Using High Frequency Propagation to Calculate Basic Maximum Usable Frequency
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A Simplified Mathematical Model to Calculate the Maximum Usable Frequencies Over Iraqi Territory Khalid A
A Simplified Mathematical Model to Calculate the Maximum Usable Frequencies Over Iraqi Territory Khalid A. Hadi*, Loay E. Goerge** A Simplified Mathematical Model to Calculate the Maximum Usable Frequencies Over Iraqi Territory Khalid A. Hadi*, Loay E. Goerge** * Department of Astronomy & Space, College of Science, University of Baghdad ** Department of Computer Science, College of Science, University of Baghdad Receiving Date: 25-02-2011 - Accept Date: 13-06-2011 Abstract In this project, the spatial and temporal variation of maximum usable frequency (MUF) parameter is investigated and modeled. The values of MUF for Baghdad station links, with other stations distributed over Iraq territory, where determined using the international reference model (RECF533) for HF propagation. The determined MUF dataset reflected that the spatial distribution of this parameter for Baghdad station shows circular symmetry, which stimulated the possibility of using a two dimensional second order polynomial in order to describe MUF variation. The main feature of this adopted mathematical model is its low complexity. The results of conducted analysis indicated that the spatial variation of MUF is simple while its temporal variation is more complicated and needs more sophisticated mathematical description than the polynomial description. The test results showed that the accuracy of proposed simple model lies within the tolerance of REC533 reference model. Key words: Ionosphere, HF communication prediction, MUF Vol 7 No: 4, October 2011 1 20 ISSN: 2222-8373 A Simplified Mathematical Model to Calculate the Maximum Usable Frequencies Over Iraqi Territory 1. INTRODUCTION The Maximum Usable Frequency, denoted by MUF, is an important ionospheric parameter. It is defined as the highest frequency that allows reliable long-range high frequency (HF) radio communication between two points due to ion-ospheric refraction. -
Radio Transmission and the Ionosphere
Ih S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS WASHINGTON / » ruT O v / Letter Circular LC-614 RADIO TRANSMISSION AND THE IONOSPHERE October 23, 19^0 6 . s TKD :ANK U. 3. DEPARTMENT OF COMMERCE Letter 1-6 NATIONAL BUREAU OF STANDARDS Circular Washington LC-6l4 ( Supersedes LC-E75) October 23 , 19^0 RADIO TRANSMISSION' AND THE IONOSPHERE Radio transmission over great distances is made possible by . reflection of the radio waves from ionized (electrically conduct- ing) layers in the ionosphere, the upper region of the earth* atmosphere. How far the radio waves go, and what frequencies may be used, are determined by the heights and the degree of ionization of the ionized layers, which are located between about BO kilometers (30 miles) and 400 kilometers (250 miles) above the earth's surface. Because of variations in the ionized layers, the conditions of radio wave transmission vary with time of day, with season, and from year to year. For the efficient maintenance of radio services it is important to have a constant supply of information on these changes. To this end an ionosphere observing, reporting, and predicting service is provided by the National Bureau of Standards. It is analogous to the weather reporting service, though quite independent of it-; the factors producing or affecting weather exist at much lower levels of the atmosphere than the ionosphere. The results of the Bureau * work on the ionosphere arid -radio transmission are made available to the public by a Science Service Urslgram and radio broadcast each week, and regular publication each month and each quarter, as well as through special papers (see References at end hereof) published from time to time on particular phases of the subject. -
Radio Communications
