Patent ID: 7420503

Claim:
A short-range radar comprising: a transmitter section which radiates a short pulse wave having a predetermined width into space each time receiving a transmission trigger signal; a receiver section which performs reception and detection processing on a reflected wave of the short pulse wave when having received a reception trigger signal; a variable-period pulse generator including a direct digital synthesizer which outputs a signal having a frequency corresponding to frequency data specified from an outside, the variable-period pulse generator generating a variable-period pulse whose period changes in accordance with the frequency data; a first pulse generation circuit which receives the variable-period pulse generated by the variable-period pulse generator, and which outputs a first pulse whose level shifts in a predetermined direction as the transmission trigger signal at a reference timing that is assumed to be a timing at which a level of the variable-period pulse shifts in a predetermined direction first since a search instruction is input; a second pulse generation circuit which receives the variable-period pulse generated by the variable-period pulse generator, and which outputs as the reception trigger signal a second pulse whose level shifts in a predetermined direction at a timing when the level of the variable-period pulse has shifted in a direction opposite to the first predetermined direction after the reference timing; a trigger signal generating section including the variable-period pulse generator, the first pulse generation circuit, and the second pulse generation circuit, the trigger signal generating section outputting the transmission trigger signal from the first pulse generation circuit to the transmitter section each time the variable-period pulse generator receives the search instruction, and also outputting from the second pulse generation circuit to the receiver section as the reception trigger signal a signal that is delayed by an arbitrary lapse of time with respect to the transmission trigger signal in order to give delay time between transmission and reception; and a frequency data varying section including a memory in which a relationship between the frequency data and the delay time between transmission and reception is stored beforehand in a form of a table of computation expressions or calculation results, the frequency data varying section varying the frequency data destined for the direct digital synthesizer in the variable-period pulse generator based on the relationship between the frequency data and the delay time between transmission and reception stored in the memory, thereby enabling arbitrarily varying delay time of the reception trigger signal with respect to the transmission trigger signal.