A Simplified Sounding System for Finding NVIS Channel Availability to Support Government Radio Networks in Indonesia

Abstract

Mostly natural disasters in Java Island such as landslides are within the vicinity of not more than 200 Km from the district capital. Cellular communications require complex systems and rather vulnerable  to cope with disasters. NVIS mode is considered as a simple radio link during disaster mitigation initiation process. It needs a valid estimation to figure out the condition of the ionosphere. There are two purposes of this study, the first of which is an attempt to find out a fact the existences of authorized HF users who still work in the band of 3 MHz – 10 MHz. The second is to integrate low cost HF radio communication, commonly available small single board computer hardware, and opensource software, to build a sounding system to evaluate the quality of NVIS channels. Prediction system such VOACAP give hourly prediction data, however it has an inherent limitation because of  nature the underlying databases is monthly average based, therefore, the estimation could not be made in a daily bases. However, a real-time channel evaluation (RTCE) able to purify maximum observed frequency (MOF) estimation, and consequently, its able to select the best available frequency for short term and real time operation. In this study, we used WSPR to perform a simple RTCE technique. Furthermore, we also reviewed the current regulatory status regarding the availability of sub-10 MHz band for NVIS radio operation. The results show that discrepancies between simulation and measurement are occurred mainly because of sporadic data in the band of 60m and 80m. However, all of the measurement results and simulations almost have the same agreement regarding the quiet period between local midnight and local sunrise. The results of measurements show that 60m band is the most reliable NVIS channel between local sunrise and local midnight. Furthermore, 100 watts is a proper transmitter power to reach the required SNR for reliable voice communication.Â

Analisis Kompatibilitas Sederhana Terhadap Kemungkinan Layanan Komunikasi Radio Nelayan Tradisional di Laut Jawa dengan Layanan Komunikasi Radio Lain pada Pita Frekuensi 5,2 MHz

“…Dengan demikian maka derajad kegunaan gelombang langit pada komunikasi radio HF tergantung pada kondisi propagasi gelombang radio maupun ketiadaan nois dan interferensi. Atau dengan kata lain hal ini dapat dikatakan merupakan derajad kesehatan kanal KR, yang dievaluasi dengan memanfaatkan sistem WSPR (Weak Signal Propagation Reports) [3], dan sebagai bahan pembanding hasil pengukuran, kami memanfaatkan paket program VOACAP. WSPR adalah program open-source atau perangkat lunak sumber terbuka [4], sedangkan VOACAP adalah freeware atau perangkat lunak gratis [5].…”

“…Lisensi diberikan kepada operator stasiun radio atas dasar permohonan serta kesesuaian dengan perencanaan frekuensi yang komprehensif oleh fihak regulator manajemen penataan frekuensi. Studi pemanfaatan pita sub-10MHz berdasarkan pemeriksaan ISR sudah pernah dilaksanakan [3]. Dari hasil pemeriksaan ISR dapat disimpulkan bahwa jumlah ISR pita frekuensi sub-10MHz terus menurun dari tahun ke tahun.…”

Using the WSPR Mode for Antenna Performance Evaluation and Propagation Assessment on the 160-m Band

“…WSPR has been used to analyse the behaviour of antennas [2][3][4][5], or to investigate the behaviour of the ionosphere and to analyse propagation prediction [6,7]. For example, the High-Frequency Active Auroral Research Program (HAARP) used WSPR to model the ionosphere [8] and to study the propagation effects in the frequency range of 3 Hz to 30 kHz by using different uplink angles with respect to the magnetic field lines of the Earth [9].…”