摘要:
The present disclosed subject matter relates to a method for measuring the distance of targets in the surroundings by way of a time-of-flight measurement of pulses reflected at said targets, in particular laser pulses, said method comprising: emitting a sequence of transmission pulses having varying pulse intervals, and receiving at least one receive pulse after each one of two different transmission pulses; for each receive pulse: generating a group of M candidate distances, each based on a different transmission pulse among M transmission pulses preceding the receive pulse, wherein each candidate distance is assigned to the corresponding transmission pulse on which it is based; for each candidate distance: determining a weighting value on the basis of at least the closest of the candidate distances assigned to such a transmission pulse which is adjacent to the transmission pulse to which the candidate distance being considered in this determining process is assigned; for each group: selecting the candidate distance with the highest weighting value as the distance measurement value of the receive pulse for which the group was generated.
摘要:
The present disclosure relates to position, navigation and timing (PNT) methods, systems, and transmitters. A method comprises receiving radio-frequency (RF) signals from a plurality of virtual transmitters and determining PNT information of a target object based on information obtained from the RF signals. A system comprises a plurality of virtual transmitters and a receiver. The plurality of virtual transmitters is configured to transmit radio-frequency (RF) signals that include PNT information. The receiver is configured to determine PNT information of a target object based on the PNT information. A transmitter comprises a high-frequency (HF) carrier generator, a waveform generator, and an antenna system. The HF carrier generator generates an HF carrier signal. The waveform generator generates a waveform that includes PNT information. The antenna system transmits the HF carrier signal to generate a subject ionospheric duct. The antenna system is further configured to transmit the waveform through the ionospheric duct.
摘要:
A radar transmits electromagnetic energy in pulse repetition intervals and receives reflections from objects in range gates including Doppler filters. The radar approves desirable ambiguous echoes and suppresses ambiguous echoes of no interest or that interfere with the radar's display. The radar frequency varies according to a staggered or wobbling pattern. The ambiguous echoes produce one pulse in the range gates within a predetermined number of periods. The Doppler filter works with an impulse function response that includes a small number of samples. The Doppler filter, during the predetermined number of periods, gives rise to independent samples from reflectors within the radar's unambiguous range. When the independent samples exceed the small number of samples, the radar approves the ambiguous echo. Otherwise, it is suppressed. In this way, ambiguous echoes are prevented from interfering with the reception or display of echoes. The suppression of asynchronous interferences can be made easier.
摘要:
A pulse radar system including an RF exciter for generating a repeating sequence of internal pulses of RF energy of different frequencies. A transmit circuit responsive to the internal pulses of RF energy generates a transmit radar signal comprising a transmit repeating sequence of transmit intervals during which pulses of RF energy are transmitted. A single receiver responsive to the repeating sequence of internal RF pulses receives radar return signals based on all of the RF frequencies in a receive repeating sequence of receive intervals which do not occur at the same time as said transmit intervals.
摘要:
The present invention relates to a process for measuring the ambiguous distance in a pulse Doppler radar of repetition frequency (f.sub.R).The device comprises means (3) for transposing the signal received R(t) by a signal of frequency p.multidot.f.sub.R, where p is a positive integer; first and second narrow band filtering means (2,5) isolating the principal line of the signal received R(t) and of the transposed signal d(t) respectively, and means (6) for measuring the phase difference (.DELTA..phi.) which exists between the two filtered signals and which is proportional to the ambiguous distance with a coefficient g.
摘要:
This invention is a modification to the ABC range correlators of U.S. Pat. No. 4,095,222 to Mooney, Jr., used in medium PRF radars. It extends the functioning of the range correlators to not only derive target unambiguous range while suppressing detections of clutter discretes but also to reduce the occurrence of false target reports (range ghosts) and blanking of true targets that would otherwise occur when the radar is operated in dense target environments. The specific point of novelty in this design is the operation of two sets of correlators, designated ABC and A'B'C', each with a different M of N detection criterion.
摘要:
Radar signals are generated to have signal characteristics that define multiple sub-pulses in each of a plurality of pulse repetition intervals (PRIs) of a single radar dwell. Electromagnetic radiation is emitted according to the radar signals and the emitted electromagnetic radiation is sensed as radar return signals over a receive interval in each PRI. Coherent integration is performed on a set of the radar return signals and non-coherent integration is performed on another set of the radar return signals.
摘要:
In general the systems and methods described herein relate to velocity ambiguity resolution in an automotive radar system. More particularly, systems and methods produce a unique composite waveform that alternates between, interleaves or otherwise combines a plurality of component waveforms, each characterized by a different velocity ambiguity. Velocity ambiguity is then resolved by determining corresponding Doppler bins which correctly reflect ambiguous velocity calculations for both component waveforms. The systems and methods of the present disclosure are applied to a unique composite linear frequency modulated continuous waveform where component waveforms are generated by modulating one or more parameters of the waveform to change the velocity ambiguity range. Moreover, the systems and methods may selectively apply ambiguity resolution based on the velocity of a host vehicle.
摘要:
A method for calculating a center frequency and a bandwidth for a radar doppler filter is herein described. The center frequency and bandwidth are calculated to provide radar performance over varying terrain and aircraft altitude, pitch, and roll. The method includes receiving an antenna mounting angle, a slant range, and velocity vectors in body coordinates, calculating a range swath doppler velocity, a track and phase swath bandwidth, and a phase swath doppler velocity. The method continues by calculating a range swath center frequency based on the range swath doppler velocity, calculating a phase swath center frequency based on the phase swath doppler velocity, and calculating a level and verify swath bandwidth based upon the track and phase swath bandwidth.
摘要:
A method for processing radar return data to determine a physical angle, in aircraft body coordinates to a target, is disclosed. The radar return data includes a phase difference between radar return data received at an ambiguous radar channel and a left radar channel, a phase difference between radar return data received at a right radar channel and an ambiguous radar channel, and a phase difference between radar return data received at a right radar channel and a left radar channel. The method includes adjusting a phase bias for the three phase differences, resolving phase ambiguities between the three phase differences to provide a signal, and filtering the signal to provide a physical angle to the target in aircraft body coordinates.