# 11pm and still stuck on physics - any help?

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Thread starter 17 years ago
#1
A signal is to be encoded using four bits par value. Each bit takes 10^-8 s to transmit. How many different signals sampled in the same way could be transmitted along a single fiber.

Frequency of signal = 1000Hz
The signal is being sampled 8 times in one second

Any ideas??

Oh, i also have a question that is basically asking what effect NOT having a diode in a circuit will have on a capacitor. Any ideas for that?
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17 years ago
#2
8 samples a second*4 bits per sample = 32 bits per second per signal.

frequency of bit transmission = 1/10^-8 = 10^8 bits per second

signals in a wire = 10^8/32 = 3125000 signals
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Thread starter 17 years ago
#3
(Original post by elpaw)
8 samples a second*4 bits per second = 32 bits per second per signal.

frequency of bit transmission = 1/10^-8 = 10^8 bits per second

signals in a wire = 10^8/32 = 3125000 signals
life-saver - cheers - might actually get some sleep tonight
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Thread starter 17 years ago
#4
(Original post by elpaw)
8 samples a second*4 bits per sample = 32 bits per second per signal.

frequency of bit transmission = 1/10^-8 = 10^8 bits per second

signals in a wire = 10^8/32 = 3125000 signals
How did you get the frequency of bit transmission = 1/10^-8 (sorry probably stupid question - i'm tired)

Also any ideas on the diode (added it in the edit)
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Thread starter 17 years ago
#5
(Original post by piginapoke)
The ripple voltage will be increased.
Man......what's 'ripple voltage'?
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17 years ago
#6
(Original post by need_help)
How did you get the frequency of bit transmission = 1/10^-8 (sorry probably stupid question - i'm tired)

Also any ideas on the diode (added it in the edit)
f = 1/T
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Thread starter 17 years ago
#7
(Original post by piginapoke)
Its the variation in current left over after a diode rectifies AC into DC.

Show us the circuit, its a pretty general question.
It's really complicated to do on here:

Power Cell -- (DC) -- Converter -- (AC) -- Transformer (all in series then something like this)

-------Diode--------/-------<Switch>-----/
/ Capacitor / Flash Lamp
-------------------- /--------------------/

Sorry, that's crap
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Thread starter 17 years ago
#8
(Original post by piginapoke)
Ok, light will be constantly on with the diode in place; with the diode removed it will repeatedly dim and brighten.

EDIT - sorry again(!) didn't see it was a flash lamp, the flash lamp will go on and off without the diode.
cheers
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