N6152A & W6152A Digital Cable TV X-Series Measurement Application

Introduction

This demonstration guide follows the list from page 2, which shows the demonstrations included in this document. Each demonstration is given a brief description of its function and the corresponding measurement steps on the signal generator and/or signal analyzer.

Digital Cable TV Measurement Application

Measurement Details

All of the RF transmitter measurements as defined by the Digital Cable TV standards, as well as a wide range of additional measurements and analysis tools, are available with a press of a button. These measurements are fully remote controllable via the IEC/IEEE bus or LAN, using SCPI commands.

Analog baseband measurements are available on the MXA signal analyzer equipped with BBIQ hardware. Supported baseband measurements include all of the modulation quality plus I/Q waveform and CCDF measurements.

Demonstration Preparation

All demonstrations use an X-Series signal analyzer with the Digital Cable TV measurement application and the N5182A MXG vector signal generator. Keystrokes surrounded by [ ] indicate front-panel keys; keystrokes surrounded by { } indicate softkeys located on the display.

Demonstration Setup:

Connect the PC, X-Series Signal Analyzer and MXG

Connect a PC (loaded with N7623B Signal Studio for Digital Video software and Keysight I/O libraries) to the N5182A MXG via GPIB or LAN. Follow the Signal Studio instructions to complete the connection, then perform the following steps to interconnect the X-Series signal analyzer and MXG (see Figure 1 for a graphical overview):

a. Connect the MXG RF output port to the X-Series signal analyzer RF input port

b. Connect the MXG 10 MHz out to the X-Series signal analyzer Ext Ref in port (rear panel)

Demonstration 1:

Set up Signal Studio for digital video on the MXG

The N7623B Signal Studio for Digital Video is a Windows-based utility that simplifies the creation of standards based or customized digital cable TV signals, including DVB-C (J.83/A), J.83/B, and J.83/C, and then the parameters are downloaded into the MXG vector signal generator, which creates the desired waveform. In this demonstration guide, DVB-C (J.83/A) signals are used as an example.

Demonstration 2:

Channel power

The channel power measurement measures and reports the integrated power in the digital cable TV defined bandwidth and power spectral density (PSD) displayed in dBm/Hz or dBm/MHz.

Demonstration 3:

Adjacent channel power (ACP)

Adjacent channel power can measure and report the power in one or more transmit channels. The text window shows the total power within the defined carrier bandwidth and at given frequency offsets on both sides of the carrier frequency.

Demonstration 4:

Power stat CCDF

The power stat complementary cumulative distribution function (CCDF) is a statistical method used to interpret the peak-to-average ratio of digitally modulated noise-like signals. It is a key tool for power amplifier design for digital cable TV transmitters, which is particularly challenging because the amplifier must be capable of handling the high peak-to-average ratio while maintaining good adjacent channel leakage performance.

Demonstration 5:

Spectrum emission mask

The spectrum emission mask (SEM) measurement compares the total power level within the defined carrier bandwidth and the given offset channel on both sides of the carrier frequency to levels allowed by the standard or manually set by the user.

This measurement refers to the design of the power amplifier in the transmitter, and it is a key measurement linking amplifier linearity and other performance characteristics to the stringent system specifications.

Demonstration 6:

Modulation accuracy

Measurement of modulation accuracy and quality are necessary to meet test requirements defined in ETSI TR 101 290 and ensure proper operations of the transmitters.

Error vector magnitude (EVM) and modulation error ratio (MER) present the total signal degradation including noise, interferences, or distortions at the input of a commercial receiver’s decision circuits to give an indication of the ability of that receiver to correctly decode the signal.

The modulation accuracy measurement provides many methods for measuring the errors in a digital cable TV transmitter. In the measurements, you can measure the EVM, MER, magnitude error, phase error and more.

Demonstration 7:

Monitor spectrum

The monitor spectrum measurement is used as a quick, convenient means of looking at the entire spectrum. While the look and feel is similar to the spectrum analyzer mode, the functionality is greatly reduced for easy operation. The main purpose of the measurement is to show the spectrum.