Automatic control of open-cut pits requires the construction of a radio system for transmission of digital information with a large number of scattered, mobile sources. To synthesize an Optimum radio system it is necessary to investigate the electromagnetic environment in the coal pit in which the radio system is to function. The electromagnetic environment [1] is governed by a combination of electromagnetic disturbances (radio noise) in the pit which interfere with radio reception.In this article we give the method and results of an investigation of the electromagnetic environment in coal pits of the Kuzbass and Kazakhstan in 1970-1972.
A Priori Model of Electromagnetic EnvironmentIn constructing an a priori model we used the idea that the electromagnetic environment of a system consists of a set of isolated interrelated groups { *i}" Each group is defined by the set *i ={Qi' Li' Ti}' where Qi' Li are the weighting and functional characteristics and T i is the interval of determination (i = 1, 2, 3 .... ) (see Appendix I). In general {*i} depends on the frequency f of the radio spectrum and the coordinates x, y, z.Using the physical nature of the electromagnetic environment and the research results in [2-4] we defined an a priori model (Fig. 1). We can assume that L 0 is a nonsteady random function. The dependence of the electromagnetic environment parameters on f and the coordinates in the pit have been insufficiently investigated.Experimental Method i 1. The method was developed with reference to the a priori model of the electromagnetic environment, the technical means of obtaining and processing the experimental information, and the theory of design of experiments [5,6].2. From the a priori model we can get an estimate of the total duration of the measurements in the pit (Appendix II~.
Tmeas~ To 9For known values ofQ i we can take Tmeas as equal to the maximum of the aggregate 3o In forming technical means of obtaining information it is necessary to start from the requirements of accuracy of measurement and correspondence to the conditions of measurement in the pit.4. The method of processing the information is formed from the requirements of identification of L 0, in particular if L 0 is a nonsteady random function. The methods of identification were described in [7].5. Under pit conditions it is advisable to use compact field strength meters for radio noise, of the types P4-12A, P4-13A, BSM-301, or BSM-401, and measuring receivers of series P5. The signal from the devices is recorded by hand and on magnetic tape.Institute of Mining, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk.