1. A train position detection device,
characterised in that
a receiver (120, 320) to receive electric waves as reception signals respectively through a plurality of antennas, said plurality of antennas placed on a train traveling on a track with a specified interval therebetween, and said electric waves provided from a stationary wireless apparatus (200) that is placed beside the track of the train and radiates, as an electric wave, a transmission signal having a specified frequency, amplitude or phase; and
a position detector (130, 130a to 130c) to calculate a relative position of the plurality of antennas to the stationary wireless apparatus (200) from a ratio between Doppler frequencies calculated respectively from the plural reception signals.
2. The train position detection device as claimed in claim 1, comprising a train position detector (140, 140a) to calculate a position of the train from the relative position, a placement position of the stationary wireless apparatus (200) and placement positions in the train of the plurality of antennas.
3. The train position detection device as claimed in claim 2, wherein, when the ratio between the Doppler frequencies calculated from the plural reception signals becomes negative, the position detector (130, 130a to 130c) detects that the plurality of antennas are present in an area near to just beside the stationary wireless apparatus (200), to thereby calculate the relative position of the plurality of antennas to the stationary wireless apparatus (200) on the basis of a distance between the stationary wireless apparatus (200) and the track, and the interval between the antennas.

4. The train position detection device as claimed in claim 2, wherein the position detector (130, 130a to 130c) calculates a traveling speed of the train from a timewise variation of the relative position.
5. The train position detection device as claimed in claim 2, wherein the position detector (130,130a to 130c) calculates an electric-wave reaching angle at which the electric wave radiated from the stationary wireless apparatus (200) reaches the antenna, from the relative position, a distance between the stationary wireless apparatus (200) and the track, and the interval between the antennas.
6. The train position detection device as claimed in claim 5, wherein the position detector (130, 130a to 130c) calculates a traveling speed of the train, using the electric-wave reaching angle, the Doppler frequency and the specified frequency.
7. A train position detection device, characterised in that
a receiver (120, 320) receive electric waves as reception signals respectively through three or more antennas, these antennas placed on a train traveling on a track with specified intervals therebetween, and said electric waves provided from a stationary wireless apparatus (200) that is placed beside the track of the train and radiates, as an electric wave, a transmission signal having a specified frequency, amplitude or phase;
a Doppler frequency calculator (131, 330) to calculate three or more Doppler frequencies respectively from the reception signals received by the receiver (120, 320);
a passage judgement processor (141, 141a, 341) to judge, when it detects that a ratio between those among the plural Doppler frequencies becomes -1, that any two of antennas among the three or more antennas is passing through just

beside the stationary wireless apparatus (200), to thereby calculate a plurality of passage judgement signals;
a setting-angle correction calculator (342) to calculate a setting angle of a line that connects the three or more antennas relative to a traveling direction of the train, from the plurality of passage judgement signals and a traveling speed of the train; and
a position calculator (142, 344) to calculate a relative position of the three or more antennas to the stationary wireless apparatus (200) on the basis of the setting angle, a distance between the stationary wireless apparatus (200) and the track, and the intervals between the antennas.
8. The train position detection device as claimed in claim 7, comprising a train position calculator (142, 344) to calculate a position of the train from a placement position of the stationary wireless apparatus (200), placement positions of the three or more antennas in the train, and the relative position.