Oscilloscopes are 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&SRTH-K38 user scripting software option makes the R&SScope Rider RTH handheld oscilloscope 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&SRT-ZC03 current clamp is connected to the railway track and channel 1 of the R&SRTH. Then the R&SRTH-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, 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 Autorange function automatically sets the vertical scaling of the oscilloscope to match the current values and avoid overranging.
You can find an exemplary display screenshot below:
Detailed instructions on how to generate a user script for the R&SRTH-K38 option and how to load it onto the device can be found in the R&SScope Rider RTH user manual.