Channel Quality for Group Delay (N/E9056EM0E) Noise Power Ratio (N/E9056EM1E) Measurement Application

Key Features

• Characterize RF components with spectrum, waveform, amplitude, phase, gain amplitude, gain phase, and group delay (absolute or relative) etc. measurements

• User can flexibly define the number of tones and tone spacing for group delay measurement

• Support burst search for large group delay measurement

• Support U9361 RCAL receiver calibrator as “Use Current Measurement”

• Tones phase can be defined with phase type as zero phase, random phase or parabolic phase. You can also import a tone table as txt or csv format.

• Support Keysight X-Series Signal Generators (MXG, EXG) and VXG Microwave Signal Generator for multi-tones signal generation

• Support Keysight X-Series Signal Analyzers (UXA, PXA, or MXA) for channel quality/group delay measurement

• Use multi-touch user interface and SCPI remote interface

• Extend test assets with transportable, USB Portal or floating licenses between X-Series signal analyzers with multi-touch UI

Group Delay

N9056EM0E Channel Quality/Group Delay measurement application provides a solution to make repeatable channel response measurements such as group delay and other characteristics of multi-channel signals targeting wideband components testing in 5G NR, WLAN etc. N9056EM0E is running inside Keysight X-series Signal Analyzers which can connect Keysight Signal Generators for multi-tone signal generation to make group delay measurements as the typical measurements shown below.

Instrument Connection

The instrument itself can introduce uncertainty in the measurement, including internal phase distortion and trigger delay. On the other hand, the initial phases for individual tones may be randomly generated to achieve better PAPR. To eliminate those uncertainties, a 2-step group delay measurement is recommended as the following diagram.

What is Group Delay?

Group delay is a measure of the phase distortion with respect to frequency after passing through a device. From time domain perspective, it’s also a measure of how long it takes for the signal to pass through a device. Here ‘group’ means a group of frequencies that is considered to have the constant delay after passing the device. Then, for a wider bandwidth, the delay values should be measured at many groups to form a complete group delay curve covering the whole bandwidth.

Mathematically, group delay is defined as:

𝝉𝝉=−𝟏𝟏 𝟐𝟐𝟐𝟐 𝒅𝒅∅ 𝒅𝒅𝒅𝒅

Taking a look at the phase-to-frequency response, the linear phase is represented by the green line for the ideal case, and its slope represents the group delay for the overall frequency range. However, in a practical test with DUT, the phase response would be something like the red line, where deviations (called phase distortion) to the ideal slope could be observed. The phase distortion will result in a variable group delay for different frequency components in the signal, like a ripple. 

Connect to Signal Generator via LAN Connection

If it is the first time to use a new generator, you'll need to input the IP address or Host name. Then you can add the configuration to the Signal Generator List, which will be stored even after instrument reboot. After connection is established between SA and SG, the SG Information is shown automatically in the information box and the button will be changed to "Disconnect". You can add more Signal Generators in the list, only the "Connected" SG is highlighted in green color.