Abstract: A system and method are disclosed for the generation and processing of waveforms utilized to modulate the carrier frequency of a microwave sensor employed, to determine the range and velocity of an object of interest. The system and method result in improved performance in environments with high levels of interference.

Abstract: There is described a pulse analyzer (1) for sampling a pulse or a repetitive stream of pulses. The pulse analyzer multiplies a pulse by a set of basis functions (c1, c2) to generate a plurality of multiplied pulse functions, and a synthesizer (9a, 9b, 13) combines the multiplied pulse functions to generate a pulse sample. In particular, the synthesizer performs at least one integrating operation over an integration interval substantially corresponding to the duration of the pulse and at least one adding operation. The basis functions are such that the output of the synthesizer corresponds to a pulse sample for a sample time interval shorter than the integration interval.

Abstract: An interference classifier is disclosed for determining the type of interference present in a signal. The interference classifier 601 comprises a buffer 602 operable to receive and store data comprising samples of a signal; a scale factor calculator 603 operable to use the signal samples to calculate a scale factor in dependence upon the levels of the signal samples; a normaliser 604 operable to calculate normalised signal samples by using the scale factor to normalise the signal samples; a nonlinear transformer 605 operable to perform a nonlinear transform on the normalised signal samples to calculate transformed signal samples; an averaging circuit 606 operable to calculate an average of the transformed signal samples; and a comparator 607 operable to compare the calculated average of the transformed signal samples to a predetermined threshold level in order to determine the type of interference present in the received signal.

Abstract: An object ranging system operates by transmitting pulses derived from a frequency-swept signal and determining the beat frequency of a combination of the frequency-swept signal and its reflection from an object. To determine the range of close objects the beat frequency is determined in the time domain by integrating samples of the beat frequency signal to obtain a value representing the integral of a half cycle of the sine wave, establishing integration thresholds representing when, according to the integration value, the sine wave would have reached predetermined stages in its cycle, and measuring the time taken for the integral of the sine wave to change from one threshold to another, this time thereby indicating the period of the beat frequency.

Abstract: An automotive radar system to determine a sweep pattern to be transmitted as an output radar waveform in a multiuser transmission environment is disclosed. The system includes: a receiver to receive noise signals; a signal generator to generate a plurality of different frequency sweep signals; a signal combiner to combine each frequency sweep signal with a received noise signal; an interference classifier to identify combined signals corresponding to one or more received noise signals including frequency chirp signals and to determine the respective noise levels of the identified combined signals corresponding to one or more received noise signals including frequency chirp signals; a selector to select a plurality of frequency sweep signals in dependence upon the noise levels determined by the interference classifier; and a control unit to determine a sweep pattern comprising the selected plurality of frequency sweep signals to be transmitted as an output radar waveform.

Abstract: A method of processing an input signal to perform frequency analysis is disclosed. The input signal comprises a desired signal and an interference signal. A crosslation is performed to generate a representation of the frequency content of the input signal. The representation comprises initial crosslation values predominantly corresponding to interference and subsequent crosslation values corresponding to the desired signal. For the crosslation values corresponding to interference, a maximum value and slope are calculated. These are used as parameter indicators of the interference and also to identify which values should be discarded in the processing of the desired signal. With the crosslation values corresponding to interference discarded, the remaining crosslation values are processed to calculate properties of the desired signal.

Abstract: An object is detected by generating a m-ary primary signal having an irregular sequence of states. Each transition results in the transmission of a pulse encoded according to the type of transition. Reflected pulses are processed with a delayed, reference version of the primary signal. The presence of an object at a range corresponding to the delay is determined from the extent to which the reflected pulses coincide with transitions in the reference signal. In one aspect, transitions between states of the primary signal occur at varying time offsets with respect to nominal regular clock pulses. In another aspect, the object-detection system is operated while inhibiting the transmission of pulses, and if a significant output is obtained, the parameters of the transmitted signal are altered.

Abstract: An automotive radar system is disclosed that comprises an interference classifier 203 for determining a type of interference in a signal received from a multiuser environment. A sweep pattern comprising frequency sweep signals for a transmitted radar waveform is then advantageously determined in dependence upon the level of interference experienced by frequency sweep signals for the determined type of interference.

Abstract: An interference classifier is disclosed for determining the type of interference present in a signal. The interference classifier 601 comprises a buffer 602 operable to receive and store data comprising samples of a signal; a scale factor calculator 603 operable to use the signal samples to calculate a scale factor in dependence upon the levels of the signal samples; a normaliser 604 operable to calculate normalised signal samples by using the scale factor to normalise the signal samples; a nonlinear transformer 605 operable to perform a nonlinear transform on the normalised signal samples to calculate transformed signal samples; an averaging circuit 606 operable to calculate an average of the transformed signal samples; and a comparator 607 operable to compare the calculated average of the transformed signal samples to a predetermined threshold level in order to determine the type of interference present in the received signal.

