Test & measurement
be examined separately. The required trigger settings are described in detail in an application card. Pulses are selected according to time criteria in A-B-R trigger mode. In this example, the A-B-R trigger will only cause pulses with a width of 1 µs to be acquired (Fig. 5). Another analysis option is fast segmentation mode. If an airborne radar
transmits pulses with a PRI of 100 µs, a 1s simulation period would require 40 Gbyte of memory capacity (40 Gsample/s × 1s × 1 byte/sample). Using the A-B-R trigger, the recording period per acquisition is reduced to 1.2 µs (48 ksample), and a period of 4.16 s is continuously recorded in the oscilloscope 2 Gsample segmented memory.
Fig. 2: Simulated DRFM scenario. The envelopes of the original and the replicated pulse are calculated using math functions. The time delay between the two pulses is determined over all acquisitions (here: 1000) and displayed over the entire measurement time using the oscilloscope’s delay measurement function. The sawtooth curve indicates that an object is moving away.
Fig. 3: Example measurements on a radar warning receiver. The radar scenario was generated with the R&S Pulse Sequencer software.
Fig. 5: The radar of the patrol aircraft is isolated in the multiradar scenario using A-B-R triggering on one of the two RWR receive channels (yellow channel).
DeDicateD solution for aDvanceD multichannel pulse analysis
Radar developers often need to measure specific pulse parameters such as pulse width, droop and PRI. Here it is advisable to use specialised software that can determine these parameters automatically. The R&S VSE K6A extended pulse analysis option available for the R&S VSE vector signal explorer software now supports phase coherent multichannel analysis. All functions of the oscilloscope trigger unit are available with this option, ensuring stable and precise detection of the pulses to be analysed.
Fig. 4 (above): Radar scenario simulated with the R&S Pulse Sequencer software in the program-specific representation. In this scenario, the radar warning receiver, or the oscilloscope, sees multiple different pulse shapes (screenshot below).
Fig. 6: Using the R&S VSE software to analyse the example airborne radar signal on the simulated outputs of a dual-channel radar warning receiver. R&S VSE automatically measures the radar parameters and displays them in tabular form. Phase and amplitude differences can be determined in detail using markers
Beside comparing the input and output signals of a DRFM module, the
R&S VSE software can be used to analyse radar warning receiver performance. In A-B-R trigger mode, the software measures in detail the airborne radar signals in the RWR (Fig. 6). Using the R&S VSE analysis routines, the phase difference between the two receive channels can be determined, either via markers or from tabular values. The results can be used, for example, to determine RWR long-term stability by observing the trend or the phase distribution.
Rohde & Schwarz Instrumentation Monthly August 2021
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