Telecom formula sheet

y = sin(2πf t), t = time in seconds, f = frequency in Hertz (cycles/sec)

Decibels: 10 log₁₀ P_out/P_in

Nyquist: C = 2B log₂ M

Shannon: C = B log₂ (1+SNR)

B = bandwidth, C = max data rate, M = # of signal levels, SNR = signal-to-noise ratio

Thermal noise: N₀ = kT, T in Kelvins, N₀ in Watts/Hz, k = 1.38 x 10^-23 J/K

NRZ: 0=high, 1=low

NRZI: 0 = no transition, 1 = transition

Manchester: NRZI alternating with transitions due to the clock signal

Bipolar-AMI: 0 = no signal, 1 = alternating positive and negative for successive 1-bits

B8ZS: same as bipolar, but 0000 0000 is replaced by 000+-0-+ or 000-+0+-, depending on whether previous 1-bit was + or -.

HDLC:

RR: ACK, Receiver Ready for more

RNR: ACK, Receiver not ready for more

RR-P: poll packet sent by sender to elicit Receiver’s current RR/RNR

TDM

DS0: 64kbps voice line

DS1: 24 DS0’s plus 1 bit

DS2: 4 DS1’s plus bit-stuffing (pulse-stuffing) room

DS3: 7 DS2’s / 28 DS1’s, plus bit/pulse stuffing room

STS-1: 51.84 Mbps

STS-N: N x STS-1, exactly