Trunks & Multiplexing
Frequency Division Multiplexing (FDM)
- 4Khz bands, 3Khz useable bandwidth
- 12 channels in 60-108Khz band = group
- 60 channels = 5 groups = supergroup, etc
Wavelength Division Multiplexing (WDM)
- same as FDM but different hardware
Time Division Multiplexing (TDM)
- codec makes 8000 samples per second (125µsec)
- 7 or 8 bit sample, 56Kb/s or 64Kb/s, PCM (sample amplitude,~PAM, & then quantize)
- T1 = 24 voice channels + 1 bit = 1.544 Mb/s
- T3 = 24 T1 streams = 44.736 Mb/s