AM radio coverage on the theory of computation and effect of the digital mapping

[Paper Keywords] broadcast coverage from the coverage radius of the Java language spread of relational database
[Abstract] This paper covers work on the medium wave broadcast data calculation, the effect of digital mapping studies carried out, the key to the realization of the digital algorithm was analyzed, using computer systems to achieve a medium wave radio wave transmission distance calculation, broadcast coverage of results mapping and coverage statistics and so on.

O Introduction
AM radio of the older, broader coverage, the more common form of broadcasting. AM radio is the medium wave radio coverage planning, resource management foundation. MW shortage of radio frequency resources for better use of limited AM radio frequency and other resources needed during the broadcast coverage of the frequency on the AM broadcast, transmit power and geographical location and other information for various calculations, analysis and statistics, in practice often broadcast coverage radius to be calculated from data covering the effect of mapping and coverage of statistical computing, when a heavy workload, cumbersome procedures, working long period of time and effort invested more.

Digital broadcast television technology development, with the number of radio and television continued to deepen the process. Digital broadcast television will permeate all aspects of technology and production among the coverage of AM radio design, planning and other Research results related to the calculation and mapping of data and so digitized, that the use of computer systems quickly, accurately and directly calculated and displayed all over the radio frequency and transmitted power of all the coverage map and the statistic results, can improve efficiency, saving time and effort to carry out the decisions of other, more abstract work
2 manual process of calculation and drawing
AM radio coverage, etc. have to perform the theoretical calculation of the radius of radio coverage, more theoretical approach, the actual ball used in the calculation formula for the ground wave propagation with wave propagation curve of the wave form to estimate the value of radio propagation distance, closer to the field received radio field strength measurement value. So as a medium wave radio broadcast coverage of the coverage radius of working with.

Spherical wave propagation on the ground formula is:
E =, E +101 gP +10 lgD (1)
The first use of the formula (1) for field strength calculation, the results obtained with field wave propagation curve table. Limit the field strength values found under the AM radio wave propagation from the theoretical value, and as a medium wave frequency and transmission power of the broadcast coverage radius. According to coverage radius on the map in the plane wave with a compass to draw out the effect of broadcast coverage map , and conduct all the statistical work.

3, calculated from data in digital and graphic rendering processes
Mathematical calculations and computer graphics rendering, the first parameter should be needed, graphics and other data input into the computer, stored in a database, and then find a suitable algorithm for computing the data, and finally use a computer programming algorithm logic.


3.1 The basic data of digital
(1) Select the appropriate regional maps of the planar map regions into electronic documents, according to the linear scale map of the regional plane, calculate the area of electronic documents in the planar map distance between two points (the number of pixels) between two points and the actual area Distance (kilometers) conversion factor. the actual use of the coefficient can be calculated straight-line distance between two points in the zone in the region in the planar map representation of electronic documents, in pixels, the line length.

(2) recorded in the area of electronic documents as maps of the boundaries of the closed area and the pixel coordinates of the region that contains the total number of pixels used for statistical coverage.

(3) record in the region around the electronic documents as maps, city or county location of the pixel coordinates, which cover the effect of the value of broadcast coverage map center coordinates of the transmitter.

(4) wave propagation curves for the table is made to electronic files, and vector wave propagation curves form electronic documents. Used to calculate the wave propagation distance.

3.2 calculated from data covering radius
(5) Set parameters of radio frequency and transmission power, by the formula �� and (4) in the wave propagation vector of the curve of the table to calculate the electronic document to the point that radio wave propagation from the coverage radius, and then use (1) obtained from the conversion factor to calculate the area of electronic documents as maps of the number of pixels in the value of the broadcast transmitters covering effect of the figure covered the radius of the circle.

3.3 The effect of drawing
(6) plane in the region on the map to the electronic document (3) a place, city or county is the center pixel coordinates to (5) derived the number of pixels is the radius of coverage radius to draw circle, circle area said of a certain frequency and power of a theory of effective coverage.

Coverage of statistical computing 3-4
(7) According to (6) the coverage generated renderings and (2) in the pixel coordinates of the boundary region and the number of pixels in the region that contains the sum of the statistics cover. If the statistics cover population. Need to generate a population distribution of electronic documents, and covering an area of statistical calculation similar. In addition to the preparation of basic data, the other through the computer program the steps to calculate the user input data and stored in a computer server in the data, calculate derived The results, drawn graphics, complete statistics.

