Definity - Exposition of circuits

• PROCESSOR card
• Processor card is the main unit of the central computer. Processor provides the procession of the calls in the memory (200 kbyte ROM/EPROM, 40 kbyte RAM) on the basis of the stored program and configuration. It observes and controls the connection between the peripheries, and gives statement signals to the user. Besides these issues it has the following roles:
  • interface towards the handling terminals
  • channel interface (in case of a remote access, or a remote alert)
  • maintaining circuit interface

• NETWORK CONTROL card
• Network control is a controlling circuit of the central network. Network control forwards signal messages through the TDM bus between the processor card and port cards. It controls the four data channels, (Netcon-1..4), that can help the operator to come into a contact with the processor. It observes the statement of the clock signals of the exchange.It controls the FLASH card storing the central configuration. Restoration of parameters of the system, and loading of a new operation software can happen with the help of the FLASH card.

• PACKET CONTROL - Card handling packet switched messages
• A PACKET CONTROL card forwards through the TDM bus HDLC framed messages, and messages forwarded on the basis of the LAPD protocol between the processor card and port cards. Digital ISDN telephones communicate with the exchange with the help of these kind of messages.

• TONE CLOCK card
• It generates sound signals in connection with the call processing, DTMF sound frequency codes, dial sounds (touch-tone), answer sounds, and sound frequency signals necessary to the transmission measurement.

• TONE DETECTOR card
• It contains 4 DTMF-receivers and 2 general purpose sound receivers, which detect sound signals in connection with the call processing, answer sounds, modem answer sounds, sound signals of transmission measurements, and noise.

• TDM bus
• Time Division Multiplex (TDM) bus is the switching field of the exchange. For protecting sinultaneity of transmission (speech) and reception (listening), TDM bus consists of 2 x 8 wires. Frame organization of the 8 wires based on the primary PCM time frame with a difference, that eight bits of a time-gap are forwarded parallel through the 8 wires. Thus there are 256 channel time-gaps on a bus consisting of 8 wires, from that 240 wires serve for switching, and 16 wires serve for controlling and signal transmission purposes. Port circuits are in connection with each other through the TDM bus, and through the network controlling circuit with the processor.

Peripheral unit

• ANALOG LINE - Analogue device interface card
• This card realizes the connection of eight sound frequency subscriber devices.

• DIGITAL LINE - Digital device interface card
• This card realizes the connection of eight digital devices

• CO TRUNK - Analogue central office trunk interface card
• This card provides four connections towards the other exchange through the sound frequency subscriber interface.

• ISDN LINE - ISDN S0 interface card
• This card realizes the connection of 12 devices with ISDN S0 interface.

• E/M TIE TRUNK - Analogue tie trunk interface card
• This card provides four connections towards the other exchange through a sound frequency trunk interface.

  DS1 INTFC 24/32 - Digital trunk interface card

• This card provides an American (24-channel) or a European (30-channel) PCM or ISDN PRI access between exchanges. One from the 32 channels realizes the DSS1 signalling system in ISDN applications. Furthermore, the presently used European digital signalling systems can be realized, too.

Attention!!! We can change cards in the equipment during operation, but we must necessarily use the grounding contact to avoid errors caused by electrostatic voltages!