Things you always wanted to know the answer to [Vol. 3]
Discussion
wiggy001 said:
Lazadude said:
As a simple level, the main issue I'd think would be database key'ing and processing power to search/return.
Say they are sampling at 60Hz (1/60th of a second), for the 10 seconds it takes, that's 600 datapoints!
Times that by the amount of songs on there, according to Wikipedia, 15 billion as it includes TV and Radio advert links as well as remixes... that's 9 trillion data points if you just sample the 10 seconds..
Mind boggling.
A slightly less mind boggling Shazam fact is that, before smart phones and apps, you could use it by calling 2580 on a mobile. The company I worked for at the time had company mobiles that could use our short dial codes. My extension was 2580...Say they are sampling at 60Hz (1/60th of a second), for the 10 seconds it takes, that's 600 datapoints!
Times that by the amount of songs on there, according to Wikipedia, 15 billion as it includes TV and Radio advert links as well as remixes... that's 9 trillion data points if you just sample the 10 seconds..
Mind boggling.
Every Friday and Saturday night without fail I would get calls to my mobile and just hear music from some club or bar in the background, often from the same few partners. If I recognised the song I'd usually text them back with the details
glazbagun said:
Do Germans and French have caricatured ways of speaking like Brits like we do with Allo Allo or John Cleese in Fawlty Towers?
If so what do they sound like?
Here is a bit of classic French humour about speaking English.If so what do they sound like?
https://www.youtube.com/watch?v=J_9X8PVlfBE
The bit where they try to pronounce "the" is particularly true for a lot of french people.
A bit of a joke with my old French boss as he could never say "ztthe strooth" [the truth]
Dr Jekyll said:
When my sat nav gives an average speed, how long is it averaged over?
Surely there's no possible answer to that as it'll vary between sat navs and possibly settings.Are you talking about current speed being averaged over a couple of satellite polls to remove erroneous data or average speed camera zones or trip average speed?
Lazadude said:
Dr Jekyll said:
When my sat nav gives an average speed, how long is it averaged over?
Surely there's no possible answer to that as it'll vary between sat navs and possibly settings.Are you talking about current speed being averaged over a couple of satellite polls to remove erroneous data or average speed camera zones or trip average speed?
Dr Jekyll said:
Lazadude said:
Dr Jekyll said:
When my sat nav gives an average speed, how long is it averaged over?
Surely there's no possible answer to that as it'll vary between sat navs and possibly settings.Are you talking about current speed being averaged over a couple of satellite polls to remove erroneous data or average speed camera zones or trip average speed?
Whilst we're chatting about Sat-Navs and speed.
Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
P-Jay said:
Whilst we're chatting about Sat-Navs and speed.
Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
The speedo doesn't know the diameter of the wheel. Tyre pressures, tyre model differences and varying tread-depth means it's always going to be out by some degree.Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
P-Jay said:
Whilst we're chatting about Sat-Navs and speed.
Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
More information here plus there is a bit more detailed info on the GPS factors tab. You can find morebinfirmation by looking in more detail into specific bits of kit but it will need a trawl round VBox website.Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
Short version; at the sampling rate and accuracy of cheap gps receivers, such as those in phones and sat nav, using position and time as a basis for calculation unusable. Doppler shift is used. Sampling rates of once per second are insufficient and at least 20Hz is needed with up to 100Hz for decent analysis.
P-Jay said:
Whilst we're chatting about Sat-Navs and speed.
Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
European Union member states must also grant type approval to vehicles meeting similar EU standards. The ones covering speedometers[7][8][9] are similar to the UNECE regulation in that they specify that:Why does everyone I know 'know', with absolute certainty that the readout that actually connected to the wheels on the car, the speedometer is wrong, and the device that is trying to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
The GPS built into my phone can is pretty as being accurate to maybe 5m, but can be as bad as 20m - my Sat-Nav in my car get confused from time to time if there's a say a B-Road running near parallel with a motorway, yet we assume when it comes to speed it's a given that a sat-nav showing a 3mph difference is always right.
The indicated speed must never be less than the actual speed, i.e. it should not be possible to inadvertently speed because of an incorrect speedometer reading.
