Digital Audio Flashcards
What does PPM stand for?
Pulse Position Modulation
DEF: Pulse Position Modulation (PPM)
for each number there is a position in time with subdivisions, the subdivision within that time dictates the number being communicated
what does PNM stand for?
Pulse Number Modulation
DEF: Pulse Number Modulation (PNM)
for each number communicated you have a series of pulses equal to the number similar to morse code: 1 pulse = 1, 6 pulses = 6, 13 = 1 pulse followed by 3 pulses, etc.
what does PWM stand for?
Pulse Width Modulation
DEF: Pulse Width Modulation (PWM)
the length of the pulse dictates the number being communicated short pulse = small number, longer pulse = bigger number
what does PAM stand for?
Pulse Amplitude Modulation
DEF: Pulse Amplitude Modulation (PAM)
Amplitude dictates the number being communicated lower amplitude = lower number wasn’t very accurate so they needed to develop a better way
what does PCM stand for?
Pulse Code Modulation
DEF: Pulse Code Modulation (PCM)
uses binary code range of numbers to be communicated is established, which gives you bit depth. Bit depth is then used to communicate the information on and offs that allow transmission of data (think morse code)
what is the binary system
a two digit system (base 2 system) made up of 0 and 1 used to represent a larger amount of information
What is a BIT?
A binary digit
What is a byte?
8-bit word
what is a nibble?
4 bits
Bit depth indicates what in binary code?
the word length i.e. 4 bit, 24 bit, etc.
what are the sample rate and bit depth setting used for CD?
44.1 kHz, 16-bit
DEF: sample rate
the number of measurements taken in a second
DEF: bit depth
the amount of values you can give to each sample taken
DEF: quantisation
the act of assigning a binary value to the voltage amplitude that is read for each sample in the sample
DEF: Nyquist theorem
double the highest frequency you wish to accurately reproduce
What two factors determine the quality of resolution of a digital signal?
bit dept and sample rate
How do you calculate the number of bits in the binary word?
2^n n = binary word length
how does the dynamic range change for each bit added to the binary word length?
dynamic range increases by approx 6 dB for each bit added
DEF: oversampling
a process of sampling your signal at a sampling rate significantly higher than the Nyquist frequency, which improves resolution, reduces noise, and helps to avoid aliasing and distortion in the D/A conversion process
