yourself as belonging to any particular religion?" (taken from the National Centre for Social Research). A typical type of survey question whose data will end up somewhere important. But the answer is not necessarily straight-forward. If you are an atheist, the answer is simple, if you are Muslim or even Catholic, the answer is probably also straight-forward. But think about a bog-standard Christian. Firstly I don't call my faith a religion because religion to me is not synonymous with faith and is not what I practice (even though I call myself a Christian). Also, even if I do consider my Christianity a religion or understand that the question probably does not make the distinction that I do, do I belong to a particular religion? How particular? I am a Christian but do not call myself Anglican or Evangelical so should I answer "No" because I am not particular?
The problem for statistics involving large numbers of people is that if 30% of Christians say, "No" to the above question, the figures might suggest that the number of Christians is only 70% of the actual figure and then this figure is used to derive all sorts of "scientific" conclusions.
No doubt some people are supposed to be experts in these things but I would suggest any self-respecting information expert reject attempting to make any conclusions based on questions that are hard to decipher or at least provide a box labelled, "I am not sure I understand the question" which allows us to distinguish "I don't care" from "I'm not sure".
Another thing that has come up recently however is the weakness of survey questions. An article I read on the BBC news site was talking about how the "don't knows" might not be people who don't care as much as people who can't answer the question because they are not sure quite what it means.
Consider the question, "Do you regard yourself as belonging to any particular religion?" (taken from the National Centre for Social Research). A typical type of survey question whose data will end up somewhere important. But the answer is not necessarily straight-forward. If you are an atheist, the answer is simple, if you are Muslim or even Catholic, the answer is probably also straight-forward. But think about a bog-standard Christian. Firstly I don't call my faith a religion because religion to me is not synonymous with faith and is not what I practice (even though I call myself a Christian). Also, even if I do consider my Christianity a religion or understand that the question probably does not make the distinction that I do, do I belong to a particular religion? How particular? I am a Christian but do not call myself Anglican or Evangelical so should I answer "No" because I am not particular?
The problem for statistics involving large numbers of people is that if 30% of Christians say, "No" to the above question, the figures might suggest that the number of Christians is only 70% of the actual figure and then this figure is used to derive all sorts of "scientific" conclusions.
No doubt some people are supposed to be experts in these things but I would suggest any self-respecting information expert reject attempting to make any conclusions based on questions that are hard to decipher or at least provide a box labelled, "I am not sure I understand the question" which allows us to distinguish "I don't care" from "I'm not sure".
Thursday 9 September 2010
Free Speech (or not)
I was reading about the US pastor who has organised a book burning of the Koran on September the 11th, "It is possibly time for us in a new way to actually stand up, confront terrorism". I really don't know whether his event could actually have any genuine benefit other than stirring up hatred but it certainly does raise interesting questions about free speech. Of course, it is not just his speech which will cause trouble but the excessive use of that 'freedom' to go into the realms of provocation but is this wrong?
What exactly is free-speech? In a sense we do not have free speech in the UK. I can be charged with "inciting racial hatred" and presumably various homophobic speech crimes which can be a very broad brush against my supposed "right" to express my own opinion.
The origins of the idea of free speech come from various political and religious attempts to silence dissenters under the legal system which would then prevent the intended operation of democracy where the voice of the population could be silenced by a miniority only because they happened to be in government.
I guess the question is, where does this freedom end and responsibility begin? It is all very well saying, "I think Islam is a terrorist religion" and leaving it at that but I guess this guy thinks unless he ups the ante, he won't get enough people to agree with him to do something about it (whatever that might be).
Look at Nelson Mandela. Back in the day he was accused of terrorism and inciting violence and hatred but his cause has only been redeemed over time and he presumably argued that he had no choice to change the system in any other way. I guess pastor Terry Jones thinks the same thing.
Will time show him to be correct or will he simply get silenced by those who preach tolerance and freedom as the tenets of civilisation on the one hand and yet avoiding conflict with anyone who might not agree!?
I guess I have that niggling conflict, "why does the pastor have to tolerate Islam but Muslims do not have to tolerate him"?
What exactly is free-speech? In a sense we do not have free speech in the UK. I can be charged with "inciting racial hatred" and presumably various homophobic speech crimes which can be a very broad brush against my supposed "right" to express my own opinion.
The origins of the idea of free speech come from various political and religious attempts to silence dissenters under the legal system which would then prevent the intended operation of democracy where the voice of the population could be silenced by a miniority only because they happened to be in government.
I guess the question is, where does this freedom end and responsibility begin? It is all very well saying, "I think Islam is a terrorist religion" and leaving it at that but I guess this guy thinks unless he ups the ante, he won't get enough people to agree with him to do something about it (whatever that might be).
Look at Nelson Mandela. Back in the day he was accused of terrorism and inciting violence and hatred but his cause has only been redeemed over time and he presumably argued that he had no choice to change the system in any other way. I guess pastor Terry Jones thinks the same thing.
