Video: Physics Past Exam • 2017/2018 • Pack 1 • Question 15

Physics Past Exam • 2017/2018 • Pack 1 • Question 15

02:16

Video Transcript

How can the effects of electrical noise be reduced when transmitting information wirelessly?

Say we have some information we want to transmit wirelessly. The information we’ll say consists of a wave of uneven amplitude. If we write down the various heights and depths of the peaks and troughs of this wave, let’s say we record them as 3.50, negative 4.75, positive 2.50, negative 3.00, and positive 6.00, to transmit this information we might write down in order these peak and trough values and then send it across our system wirelessly.

We know though when we do this, the effects of electrical noise might change the values that we’ve input. The effects of electrical noise could be significant enough to distort these values to change perhaps the digit in the hundredths place to something we didn’t intend for it to be. And depending on the severity of the noise, even the digit in the tenths place might be affected by this distortion.

Rather than transmitting information in decimal format, where highly precise values are likely to be changed by the effects of noise, we would prefer to send information in a way that is unlikely to change. An effective way to do this is to convert our values from decimal format to binary format.

In binary format, where all values are either a zero or a one, nothing short of one of these zeros or ones changing to be its complete opposite will change the information that we’ve sent. Since a one changing to a zero or a zero changing to a one is a dramatic change, it’s probable that the noise in our transmitting system won’t be able to affect a change this dramatic.

What we can recommend then is to take our signal in its analogue decimal format. To encode that information by converting the decimal to binary, this information is then sent through the communication channel, decoded back from binary to its original form, and then output for the receiver on the other end of the communication channel.

By encoding the information in the signal in a binary format, the effects of electrical noise during signal transmission can be reduced.

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