Measurements of wireless information and power transmission parameters
Description of the Technology
The measuring system consists of a transmitting device and a receiving device. The transmitting equipment consists of a program-controlled radio module USRP B210 together with a radio frequency signal amplifier and an antenna. The operation of the USRP B210 is controlled by a USB interface using the MATLAB computer program, which allows to define the shape and frequency of the radio frequency signal from 70MHz to 6GHz. The transmitter together with the amplifier can generate signals of the user-selected shape with output power levels from -60 dBm to 30 dBm. The receiving device consists of a receiving antenna to which the research module is connected (Fig. 1 is a sample connected to a converter that stores energy from the transmitted radio frequency signal). The output voltage and power of the study module are measured with the help of the high-frequency oscilloscope Tektronix 72004C. The oscilloscope has 4 channels with a 20 GHz input signal band and a 100 GS / s drop rate. The oscilloscope data is read by a computer using the developed MATLAB computer program. This allows data to be saved for further processing. On the other hand, if various RF-DC converters are used, it is possible to accurately measure the output voltage with a controlled power supply Keysight B2901A, which is also controlled by a computer.
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Fig. 1. Wireless channel measurement system
Applications
The system can experimentally test the effect of the transmitted signal's shape on the performance of wireless power transmission (WPT), the efficiency of the wireless power transmission depending on the distance between the antennas of two devices, and a comparison of the performance of different RF-DC converter modules. With the given measurement system, it is possible to determine the influence of the wireless channel on the radio signal transmission depending on the parameters of the indoors wireless channel, the frequency of the transmitted signal, antenna type, antenna orientation, and distances between equipment.
Advantages
The system offers a wide range of research parameters: testing the effect of antenna distance, type and position, researching the parameters of the signals for wireless transmission, researching the performance of the receiver module for information or energy transfer. Measurement data is obtained automatically using developed MATLAB programs and is easily available for post-processing. The system can perform measurements in the most common freely available frequency bands that are part of ISM bands: 433.05 - 434.79 MHz, 863 - 870 MHz, 902 - 928 MHz, 2.4 - 2.5 GHz, 5.180 - 5.875 GHz. It is possible to perform measurements for 5G devices, WSN sensor nodes (for IoT), WPT systems.
Keywords
Measurements,wireless power transfer,wireless channel,antennas,signals