Introduction
Wireless connections in ordinary cars use RF (radio frequency) waves which are controlled using a special remote. The ease of control and the security system that can be monitored using only one communication device such as a smartphone that can support a wifi network connection is an opportunity to develop a car security system. In use, wifi.
2.1 Wi-fi[2]
Wifi is short for Wireless Fidelity, which means a set of standards used for wireless local networks.
2.2 Microcontroller AVR ATMega8535
AVR has 32 general-purpose registers, flexible timer / counter with compare mode , internal and external interrupt, UART serial, programmable watchdog Timer, and power saving mode, ADC, and internal PWM . The AVR also has an on-chip In-System Programmable Flash which allows program memory to be reprogrammed in the system using a Serial Peripheral Interface
connection
2.3 Module Ethernet Wiz110SR[4]
WIZ110SR is a gateway module that converts RS-232 protocol to TCP/IP protocol. It allows control of devices over networks based on ethernet and TCP/IP by connecting to existing equipment with an RS 232 serial interface. The physical form of the WIZ110SR ethernet module can be seen in Figure 1
2.4 Android Operating System[5]
Android is a mobile operating system that adopts the Linux operating system, but has been modified. Android was taken over by Google in 2005 from Android, Inc. as part of a strategy to fill the mobile operating system market.
2.5 IP Camera[2]
An IP Camera is a CCTV (Closed-circuit television) camera that uses the Internet Protocol (IP) to transmit image data and control signals over a Fast Ethernet link. IP Cameras can also be referred to as network cameras, a number of IP Cameras.
2.6 Central lock[6]
Central lock is a car door security system (car door lock) that is driven electrically (using an electric motor) and regulated electronically by the control module, so that it can be operated centrally (central). This means that by only locking/opening one door that is used as the center, then the other doors are also locked/opened
3.1 Block Diagram
The system will consist of 2 blocks, namely the remote block and the car block. The remote block is a smartphone device, while the car block consists of several devices such as an access point, IP camera, WIZ110SR AVR module, Atmega single 8535, chip central lock, car starter, and alarm sensor.
In flowchat remote block program will be declared character and IP address then the program will check whether the alarm sounds or not. If correct, the smartphone will receive the number 3 and there will be a warning sound on the smartphone. If the alarm does not sound, the program will perform monitoring and control. When the smartphone is monitoring, the program will be connected to the IP Camera so that the image from the IP camera will be displayed to the smartphone.
In the flowchat, the car block program will declare characters and IP addresses, then the program will check whether the alarm sounds or not. If true, the single chip will send the number 3. If the alarm does not sound, the program will monitor and control. When monitoring, the program will be connected to the IP Camera so that the image from the IP camera will be displayed to the smartphone.
3.4 Android Smartphone Display Design
The design of the security system display on an android smartphone that is used as control and monitoring can be seen in Figure.
3.5 Device Design in Cars
The design of the device in the car security system that is used as control and monitoring is shown in Figure 9
4.1 Current Measurement on the Device Used
Current measurement on the device is carried out to determine the current consumption of conventional devices and car block devices.
The power level measurement is carried out to determine the effect of distance on the received transmit power on conventional devices and on Android smartphones. The block diagram
of the power level measurement can be seen in Figure 13, Figure 14
Figure 16 is the result of measuring the average power level carried out for 5 times taking at each distance with the center frequency on the spectrum analyzer, which is 300,151 MHz. The
block diagram for measuring the power level on the car remote can be seen in Figure 13. In Figure 13 it can be seen that it functions as a transmitter, namely a remote car and on the
receiving side in the form of a periodic log antenna using a spectrum analyzer to determine the received power level, while in Figure 14 and Figure 15 the transmitter function is an Access Point device and on the receiving side. in the form of an android smartphone using the wifi analyzer application to determine the received power level. For measuring the distance of the signal range when the antenna is in a position in the car, the maximum range of conventional remotes and smartphones is the same, which is 75 meters. Meanwhile, when measuring the distance of the signal range when the antenna is in a position outside the car, the maximum distance using an Android smartphone is 175 meters compared to a conventional remote which is only 100 meters. So to extend the signal range, the wifi antenna should be outside the car and picture 15.
From these 5 results, the average power level will be obtained. From Figure 16 it can be seen that the power level generated by the remote is quite small because the remote uses ASK communication. In Figure 16 it can also be seen that the effect of remote distance on the received power level on the spectrum analyzer where the closer the remote car distance to the receiving antenna (log periodic) the greater the received power level.
In Figure 17, 5 times the power level is taken at each distance with the current condition without obstacles or with obstacles. From Figure 17 it can be seen that the comparison of the received power level without a barrier with when there is a barrier.
5.1 Conclusion
1. The current consumption of the car block device is greater than that of the conventional device, this is due to the presence of several additional devices.
2. The wifi coverage distance reaches 175 meters in an open area in the parking lot with the antenna condition being outside the car.
3. The power level received on android smartphones when there are obstacles is smaller than when there are no obstacles.
4. The acceptable range on an android smartphone when the antenna is outside the car is farther than when the antenna is in the car, both when there is an obstacle or without a barrier.
5. The closer the smartphone is to the wifi antenna, the greater the received power level.
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