RADIO COMMUNICATIONS An Amateur Radio Technician and General Class License Study Guide Prepared by John Nordlund – AD5FU and Edited by Lynette Dowdy - KD5QMD Based on the Element 2 Technician Exam Question Pool Valid from 7/1/06 until 7/1/2010 and the Element 3 General Exam Question Pool Valid 7/1/2007 until 7/1/2011 Page 1 of 78 Acknowledgment: My greatest thanks to Lynette – KD5QMD, for her understanding and assistance, without which this book would be filled with countless typographical and grammatical errors and an overload of confusing jargon and bewildering techno-babble. | | This publication is the intellectual property of the author, and may not be reproduced for commercial gain for any purpose without the express permission of the author. | | However, Share the Fun. | | This publication may be freely distributed for the educational benefit of any who would care to obtain or upgrade their amateur radio license. | | | If you love the hobby you have a duty of honor to pass it along to the next generation. | | | 73 de AD5FU Page 2 of 78 How to use this study guide. Contained within the next 73 pages is a text derived from the official exam question pools for Element 2 Technician and Element 3 General class exams. It is the expressed opinion of the author and editor of this study guide that studying the full question pool text is counterproductive in attempting to obtain your Amateur Radio License. We therefore do not recommend downloading the actual exam question pool texts. This study guide is divided into sections of related information. -
HF Radio Propagation
Introduction to HF Radio Propagation 1. The Ionosphere 1.1 The Regions of the Ionosphere In a region extending from a height of about 50 km to over 500 km, most of the molecules of the atmosphere are ionised by radiation from the Sun. This region is called the ionosphere (see Figure 1.1). Ionisation is the process in which electrons, which are negatively charged, are removed from neutral atoms or molecules to leave positively charged ions and free electrons. It is the ions that give their name to the ionosphere, but it is the much lighter and more freely moving electrons which are important in terms of HF (high frequency) radio propagation. The free electrons in the ionosphere cause HF radio waves to be refracted (bent) and eventually reflected back to earth. The greater the density of electrons, the higher the frequencies that can be reflected. During the day there may be four regions present called the D, E, F1 and F2 regions. Their approximate height ranges are: • D region 50 to 90 km; • E region 90 to 140 km; • F1 region 140 to 210 km; • F2 region over 210 km. At certain times during the solar cycle the F1 region may not be distinct from the F2 region with the two merging to form an F region. At night the D, E and F1 regions become very much depleted of free electrons, leaving only the F2 region available for communications. Only the E, F1 and F2 regions refract HF waves. The D region is very important though, because while it does not refract HF radio waves, it does absorb or attenuate them (see Section 1.5). -
Comparison of Maximum Usable Frequency (MUF) Variability Over Peninsular Malaysia with IRI Model During the Rise of Solar Cycle 24
Journal of Atmospheric and Solar-Terrestrial Physics 138-139 (2016) 87–92 Contents lists available at ScienceDirect Journal of Atmospheric and Solar-Terrestrial Physics journal homepage: www.elsevier.com/locate/jastp Research paper Comparison of maximum usable frequency (MUF) variability over Peninsular Malaysia with IRI model during the rise of solar cycle 24 R.A. Malik a,b,n, M. Abdullah a,c, S. Abdullah c, M.J. Homam d a Department of Electrical, Electronic and Systems Engineering, Universiti Kebangsaan Malaysia, Malaysia b Science & Technology Research Institute for Defence (STRIDE), Malaysia c Space Science Centre (ANGKASA), Universiti Kebangsaan Malaysia, Malaysia d Universiti Tun Hussein Onn Malaysia, Malaysia article info abstract Article history: The aim of this paper is to study maximum usable frequency (MUF) variability over Peninsular Malaysia Received 27 July 2015 (112.5°E, 2.5°N) which is located in the equatorial region during the rise of Solar Cycle 24 (2009–2011). Received in revised form The MUF Test data was obtained from high frequency (HF) transmission tests that were conducted from 16 December 2015 April 2009 to September 2011. Relative variability VR was used to compute the relative variability of MUF. Accepted 26 December 2015 Variability of diurnal, seasonal and sunspot effect on MUF of test was compared to International Re- Available online 29 December 2015 ference Ionosphere (IRI) version of 2012. The results show that: (a) MUF from the IRI model is higher Keywords: than the MUF Test but the magnitude for the -
SDSU Template, Version 11.1
