# Non-Real-Time Wireless System for Lightning Effect Measurements
## 5 Results  
In order to present the operation of the proposed solution, measurements of impulse voltages are presented. To verify the obtained data, they were compared with the readings made by the RIGOL oscilloscope. The first example regards the impulse, which is similar to those defined in DO-160 (WF4 with the waveshape 6.4/69 \(\upmu\)s) but is 10 times faster (Figure 5). The accuracy of the measurement was 85%. The shape of the tested signal is good. The number of samples allowed to recreate the pulse shape and observe the disturbances. The amplitude of the signals measured with the prototype system was about 10% lower than the reference. This can be corrected by calibrating the device. The influence of electromagnetic disturbances produced by circuits of the impulse generator and propagating in the air was significant, and the shielding allowed for their reduction. Figure 6 shows disturbances without (the accuracy of the measurement was 66%) and with shielding (the accuracy of the measurement was 85%)  
Figure 4: Block structure of the measuring device. Figure 5: The measured waveform of the shock pulse along with the reference measurement. using steel cover. The reference signal was presented too, directly from the oscilloscope to compare differences between shapes of impulses. During the selection of the shielding material, 0.5 mm thick aluminum alloy and 1 mm thick carbon steel were tested. For the screen made of steel, a clear reduction of the disturbances in the course of the recorded pulse was observed. For the aluminum screen, the change was less pronounced (Figure 7) and the accuracy of the measurement was 48%. A combination of both types of materials was also used because aluminum has better absorption properties for the electric component of the field, and steel for the magnetic component of the field [22]. The effectiveness of shielding is influenced not only by the type of material, but also by its thickness and shape as well as the correct selection of holes required  
Significant disturbances are clearly visible in Figure 8, which shows the registered impulse waveform without and with the shielding enclosure. Their source was the semiconductor switching circuits and other elements being a part of the generator. These disturbances are even more clearly shown in Figure 9 when the reference signal represents a sine wave with a frequency about 10 times greater than the maximal frequency in the signal spectrum depicted in Figure 6, and 100 times greater than in the WF4 type signal. With such a high frequency signal, the capabilities of the proposed measuring system were clearly visible. A negative polarity was chosen to verify the correctness of the measurements for the entire measuring range. Interference without shielding of the tested device prevents correct measurements. Periodic disturbances are clearly visible in the sine wave. On the rising edge, they have a positive component (amplitude gain) and for the falling edge they have a negative component (they reduce the signal) as shown in Figure 9. The measurements were made for the maximum sampling frequency and sinusoidal signal with a frequency of 300 kHz. Figure 8: Pulse recorded with and without a shielded device for the maximum sampling rate. Figure 9: Noise in the sinusoidal waveform for unshielded measurements in relation to an oscilloscope. The accuracy of the measured signal was not tested. This example was intended to show generator noise and propagation in the environment. The influence of the measuring probe grounding on the intensity of the electromagnetic disturbance in the measured impulse was also verified. When measuring surge discharges, it is very important to ground all components of the measurement system. This ensures noise reduction. In the configuration with the earthing system, a steel casing connected to the protective conductor (PE) of the TN-C-S electrical system was used (Figure 10). The lower disturbance absorption capacity of the steel cladding made it possible to show the differences.