Heroe Wijanto

Automated ground station with customized rotator for antenna pointing using compass sensor

The antenna pointing system is very important to obtain an optimum received signal level. To achieve it, the pointing mechanism has to be set in automatic mode. In this research, the automatic antenna pointing system is developed by using compass sensor CMPS10 as a feedback. Beside CMPS10, the angle estimation has been calculated by TLE orbital satellite to predict the movement of tracked satellite. This system has been tested to track NOAA19 with differences between the prediction angle with the real satellite angle about 5 degree on the average. On the rotator system, by using 2 gears and 2 DC motors with customized frames, the system has been realized and tested. There are 3 tests to be done: the test of power supply circuit, the elevation and azimuth power requirement tests, and the mechanical tests. The design of the customized rotator system resulting the azimuth speed is 7.3 degree per second on the average, while the elevation speed has 7.7 degree per second on the average. The rotator also has been tested with some loaded-unloaded schemes to clarify the ability of rotator system. The load-tests show that on the average 98 kilograms-load for azimuth movement needs 58.8 Watts supply; and 54 kilograms-load for the elevation movement needs 198 Watts.

A preliminary design and testing of the On Board Data Handling (OBDH) for nano-satellite using an atmospheric balloon

There are must-to-do steps in the nano-satellite development process, including the engineering model and flight model test. The atmospheric balloon test can be used to analyze the On Board Data Handling (OBDH) performance. The obtained results from the test are 13 images data captured from the 2900 MASL maximum altitude, also the sensor data i.e. temperature, pressure, humidity, position, and the direction of the balloon payload.

Analysis of camera array on board data handling using FPGA for nano-satellite application

Nanosatellite has limited functions because of the mass constraint from 1 to 10 kg. Therefore, the requirement of low cost, low mass, low dimension, and low power consumption must be fulfilled in designing and choosing the component of nanosatellite. To obtain wider coverage area while maintaining the low dimension, camera array was used to produce image with wider area. In this research, On Board Data Handling (OBDH) implemented in FPGA used below 100% of the total FPGA resource. LUT-FF pairs was the most used resource with 75% of usage. OBDH also combined the image from each camera to get image with wider area. The FPGA and 4 cameras used 2264.44 milliwatt of power consumption, higher than the remote sensing system of SNAP-1 nanosatellite which used 1 milliwatt of power consumption.

Statistical properties proposed for blind classification OFDM modulation scheme

Classification of modulation scheme, previous step before demodulation, is the main part of an intelligent receiver at military or commercial application. Moreover, without definite parameters of the transmitted signal, blind modulation classification becomes a difficult task. Modulation classification becomes more challenging in real application with multicarrier modulation at fading channel. Furthermore, in recent years, the wireless communication has concerned to the orthogonal frequency division multiplexing (OFDM) because of spectral efficiency by using orthogonal multicarrier modulation. In this paper, we provided statistical characteristics of different modulation schemes from the OFDM signal with multipath (Rayleigh) fading channel. Based on standard of IEEE 802.16e, there are three possible modulation schemes used like a Quadrature Phase Shift Keying (QPSK), 16-QAM (Quadrature Amplitude Modulation), and 64-QAM. We analyzed those three modulation schemes by using statistical properties, such as, mean, variance, skewness, kurtosis and moment order.

Analisis Pengaturan Sistem Catu Daya Pada Satelit Nano

Keberhasilan suatu misi satelit nano sangat bergantung kepada keandalan Electrical Power System (EPS) untuk menjaga subsistem-subsistem pada satelit nano agar tetap berfungsi. Oleh karena itu dibutuhkan sebuah pengendalian distribusi daya yang efektif. Penelitian ini menjelaskan tentang bagaimana cara pendistribusian daya listrik yang efektif dan sesuai dengan kondisi satelit nano ketika terkena sinar matahari atau ketika kondisi gelap pada saat mengorbit diluar angkasa. Untuk menjelaskan hal tersebut dilakukan simulasi dan analisis pada perancangan modul power management EPS yang terdiri dari rangkaian boost converter LT3757 dan battery charger IC LT3652. Hasil simulasi menunjukan bahwa pada saat kondisi terang sistem akan mencatu daya beban menggunakan daya masukan panel surya yang sebelumnya telah melewati komponen boost converter (12 Volt), sekaligus mengisi daya batere hingga terisi penuh (7,4 Volt). Tetapi pada saat kondisi gelap sistem akan mencatu beban dengan daya yang dihasilkan oleh batere (7,4 Volt).