AN HF MULTITONE MODEM _______________ A Thesis Presented to the Faculty of San Diego State University _______________ In Partial Fulfillment of the Requirements for the Degree Master of Science in Electrical Engineering _______________ by Louis A. Rey Summer 2017 iii Copyright © 2017 by Louis A. Rey All Rights Reserved iv DEDICATION This thesis is dedicated to my wife, two daughters and all who have loved and supported me throughout this journey. v ABSTRACT OF THE THESIS An HF Multitone Modem by Louis A. Rey Master of Science in Electrical Engineering San Diego State University, 2017 In today’s world, we can find signals being transmitted on every portion of the frequency spectrum from a few Hertz up to several Giga Hertz. Frequencies of upwards of 60GHz are common today. Although it is now common to operate in ever higher frequencies, High Frequency (HF) frequencies (3 to 30 MHz) enjoyed huge popularity during the advent of early long-range communication work. Before satellites were invented, it was the only means of transmitting information at long distances wirelessly. Initial work in the defense industry gave fruit to Multitone modems which were then superseded by single tone modems for both data and voice communications at 2400bps, 9600bps and 19400bps. With the growing popularity of digital signal processing and software radio, these modems are now easily implemented. This thesis revisits Multitone modems, also known as parallel tone modems, which use 16 and 39 tones for data and voice respectively. A comparison with modern communication systems will be explored. A description of the Modem sections will be created using MATLAB. -
Observations of F-Region Critical Frequency Variation Over Batu Pahat, Malaysia, During Low Solar Activity
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UTHM Institutional Repository OBSERVATIONS OF F-REGION CRITICAL FREQUENCY VARIATION OVER BATU PAHAT, MALAYSIA, DURING LOW SOLAR ACTIVITY SABIRIN BIN ABDULLAH A thesis submitted in fulfilment of the requirement for the award of the Doctor of Philosophy (Electrical) Faculty of Electrical and Electronic Engineering Universiti Tun Hussein Onn Malaysia JUNE 2011 ABSTRACT Wireless radio in the HF band still uses the ionospheric layer as the main medium for communication. Critical frequencies are important parameters of the ionosphere. Due to the activities of the sun, the critical frequency varies diurnally, following the pattern of day and night. The critical frequency for the Parit Raja station is determined using an ionosonde at latitude 1° 52' N and longitude 103° 48' E which is close to the geomagnetic equator at geographic latitude 5° N. This work analyses the dependence of the critical frequency during the solar minimum of Solar Cycle 23. The median critical frequency value is used to develop a model using regression and polynomial approaches because it is more accurate than using average values. From the observations, the critical frequency observed in 2005 is the highest, corresponding to a higher sunspot number of between 11 and 192. In contrast, the critical frequency is lower in 2007 due to the decrease in the sunspot number of between 11 to 63. The general trend of the daily critical frequency is 6.8 MHz to 12.0 MHz from 00:00 to 17:30 UTC and decreasing to 7.0 MHz from 18:00 to 23:00 UTC. -
The Ohm Town News
THE OHM TOWN NEWS Voice of the Bridgerland Amateur Radio Club >>>>>>>> http://www.barconline.org <<<<<<<< MarchMarch 20201010 Some Contents… Presidents Message ................................ 2 Ham Profile: Kevin Reeve (N7RXE) .......... 3 2010 Club Budget Voting Form .............. 4 Upcoming Activities ................................ 5 D-Star update information .................... 6 ARRL newsletter information ................. 8-11 Test Questions for Extra Class License ... 12 PRESIDENT’S MESSAGE For the past several years, we have been at the bottom of one of the lowest solar activity cy- cles in history. But it looks like solar cycle 24 is starting its upward trend. The past 10 weeks have seen only three days with no sunspots. The prediction is that solar cycle 24 will peak in mid 2013. In other words, at the peak of the cycle you can basically make contact with other amateur radio operators all over the world. On the other hand, when the sunspot activity is in the low part of the cycle (like it is now) radio signals don't normally travel very far -- but some- times they do and that uncertainty is one of the many things that make the hobby fun. Any form of radio communications that uses the High Frequency (HF) bands and iono- spheric radio propagation is very dependent upon the state of the ionosphere. The higher the levels of radiation received from the Sun, the greater the levels of ionization in the ionosphere and in general this brings better propagation conditions for HF radio communications. The importance of the ionosphere lies in its ability to reflect some radio waves back to earth under certain conditions. -
High Frequency Communications – an Introductory Overview - Who, What, and Why?