The indicated speed must not be more than 110 percent of the true speed plus 4 km/h at specified test speeds. For example, at 80 km/h, the indicated speed must be no more than 92 km/h.
The standards specify both the limits on accuracy and many of the details of how it should be measured during the approvals process, for example that the test measurements should be made (for most vehicles) at 40, 80 and 120 km/h, and at a particular ambient temperature and road surface. There are slight differences between the different standards, for example in the minimum accuracy of the equipment measuring the true speed of the vehicle.
So basically they Must all ways show a higher inficated speed but with a limit to to how high. So there is a general feeling that they over read by 10%
Is there a "maximum" brightness something can be? Say we take an empty room, and put a light in it, then 1000 lights more, does it keep getting brighter or is there a point where adding more lights doesn't make any difference to the actual brightness?
I ask as I saw a jeep, with about 25 lights across the front/roof and wondered if it was worth it, or would 10 do as good job..
I ask as I saw a jeep, with about 25 lights across the front/roof and wondered if it was worth it, or would 10 do as good job..
Urine and hydration.
When I am super hydrated my urine is colourless.
When I am dehydrated my urine is dark yellow.
I deduce that colourless super-hydrated urine contains more water than is strictly needed to excrete whatever wastes urine excretes.
My question: If I am super hydrated, and then do not urinate but exercise hard and drink no more water, is the excess water contained in my bladder re-absorbed into the body?
When I am super hydrated my urine is colourless.
When I am dehydrated my urine is dark yellow.
I deduce that colourless super-hydrated urine contains more water than is strictly needed to excrete whatever wastes urine excretes.
My question: If I am super hydrated, and then do not urinate but exercise hard and drink no more water, is the excess water contained in my bladder re-absorbed into the body?
Ayahuasca said:
Urine and hydration.
When I am super hydrated my urine is colourless.
When I am dehydrated my urine is dark yellow.
I deduce that colourless super-hydrated urine contains more water than is strictly needed to excrete whatever wastes urine excretes.
Generally but not strictly. Diuretics like alcohol usually cause colourless urine but can still dehydrate. Not that you should let that discourage you from a pint, just stay hydrated.When I am super hydrated my urine is colourless.
When I am dehydrated my urine is dark yellow.
I deduce that colourless super-hydrated urine contains more water than is strictly needed to excrete whatever wastes urine excretes.
Ayahuasca said:
My question: If I am super hydrated, and then do not urinate but exercise hard and drink no more water, is the excess water contained in my bladder re-absorbed into the body?
IIRC, no. If you're not drinking enough water your body will start to leach it from other parts of your body (I.E. your muscles). The bladder contains waste and can be toxic if re-entered into the body.The odour of your urine is an indicator of how much toxin and bacteria is in there. That's why your urine reeks when you've had a skinful. OTOH this isn't strict either, bad smelling pee could also mean you have a urinary tract infection.
Hugo a Gogo said:
P-Jay said:
Whilst we're chatting about Sat-Navs and speed.
...
to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
20,000 km, innit? 12k miles...
to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
MartG said:
Hugo a Gogo said:
P-Jay said:
Whilst we're chatting about Sat-Navs and speed.
...
to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
20,000 km, innit? 12k miles...
to measure it's distance from a number of satellites that are 22k miles above the earth or whatever and is right?
Jonnny said:
Is there a "maximum" brightness something can be? Say we take an empty room, and put a light in it, then 1000 lights more, does it keep getting brighter or is there a point where adding more lights doesn't make any difference to the actual brightness?
I ask as I saw a jeep, with about 25 lights across the front/roof and wondered if it was worth it, or would 10 do as good job..
Good question.I ask as I saw a jeep, with about 25 lights across the front/roof and wondered if it was worth it, or would 10 do as good job..
IIRC, the amount of 'light' is limited only by the energy needed to create it. So in theory; limitless energy = limitless light.
It's not a straightforward answer as our eyes will only register a certain number of photons but that doesn't mean to say that there are more than we can register.
The room example you give; taking it to the max, the light (photons) would in sufficient quant,ty start to behave like radiation, melting the room.
Others with a higher intellectual pay-grade may be able to explain better or rebuff my clumsy recall!
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