Operation Manual
NPRT 2200
1. Introduction
The Noise Power Ratio quantifies performance degradation in active RF components, primarily
inter-modulation distortion.
The Applied Instruments Model NPRT 2200 Noise Power Ratio Test Set performs this test for
cable return band components and other equipment that operates in one of the available
frequency ranges. Many frequency bands are available from 5 to 42 MHz up to 5 to 300 MHz.
The NPRT 2200 operates as a stand-alone device or in conjunction with a PC application
software package. The NprGraph Windows
software is provided with the instrument.
1.1.
NPR Measurement
The Noise Power Ratio test compares the power of a carrier signal to the power of the noise
generated by signal distortions. The technique uses a deep notch filter to remove a portion of the
carrier signal in a very narrow frequency band where the noise power is measured. Then carrier
power is measured at the same frequency with the notch filter removed.
1.2.
NPRT Block Diagram
The NPRT 2200 consists of a calibrated signal source that generates a noise signal with a
precise power level. This signal is used as the input stimulus to a Device Under Test (DUT). The
DUT may be any active RF component that operates in the frequency band of the instrument.
The output from the DUT is measured by the receiver portion of the NPRT 2200, with and without
the notch filter inserted into the input signal, and the NPR is calculated.
Signal Source
Receiver
DUT
Page 1
