EXPERIMENTAL INVESTIGATION TO DETERMINE IMMUNITY OF AIRBORNE RADIO-NAVIGATION EQUIPMENT FROM INTERFERENCE FROM GSM STANDARD CELLULAR MOBILERADIO TRANSMITTERS

One of the main problems complicating the development of cellular mobi le radio (CMR) systems under the GSM standard in Russia is the fact th at the Federal Plan on Radio Frequency Use does not comply with intern ational requirements. Section 704 of the Radio Communications Code sti pulates that the 890-960 MHz band shall be assigned to the radio equip ment used in the airborne radio-navigation service, namely, the on-boa rd equipment (OE) for short-range radio navigation and landing systems (SNLS) for aircraft. A comparison of the frequency bands used for SNL S on-board equipment and an aircraft landing system with the frequency bands of transmitters employed in the mobile and base stations in a c ellular mobile radio system under the GSM standard reveals that these bands overlap. Since such radio equipment operates independently, it i s possible that unintended radio interference may be generated on the azimuthal and ranging channels of aircraft SNLS equipment in the ''nav igation'' mode as well as on the course and glidepath channels in the ''landing'' mode, i.e., electromagnetic compatibility (EMC) will be lo st. Such traditional methods as frequency-territorial separation (FTS) , the value of which is, to a known extent, determined by the signal/n oise protection ratio at the receiver input for which useful signal re ception is achieved with a prescribed quality, are used to achieve com bined operation of CMR equipment and aircraft SLNS equipment without m utual radio interference. This paper presents one method for an experi mental determination of the protection ratio for aircraft SLNS equipme nt together with the results of measurements which are used as the bas is for developing frequency and territorial separation standards for C MR equipment under the GSM standard and aircraft SLNLS equipment emplo yed in the Russian Federation.