Will time show him to be correct or will he simply get silenced by those who preach tolerance and freedom as the tenets of civilisation on the one hand and yet avoiding conflict with anyone who might not agree!?
I guess I have that niggling conflict, "why does the pastor have to tolerate Islam but Muslims do not have to tolerate him"?
Tuesday 7 September 2010
Noise Gates - Attack, hold and release
The most advanced settings on the gate relate to attack time, hold and release time. This affect the shape of the gates behaviour.
Let us take our example of a Tom Tom. When you strike it, the initial transient is quite high and then the Tom fades away for a time depending on the way it is tuned. This can sound very muddy through a PA system so the gate is often used to try and make the sound much more 'clicky' than it does by default. If however you simply set the threshold for the drum, you might find that the sound is made very short and transient and loses all its resonance since the sound quickly drops back below the threshold. By adjusting the hold time, you are telling the gate to stay open for a short time after the key drops below the threshold (usually micro or milliseconds) and then close. This gives you the basic functionality to allow a little bit of 'ring' from the drum before slamming the gate but then you might have a noticeable slamming of the gate which makes the drum cut off very abruptly and not very musically. What you can do to resolve that is to add a slight release time which slows the shutting of the gate.
The attack time is used less often and is like the opposite of release, it sets the time taken for the gate to fully open and would be used if the level of the sound is sometimes very close to the threshold of the gate and causes noticeable sudden gate opening and stuttering. By slowing the attack time of the gate, you allow more subtle variation but this would not generally be used on transient sounds like drums where you need the gate open as soon as possible to avoid cutting off the transient.
Let us take our example of a Tom Tom. When you strike it, the initial transient is quite high and then the Tom fades away for a time depending on the way it is tuned. This can sound very muddy through a PA system so the gate is often used to try and make the sound much more 'clicky' than it does by default. If however you simply set the threshold for the drum, you might find that the sound is made very short and transient and loses all its resonance since the sound quickly drops back below the threshold. By adjusting the hold time, you are telling the gate to stay open for a short time after the key drops below the threshold (usually micro or milliseconds) and then close. This gives you the basic functionality to allow a little bit of 'ring' from the drum before slamming the gate but then you might have a noticeable slamming of the gate which makes the drum cut off very abruptly and not very musically. What you can do to resolve that is to add a slight release time which slows the shutting of the gate.
The attack time is used less often and is like the opposite of release, it sets the time taken for the gate to fully open and would be used if the level of the sound is sometimes very close to the threshold of the gate and causes noticeable sudden gate opening and stuttering. By slowing the attack time of the gate, you allow more subtle variation but this would not generally be used on transient sounds like drums where you need the gate open as soon as possible to avoid cutting off the transient.
Noise Gates - Frequency control of the key
A common problem when using Gates is that the key signal might be picked up from another sound source and open the gate to the signal you are trying to control, basically this happens when a microphone is picking up something from more than one source unintentionally.
Imagine you are mic-ing up Toms on a drum kit, the chances are that the mic for Tom 1 can also 'hear' Tom 2. You setup a gate on Tom 1 to control the sound of it but when you hit Tom 2, the mic from Tom 1 hears it, opens the gate and allows all the ringing from Tom 1 to be heard unintentionally. You can EQ the channel but the Toms are usually so close in frequency that you can EQ out the unwanted sound of Tom 2.
On some gates, you have the ability to frequency control the key signal, either with a hi-pass and lo-pass filter or with a frequency selector and Q control.
It is important to realise, these settings do NOT alter the frequency of the audio signal, they simply filter the part of it being used to key the gate. By making this as narrow as possible, we can allow the key to respond only to the fundamental frequency of Tom 1 and not to anything overheard from Tom 2 (and likewise for any gates you might have on the other Toms).
You will need to either recognise the rough frequency of the Tom by ear and then use trial and error to set up the unit or you will need a frequency analyser to work it out. You should be able to keep the frequency very narrow since the fundamental frequency of a tom is narrow.
Imagine you are mic-ing up Toms on a drum kit, the chances are that the mic for Tom 1 can also 'hear' Tom 2. You setup a gate on Tom 1 to control the sound of it but when you hit Tom 2, the mic from Tom 1 hears it, opens the gate and allows all the ringing from Tom 1 to be heard unintentionally. You can EQ the channel but the Toms are usually so close in frequency that you can EQ out the unwanted sound of Tom 2.
On some gates, you have the ability to frequency control the key signal, either with a hi-pass and lo-pass filter or with a frequency selector and Q control.
It is important to realise, these settings do NOT alter the frequency of the audio signal, they simply filter the part of it being used to key the gate. By making this as narrow as possible, we can allow the key to respond only to the fundamental frequency of Tom 1 and not to anything overheard from Tom 2 (and likewise for any gates you might have on the other Toms).
