Analog vs Digital Recordings
Everybody have seen the gramophones, and how there is a small needle scratching the smallest surface of the records, and as a result sounds are produced. One can ask, what is the needle scratching on the record? That is the analog wave, the sound waves that erupt from our mouths when we speak or make an audible sound. These analog waves are hard to interpret when seen via an oscilloscope or any other means. The recognition of analog waves leads to its recording and thus invention of many means of communication. However, the problem was that it was hard to record the analog wave exactly as they sound: low fidelity. To overcome this problem, the method of Digital recording was invented, which records Digital waves, which is nothing but reconstructed analog waves, digitally. The question is how the analog recordings differ from its counterpart.
Initially, analog recording was done in a straightforward method, where a tin foil was scratched, with foil vibrating at 1000 oscillation/second. But this scratching is the one thing that effect the fidelity of the signal, and one can hear noise with the signal. Vinyl records, similar to the tin foils in many ways, are also a method of analog recording. There are grooves imprinted in it, which is similar to the waveform of the signal. The player which plays the vinyl is also analog device. Although, the vinyl recordings done now are more noise free than ever, even small specks of dust could ruin its quality. Also that the more the records are played, they more they lose their qualities.
Why the need for Digital Recordings?
In order to overcome the disadvantage of low fidelity and deterioration of the quality of vinyl recordings with time, digital recordings were used. The basics of digital recordings will start from the Compact Discs or CD, which looks like a shrunken and slicker version of vinyl records. The CDs require a method of digital recording as well as digital playback. In digital recordings, the analog wave is recreated digitally, which is sampling the analog wave at very close discrete points. The fidelity of the signal could be kept high is the sampling rate and quantization levels are kept high. The quantization level helps to determine the size of the signal, and the closeness of the sample point. The sampling rate, the number of samples read per second also determines the quality of the digital signal.
To overcome the disadvantages of analog recordings mentioned above, the sound wave is interpreted into numbers, using the quantization levels, and storing them into the CD’s tracks/segments. Analog to Digital conversion or ADC is the key here, which sets the numbers to every level of the analog signal. When playing back, the numbers are then used to create the analog signal back, and thus analog signal plays back. This is done in the opposite manner to the ADC, which is the Digital to Analog converter. Since the numbers denoting the analog signal never changes, there is negligible chance that the signal or sound will not be same as the original sound. There are of course chances of wear and tear in CDs as well, in form of scratches, but small scratches hardly have any effect on the quality of the sound.