Test application case of DTF function in RSA spectrum analyzer vector network analysis mode

In the previous technical articles "Revealing the Vector Network Analysis (VNA) Mode of RIGOL RSA Spectrum Analyzer" and "Understanding VNA Advanced Testing in One Article", the editor introduced the basic principles and corresponding functions of the vector network analysis mode of RIGOL RSA Spectrum Analyzer. functions and applications.

In this article, the editor will introduce to you the test application case of DTF function in Yanet analysis mode, so as to better help engineers solve practical application problems!

Contents of this issue

Video demonstrates how to use the DTF function in the VNA mode of the RSA spectrum analyzer to measure cable length and locate fault points.

Case Background Cable Fault Point Testing

During the installation, operation and maintenance of telecommunications systems, line damage due to improper installation or over time is one of the main causes of transmission failures. For example, before and after installation, cables may become dented, crushed, or damaged due to improper routing, thereby degrading electrical performance. In on-site operations, it is important to quickly diagnose and locate cable faults and damage. The use of DTF can detect line problems and hidden dangers early and deal with them as soon as possible, which can largely avoid the occurrence of communication interruption accidents and reduce the impact and cost of accident handling.

Quick Review of DTF Testing Principles Testing Principles DTF Functions

DTF is an extended application of S11 measurement. It measures the reflected wave of the cable under test in the frequency domain to locate fault points in the cable. DTF first determines the reflection vector within the frequency band by comparing the reflected signal to a reference signal created by the tracking source, and then performs an inverse fast Fourier transform (IFFT). Combined with the characteristics of the cable model, the distance of reflection propagation can be quickly determined and the fault point in the cable can be accurately located.

Teach you how to use the DTF function in three minutes

Measure cable length and fault point

Video demonstration

Test steps

How many steps are needed to measure the cable length and fault point?

test preparation

1. Prepare a spectrum analyzer with built-in VNA vector network analysis mode. This time we use RIGOL RSA5065N;

2. Prepare RIGOL CK106A calibration kit for open circuit, short circuit and load calibration;

3. Connect the cable to be tested and prepare for testing.

Instrument calibration

1. Click MODE to enter the mode selection interface and select the VNA vector network analyzer function;

2. Click meas to enter the test options and select the DTF function;

3. Use the calibration piece for calibration, connect the open-circuit calibration piece to the measurement port of RSA5065N, and click Calibrate;

4. After the display calibration is completed, connect the short-circuit calibration piece and the load calibration piece respectively to perform calibration.

Cable test

1. Connect the test cable, click peak, and the test cable length will be displayed in the upper left corner of the screen;

2. If there is damage inside the cable, you can locate the cable damage point through the length of the cable where the peak value is located.

Things to pay attention to and focus on

Please do not come into contact with the calibration parts during the calibration process to ensure the accuracy of the calibration.

The speed factor of the cable under test needs to be confirmed before calibration.