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Simplify railway field maintenance with R&S®Scope Rider RTH user apps

Oscilloscopes are basic everyday instruments for engineers and electricians. Maintenance tasks, however, sometimes require very specific measurements that are not available as standard functionality or are difficult to set up manually. For instance, the R&S®RTH-K38 user scripting option solves one of such non-conventional requirements.

Use case

As are a railway engineer, a user is definitely dealing with the task of verifying the quality of elec­tric communications signals, for example, to determine the position of a train on its track. This is usually done by dividing the track into sections of rail with alternating frequencies, typically 95 Hz and 105 Hz. When a train is located within a specific section, the wheels short circuit the signal, indicating the position of the train to the receiver.

Such a specific measure­ment is certainly not a standard functionality on any hand­held oscilloscope. Sometimes auto­matically executed setup on the device, a display of the maximum values of the currents and a graphical represen­tation are requested in order to make operation as simple as possible for the engineers.

Measurement with user apps

The R&S®RTH-K38 user scripting software option makes the R&S®Scope Rider RTH handheld oscilloscope (125-9462) a power­ful tool for automated or guided non-standard measure­ments in maintenance and service applications. The option allows users to run individual measurement scripts on the device using the built-in web browser, JavaScript and the full functionality of the instrument via SCPI commands. It provides an easy-to-program and easy-to-use HTML user interface for fast measurement in the field. The user script is a combination of HTML to for the user interface and JavaScript to control the instrument via SCPI commands. Besides, a simple user interface can be designed with the help of this option.

Automated measurement script

To measure the railway isolation, an R&S®RT-ZC03 current clamp is connected to the railway track and channel 1 of the R&S®RTH. Then the R&S®RTH-K38 user script option is activated. Overall, it is an extremely simple process and only requires three interactions.

The user script automatically configures the instruments into spectrum mode, sets the cursor to the defined fre­quencies and reads out the spectral amplitude at the re­spective frequencies. The currents for the four defined fre­quencies are converted into Ampere from the dBA values in spectrum mode as follows:

The current values are displayed in A, mA or μA in an HTML based browser window of the oscilloscope. The script not only automates the entire measurement proce­dure, but it also makes it possible to perform sequenced cur­sor measurements at more than two frequencies.

In the JavaScript program, four additional variables are used to track the maximum current for each frequency and to display this information. In addition, a trend plot displays and logs the current values over time with automatic adjustment of the vertical scale of the graph. To reset the maximum value and restart the measurement, a counter and a “Reset Max Values” button were added. Finally, an Auto range function automatically sets the vertical scaling of the oscilloscope to match the current values and avoid over ranging.

You can find an exemplary display screenshot below:

Detailed instructions on how to generate a user script for the R&S®RTH-K38 option and how to load it onto the de­vice can be found in the R&S®Scope Rider RTH user manu­al.

Rohde & Schwarz is a high-tech company that thrives on innovation. To maintain its high quality standards, Rohde & Schwarz keeps almost the entire value chain within the company while the majority of products are developed in Germany. The Munich based technology group develops, produces and sells a wide range of electronic capital goods for industry and government customers with a focus on solutions that contribute to a safer and connected world.

20 May 2020, 9:48