Power measurement system
View Patent ↗A power meter is provided in which calibration is carried out as an automated procedure controlled by the meter.
1. A power measurement system for measuring power of an electromagnetic signal, the system comprising:
a measuring unit for translating an electrical signal originating from a sensor into a power measurement;
a sensor unit comprising the sensor and an amplification circuit;
a cable for coupling the measuring unit to the sensor unit, the sensor unit and the cable defining a path for communicating the electrical signal originating from the sensor to the measuring unit; and
a reference source that generates a reference signal arranged to be selectively coupled to the amplification circuit in at least one of the following configurations:
coupled to the amplification circuit in place of the sensor; and
coupled to the amplification circuit in addition to the sensor to provide a stimulus to the sensor via the amplification circuit.
2. A system as claimed in claim 1 , wherein the reference signal is a Direct Current (DC) signal.
3. A system as claimed in claim 1 , wherein the sensor unit further comprises a temperature dependent component for providing an indication of the temperature within the sensor unit.
4. A system as claimed in claim 1 , wherein the reference source is arranged to be selectively coupled to the amplification circuit in addition to the sensor to provide a stimulus to the sensor via the amplification circuit, and the reference signal is varied in amplitude to characterise the sensor.
5. A sensor unit apparatus for a power measurement system, the apparatus comprising:
a sensor;
an amplification circuit coupled to the sensor; and
a reference source that generates a reference signal arranged to be selectively coupled to the amplification circuit for communicating the reference signal to a measuring unit via a cable in at least one of the following configurations:
coupled to the amplification circuit in place of the sensor; and
coupled to the amplification circuit in addition to the sensor to provide a stimulus to the sensor via the amplification circuit.
6. An apparatus as claimed in claim 5 , wherein the reference source is arranged to generate a fixed reference signal.
7. An apparatus as claimed in claim 5 , further comprising a temperature dependent component for providing an indication of the temperature within the sensor unit apparatus.
8. An apparatus as claimed in claim 5 , wherein the reference signal is a Direct Current (DC) signal.
9. An apparatus as claimed in claim 5 , wherein the reference source is arranged to be selectively coupled to the amplification circuit in addition to the sensor to provide a stimulus to the sensor via the amplification circuit, and the reference signal is varied in amplitude to characterise the sensor.
10. A method of maintaining accuracy of a power measurement system comprising a sensor unit coupled to a meter unit by a cable, the method comprising the steps of:
generating a test signal;
receiving the test signal at the meter unit via a path defined by the sensor unit, the cable and the meter unit; and
calibrating the meter unit in response to the test signal;
the test signal being a reference signal that is arranged to be selectively coupled in at least one of the following configurations:
coupled into the path in place of the sensor; and
coupled into the path in addition to the sensor to provide a stimulus to the sensor via an amplification circuit.