Home engineer reference and training manuals maximum usable frequency. A simplified mathematical model to calculate the maximum usable frequencies over iraqi territory vol. The map is useful in determining the maximum frequency that can be used for nvis communications, however, the dlayer absorption frequency, which is not depicted on the map, must be considered in order to determine the minimum frequency that is usable for nvis or longhop communications. The instantaneous muf is a direct function of ionospheric electron density and is an absolute frequency limit, since the ionosphere is not capable of. Critical frequency is the highest frequency signal that can be transmitted straight up and reflected from the ionosphere. This form of muf has the emphasis on the operational acceptability of the circuit. Based on oblique sounding system, a shortterm forecasting method of maximum usable frequency for hf communication was presented. The blue curves show the lowest usable frequency luf for a 1500w cw transmitter. A midlatitude region selected for this research work by using data from station wakkanai 45. Pdf using high frequency propagation to calculate basic. Hf high frequency maximum usable frequency muf model. Shortterm forecasting method of maximum usable frequency for.
Given the maximum observed frequency mof for a mode on each day of. A database of,054 hours of oblique sounder mofs measured on 70 paths was compared with the predicted muf values from minimuf3. In radio transmission using reflection from the regular ionized layers of the ionosphere, the upper frequency limit that can be used for transmission between two points at a specified time. Where the above map indicates the fof2 nvis critical frequency, the relationship between the fof2 frequency and the maximum usable frequency muf is approximately 1. Glossary of terms for the data available in the n0nbh solar. These radio frequencies are a percentage below the muf maxiumum usable frequencies, and should be acurate for about 80 percent of the month. High frequency and vhf radio propagation data, solar, sunspot cycle, and geomagnetic realtime and historic data, as well as forecasts. A statistical analysis of observed oblique sounder median maximum observed frequencies mof and predicted maximum usable frequencies muf was used to assess the accuracy of high frequency muf prediction. This paper presents the method of calculating the maximum usable frequency muf and field strength of radio waves reflecting 2 times at the f2 ionosphere.
Provides the maximum usable frequency in mhz at one of 11 locations worldwide. Download pdf article of maximum useable frequency prediction using vertical incidence data written by courage mudzingwa, action nechibvute, albert chawanda low values indicate that the maximum useable frequency will be low and overall conditions will not be very good. A statistical analysis of observed oblique sounder median maximum observed frequencies mof and predicted maximum usable frequencies muf was used to assess the accuracy of highfrequency muf prediction. Maximum usable frequency 2 to 50 mhz distance between transmitter and receiver 0 to 7r radians latitude of the path midpoint 7r 2 to 7r2 radians west longitude of the path midpoint 0 to 27r radians latitude of a point km from receiver 7r 2 to ir2 radians west longitude of a point km from receiver 0 to 27r radians. Maximum usable frequency muf lowest usable high frequency luf and a. Introduction the maximum usable frequency, denoted by muf, is an important ionospheric parameter.
Download pdf article of maximum useable frequency prediction using vertical incidence data written by courage mudzingwa. From these data, the maximum usable frequency muf as a function of range is determined and. However, if a geomagnetic storm, a solar flare, or other event occurs, there is no promise that a signal will actually make it through the path in question. It also shows the current location of the auroral ovals, the sunrisesunset terminator and the regions of the world where the sun is 12 degrees below the horizon which estimates the grayline corridor where hf propagation is usually enhanced. Sunspot cycle forecast and current optimal frequency chart. For broadcast sound purposes, 15 khz is often chosen as the maximum usable frequency on landlines. Technical data panaray msa12x modular steerable array loudspeaker pro. Critical frequency, sky wave propagation in antennas and.
The maximum frequency returned at a 0 takeoff angle is called. Depending on what model you use for determining muf and owf, this percentage of usable days may be 50% or 90%. Maximum usable frequency usable frequency window radio. The maximum usable frequency for any distance is defined as the highest frequency which can be used for radio skywave transmission over the given distance. Find out information about maximum useable frequency. By using typical figures for the heights of the different ionospheric regions the factors may be determined. The main category is muf indicators that is about muf indicators. The highest frequency, which is reflected from the ionosphere to the receiver is called as critical frequency, fc.
