TAM / TASMAn uncased working sample of a 100 line circuit Test Access Switch Matrix. The assembled unit fits into an 19" standard cabinet or ETSI rack. A second parallel card offers service protection should the card ever need changing. This is set up as a master/slave configuration and gives added protection on the circuit. |
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TASM CircuitryAn extra switch stage has been introduced to overcome the limitation of only being able to test one line circuit out of the 100 circuits available. A two stage switch matrix is added as shown in the diagram to the right. The first stage is split into four seperate 25 to 1 four wire matrix switches. The output of each of these 25 to 1 switches is connected to the second stage switch, this allows the output to be switched to any 1 of 4 common TestBus Ports. This makes it possible to switch one customer circuit in each group of 25 onto one of the four Test Busses simultaneously. The 4 Test Bus Ports on each TASM are presented on pairs of RJ45 connectors. TestBus Ports from a number of TASMs are easily interconnected by simply daisychaining the ports together using standard Cat 5/Cat 5e network cabling. This cable then terminates at the Test Head. A Test Head with four test bus inputs can still be a limitation on the system, it is possible to overcome this by adding more test heads across the TAM / TASM units. In practice four ports have been more than adequate across thousands of circuits by using a queuing method in the controlling circuitry. Photos Coutesy of UTEL |
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Final Product - Master CardOnce housed the unit is fully protected and designed to fit into a dedicated rack mounting. The daisy chain from the test bus can be seen below. |
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