3.5.8 Discuss two applications that require conversion of data between
analogue and digital formats including temperature sensing.
Teaching Note:
Teachers are free to choose the second application. Other software
examples include: speech recognition, light detection, image
processing, OCR software.
Sample Question:
With respect to entering and storing voice data in a computer system:
...
(b) Describe the process of storing voice data in digital form on a computer. [2 marks]
JSR Notes:
This is much easier than 3.5.7, and together with it, deserves to be. But again, if the question says something like discuss, outline, etc. analogue and digital... don't just give examples. Only just give examples if they only require them. Never-the-less, the two examples you should have ready to go for 3.5.8 are: temperature sensing (required by the assessment statement) and sound capture and reproduction.
Temperature sensing: Well, as many of you very adequately pointed out, temperatures don't go up by half degrees, for example, all at once, but at definite changes in temperature, a digital sensor will be triggered to record change. It can be very sensitive, but never be able to perfectly, continuously, record all temperature change.
Digital sound capture and playback: At CD standard quality, as set by the company Phillips years ago, and stuck with as a standard ever since, 44 100 samples are recorded ever second. These are samples of pitch. The other factor affecting sound quality is the range of sounds that can be recognized by the digital recording device. 16 bit sound can distinguish between, you guessed it, 2 ^ 16 different pitches (or frequencies of sound), and 24 bit sound 2 ^ 24 pitches. Played back, this digital information somehow has to be converted into sound waves pulsing through the air toward our ear drums. Electricity is perfect for this, and at the woofer or tweeter of a speaker the digital combinations are converted to vibrations of cardboard which suffice to reproduce the sound in an analogue way.