Penerima Sinyal Emergency Locator Transmitter dengan Metode Direct Receiver pada Frekuensi 121,5 MHz

To find out the location of an aircraft accident from an ELT signal beam of 121.5 MHz, search and rescue (SAR) officers or civil aviation authorities need an ELT signal receiver device that works at the same frequency, which is 121.5 MHz. The purpose of this research is to produce an ELT signal receiver with direct receiver method at a frequency of 121.5 MHz which is simpler, requires fewer RF devices, and is according to specifications for civil aviation. In this research, the design and realization of ELT signal receivers are carried out using the direct receiver method, including: a BPF and a RF amplifier as a direct receiver circuit, an AM demodulator, and an audio amplifier. Based on the results of measurements and tests that have been done, the direct receiver circuit can receive an ELT signal at a frequency of 121.5 MHz in the range of 121.330 to 121.617 MHz with -40.35 dB sensitivity, the AM demodulator can demodulate the audio signal at a frequency of 346.6 Hz, and the audio signal at a frequency of 337.6 Hz as a pointer to an ELT signal can be heard through the loudspeaker. The results of this study are ELT signal receivers with direct receiver method at a frequency of 121.5 MHz which are according to specifications for civil aviation.

OSILATOR 121,5 MHZ PADA ELT MENGGUNAKAN VCO MC1648

Pada saat terjadi kecelakaan pesawat terbang di suatu tempat, dapat diketahui posisi atau lokasinya dengan menggunakan suatu alat yang diletakkan pada badan pesawat terbang tersebut, yaitu emergency locator transmitter (ELT). Pada ELT terdapat komponen osilator sebagai pembangkit sinyal pada frekuensi 121,5 MHz, dengan spesifikasi militer yang tidak tersedia di pasar bebas. Pada penelitian ini dilakukan perancangan dan realisasi voltage controlled oscillator (VCO) menggunakan MC1648 sebagai osilator pada frekuensi 121,5 MHz, serta implementasinya pada pembangkit sinyal ELT. Hasil pengukuran menunjukkan VCO sebagai osilator dapat membangkitkan sinyal keluaran berupa gelombang sinusoida dengan tegangan antara 11,60 s.d. 41,5 mVpp dan rentang frekuensi 90,88 s.d. 126,75 MHz, dimana frekuensi = 121,5 MHz dapat dibangkitkan pada tegangan DC masukan = 4,25 VDC. Rangkaian VCO sebagai osilator 121,5 MHz hasil penelitian ini, dapat diimplementasikan pada pembangkit sinyal ELT hasil penelitian sebelumnya, sehingga dapat dibangkitkan sinyal ELT pada frekuensi 121,5 MHz, berupa gelombang AM dengan indeks modulasi = 24,05%.

ACQUISITION OF SARSAT INFORMATION USING AN AUTO-CORRELATION BASED ADAPTIVE LINE ENHANCER

This paper develops a new approach to the detection of the emergency locator transmitter (ELT) signal using an adaptive line enhancer (ALE). The input signal to the ALE is replaced by its autocorrelation function (ACF) because noise affects the central samples of the autocorrelation function only while it affects all samples of the noisy signal. This gives the ALE the ability to get rid of noise, easily. The output ACF is then used in the spectral estimation and detection of the ELT signal. This approach is related to the signal processing using Higher Order Statistics (HOS) since the ACF is the used input. The paper also compares the results of the new approach to other different previously used methods foe ELT signal detection. The first method uses the signal xk as an input to the ALE, and the second method uses [Formula: see text]. Results illustrate the superiority of the proposed method over the other two methods. A comparison study between the performance of two types of ALE; Fixed pole radius and variable pole radius ALEs in detecting the ELT signal, is introduced.