An algorithm for the rapid calculation of the mfactor at a given range is developed, and shown to be accurate to within 5%. Critical frequency an overview sciencedirect topics. Figure 4 shows the curved path of a refracted ray associated with frequency f ob. Examples for usable frequency and how to use it nyanglish. Hf maximum usable frequency muf model uncertainty assessment. It is also a map showing the current location of the auroral ovals, the sunrisesunset terminator and the regions of the world where the sun is 12 degrees below the horizon which estimates the grayline corridor where hf propagation is usually. This study included 12 monthly median data from year 2001, r 12. It is shown that under conditions of a quiet ionosphere where the adapted. Request pdf a simple method to calculate the maximum usable frequency font. Maximum usable frequency article about maximum usable. In the transmission of radio waves via ionospheric reflection, the fot is the highest effective frequency or best working frequency for a given path that is predicted to be usable for a specified time for. M3000f2 is defined as the ratio of the maximum usable frequency at a distance of 3000 km to the f2 layer critical frequency, fof2. Antenna theory terms in wave propagation in the process of propagation of a wave, there are few terms which we come across quite often.
Maximumusablefrequency graph paper by interservice radio propagation laboratory. It is defined as the highest frequency that allows reliable longrange high. A simplified mathematical model to calculate the maximum. Simple mfactor algorithm for improved estimation of the. Muf maximum usable frequency cf critical frequency. Antenna theory terms in wave propagation tutorialspoint. Maximum usable frequency usable frequency window radio blackout.
Each chart displays the fot or optimal working frequency at each utc hour, for the paths given. Using high frequency propagation to calculate basic. Jun 02, 2017 maximum usable frequency meaning maximu. This is the maximum usable frequency, muf that would permit acceptable operation of a radio service between given terminals under specific working conditions. We present the results of prediction and extrapolation of the maximum usable frequency muf on the subauroral and midlatitude paths of the euroasian region by adapting the reference ionosphere model iri2007 based on the results of the oblique chirp sounding of the ionosphere on the reference and working radio links. Solar weather, geomagnetic, aurora, ionospheric reports via. Com 1 of 2 product overview the bose professional panaray msa12x is a selfpowered digital beamsteering loudspeaker that enables improved room aesthetics. Critical frequency, lowest useable frequency, luf, and maximum usable frequency, muf and optimum working frequency, owf used in radio signal. High frequency radio propagation current optimal frequency. However, there may be a third propagation mode, that i have dubbed layer trapping, and capable of supporting even higher mufs, which i will discuss later. Muf, luf, and fot the basics of the maximum usable. Calculation of the maximum usable frequency and field strength of. For ssb or a lower transmitter power, the luf will be somewhat higher than the blue curves indicate.
Mode b, petit chordal hop, nearly doubles the muf for a path, yielding mufs to at least 230 mhz with intense es. Maximum usable frequency how is maximum usable frequency abbreviated. Maximum usable angle maximum usable angle is the highest angle signal that can be transmitted, at an operating frequency of fo, and still be refracted by the ionosphere if the critical frequency is fc. Muf is a median frequency applicable to 50% of the days of a month, as opposed to 90% cited for the lowest usable high frequency luf and the optimum. The existence of the critical frequency is the result of electron limitation, i. The maximum usable frequency muf is the highest frequency delivered by the transmitter regardless of the power of the transmitter. Maximum usable frequency muf generally, radio waves leave the transmitting antenna at angles of 0 to 30 degrees and hit the ionosphere obliquely, requiring less bending be returned to earth, thus frequencies above the critical frequency can be returned. Extrapolation of the maximum usable frequency by adapting the. Jun 28, 2019 we present the results of prediction and extrapolation of the maximum usable frequency muf on the subauroral and midlatitude paths of the euroasian region by adapting the reference ionosphere model iri2007 based on the results of the oblique chirp sounding of the ionosphere on the reference and working radio links. Maximum usable frequency how is maximum usable frequency. E the angle of elevation of the signal radiating from your antenna. Find out information about maximum usable frequency. The following image is a recent highresolution map of maximum usable frequencies mufs for 3,000 kilometer radio signal paths. Arial bold, 9 radio communication community has great interest to know the daily behavior of the maximum usable frequency muf for its applications.
On which of the following bands is a general class license holder granted all amateur frequency privileges. These nw7us radio signal path propagation tables are set up to cover main regions of the world. Frequency of optimum transmission fot the maximum usable frequency regularly drops below 10 mhz in darkness during the winter months, while in summer during daylight it can easily surpass 30 mhz. Wavelength meters is equal to the speed of light meters per second divided by the frequency hz. Earth f layer station a station b e m 1 c m o f mua e sin f. This image is a recent highresolution map of maximum usable frequencies mufs for 3,000 kilometer radio signal paths. Shortterm forecasting method of maximum usable frequency.
