## 3 Experimental Data and Results
### Utility of Environmental Sensors in Mobile Telephony in the Direct Communication Process
The cause of this anomaly is a much higher bit error rate (BER) and low efficiency, putting delay thresholds in LED lighting of about 50 ms; if we add this fluctuating delay every 10-15 ASCII characters, we obtain an extremely useless 200 ms time factor. During the external measurements, the reception was configured on the threshold of light intensities from 1 to 255 to be able to have data even from small intervals. A serious problem is that of the refresh rate and the saturation of the sensor; when the light is too strong, it fails to differentiate the ASCII characters, the demodulation being performed with a delay of about 5 ms. In the external environment, the following aspects were highlighted at distances of 5 m, 10 m and 15 m in a straight line from a traffic light area:  
* Divide the brightness range between minimum and maximum equally for each character; the ambient light sensor will not be effective if it needs to analyze all 255 characters from a greater distance. * TrafficLight2P color and hazardous area identification returned tangible values regardless of background noise or brightness value. * The measurements were performed at a time of day when the entire lighting system was at full capacity and created a disruptive factor in most of the areas analyzed. * Messages sent from another device in the nearby area complied with the algorithm, and the transmission interval for ASCII and decoding characters did not exceed 10 ms.  
As we can see in Figure 15, the application is structured extremely minimalist, with a relative layout, with a progress bar that collects information from sensors and classifies them according to the constraints created in the activity log. Regarding the identification of the traffic light colors, it was chosen to add a contrasting traffic light that changes its color according to the identified detection, with the mention that besides this aspect, the application also leaves alert-type messages. Messages are designed to warn the user and make them check the information. The center of the screen shows the data collected from the sensors and the warning messages; if things degenerate, there are predefined functions that automatically call the emergency numbers if the user does not close the information note within 10 s of its triggering. According to Figure 16, we exemplify the process of analysis and identification of light signals emitted by the traffic light system. The illustration shows the maximum distance at which the light intensity was identified, namely 15 m, enough to create a decision-making factor to prevent a major situation in which a pedestrian is involved without endangering their life. Therefore, analyzing the distance, we can show the aspect that the application and the researched direction offer perspectives in future developments with the mention that at this moment this type of communication can be viable only at night. The transmitted messages are received in the form of ASCII characters, displaying a warning message; considering BER, this is uncertain due to the mapping of the data for each bit exposed to light resonance. If we change the position of the device, we can have an area of incidence of +/ - 10 mm, the BER being extremely high and the data inconclusive. According to Table 4, the information shows the light intensity that the device receives and the distance that it is at. Figure 16: Exposure of the application in a dynamic environment, making measurements over a maximum distance of 15 m.  
Figure 15: Android Studio interface dedicated to the color analysis of traffic lights and direct communication with other users. Pedestrian and road safety and prevention events. Depending on the amount of light received, we can show another aspect: in conditions of heavy traffic or taillights, we have a high degree of saturation and stray light. Being in an early stage of development, the goal was to demonstrate the ability to communicate through visible light using mobile devices.