4. Key Algorithm
4.1 Plane Mapping
Plane through the projection map and the map from the surface is calculated, so the accuracy of the map plane is directly related to graphics rendering and statistical accuracy of the calculation. In general, the distance between two points on the map and the actual total compared to a certain geographic distance errors, in order to facilitate Research and reasonable control of the error range, calculated by a computer program several times, drawing and revealed, the direct use of spherical wave propagation on the ground, the radio transmission distance formula to obtain the value of 1:100 million in small-scale flat map Draw the resulting error can be ignored, so this article 1:100 million computer program selected small-scale flat map of the region, and the direct use value as the distance covered by covering radius drawn renderings.


Table 4.2 vector curve
Wave propagation curves form of electronic documents in the accuracy and wave vector of the curve table method and the use of electronic documents to electronic documents wave curve table calculation algorithm for ground wave propagation distance determines the distance to the accuracy of wave propagation.

The ground wave propagation curves for the table into electronic document and stored in a database, is to preserve its pixels set, this ground-wave propagation curves for the table electronic document data is scalar data, the computer can not determine the field strength value and the distance value corresponding relationship therefore need to "conversion table" to the value of field strength and distance and height pixel values correspond with the width of the pixel values to complete the distance from the field to calculate. as shown:

"T1 Table" records the electric field intensity and ground wave propagation curve table Y-axis direction of electronic documents, correspondence between pixels, "T2 Table" records the wave curve table to the electronic documentation of different frequency field strength decay curves Xiangsu coordinate values, different frequencies have different shape of the curve, so its not the same pixel coordinate value is not, "T3 Table" records the wave propagation curves form of electronic documents and the transmission distance of x-axis pixel correspondence. Thus, by "T1 Table "A" T Table "a" T3 table "corresponding clues, can be transmitted from the value.

5 Program for
AM radio using the computer system to achieve coverage program. First, the calculation to select the appropriate description language, confirm the accuracy of the language, the actual demand can be achieved, then select a convenient and reliable data storage, the final design software architecture, interface and program processes.

5.1 Language Selection
There are many computer programming languages, we use JavaTM Platform StandarEdition6 programming platform to complete the coverage of the preparation process. Java programming language can be used to create any conventional programming language can create an application, it is flexible and convenient image Chuli written after completion of compiled to run on any operating system environment to use.

5.2 Data Storage
Relational database systems are often used as a storage platform data access. Java language has a variety of relational database interface, the procedures used relational database system is MicrosoftSQLServer2000 (sp4) database system, the system easy to use, good scalability, and degree of software integration advantages.

Program needs to permanently store the data in the database include: Regional surface map of the electronic document from the conversion coefficient, local cities and counties in which the pixel coordinates and the name, closed the border region and the pixel coordinates of the pixels contained in the region The total number of wave propagation vector of the curve form of electronic documents, full-wave frequency band, transmit power value and so on. reposted elsewhere in the Research Papers Download http://www.hi138.com 5.3 software architecture, program execution sequence and interface design
Cover the software is based on client / server (c / s) mode, and requires the ability to stand-alone or run in a network environment, system structure shown in Figure:

Figure 2 in the "client" program running coverage through the program's graphical interface to "user" parameter specifies a necessary input into the program. Procedures in dealing with the process if you want to use the data stored in the "server" in the data, then the "server" sends out a data request command to query data, "server" receives the instruction to find the required data and return, covering the program uses data in accordance with the procedures computing algorithms, the results will eventually cover both the radius and coverage results chart shows the "client" computer graphics interface for users. overwrite process requires the user to enter location, transmit power and frequency, and other basic information. Enter the basic graphical interface of the information shown:
Figure 3 shows the input interface of the program is the most drop-down selection box on the line. Used to select the "Location", "frequency" and "power" the basic parameters of the information, then use the "Add" and "delete" button will determine the increase in the number of data input interface in the lower part of the list box. List box contains a multi-site distribution and parameter setting AM radio data, covering the parameters set, a collection of elements of different effects in different coverage or coverage scheme.

In this program, "coverage radius" is only "frequency" and "power" function. To determine the "coverage radius" and "place" to cover the effects can be drawn map. The procedure in Figure 3 shows the input interface, the user use the mouse to click on the "map" tab will have coverage of rendering:
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Figure 4 using a circle that broadcast coverage of the launch point, you can display the same frequency or a multi-point distribution effects of multiple frequencies covering visual effects, and more reference information, the information input by the interface of the list in Figure 4 collection of data generated by the decision box, and a round of different colors represent different transmission power values. overwrite rendering in the program can be enlarged or reduced. statistic displayed in the image upper left corner area.

6 Conclusion
This article covers only medium-wave radio and other basic design or planning work for the digital part of the Research, hoping for other work can be helpful. Paper to the ground wave transmission distance is calculated in the ideal environment for the conduct of, therefore draw on this basis the coverage is idealized renderings.


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