Results of an Investigation into the use of 1175 MH and 1202 MHz for GNSS signals in European Airspace

J.I.R. Owen

Abstract:	An investigation was performed into potential interference to future GNSS signals from Distance Measuring Equipment (DME) operating in the ARNS band in European airspace. Simulations of the operation of GNSS signals in the proposed Galileo ‘E5’ band at 1202 ± 12 MHz and the GPS L5 band at 1175 ±12 MHz. indicate that at certain geographic locations severe interference may occur. These regions occur at altitudes of 30000 Ft plus where the density of air traffic is high. The investigations measured the RF environment at altitude over the location where the highest interference was predicted in Europe and also developed equipment to assess the operation of wideband GNSS signals. An existing GPS receiver system was modified to produce an Interference Measurement Equipment (IME) that enable the effect of DME interference into GPS P(Y)- code to be assessed. The IME incorporated a pulse blanker circuit as specified by RTCA to remove peek interference power over –116 dBW. The effect of the DME interference was assessed by the reduction in C/No in the receiver’s carrier tracking loop. Apart from a 3 dB degradation in C/No caused by the addition of two noisy signals in the receiver there was little evidence of any further degradation in its performance, although there were 900 aircraft within a 400 nm box of the trials aircraft. The results are being used to refine the simulations performed of DME interference to ensure that additional services operating in the band eg JTIDS/MIDS can be modelled and their effect evaluated.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	742 - 749
Cite this article:	Owen, J.I.R., "Results of an Investigation into the use of 1175 MH and 1202 MHz for GNSS signals in European Airspace," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 742-749.
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