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The above picture shows a GPS10RB  Redundant system.  This system had ten 10 MHz outputs and was supplied to a leading UK based telecommunication company

General Description

Option 08 adds redundancy to the GPS10RB. With redundancy, two separate GPS10RB's are interconnected to form a redundant frequency standard system. There are ten 10 MHz outputs, although the number of outputs can be increased with extra distribution amplifiers.

Both GPS10RB's are identical; there is not a master or slave unit. Whatever unit is initially powered up first has its output amplifiers enabled and supplies the 10 MHz outputs. If this unit should fail, the 10 MHz outputs will automatically be switched over to the second GPS10RB

As both units are identical, any faulty unit can easily be replaced without interrupting the main 10 MHz outputs

The system is fully operational when both GPS10RB's are operating correctly with their rubidium oscillators locked to the GPS satellite system. In this case both GPS10RB's are continually monitoring the following parameters.

• The status of the GPS Satellite Signal, including the number of satellites, the signal strength of the satellites etc. Also the antenna current is monitored so an open circuit or short circuit antenna can be immediately detected
• All GPS10RB Power Supplies
• The status of the Rubidium Oscillator including its case temperature, various internal voltage settings and the status of various phase lock loops
• The status of the internal distribution amplifiers including the signal amplitude of the 10 MHz signal
• The status of the other GPS10RB in the system

In the event that any of the above parameters fail, the enabled unit will be disabled, and the second unit will take over in supplying the 10 MHz outputs.  The switch over time is less than 25 ms.  The faulty unit can then be disconnected from the system, repaired, and reconnected, without ever disturbing the 10 MHz outputs.

Normally both GPS10RB's have their own GPS antenna. So in the event that one antenna fails the second unit will take over as already described. However, even if both GPS antenna fails at the same time, the 10 MHz signal will still be maintained as the active GPS10RB will automatically switch to Free Run mode. In Free Run mode, the rubidium oscillator maintains an accurate frequency output. In Free Run mode the signal will still be accurate and have a drift rate of less than 5 x 10^-11 per month.

Click Here for an actual redundant system with full explanation of operation