Lambda SR1, Operation Manual, Page: 168 / 317

SR1 Operation Manual 168
© 2014 Stanford Research Systems
Processing
The MTA has two distinct processing modes: Synchronous and Windowed. Synchronous processing
assumes that the DUT does not shift frequencies at all and that therefore all the tone frequencies and
harmonics will fall on exact bin frequencies in the received FFT. When operating in the synchronous
mode the MTA does not use a window function which would otherwise smear the bin frequency tones
over several lines in the received spectrum. When the DUT does shift the frequencies of the multitone
generator signal, the MTA must apply a window function to the received signal to limit the smearing of
the received tones. In windowed mode certain MTA measurements, such as phase and noise
measurement are disabled.
Distortion Products
This panel allows selection of the minimum and maximum harmonics that will be included in
measurements like THD and THD+N as well as the maximum order of the intermodulation products that
will be included in the IMD measurements.
Equalization
The file selection box allows specification of an EQ file which is then applied as a weighting function to
all MTA measurements. EQ files are files which specify a relative response as a function of frequency.
EQ files are detailed in the SR1
File Reference . When an EQ file is specified the MTA weights all bins in
the received FFT by the frequency response of the EQ file before computing measurements.
Relative Measurements
Certain MTA measurements can be expressed either as an absolute voltage, or relative to various tone
amplitudes. The measurements affected by this choice are: THD+N (Bins and Scalar Measurement),
THD (Bins and Scalar Measurement), Noise (Bins and Scalar Measurement), Total Distortion (Bins and
Scalar Measurement), and IMD (Bins and Scalar Measurement). The allowed relative values are:
Measurement Relation selects the relative mode for the measurements mentioned above.
Absolute Amplitude The measurements are expressed as absolute voltages.
Relative to The absolute voltage for each measurement is divided by the peak voltage of the