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# Questions watch

1. Have i got this right? part e suggests i havnt....

The spiral track of a music CD plays for 1 hour, read at 1.25 ms-1. The two track stero music on the CD has frequencies extending up to 20kHz. The samplong frequency on each channel is 44.1kHz. Samples are digitised at 16 bits per sample.

a) Show that the track is 4.5km long

- 1.25ms-1 for one hour = 1.25m * 3600s = 4500
Speed = 1.25ms
Distance = 4.5Km
Time = 3600s

b) Give a reason why the sampling frequency is more than 40kHz.

Sampling frequency must be >(or equal to) maximum frequency of wave to prevent loss of detail, Nyquist rate.

c) How many bits does the player have to read per second for each stero channel?

no. of bits per second = no. of samples per second x no. of bits per sample

44.1 * 16 = 705.6

d) Estimate the bandwidth of the communication between reading head and player?

20kHz..?

e) Show that there are 5x10^9 bits for one hour of stero music.

f) How much track length is there per bit, comment on this,

0.0000009m, small.
2. Bump...

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