Consumer Electronics

DIGITAL COMPUTER

Music may be synthesized by means of a digital computer. The key process involves a digital-to-acoustic converter. A schematic block diagram of the conversion process is shown in Fig. 26.10. A magnetic tape is prepared by the computer, on which are recorded successive digitized samples of the acoustic output. The numbers are then converted to pulses, the amplitudes of which are proportional to the numbers. The pulses are smoothed by a low-pass filter to obtain the input for an audio loudspeaker. If the sampling rate is 20,000 per second, the top frequency from the loudspeaker will be 10,000 Hz. Each sample is produced from a four- decimal number. The signal to noise ratio will be of the order of 60 dB. Within the limits of frequency ...