CLIAMS:1.- A radio altimetry system that can be fixed to an aircraft and provide the distance of that aircraft from the surface, capable of operating in a multiple radio altimetry installation (2) including at least two such radio altimetry systems, said radio altimetry system including a frequency-modulated radio wave generator using a modulation signal including a repetition of frequency variation sequences, two successive sequences being separated by a variable duration waiting plateau,
characterized in that it includes means (26) for obtaining an identifier making it possible to distinguish said radio altimetry system from any other radio altimetry system of said multiple installation (2),
and means (30) for selecting a configuration of the waiting plateaus for said modulation signal as a function of the obtained identifier.
2.- The radio altimetry system according to claim 1, characterized in that said configuration of the waiting plateaus defines the variable durations of said waiting plateaus, said durations being obtained by applying a pseudo-random number generator.
3.- The radio altimetry system according to claim 2, characterized in that said pseudo-random number generator includes applying a predetermined polynomial.
4.- The radio altimetry system according to any one of claims 2 or 3, characterized in that said multiple installation includes a predetermined maximum number N greater than or equal to two of such radio altimetry systems, and the system comprises storage means (31) for N pseudo-random number generators.
5.- The radio altimetry system according to claim 4, characterized in that said storage means are capable of storing a predetermined pseudo-random number generation polynomial and N different startup values, one said pseudo-random number generator being obtained by applying said polynomial with one of said startup values.
6.- The radio altimetry system according to any one of claims 4 or 5, characterized in that the identifier is a number encoded on a predetermined number of bits that depends on the predetermined maximum number N of radio altimetry systems in said multiple installation.
7.- The radio altimetry system according to one of the preceding claims, characterized in that it further includes means (42, 44) for receiving radio waves, means (48) for subtracting the transmitted radio wave and the received radio wave to form a beat signal and means (52) for filtering said beat signal in a predetermined frequency band.
8.- The radio altimetry system according to one of the preceding claims, characterized in that the means (26) for obtaining the identifier include means for reading an identifier introduced by an operator using a suitable interface (28).
9.- A multiple radio altimetry installation including at least two radio altimetry systems according to one of claims 1 to 8. ,TagSPECI:As Attached