RANCANG BANGUN DEMODULASI DOPPLER TONE 500 HZ
PADA RADIO DIRECTION FINDER JALUR
VERY HIGH FREQUENCY
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Institusion
INSTITUT TEKNOLOGI DIRGANTARA ADISUTJIPTO
Author
AFFAN ROSADI, AHMAD
Subject
T Technology (General)
Datestamp
2024-03-27 02:16:25
Abstract :
At this time communication is growing rapidly so that it can track the location of its users. However, this system is expensive, at the same time volunteers and public service organizations are constantly struggling with shrinking budgets. One method of detecting the presence of a radio transmitter can be detected using the Doppler effect method, by using the frequency difference that occurs at 500 Hz Doppler when the radio transmitter moves closer to or away from the detector. The 500 Hz Doppler generated by RDF is modulated with a frequency of 146 MHz used in Handy Talky (HT). The received 146 MHz frequency is outputted as voice data while the 500 Hz Doppler frequency received is returned in its original form by forwarding the frequency to the demodulation system and processed in the HPF and LPF circuits and then forwarded to the digital filter. After the filtering process the 500 Hz frequency is forwarded to the zero-crossing detector to change the frequency form from sine to square. The square frequency output is passed to the adjustable delay to determine the pulse width and is displayed on the LED display. The results of the research show that the tool can function properly to determine the location of the transmitter by utilizing the Doppler effect. The antenna used can detect when there is a difference in the received frequency when the transmitter moves closer to or away from the detection antenna. This research detects Very High Frequency (VHF) 146 MHz which is modulated with 500 Hz Doppler tone. On the LED display which is designed in a 360-degree circle with a total of 16 LEDs and the distance of each LED is 22.5 degrees, it can display the location of the transmitter well.
At this time communication is growing rapidly so that it can track the location of its users. However, this system is expensive, at the same time volunteers and public service organizations are constantly struggling with shrinking budgets. One method of detecting the presence of a radio transmitter can be detected using the Doppler effect method, by using the frequency difference that occurs at 500 Hz Doppler when the radio transmitter moves closer to or away from the detector. The 500 Hz Doppler generated by RDF is modulated with a frequency of 146 MHz used in Handy Talky (HT). The received 146 MHz frequency is outputted as voice data while the 500 Hz Doppler frequency received is returned in its original form by forwarding the frequency to the demodulation system and processed in the HPF and LPF circuits and then forwarded to the digital filter. After the filtering process the 500 Hz frequency is forwarded to the zero-crossing detector to change the frequency form from sine to square. The square frequency output is passed to the adjustable delay to determine the pulse width and is displayed on the LED display. The results of the research show that the tool can function properly to determine the location of the transmitter by utilizing the Doppler effect. The antenna used can detect when there is a difference in the received frequency when the transmitter moves closer to or away from the detection antenna. This research detects Very High Frequency (VHF) 146 MHz which is modulated with 500 Hz Doppler tone. On the LED display which is designed in a 360-degree circle with a total of 16 LEDs and the distance of each LED is 22.5 degrees, it can display the location of the transmitter well.
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