摘要:
The present invention relates to a CW radar method for measuring distances between and relative speeds of a vehicle and one or more obstacles. The present invention further provides that the transmission (s(t)) can be composed of at least four consecutive chirps (A, B, C, D), each having different slopes. The intersection points of all lines in the distance-relative speed diagram from two chirps (A, B) can be calculated from all the ascertained frequency positions K1,n and K2,p. To validate those intersection points, one may observe whether a peak exists in the Fourier spectrum of a third chirp C at a frequency position K3,q, whose assigned line intersects a surrounding area of the intersection point in the distance-relative speed diagram. A further validation of those intersection points involves observing whether a peak exists in the Fourier spectrum of a fourth chirp D at a frequency position K4,r, whose assigned line intersects a surrounding area of the intersection point in the distance-relative speed diagram. The intersection points are then regarded as valid, when they satisfy both conditions.
摘要:
The distance and relative speed of an object remote from an observation point determined using a signal form which includes two signals having a predetermined spacing relative to each other. The two signals are transmitted for a certain time interval during which the frequency of the signals is modulated in a stepwise fashion. Additionally, the signal sections of the two signals are transmitted alternately for each step so that there is a predetermined frequency spacing between the signal sections being emitted consecutively.
摘要:
A vehicle radar emits four groups of single-frequency stepped radar pulses. In group A, the frequency of each pulse is a fixed amount higher than that of the preceding pulse. In group B, the frequency of each pulse is a fixed amount lower than that of the preceding pulse. In group C, the frequency of each pulse is the same as that of the preceding pulse. In group D, the frequency of each pulse depends on a modulo algorithm. The signals reflected from other vehicles may readily be processed with inexpensive equipment to discriminate among such other vehicles, and to determine the distance to, and relative speed of, each such vehicle.
摘要:
In the particular embodiment disclosed in the specification, a CW radar process for measurement of distances and relative speeds between a vehicle and one or more obstructions including transmitting a sequence of constant-frequency radar signal bursts which follow one another without any time interval during four successive measurements. In the first measurement, the radar signal bursts are of sequentially increasing frequency and in the second measurement they are of sequentially decreasing frequency while in the third measurement they have the same frequency and in the fourth measurement the burst frequencies follow a coded pattern. Demodulation of the signals which are reflected by obstructions is carried out by mixing them with the transmitted signals using only one single-channel mixer providing an output signal which is not the signal of a phase curve but of an amplitude curve.
摘要:
OFDM symbols are generated using data from one or more users or from one or more data sources represented on a number of sub-carriers. To inhibit multiple-access interference on application of the CDMA principle, the data are transformed in a data-source specific manner and only subsequently allocated to the sub-carriers, independently of the transformation.
摘要:
In a method for the error-monitored transmission of data via interfaces of a multi-step communication system, the data is transmitted from a transmitter station to a data-receiving station via at least two relay stations which are connected therebetween and receive and further transmit the data parallel to each other. The data is retransmitted if the transmission has been insufficient due to a request from the receiver end and/or due to the lack of a confirmation from the receiver end. In order to increase performance while reducing power consumption of the system, the request or confirmation is generated only by the receiver station and is sent back to the transmitter station. The relay stations consequently do not generate any confirmations or requests.
摘要:
A method synchronizes a radio communication system divided into radio cells. Data is transmitted in the radio communication system by a multiple access method. Each radio cell thus has a base station for the radio feed of several mobile stations, allocated to the radio cell. A synchronization of the base station is carried out using the received signals from mobile stations in the same radio cell and also in adjacent radio cells. The base station determines at least one pilot signal and signals said pilot signal to the allocated mobile stations in a downwards direction. The allocated mobile stations transmit the signaled pilot signal in an upwards direction to the base station. The base station determines a synchronization value, from the received pilot signals from the radio cell thereof and also from the adjacent radio cells, fro a time synchronization and/or for a frequency synchronization on which the bas station is synchronized.
摘要:
A method and arrangement for controlling a system of multiple traffic signals for regulating the traffic of vehicles is described. Traffic data is transmitted by wireless transmission to traffic data processing units assigned individually to a locally limited group of traffic signals, and each traffic data processing unit performs an analysis of the local traffic situation for the environment of the locally limited group of traffic signals up to, at the maximum, the neighboring locally limited groups of traffic signals.
摘要:
In a method for HPRF-radar measurement of the range and Doppler frequency of at least one target, a transmit signal is generated which consists of two pulse sequences that are interleaved on a pulse to pulse basis, and have the same pulse repetition frequency PRF and the same transmit frequency. The pulses of a first one of the two pulse sequences have a linearly increasing phase value with a fixed phase difference &phgr;1n (greater than zero) from pulse to pulse with &phgr;1n≧0, while the pulses of the second pulse sequence have a linear increasing phase value with a fixed phase difference &phgr;2n which differs from &phgr;1n. The two received base band signals of each individual pulse sequence are Fourier transformed, and the amplitude peaks of the resulting two Fourier spectra are determined. The amplitude peaks of the two Fourier spectra are then clustered to determine pairs of spectral lines of a Doppler frequency shift of Δ f = ϕ 2 n - ϕ 1 n 2 π · PRF . The target Doppler frequency is calculated based on two Doppler frequencies of a previously determined spectral line pair, and the target range is calculated based on the phase difference between the two spectral lines of a previously determined spectral line pair.
摘要:
With a frequency-agile pulsed doppler radar with high pulse repetition frequency (HPRF) in the unambiguous velocity region, in order to measure the range of a target the complex time signal derived from the echo signals of a coherent processing interval (CPI) is transformed into the frequency domain, the transformed spectrum is multiplied by a bandpass function with a mean frequency coinciding with the doppler frequency of the target, and the product is transformed back into a time signal. The real envelope of this re-transformed time signal displays a definite leading edge and a steady state region, from which the echo travel time can be estimated. Particular advantages may be derived for the pulsed doppler radar set from a plurality of frequency agile transmitter/receivers operated at the same time at different frequencies, and whose frequency switching times are time-staggered.