National Frequency Management System

Communications and Spectrum Management Research Center is developing the National Frequency Management System (NFMS) as part of the National Monitoring System (NMS) for General Directorate of Radiocommunications of Turkey. The Principle tasks of the NMS are:

  • Supervision of the radio signals,
  • Measurement of spectrum occupancy,
  • Measurement of technical parameters,
  • Measurement of radio and TV broadcast transmissions,
  • Determination of infringements,
  • Determination of radio coverage areas,
  • Interference analysis,
  • Location of unlicensed radio stations,
  • Gathering statistical data for frequency management purposes.

The system comprises one National Control Center and seven Regional Monitoring Centers. There are numerous fixed and transportable regional remote stations, direction finding and monitoring stations and two mobile broadcast measurement vehicles.

NFMS contains the spectrum engineering support as well as the database for the licencing, monitoring, frequency management, accounting and other functions of the Directorate of Radiocommunications. The spectrum engineering support comprises the technical analysis, interference analysis, frequency planning and assignment, international coordination, system engineering, and other technical duties. The frequency range to be covered is 10 kHz – 40 GHz. The system will be delivered as a turnkey system.

TNTview is integrated into the spectrum engineering and monitoring support systems. All the visualisation and spatial data manipulations are done through TNTview. Propagation simulation results obtained by engineering calculations (e.g. field strength, received power) are imported and i nterpolated through TNTsdk to yield a smooth surface, then visualized by TNTview. Contouring is applied on these resultant surfaces to identify the coverage and interference areas. These analysis results are combined with raster map data to identify the centers of population in the coverage or interference contours.

Similarly for digital audio and video broadcasts, TNTsdk functions and TNTview are utilized to import and visualize the calculation results. Once more, surface fitting and contouring are the main abilities of TNTview which enabled proper display of analysis data. Coverage areas, coverage probabilities, useful and interfering signal levels are the main results displayed for digital broadcasts. In the monitoring support system, the pinmap objects of all stations operating in a defined geographic region are displayed on a raster map. By clicking the mouse on a pinmap object, one can reach to the technical database information about the station at the cursor position. Another use of TNTview is the visualization of the triangular region determined through three Direction Finding Antenna Systems. The triangle shows the region where the monitored station is most likely located.

It is to be noted that the spectrum engineering and monitoring support systems perform computationaly intensive and time consuming engineering calculations. For this reason, we have developed them by using C and C++ programming languages which enabled us to call in TNTsdk library functions in our program modules witout any special programming tools.