1. Sample the analog signal a lot (8000 times a second actually)
2. Create a number that represents each sample (Aka Quantization)
3. Convert that number to binary (PCM Scale: -127 TO +127 – MULAW/ALAW)
4. Compress if desired
Human voice frequency range – 20-9000hz
20-4000hz range = ‘meat’ of human voice
Sample the highest core frequency by 2 per second = 8000
The reason for low quality voice on AM radio is to only the ‘meat’ of human voice.
Goal: Recognise the voice and tell their mood!
PCM Scale – ‘Post Code Modulation’
8000 times a second it will state the binary number
127 up and 127 down on Left Axis (256 is highest number from 8 bits)
Time in 1 second intervals via Right Axis
8000 x 8 = 64Kbps
ulaw and alaw with G.711.. (PCM Scale)
ulaw is USA and is backwards to alaw. alaw just makes sense!