| 摘要 |
In a Doppler log for a vehicle equipped with transmitting and receiving units associated with two mutually transverse measuring axes which are parallel to a plane defined by the longitudinal and transverse axes of the vehicle, for the emission of directed beams of sound energy in directions which extend along the measuring axes, each beam being inclined with respect to the plane by a known emission angle such that all of the beams are to the normal to the measuring axes, the transmitting units operating at selected, known transmitting frequencies, and each receiving unit being connected for receiving the reflected components of the sound energy from a respective emission direction, the log further including a Doppler frequency analyzer connected to the output of each receiving unit for producing a representation of the Doppler frequency component of the sound signal received by that receiving unit, and a ratio former connected to the output of each analyzer and the associated transmitting and receiving unit for producing an output signal representing the quotient of the respective Doppler frequency with the corresponding transmitting frequency, there are provided: summing members connected to the units for forming representations of the sum of the ratio former output signals associated with each measuring axis; multiplying members connected to the summing members for multiplying each sum representation by a representation of the cosecant of the associated emission angle; and a testing device connected to the multiplying members for comparing the multiplication results and emitting a signal indicating proper Doppler log operation whenever such multiplication results are substantially identical. |
