HARDWARE IMPLEMENTATION OF FISHERMEN RADIO FOR DATA COMMUNICATION VIA AUDIO SIGNAL ON VERY HIGH FREQUENCY (VHF) SPECTRUM

• Main Author: Shafira Khoirunnisa, Dian
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63738
• Institution: Institut Teknologi Bandung

Communication is one of the important aspects in the world of shipping. However, this communication is limited to large vessels, which incidentally have a gross tonnage (GT) value of more than 300. Apart from that, small ships and boats with a gross tonnage value of one to three GT, which are usually driven by small fishermen, do not yet have an adequate and structured communication system. In addition, the price of ship communication equipment, which tends to be high, is also why small fishermen are reluctant to use it. Due to the absence of this communication tool, the fishermen do not have access to contact the mainland if something unexpected happens while at sea. Although some fishermen already have their own means of initiation, the frequencies used are still mixed with the frequencies used by airlines. This can be dangerous for the user of the flight frequency. Therefore, it takes a communication tool in the form of a low-cost fisherman's radio that specifically operates on maritime frequencies and can send fishermen's location points when they are at sea so that rescue actions can be taken immediately if something unexpected happens while the fishermen are at sea. The manufacture of Fisherman's Radio made in this Final Project has the main purpose of providing security and safety facilities for small fishermen who are at sea. This Fisherman's Radio is deliberately designed with components that can be afforded by small fishing communities. The hardware part of the Fisherman's Radio consists of a transmitter and a receiver. These two hardware components will communicate to send and receive data in the form of fishing boat locations using a GPS (Global Positioning System) module on the Very High Frequency (VHF) spectrum for the Indonesian maritime frequency, which is more precisely at the frequency of 156.5 MHz. The data which is a series of strings is first translated into an audio signal. The translation process is carried out using Morse code. Morse encoding was deliberately chosen because this method is commonly used in conventional shipping communications.The Morse encoding process occurs on the Arduino Nano microcontroller. Audio signal transmission is carried out using the DRA818V module. The audio signal will be sent by a transmitter located on the fishing boat and will be received by a receiver on the mainland. The audio signal that has been received by the receiver is then retranslated back into a string of strings in the form of fishing boat locations. This re- iv translation process is carried out using the Groetzel algorithm which is often used to detect the tone of an audio signal. The result of this re-translation is then processed in such a way that it can be viewed through a website-based dashboard display so that it can be accessed easily by anyone. The frequency of the transmitter and receiver is set to 156.5 MHz in accordance with maritime VHF frequency rules in Indonesia. The audio signal sent by the transmitter has a bandwidth of 3,833 kHz. In the test, several next peak frequencies were detected. However, the power from the next peak frequency is much lower than the power at 156.5 MHz. Thus, the possibility of interference resulting from the next peak frequency can be ignored. The decoded result of the audio signal received by the receiver and processed by the audio amplifier can be seen on a liquid crystal display (LCD). Decode testing on the receiver can be done with the furthest distance from the transmitter, which is 290 meters. The decoding process is carried out one character at a time. Therefore, a process is needed to sort this decoded character in NodeMCU. NodeMCU will receive the decoded characters one by one from the transmitter and then sort these characters into a unified whole GPS location and group them into latitude and longitude data. This process is carried out with a finite state machine (FSM). The result of this sorting is in the form of data of type String consist of latitude and longitude data. This string will then be sent to the dashboard database to be displayed in the form of a website. This integration test with NodeMCU shows an error rate of 0.367 or 3.67%. This Fisherman's Radio was made based on the development of maritime communication radio which was initially only used to transmit voice, but now can also transmit data, with the same type of modulation. Thus, the existence of this Fisherman's Radio can provide an insight into data communication systems that can be carried out using analog modulation.