The influence of sunspot number on high frequency radio propagation

Abstract

Abstract-This paper aims to study the influence of sunspot number on High Frequency (HF) radio communications in Peninsular Malaysia for the years 2009 to 2011. Sunspots, which are a natural phenomenon that occurs due to magnetic activities on the Sun's surface, can be counted using smoothed sunspot number (SSN). HF signal propagates through the ionosphere where the ionospheric properties have been ionized by flares and prominences from sunspot number. This has significant effect on the stability of the ionosphere, resulting in the frequencies that can be used for HF communications to vary depending on the time of day, season, year and the 11-year solar cycle. This study was carried out during a period when the sunspot values rose from a low level in 2009 to a much higher level in 2011, making it suitable to observe the influence of sunspot number values on the HF frequencies employed. Maximum Usable Frequency (MUF) was determined based on HF transmission tests that were conducted from April 2009 to September 2011. It was observed that as the SSN values increase, the range of the operating HF frequencies and the numbers of frequencies that can be used also increase. This will, therefore, affect the median frequency that can be used for daily and monthly HF communications.

The Suggested Reciprocal Relationship between Maximum, Minimum and Optimum Usable Frequency Parameters Over Iraqi Zone

“…The data of the OWF and MUF parameters have been calculated for the years 2009 and 2014 using the suggested reciprocal correlation equations (eq. 3 -6) based on the correlation coefficients (ao, a1, a2, a3 and a4) that have been shown in Table (4). The generated datasets (Present) have been compared with other calculated values generated using the international models ASAPS and REC533 (predicted) and the theoretical criterion equation (OWF = 0.85 x MUF) W. Suparta,et al (12) (theoretical).…”

“…These parameters are affected by the primary factors influence (electron density of ionization), so these parameters will increase with higher ionization density and decrease with lower ionization density (3). The highest frequency that will reflect back to Earth by the ionized layers, the median value of (MUF) parameter is only 50% of the time (4). The (OWF) is defined as the best or "optimum" frequency to use at a given hour on a given circuit; it is possible to get value of the estimation of (OWF) by taking 85% of the (MUF) parameter.…”

Variations of ionospheric F2 layer critical frequency in Malaysia during different solar phases

“…This result is supported by the findings in [5], which stated that the value of foF2 increases early in the morning at 1000 UT (0600 LT) or from sunrise to midnight. Solar activities increase during daytime, thereby increasing the ionised layer in the ionosphere and enabling high frequencies to propagate over long distances [13]. The foF2 reaches its low values from 4.53 MHz to 3.51 MHz at 2000 to 2300 UT (0400 to 0700 LT) at night because of low solar activity.…”

Comparison of Prediction Programs for Short Wave Circuit Link from Iraq to Test points on Both Earth Hemispheres during Solar Minimum

“…The job of the prediction programs is to predict the FOT and MUF for any circuit link between two points at any time [5]. Most of the prediction program results are approximately convergent with points of one hop distance while they diverge (with acceptable error) in points with multiple hop distances, especially in points located near the geomagnetic equator line [5][6][7]. Most of these programs use input variables such as the Sun Spot Number (SSN) , date, geographical location, and the antenna type for prediction [6], and do not use important variables like K and A [8] even though the K parameter represents the status of solar winds.…”

“…The A parameter is a linear variable that represents the magnetic field of the earth. The previous papers [1][2][3][4][5][6][7][8][9][10] focused on the comparison of prediction programs at different geomagnetic circuits and different solar activity without mention to the Iraqi HF circuit link, while [11,12] studied the ionospheric parameters for Iraq's zone only when solar winds were at their maximum. The novelty of this work is studying and comparing the propagation prediction for the HF circuit link from Iraq to the world at the solar wind's minimum using the Voice of America Coverage Analysis Program (VOACAP), ITU Recommendation RS 533 (REC533), and real radio contact during August 2018; and also to find which modulation is preferred digital mode like FT8 [13] or analogue.…”