Abstract: A method for determining at least one of the distance to and the speed of an object is discussed. The method comprises determining an indication of whether the object is approaching or moving away and generating an interrogation signal comprising a sequence consisting of segments at constant frequency and segments of varying frequency, wherein if the determining step indicates the object is approaching then the varying frequency segments have decreasing frequency and if the determining step indicates that the object is moving away then the varying frequency segments have increasing frequency. The interrogation signal is transmitted and a version of the interrogation signal reflected from the object is detected. At least one of the distance to and speed of the object is then determined using a combination of the interrogation signal and the reflected version of the interrogation signal.

Abstract: A system and method are disclosed for the generation and processing of waveforms utilized to modulate the carrier frequency of a microwave sensor employed, to determine the range and velocity of an object of interest. The system and method result in improved performance in environments with high levels of interference.

Abstract: An apparatus and method is disclosed for robustly detecting a signal in the presence of background noise which includes impulsive noise. Each value of a signal is mapped to a point on a semicircle defined by two coordinates on orthogonal axes in two-dimensional space. A respective mean is calculated of each of the two coordinates of the transformed points, and the two means are used to calculate a mean direction of the points on the semicircle. The mean direction is reverse-mapped back into the signal domain and compared against a detection threshold. The detection threshold may be set in dependence upon the concentration of the points on the semicircle.

Abstract: An apparatus and method is disclosed for robustly detecting a signal m the presence of background noise which includes impulsive noise. Each value of a signal is mapped to a point on a semicircle defined by two coordinates on orthogonal axes in two-dimensional space. A respective mean is calculated of each of the two coordinates of the transformed points, and the two means are used to calculate a detection threshold representative of the concentration of the points on the semicircle. A mean of the signal values is calculated and compared against the detection threshold. Alternatively, the mean is adjusted in dependence upon the concentration of the points on the semicircle and the adjusted mean is compared against a fixed threshold value.

Abstract: There is described a pulse analyser (1) for sampling a pulse or a repetitive stream of pulses. The pulse analyser multiplies a pulse by a set of basis functions (c1, c2) to generate a plurality of multiplied pulse functions, and a synthesiser (9a, 9b, 13) combines the multiplied pulse functions to generate a pulse sample. In particular, the synthesiser performs at least one integrating operation over an integration interval substantially corresponding to the duration of the pulse and at least one adding operation. The basis functions are such that the output of the synthesiser corresponds to a pulse sample for a sample time interval shorter than the integration interval.

Abstract: An object ranging system operates by transmitting pulses derived from a frequency-swept signal and determining the beat frequency of a combination of the frequency-swept signal and its reflection from an object. To determine the range of close objects the beat frequency is determined in the time domain by integrating samples of the beat frequency signal to obtain a value representing the integral of a half cycle of the sine wave, establishing integration thresholds representing when, according to the integration value, the sine wave would have reached predetermined stages in its cycle, and measuring the time taken for the integral of the sine wave to change from one threshold to another, this time thereby indicating the period of the beat frequency.

Abstract: An object ranging system operates by transmitting alternating up and down frequency sweeps which have randomly distributed slopes as a result of random selection of local frequency peaks and valleys according to predetermined probability tables, and determining the beat frequency obtained when combining the transmitted signal with its reflection from an object.

Abstract: Two versions of a binary signal having an irregular sequence of states are processed by deriving (i) a first value which represents the average time derivative of one signal at the times of transitions in the other signal, and (ii) a correlation value for the two signals, and then combining the first value with the correlation value. For a given relative delay introduced between the signals, the resultant combined value indicates whether the introduced delay brings the transitions in the two signals into coincidence. The process can be repeated for other introduced delays to determine the amount of delay between the two signals.

Abstract: A method of processing an input signal to perform frequency analysis is disclosed. The input signal comprises a desired signal and an interference signal. A crosslation is performed to generate a representation of the frequency content of the input signal. The representation comprises initial crosslation values predominantly corresponding to interference and subsequent crosslation values corresponding to the desired signal. For the crosslation values corresponding to interference, a maximum value and slope are calculated. These are used as parameter indicators of the interference and also to identify which values should be discarded in the processing of the desired signal. With the crosslation values corresponding to interference discarded, the remaining crosslation values are processed to calculate properties of the desired signal.

Abstract: A method for determining at least one of the distance to and the speed of an object is discussed. The method comprises determining an indication of whether the object is approaching or moving away and generating an interrogation signal comprising a sequence consisting of segments at constant frequency and segments of varying frequency, wherein if the determining step indicates the object is approaching then the varying frequency segments have decreasing frequency and if the determining step indicates that the object is moving away then the varying frequency segments have increasing frequency. The interrogation signal is transmitted and a version of the interrogation signal reflected from the object is detected. At least one of the distance to and speed of the object is then determined using a combination of the interrogation signal and the reflected version of the interrogation signal.

Abstract: A spread-period clock generator (SPC) counts basic clock pulses (XK) to generate output pulses (EQ) with varying periods, and has means (controlled by signal QS) for switching between a first mode, in which counting is carried out in response to the leading edges of the basic clock pulses (CK), and a second mode, in which counting is carried out in response to the trailing edges of the basic clock pulses (CK). Accordingly, if mode switching (signal QS) is carried out during a counting operation, the counting period is altered by a portion of a basic clock period (CK). Thus, the number of different periods of the output pulses can be increased without increasing the basic clock frequency (input WC, signal LK, CK).