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Media Copper
# of Signals 4
Symbol Rate 2.56 MBaud
Variants DS-30, DS-30A, DS-30Y

DS-30X Speech Links are used to carry speech and some signalling on Norstar Modular platforms.


  • Four wires (arrows are controller <-> card) [1]
    • Tx PCM →
    • Rx PCM ←
    • 5.12MHz Clock →
    • 1kHz Frame Sync →


  • Signal levels unknown
  • Isolation unknown


  • Clocked at 2.56MHz (half the 5.12MHz clock received from the controller)
  • Carries 32 channels of PCM voice data
  • Each channel consists of a 10-bit word
    • 8 bits of voice data (called a "timeslot")
    • 1 bit of signalling data
    • 1 bit indicating "data valid"
  • Signalling data is sent in 24-bit words, one bit at a time in each channel.
    • Sent in both directions, one on Tx PCM and one on Rx PCM

Timing Diagram/Frame Format


  1. NN43001-311 02.09 Installation CirCrdFundamentals.pdf CS1000 Circuit Card Fundamentals, Page 25