**[Keywords] Broadcasting Coverage of the propagation distance coverage radius Java language and**

**relational database**

**[Abstract]**the data broadcasting coverage in calculation, rendering the digital research, on the implementation of the key algorithms of digital is analyzed, using a computer system to achieve the radio wave transmission distance calculation, the

**broadcast coverage**effect drawing and coverage statistics work.

**O,**

Medium wave broadcasting development earlier, covering a wide range, is a common form of radio broadcasting.Medium wave broadcasting coverage is the basis of broadcasting planning, resource management.The shortage of frequency resources for medium wave broadcast, to make better use of limited radio frequency resources, the need to broadcast coverage of broadcasting frequency, transmit power and geographical location and other information for a variety of calculation, analysis and statistics, in the actual work is often broadcast coverage radius data, covering effect chart drawing and coverage statistics calculation, the workload is very large, cumbersome procedures, long work period, invest more time and effort.

Digital is the direction of development of TV technology, with the continuous deepening of the development of digital radio and television. Digital will penetrate into the broadcast television in various fields of technology and production process, the digital data involving research design, programming the calculation and effect drawing work covering on the radio, that is fast, accurate use of computer systems and directly calculated and shown around, covering effect diagram and the statistics of the radio frequency and transmission power value, can improve the work efficiency, saving time and energy, and other more abstract decision work

**2 manual calculation and drawing process of**

Medium wave broadcasting coverage often calculate the broadcast coverage radius of the theory, more theoretical calculation method, calculation formula of spherical wave propagation using the combination of ground wave propagation curves estimated value of medium wave broadcast transmission distance, closer to the on-the-spot broadcasting field testing numerical. So as the coverage radius of medium wave broadcast on the radio cover the use of.

Spherical wave propagation formula on the ground for:

E=, E 101gP 10lgD (1)

First, use the formula (1) for calculation of field intensity, the electric field results in combination with ground-wave curves. Detect limit field values radio wave propagation distance of the theoretical value, and as a frequency and transmitted power radio coverage radius.According to the coverage radius in the plane map with compass to draw medium wave broadcasting coverage effect diagram, and then the statistical work.

**3 digital data calculation and drawing process of**

Using the computer to perform mathematical calculations and graphics rendering, should first of all the parameters, graphics and other data to input into the computer, stored in the database, and then find the algorithm for the data, finally realizes the algorithm logic is used in the computer language programming.

3.1 digital data

(1) select the maps of the region suitable, electronic document made maps of the region; according to the linear scale maps of the region, to calculate the distance of two maps of the region in the electronic document (number of pixels) between distance and two actual area between the conversion coefficient (km).The use of the coefficient of length of a straight line between two points can be calculated in linear distance region represented in maps of the region in the electronic document in pixels.

(2) record maps of the region in the electronic document number of the closed boundary pixel coordinate regional value and the area contains the pixels sum, for statistical coverage area.

(3) the pixel coordinates around the city or county records, maps of the region in the electronic document location value, the value is covering center coordinates transmitter broadcast coverage map.

(4) the ground-wave curves into electronic documents, and vector propagation curve form of electronic documents used in the calculation of wave propagation distance.

3.2 the coverage radius calculation

(5) set broadcast frequency and power parameters, through the formula and (4) of the vector of the ground wave propagation curve form of electronic documents to calculate the propagation distance from the point of the broadcast coverage radius, and (1) the distance coefficient obtained in counts the number of pixel maps of the region in the electronic document value, covering effect chart of transmitter coverage radius of a circle.

3.3 the effect of drawing

(6) in the electronic document maps of the region on the basis of the pixel coordinates (3), the value of a city or county as the center, to (5) to draw a circle radius of coverage radius of the number of pixels values derived, circle area represents a certain frequency and power of the theory of effective coverage.

Calculation of 3-4 coverage statistics

(7) according to (6) the coverage effect diagram and (2) the boundary pixel coordinates of the region and the region contains the number of pixels sum statistical coverage area.If the statistics of the covered population. To the electronic document generating population distribution, calculation method and the coverage area statistics similar.In addition to basic data, other each step by the computer program, data storage and computation of user input data in computer servers, results, drawing graphics, complete statistical work.

The key algorithms of

**4. analysis**

The 4.1 plane map

Planar map by surface map by projection and calculation, so the plane map accuracy is directly related to the graphics and statistical calculation accuracy.In general, the distance between two points on the map and the actual geographical distance compared to the total has a certain error, for the convenience of the study and the reasonable control of the error range, through a computer program to calculate repeatedly, drawing and comparing found, broadcast transmission distance directly using a spherical ground wave propagation formula obtained value error produced in small scale plane drawing the 1:100 million map can be ignored, so the calculation program of this paper selects a small scale planar area map of 1:100 million, and the direct use of the transmission distance value as the covering radius value to draw the cover effect chart.

Vector 4.2 curve table

Method of electronic document vectorization accuracy and ground-wave propagation curve form of electronic documents the ground-wave curves as well as the use of groundwave propagation curve form of electronic documents to calculate wave propagation distance algorithm determines the accuracy of wave propagation distance.

The propagation graph is converted into electronic files and stored in the database, is to preserve its set of pixels, so the ground-wave electronic document profiles is scalar data, the computer can not determine the intensity and distance relation, therefore need to "conversion table" to the intensity and high pixel value and the distance value and width of pixel values corresponding up, from field to compute the distance.As shown in fig.:

"One one correspondence between the T1 table" Y axis direction pixel records the electric field strength and ground-wave curves of electronic document; "T2" record of the pixel coordinates curve field with different frequency wave propagation attenuation curve of the values in the form of electronic documents, different frequencies have different curve shape, so the pixel coordinate values are not is not the same; "T3" record of the corresponding relationship between groundwave propagation curve form of electronic documents x pixel and transmission distance.So, through the "corresponding cue T1 table" "T" "T3", can get the propagation distance value.

**5 program**

The use of computer control system of medium wave broadcast coverage program. We must first select the appropriate computational description language, to confirm the accuracy of the language to meet actual demand, then choose the way of data storage is convenient and reliable, the final design of the software structure, interface and program processing flow.

5.1 language selection

There are a lot of computer programming language, using JavaTM Platform StandarEdition6 programming platform to finish writing the cover program.Java programming language can be used to create applications that any conventional programming languages can create, image processing, it is flexible and convenient language after the completion of the compiler can be run in any operating system environment using.

The 5.2 data storage scheme

Relational database systems are usually stored as platform of data access.Java language with a relational database interface of relational database system, the program uses the MicrosoftSQLServer2000 (SP4) database system, the system has the advantages of convenient use, good scalability, high degree of integration with related software.

Procedures require permanent data stored in the database include: regional plane

Map of the electronic document, the conversion coefficient of distance, and the cities and counties of the pixel coordinates and the name, the enclosed area boundary pixel coordinates and the area contains the total number of pixels, vectorization ground-wave curves of electronic documents, medium wave band frequency, transmission power value.

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