DTMF Network Controllers

The STS Signals DTMF Network Controller product extends the range of the CONCEPT 32 telephone concentrator system to incorporate both local and remote nodes.

DTMF Network Controllers allow a number of concentrators to be combined together to appear as a single system to the Signaller in the Control Centre. Two separate data communications routes and two speech routes (primary and secondary) are used to link the DTMF Network Controllers together.

By using direct modem-to-modem connections, the Network Controllers may be a maximum of 5 miles (8Km) apart, dependent on line integrity. Should greater distances be required, a proprietary transmission system may be used.

Key benefits include:
• Full monitoring of the speech path
• Check on integrity of cabling using DTMF tones
• Diverse routing of speech and data paths
• Compatibility with existing STS Signals equipment
• Seamless upgrade path
• Provides additional security and integrity to the data exchange between Concentrator and keyboard.

DTMF Network Controllers resemble statistical multiplexers, as they combine concentrator data with PETS data and external alarm inputs for transmission over the modem link. A basic network system consists of a Concentrator Network Controller (CNC) installed with the Remote Concentrator, connected by two voice frequency circuits and two data circuits to a Primary Network Controller (PNC) installed with the Local Concentrator in the Control Centre.

The data is transmitted via modems and the speech as an analogue signal. The primary route is permanently established, whereas the secondary may be either permanent or disabled as appropriate.

Detection of a failure in either the speech or data circuit by the PNC causes the appropriate econdary route to be selected and an alarm condition raised. When the primary route fault s cleared and communication re-established, it is reactivated and the secondary route is returned to standby.