Design and realization multi layer parasitic for gain enhancement of microstrip patch antenna

Microstrip antenna has a small gain, bandwidth and efficiency. To overcome those weaknesses, this paper focused on a design of multilayer parasitic substrate for enhancing antenna gain. The distance between first layer parasitic and second layer parasitic had been optimized to maximize electromagnetic coupling and improve antenna main lobe. The microstrip antenna had been fabricated using FR-4 epoxy substrate with 4.2 dielectric constant. Measured antenna acquires unidirectional radiation pattern, 70° beamwidth azimuth, 2.333 GHz–2.377 GHz of operating frequency at VSWR ≤ 2, 44 MHz of bandwidth, and Gain = 4.64 dB. The dimension of realized antenna was 151.5 mm × 151.5 mm. This antenna was purposed to work for LTE band 40 at 2.35 GHz.

Four port diversity patch antennas for MIMO WLAN application

A four port diversity microstrip patch antennas for WLAN was designed, working in the 5.180 to 5.220 GHz frequency. Port diversity was carried out by changing the orientation of the port as of 90° between each consecutive port to reduce mutual coupling and reduce overall dimensions of the antenna. Dimension of realized antenna was 49.48 mm × 49.48 mm. All antenna element has VSWR ≤ 1.5 and mutual coupling ≤ −20 dB. Bandwidth of the antenna 1 to 4 was 92, 96, 68, and 83 MHz respectively. The resulting gain antenna 1 to 4 was 3.306, 3.428, 3.38, and 3.315 dBi respectively. The antenna had unidirectional radiation pattern with elliptical polarization.

Design and realization of circular patch antenna for S-Band Coastal Radar

In this paper, a design and realization of a coastal radar antenna that works on S-Band frequency was presented. Type of antenna that had been used in this research is a microstrip patch antenna. One antenna module consist of eight patch that was horizontally arranged. The microstrip antenna had been fabricated using FR-4 epoxy substrate with 4.6 dielectric constant and a thickness of 1.6mm. Measured antenna acquires unidirectional radiation pattern, 16° beamwidth azimuth, 2.93 GHz – 3.093 GHz of operating frequency at Voltage Standing Wave Ratio (VSWR) ≤ 2; 166 MHz of bandwidth and Gain = 11.98 dB. There was a satisfactory agreement between simulation and measurement result. This circular patch antenna will be implemented for S-Band Coastal Radar.

Pembangkit Sinyal Master Pada Sistem Navigasi LORAN-C menggunakan FPGA

Navigasi saat ini menjadi hal yang sangat penting untuk menunjang kehidupan manusia, bahkan dapat digunakan sebagai sistem pertahanan dan ketahanan negara. Saat ini, sistem navigasi di Indonesia masih tergantung dengan sistem navigasi negara lain, khususnya yang berbasis satelit. Oleh karena itu, Indonesia membutuhkan sebuah sistem navigasi yang mandiri. LORAN-C adalah sistem navigasi terestrial yang menggunakan frekuensi ground wave dengan metode triangulasi, sehingga mempunyai radius cakupan yang luas. Pada penelitian ini dibuat subsistem pemancar sinyal master pada sistem navigasi LORAN-C dengan menggunakan FPGA. Penggunaan FPGA dimaksudkan untuk pembangkitan sinyal LORAN-C analog melalui sintesa digital (direct digital synthesis) pada tingkat baseband agar diperoleh format sinyal presisi tinggi. Dari hasil penelitian diperoleh sembilan pulsa master dengan spesifikasi sesuai dengan ketentuan sistem navigasi LORAN-C, lebar pulsa 300 µs, delay pulsa 700 µs serta amplitudo maksimum pada t = 60 – 65 µs.

Design of attitude determination and control system using microstrip magnetorquer for nanosatellite

Magnetorquer is a type of active control used on nanosatellite. It can be made by using microstrip line with a circular spiral patch. In previous research, the magnetorquer system was designed by using a coil of wire wrapped around the cross-section of conductor. The magnetic field is generated by electrifying the coil of wire. The torque is produced when the magnetic field generated from magnetorquer interacts with the Earths magnetic field. The torque can be controlled to change nanosatellite orientation in its orbit. In this paper, the magnetorquer is designed with 5 V of voltage consumption and 0.5-1 A of current consumption. By supplying the magnetorquer with various amount of current, the minimum and maximum values of magnetic field are 0.811 μT and 1.596 μT respectively.