'Initializes a satellite object.
@param identifier: The PRN (unique identifier) of this satellite.
@type identifier: C{int}
@param azimuth: The azimuth of the satellite (see instance variable
documentation).
@type azimuth: C{float}
@param elevation: The elevation of the satellite (see instance variable
documentation).
@type elevation: C{float}
@param signalToNoiseRatio: The signal to noise ratio of the connection
to this satellite (see instance variable documentation).
@type signalToNoiseRatio: C{float}'

def __init__(self, identifier, azimuth=None, elevation=None, signalToNoiseRatio=None):

    PositioningBeacon.__init__(self, int(identifier))
    self.azimuth = azimuth
    self.elevation = elevation
    self.signalToNoiseRatio = signalToNoiseRatio