Synonyms for the optimal operating frequency are fot frequency of optimum traffic, otf optimum traffic frequency or optimum. On sporadic e vhf propagation and solving a mystery about. Refraction of frequency below the lowest usable frequency luf wave propagation, transmission lines, and antennas. Arial bold, 9 radio communication community has great interest to know. Listed under the propagationmuf indicators category that is about muf indicators. In this video, i have explained critical frequency which is part of sky wave propagation by following outlines. The layers above earth are troposphere, stratosphere and ionosphere. Selection of a suitable operating frequency within the bounds of frequency allocations and availability is of prime importance in maintaining reliable communications. Ive found maps for both f2layer critical frequency and maximum usable frequency, and theyre quite different the maximum usable frequency map seems much more optimistic, that is, the frequencies are much higher at any given location.
Using high frequency propagation to calculate basic maximum. This page defines cf critical frequency and muf maximum usable frequency and mentions difference between critical frequency cf and maximum usable frequency muf. Maximum usable frequency noaa reported value from 0 to 100mhz. The basic maximum usable frequency muf is defined by the international radio consultative committee ccir as the highest frequency that can propagate between a pair of terminals by ionospheric refraction alone 1. An operational format for the maximum usable frequency may also be seen on occasions. Cme coronal mass ejection noaaswpc predicted date and time in utc. Publication date 19430717 publisher national bureau of standards collection. Because of the relationship between fof2 and muf, the above map can also be used to determine frequencies for use with skywave.
In the transmission of radio waves via ionospheric reflection, the fot is the highest effective frequency or best working frequency for a given path that is predicted to be usable for a specified time for a percentage of the days of the month. The upper boundary is called the maximum usable frequency muf. The results reveal that the m3000f2factor scaled from verticalincidence ionograms using the standard ursi pro. This frequency is called the maximum usable frequency, muf. The upper limit of the frequencies that can be used at a specified time for pointtopoint radio transmission involving propagation by reflection from the.
From these data, the maximum usable frequency muf as a function of range is determined and ionospheric critical frequencies are estimated. This link is listed in our web site directory since saturday nov 14 1998, and till today nearrealtime muf indicator has been followed for a total of 26997 times. Extrapolation of the maximum usable frequency by adapting. Glossary of terms for the data available in the n0nbh. Provides the date and time of a predicted earth bound cme event. Critical frequency changes with time of day, atmospheric conditions and angle of fire of the radio waves by antenna. In radio transmission maximum usable frequency muf is the highest radio frequency that can be used for transmission between two points via reflection from the ionosphere skywave or skip propagation at a specified time, independent of transmitter power. A comprehensive propagation resource compiled by tomas hood, editor of the propagation columns of cq, cq vhf, popular communications, and monitoring times magazines. The curve path reaches an altitude of h 1 before being returned to the earth. The maximum usable frequency muf predicted by the ioncap and hfmufes programs is compared to the observed frequency from oblique soundings on the kirunastockholm path. A simple method to calculate the maximum usable frequency. English examples for usable frequency changes in solar output affect the maximum usable frequency, a limit on the highest frequency usable for communications. Results showed that the parit raja location had the highest critical frequency at an average of 8.
Muf, luf, and fot the basics of the maximum usable frequency. Click on the table of contents page 3 use the navigation at the top of each page to jump to sections or use the page forwardback arrows use the arrow keys on your keyboard use the scroll wheel on your mouse. West coast to caribbean west coast to east coast west. These techniques use groundscatter returns to define the variation in skip distance with frequency. Multiplying the fof2 critical frequency by 3 approximates the muf. About nearrealtime muf indicator the resource is currently listed in in a single category. Maximum usable frequency muf the maximum usable frequency muf is the highest frequency delivered by the transmitter regardless of the power of the transmitter. This parameter represents the optimum frequency at which to broadcast a signal that is to be received at a distance of 3000 km.
1200 556 959 22 1331 1542 951 62 1288 448 1410 101 1180 706 334 1022 807 215 1083 459 651 450 25 328 299 993 919 1562 1465 1271 1362 395 173 1355 410 760 1098 742 1370 475 533 1149 1474 1362 941 277 1375 1268