Abstract The Doppler effect is used to detect the imminence of a potential collision between a moving vehicle and an object in its path to provide a detecting signal for the safety of the vehicle occupants. A potential collision detecting system includes an ultrashort wave generator, a coupler connecting the generator to a transmitting and receiving antenna, a mixer-detector connected to the generator and the antenna through the coupler, an amplifier, a filter, an AC-DC converter, a comparator and a safety device for protecting vehicle occupants. The mixerdetector derives the Doppler signal and the time remaining until the occurrence of a collision is derived by converting the frequency of the Doppler signal to a signal level by means of a filter having certain frequency characteristics. The comparator converts the remaining time to a voltage and, when the voltage exceeds a predetermined value, the comparator issues a collision detecting signal to activate the safety device. The filter is a band pass filter which cuts off frequencies in the low frequency range, where operation of the safety device is not required, and in the high frequency range corresponding to a high relative velocity of the vehicle not likely to be met in practice.
In arrangements utilizing the Doppler effect to detect the imminence of a potential collision between a moving vehicle and an object in its path to provide a detecting signal for the safety of occupants of the vehicle, a potential collision detecting system comprising, in combination, an undulatory signal generator; an undulatory signal transmitter-receiver connected to said generator to transmit direct signals and to receive reflected signals; mixer-detector means connected to said generator and to said transmitter-receiver to derive a Doppler signal from the direct and reflected signals; frequency responsive circuit means connected to said mixer-detector means and providing an output AC signal having a level in proportion to the frequency of the Doppler signal produced in said mixerdetector means; AC-DC converter means connected to said circuit means and converting said output AC signal of said circuit means to a DC signal; and comparator means connected to said converter means and providing a collision detecting signal responsive to said output DC signals of said converter means exceeding a predetermined value.
Claim 2
Dependent Claim
169 words
In arrangements utilizing the Doppler effect to detect the imminence of a potential collision between a moving vehicle and an object in its path to provide a detecting signal for the safety of occupants of the vehicle, a potential collision detecting system comprising, in combination, an undulatory signal generator; an undulatory signal transmitter-receiver connected to said generator to transmit direct signals and to receive reflected signals; mixer-detector means connected to said generator and to said transmitter-receiver to derive a Doppler signal from the direct and reflected signals; frequency responsive circuit means connected to said mixer-detector means and providing an output AC signal having a level in proportion to the frequency of the Doppler signal produced in said mixerdetector means; AC-DC converter means connected to said circuit means and converting said output AC signal of said circuit means to a DC signal; and comparator means connected to said converter means and providing a collision detecting signal responsive to said output DC signals of said converter means exceeding a predetermined value.
Claim 3
Dependent Claim
19 words
A potential collision detecting system, as claimed in claim 1, wherein said frequency responsive circuit means comprises a filter.
Claim 4
Dependent Claim
30 words
A potential collision detecting system, as claimed in claim 1, wherein said frequency responsive circuIt means comprises a band pass filter having a cut-off characteristic in the low frequency range.
Claim 5
Dependent Claim
30 words
A potential collision detecting system, as claimed in claim 1, wherein said frequency responsive circuit means comprises a band pass filter having a cut-off characteristic in the high frequency range.
Claim 6
Dependent Claim
35 words
A potential collision detecting system, as claimed in claim 1, wherein said converter means is a converter operable to convert the AC output of said filter to a DC voltage inversely proportional to said distance.