World's Most Accurate 50Hz-20kHz Capacitance/Loss Bridge
Deviation Mode and the Analog Outputs
A new mode of operation has been added to the AH2700A called Deviation Mode. In this mode, the user is given access to the processed imbalance signal from the preamp.
At the beginning of Deviation Mode (DMode) measurements, the bridge is first set as in BMode to capacitance and loss values that are close to those of the DUT. The bridge can be used to accurately measure these values or they can be manually entered. This pair of values is called the Bridge Balanced Point (BBPoint). Once DMode measurements begin, the BBPoint remains fixed for the duration of the measurements.
The imbalance signal from the preamp now represents the deviation of the capacitance and loss of the DUT from the BBPoint. This signal is digitized at a rate of 50,098 samples/s and matrix multiplied by a DSP to convert it to two real-time data streams representing the capacitance and loss deviations.
From this point the two deviation data streams each split into two branches. One branch goes to a pair of digital to analog converters (DAC's) which produce two analog voltages at the rear panel of the instrument that correspond to the capacitance and loss deviation signals. The other branch is used to produce alphanumeric results which are sent to the front panel and may also be sent to the serial and/or GPIB ports.