# Real-Time Performance Measurement Application via Bluetooth Signals for Signalized Intersections
## 2 Materials and Methods
### Bluetooth-Based Traffic Analysis Detector  
Bluetooth-based traffic analysis detector is a sensor that includes a Bluetooth module, digital processor, peripheral equipment, communication module, and software. This sensor is designed to receive data, encode it, and transmit it to the data collection center via the communication module. The sensor detects the MAC addresses of the Bluetooth devices in its location and transmits them to the data collection center. The Bluetooth-based traffic analysis detector structure is seen in Figure 4.  
Bluetooth traffic analysis sensor is a device designed to monitor and analyze traffic flow. These sensors track the movements of vehicles and road users using Bluetooth technology. By detecting devices that emit Bluetooth signals (mobile phones, wireless  
Figure 3: Fully adaptive signaling system image-processing-based sensor. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Traffic Flows** & **Q5** & **Q6** & **Q7** & **Q8** & **Q9** & **Q10** \\ \hline
**Q5** & & O.K & O.K & NO & NO & NO \\ \hline
**Q6** & O.K & & NO & O.K & NO & NO \\ \hline
**Q7** & O.K & NO & & NO & NO & NO \\ \hline
**Q8** & NO & O.K & NO & & NO & NO \\ \hline
**Q9** & NO & NO & NO & NO & & NO \\ \hline
**Q10** & NO & NO & NO & NO & NO & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Matrix phase structures according to traffic flows. headsets, in-car Bluetooth devices, etc. ), it collects information such as traffic volume, speed, direction, and travel time in a particular area. The technical specifications of the designed Bluetooth traffic analysis sensor are given in Table 4.  
In Bluetooth traffic analysis sensors, the effective Bluetooth range and possible interferences are critical factors that directly affect the efficient operation of the sensors. Bluetooth sensors generally work effectively up to 100 m. This range can vary depending on the Bluetooth version used, the sensor's power settings, and environmental factors. Bluetooth 5.0 and above versions can offer a wider range and transmit data over longer distances with low energy consumption. If the sensor is installed in an open area and there are no obstacles in front of the signal, the range can be reached at the maximum level. Physical obstacles such as buildings, vehicles, and trees can weaken the Bluetooth signal, causing the range to decrease. This weakening can be more pronounced, especially in densely populated areas such as urban areas. The installation of the sensors should be made by taking these factors into consideration. Bluetooth traffic analysis sensors can be exposed to various interferences caused by environmental and technological factors. Bluetooth operates in the 2.4 GHz ISM band, which is also used by many other devices such as Wi-Fi and Zigbee. This can cause radio frequency interference and can lead to signal loss, range reduction, and data transmission delays. Bluetooth signals can be suppressed, especially in areas with heavy Wi-Fi traffic. In areas with many reflective surfaces, such as urban \begin{table}
\begin{tabular}{c c} \hline \hline
**Technical Specification** & **Bluetooth Traffic Analysis Sensor** \\ \hline Processor & ARM 9 \\ Signal Capture Types & Bluetooth, BLE \\ Memory & 512 MB RAM, SD Storage \\ Communication Channels & GPRS Modem, Ethernet \\ Antenna & 12 dBi 90 Degree Adjustable Antenna \\ Screen & 0.96 Inch OLED Screen 128x64 \\ Operating Voltage & AC 220 Volt \\ Operating Temperature Range & \(-30\)\({}^{\circ}\)C\(\rightarrow\)70 \({}^{\circ}\)C \\ Protection Class & IP65 \\ Case Material & ABS \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The technical specifications of the designed Bluetooth traffic analysis sensor. Figure 4: Bluetooth-based traffic analysis detector structure. areas, Bluetooth signals can reach the sensor by reflecting off surfaces such as buildings and vehicles via multiple paths. This is known as multipath propagation. The fact that signals reach the sensor at different times can reduce the quality of the signal and cause errors in distance measurements.