You will need to either recognise the rough frequency of the Tom by ear and then use trial and error to set up the unit or you will need a frequency analyser to work it out. You should be able to keep the frequency very narrow since the fundamental frequency of a tom is narrow.
How to use Noise Gates
Noise Gates (or Gates as they are usually called) are pieces of outboard equipment used in PA systems that for some people are mysterious and complicated. I will post a series of articles about these pieces of kit and what they are used for.
Firstly, a gate behaves like it sounds. It electronically shuts a gate across the audio signal going through it so nothing is let through. When a 'key' signal operates the gate, it is opened to let the signal through and when the key is removed, the gate closes again and the signal removed. All of these are configurable to a certain extent depending on what unit you are using.
The key signal can be internal (derived from the audio signal itself) or it can be external (comes from whatever you plug into the back of the unit) but we will assume that all our keying is internal.
The threshold control says at what level the key signal will open the gate, so let us assume we have a Tom from a drum kit through a microphone plugged into our gate. Our gate is set to internal key and the threshold is set to -40db. Somebody hits the drum and very shortly after they hit it, the signal passes -40db and the gate is opened. After the hit, the drum sound fades away and after dropping past the -40db position, the gate is closed again and the remainder of the sound is cut off. This is the most basic operation of a gate.
Now we have looked at the operation, what do we use them for? The two most common uses of gates are 1) To shorten the sound of a ringing (usually) Tom Tom and 2) To remove latent noise on a channel (such as an electric guitar). We will look at the second example first because it is the most simple.
For many electric guitars, because of a love of old technology, valves and single coil pickups, lots of guitar rigs have excessive noise when the guitar is not being played. Left uncontrolled, it is at best annoying and at worst unprofessional. Add a gate into the channel and you can control the threshold at which this noise is removed by the gate. You might efectively tell the gate to remove anything below -40(ish) db so that when the guitarist actually plays, assuming they never play anything really quietly, the gate will open and when they stop, it will close again.
The same basic setup applies to the Tom Tom but there are problems that you might find with Tom Toms and even with guitars that require slightly more complicated setting up which I will cover in my next post.
Firstly, a gate behaves like it sounds. It electronically shuts a gate across the audio signal going through it so nothing is let through. When a 'key' signal operates the gate, it is opened to let the signal through and when the key is removed, the gate closes again and the signal removed. All of these are configurable to a certain extent depending on what unit you are using.
The key signal can be internal (derived from the audio signal itself) or it can be external (comes from whatever you plug into the back of the unit) but we will assume that all our keying is internal.
The threshold control says at what level the key signal will open the gate, so let us assume we have a Tom from a drum kit through a microphone plugged into our gate. Our gate is set to internal key and the threshold is set to -40db. Somebody hits the drum and very shortly after they hit it, the signal passes -40db and the gate is opened. After the hit, the drum sound fades away and after dropping past the -40db position, the gate is closed again and the remainder of the sound is cut off. This is the most basic operation of a gate.
Now we have looked at the operation, what do we use them for? The two most common uses of gates are 1) To shorten the sound of a ringing (usually) Tom Tom and 2) To remove latent noise on a channel (such as an electric guitar). We will look at the second example first because it is the most simple.
For many electric guitars, because of a love of old technology, valves and single coil pickups, lots of guitar rigs have excessive noise when the guitar is not being played. Left uncontrolled, it is at best annoying and at worst unprofessional. Add a gate into the channel and you can control the threshold at which this noise is removed by the gate. You might efectively tell the gate to remove anything below -40(ish) db so that when the guitarist actually plays, assuming they never play anything really quietly, the gate will open and when they stop, it will close again.
The same basic setup applies to the Tom Tom but there are problems that you might find with Tom Toms and even with guitars that require slightly more complicated setting up which I will cover in my next post.
What can God do through you?
I rarely post actual wisdom on this blog because my life is spent moaning about things but I was talking to a young lad last night who was saying how hard it can be to know whether things like the miraculous actually happen or whether it is just hype.
In a rare-ish moment of wisdom, I asked him, "if you want to know whether the miraculous can happen, what do you do in your life that allows Him to do the miraculous through you?" You can be helped by what God does through others, although sometimes you might not believe it to be true, but only when you experience it first-hand can you really have a faith increase. Sadly for many people, God is simply not given an opportunity for healing/wisdom/knowledge etc so if we disbelieve the miraculous in others, we are left with a very bland view of God in our lives.
What do you do to give God an opportunity to work through you?
In a rare-ish moment of wisdom, I asked him, "if you want to know whether the miraculous can happen, what do you do in your life that allows Him to do the miraculous through you?" You can be helped by what God does through others, although sometimes you might not believe it to be true, but only when you experience it first-hand can you really have a faith increase. Sadly for many people, God is simply not given an opportunity for healing/wisdom/knowledge etc so if we disbelieve the miraculous in others, we are left with a very bland view of God in our lives.
What do you do to give God an opportunity to work through you?
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