High Frequency Communications – An Introductory Overview - Who, What, and Why? 12 April, 2012 Abstract: Over the past 60+ years the use and interest in the High Frequency (HF -> covers 1.8 – 30 MHz) band as a means to provide reliable global communications has come and gone based on the wide availability of the Internet, SATCOM communications, as well as various physical factors that impact HF propagation. As such, many people have forgotten that the HF band can be used to support point to point or even networked connectivity over 10’s to 1000’s of miles using a minimal set of infrastructure. This presentation provides a brief overview of HF, HF Communications, introduces its primary capabilities and potential applications, discusses tools which can be used to predict HF system performance, discusses key challenges when implementing HF systems, introduces Automatic Link Establishment (ALE) as a means of automating many HF systems, and lastly, where HF standards and capabilities are headed. Course Level: Entry Level with some medium complexity topics Agenda • HF Communications – Quick Summary • How does HF Propagation work? • HF - Who uses it? • HF Comms Standards – ALE and Others • HF Equipment - Who Makes it? • HF Comms System Design Considerations – General HF Radio System Block Diagram – HF Noise and Link Budgets – HF Propagation Prediction Tools – HF Antennas • Communications and Other Problems with HF Solutions • Summary and Conclusion • I‟d like to learn more = “Critical Point” 13-Apr-12 I Love HF, just about On the other hand… anybody can operate it! ? ? ? ? 13-Apr-12 HF Communications – Quick pretest • How does HF Communications work? a. -
FM 24-18. Tactical Single-Channel Radio Communications
FM 24-18 TABLE OF CONTENTS RDL Document Homepage Information HEADQUARTERS DEPARTMENT OF THE ARMY WASHINGTON, D.C. 30 SEPTEMBER 1987 FM 24-18 TACTICAL SINGLE- CHANNEL RADIO COMMUNICATIONS TECHNIQUES TABLE OF CONTENTS I. PREFACE II. CHAPTER 1 INTRODUCTION TO SINGLE-CHANNEL RADIO COMMUNICATIONS III. CHAPTER 2 RADIO PRINCIPLES Section I. Theory and Propagation Section II. Types of Modulation and Methods of Transmission IV. CHAPTER 3 ANTENNAS http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/24-18/fm24-18.htm (1 of 3) [1/11/2002 1:54:49 PM] FM 24-18 TABLE OF CONTENTS Section I. Requirement and Function Section II. Characteristics Section III. Types of Antennas Section IV. Field Repair and Expedients V. CHAPTER 4 PRACTICAL CONSIDERATIONS IN OPERATING SINGLE-CHANNEL RADIOS Section I. Siting Considerations Section II. Transmitter Characteristics and Operator's Skills Section III. Transmission Paths Section IV. Receiver Characteristics and Operator's Skills VI. CHAPTER 5 RADIO OPERATING TECHNIQUES Section I. General Operating Instructions and SOI Section II. Radiotelegraph Procedures Section III. Radiotelephone and Radio Teletypewriter Procedures VII. CHAPTER 6 ELECTRONIC WARFARE VIII. CHAPTER 7 RADIO OPERATIONS UNDER UNUSUAL CONDITIONS Section I. Operations in Arcticlike Areas Section II. Operations in Jungle Areas Section III. Operations in Desert Areas Section IV. Operations in Mountainous Areas Section V. Operations in Special Environments IX. CHAPTER 8 SPECIAL OPERATIONS AND INTEROPERABILITY TECHNIQUES Section I. Retransmission and Remote Control Operations Section II. Secure Operations Section III. Equipment Compatibility and Netting Procedures X. APPENDIX A POWER SOURCES http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/24-18/fm24-18.htm (2 of 3) [1/11/2002 1:54:49 PM] FM 24-18 TABLE OF CONTENTS XI. -
The Exam Corner #4
THE EXAM CORNER #4 By Steve Weeks, AA8SW This is the second in the series of three lessons on propagation. The General Class license is so desirable because it gives us access to worldwide communications on HF bands, but over-the-horizon signals have to be “bounced” (technically refracted) back down to Earth one or more times by the atmosphere (most often, by the ionosphere). Again, I will briefly discuss what you need to know about an aspect of that subject, then show you the only exam questions that could appear on that aspect, and follow with hints as to how you can remember the right answer. The correct answer is in bold. ● This unit focuses on two simple concepts – the Lowest Usable Frequency (LUF) and Maximum Usable Frequency (MUF), which are just what they sound like – between the LUF and the MUF are the frequencies that are usable for communications between two given points at a given time. Note, this is not a 24-hour average, it is as of the specific time that the communication is desired to be made. Below the LUF, radio waves are absorbed by the ionosphere and not “bounced” back. G3B07 What does LUF stand for? A. The Lowest Usable Frequency for communications between two points B. The Longest Universal Function for communications between two points C. The Lowest Usable Frequency during a 24 hour period D. The Longest Universal Function during a 24 hour period G3B08 What does MUF stand for? A. The Minimum Usable Frequency for communications between two points B. The Maximum Usable Frequency for communications between two points C. -
A History of Vertical-Incidence Ionsphere Sounding at the National
TECH, aoaot Mii22 PB 151387 ^0.28 ^5oulder laboratories A HISTORY OF VERTICAL - INCIDENCE IONOSPHERE SOUNDING AT THE NATIONAL BUREAU OF STANDARDS BY SANFORD C. GLADDEN U. S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS IE NATIONAL BUREAU OF STANDARDS Functions and Activities The Functions of the National Bureau of Standards are set forth in the Act of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards: the determination of physical constants and properties of materials: the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and technical problems; in- vention and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover. Publications The results of the Bureau's work take the form of either actual equipment and devices or pub- lished papers. These papers appear either in the Bureau's own series of publications or in the journals of professional and scientific societies.