# Wireless Data Acquisition System with Feedback Function
## Appendix D  
To test the performance of the above-described sensor and determine its range in real conditions of the SWPP ToU hardware, a simplified receiver of its signals was designed and built, not containing a real-time clock (RTC) and IR-RPG. This work was based on the technical solutions and algorithm formulated in [44]. The appearance of the testing equipment on the receiving side is shown in Figure A3a. In Figure A3a, number 1 indicates the sensor signal receiver on the Attiny2313A MCU, number 2 indicates the radio module of the JDY-40 transceiver, and number 3 indicates the TTL-USB converter connected via USB-HUB to a personal computer (PC).  
To determine the maximum range of data transmission, a program was installed in the sensor microcontroller that implements the mode of continuous automatic measurement and the cyclic transmission of measured values to the receiving and recording device. The sensor with an SWPP battery simulator and an SWPP load simulator in the form of a miniature incandescent lamp connected to it gradually moved away from the receiving set of equipment. Using the \"Terminal V.9b\" program on a PC, time stamps were generated and the voltage and current of the battery and load simulators received over the radio channel, measured by the sensor, were generated and recorded in a file. Fragments of received data recorded as the distance increases are shown in Figure A3b, with the upper lines corresponding to a sensor distance of 5 m, and the bottom lines representing a distance of 20 m. The minus sign in front of the current value indicates the battery discharge mode.  
Figure A3: The appearance of the testing equipment on the receiving side and the results of testing the system for the transmission range: the appearance of the testing equipment on the receiving side (**a**); fragments of the received data recorded as the distance increases (**b**).  
The testing equipment made it possible to record in a log file a protocol for receiving signals from a wireless sensor as it gradually moved away from the set of receiving equipment at a distance from 5 to 20 m. The receding rate was kept constant throughout the experiment, so that given the starting and final distances, the transmission distance could be determined for any time recorded in the log file. If even one erroneous parcel is received out of four sent in a row, the receiver software automatically issues a \"#\" sign to the terminal. The absence of such a sign in the line means full compliance of the received data with the transmitted data.  
Analysis of the log file shows that single reception errors (automatically marked with a \"#\") began at 13:37:37, when the sensor was moved outside the Green Energy equipment room to the far end of the corridor, and the signal was transmitted through two internal reinforced concrete walls.  
The distance from the sensor installation sites to the receiving equipment installation site in the equipment room did not exceed 4.5 m; therefore, the result of the range tests should be interpreted as the possibility of error-free data reception using the described equipment with a four-fold range margin.