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GENERAL
The OS308M is an 8 Channel 64kbps audio drop and insert multiplexer. The OS308M forms part of a telecommunication system operating in a ring network. The ring is controlled from a master unit named OS2030. The OS2030 is designed to transmit a 2 Mbps CCITT G703 data link over fibre. This unit interfaces between G704 CAS protocol and several OS308MUX units. The OS308M can also operate in a master mode allowing point-to-point operation with another OS304M on 8 channels.
The unit is housed in a 2U 19? card frame. It comes complete with its controller and power supply.
Various optic and power supply options are available. The optic card plugs directly into the card frame. The power supply is mounted on the back of the unit.
The unit has built in 8-port bus system. It can house any combination of line terminating equipment. This equipment is in the form of individual cards and can be arranged and plugged into the card frame as required. At present the following modules are available.
Exchange unit stock code ?OS3081E?
This interfaces directly with an exchange line and simulates the functions of a telephone.
Telephone unit stock code ?OS3081T?
This unit can couple directly to a telephone and simulates the functions of an exchange.
4W E & M unit stock code ?OS3081W?
This is an audio interface with E & M signalling.
RS232 interface unit stock code ?OS3081R?
This unit has a DB25 connector and supports data speeds up to 64k bits/sec sync.
Asynchronous data can be transmitted up to 28800 bits/sec. Data is sampled at 64 k samples/sec thus jitter increases with baud rate.
X.21 V11 interface unit stock code ?OS3081X?
This unit has a DB15 connector and supports data speeds up to 64k bits/sec sync.
Asynchronous data can be transmitted up to 28800 bits/sec. Data is sampled at 64 k samples/sec thus jitter increases with baud rate.
The unit also supports standards such as RS422.
The OS308M can be configured to accept any of the above line terminating units.
To configure the OS308 a PC with dedicated software is required. The configuration can be downloaded directly to the unit using its RS232 port. Or it can be downloaded to the OS2030 master unit that will in turn forward the configuration to the OS308 via the supervisory channel.
The unit is modular in design and can thus be upgraded with different optics or power supply. The distance over which the system can operate is determined by the fibre interface used. The options are limited to 3, 12, 16, 24, 36, 50 and 70 Kilometres. The power supply can be replaced by exchanging the power supply module with a 220VAC, 110VAC or 48VDC unit. Other voltages can be supplied on request.
The system uses the latest technology in line driving and decoding integrated circuits and therefore complies fully with the stringent CCITT standards.
The unit is housed in a 19" rack with a height of 2U.
Software upgrades
Should it be required, new software for the OS308 unit can be downloaded to the OS2030 master unit that will in turn forward it to the slave units. New software can also be installed using a pre programmed EEPROM. These are available form the supplier.
Setting up of channel configurations.
The software running on a PC also allows setting up of line configurations and gain adjustments for each time slot / channel. Once the alterations are done it must be downloaded. The alterations will take effect after a short delay. A Backup copy of the configuration for a particular system can be stored on the system disk. The unit will be able to allocate timeslots to users as per selection from the management system.
The unit has a built in framer. The framer will take the received data and re-time the data for transmission further down the line. Whenever a timeslot allocated to a particular outstation is reached, the time slot will be dropped off to the correct line interface and the interface data is then inserted in the frame.
Telephone line interface
The line interface will consist of a CODEC that is programmed by the intelligent unit.
The CODEC will be programmable and will control the following.
Transmit gain adjustable over a 10dB scale in steps of 0,1dB. Max gain is 6.9dB.
Receive gain adjustable over a 10dB scale in steps of 0,1dB. Min sensitivity is ?18dB
Adjustable Hybrid balance registers.
A dipswitch setting will identify the location of the OS308M.
Note that dipswitch number 4 will select between master and slave in a point-to-point system.
The system operates over a single Fibre ring. The optical interface can be interchanged to suit the application.
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