PIU Subscriber unit 4 ISDN tributaries with U interfacem



  • Provides connection to ISDN exchange for 4 remote subscribers, via multiplexers FM2x2 and FM-MSAN
  • Single pair subscriber loop with 2B1Q line code
  • PIU-LT (Line Termination) and PIU-NT (Network Termination) options
  • PIU unit, as tributary unit within multiplexers FM2x2 and FM-MSAN provides connection of remote customer to ISDN exchange. User NT1 equipment is NT (network termination), whereas U-interface at exchange side is LT. Therefore, PIU unit at customer side must be PIU-LT, and PIU unit at exchange side PIU-NT.
  • Remote subscriber can be connected with ISDN exchange via more than one PIU-LT/PIU-NT pair, but maximum number of regenerators is six (i.e. three LT/NT pairs). For test purposes ISDN exchange can send diagnostic commands through EOC channel to each PIU unit in chain. 3 bits are reserved for address. "0" is address of NT1 equipment, "1" to "6" are for PIU units in chain, and "7" is for all stations in chain (broadcast).

Basic functions

  • 4 ISDN U interfaces on PIU unit
  • One U-ISDN occupies 2.5 64kbit/s channels in FM2x2 and FM-MSAN
  • Position of U-ISDN in multiplex is configurable by management software
  • Transport via single pair is accomplished by use of 2B1Q line code with near-end echo cancellation
  • PIU-LT is equipped with remote power feed source, which can provide power feeding of NT1 without local power supply
  • Copper-pair interruption detectionShort-circuited copper-pair detection
  • Remote loopback control from ISDN exchange through EOC
  • Performance monitoring

PIU regenerators chain

Data sheets (pdf): PIU (Serbian), PIU (English)