Nissan Motor Company Limited

Hiroshige Fukuhara

Hiroyuki Kamishima

Norio Fujiki

Yukitsugu Hirota

Toshiro Muramatsu

Hideo Takai

Teruyoshi Mihara

Kraisorn Throngnumchai

Hiroshi Endo

Masazumi Sone

Yasuyuki Uekusa

Hisao Kishi

Hitoshi Tsukahara

Kouichiro Katoh

Koichiro Kato

Motoki Hirano

In a radar target position detecting apparatus, beams (, for example, light beams) irradiated from a transmitter(, for example, LED) have a predetermined divergence angle, a plurality of light (beam) receiving elements such as photodiode arrays each having a different receiving angle (directivity) are arranged in an array form, and a direction of a reflected wave (beam) is identified according to a position of the arrayed beam (wave) receiving elements in the array at which the reflected wave (beam) is captured.

Target position detecting apparatus and method utilizing radar

A low-cost compact radar apparatus measures a distance to a target and the relative speed of the target. The apparatus has a transmitter for transmitting a pulse signal and a receiver for receiving a reflected pulse signal from the target. The received signal is converted into a binary signal, which is sampled by a sampler and is accumulated in a cumulative storage unit. Addresses of the storage unit correspond to an interval between the transmission and reception of the pulse signal. According to the interval, the distance and relative speed of the target are calculated at high speed. The apparatus carries out many accumulation operations, to improve an S/N ratio and speedily detect even a weak reflected signal.

Radar apparatus with determination of presence of target reflections

Radar apparatus

An apparatus for deciding an excessive approach of a vehicle to an object in front of the vehicle. The excessive approach decision apparatus comprises a normalized time rate of change detector for determining a normalized time rate of change of a visual angle for the object as viewed from the vehicle. An excessive approach is indicated based upon the determined normalized time rate.

Vehicle collision alert system

An antenna unit for an automotive vehicle is provided. This antenna unit is adapted to be located in a non-visible position on a vehicle and includes an grounding plate, a radiating conductive plate, and a loop antenna element which is interposed between the plates and is fixed thereto. The loop antenna is formed by two bars which have configurations symmetrical to each other. One end of each bar is folded at a right angle relative to the other end thereof. The ends of the bars are connected by elastically deformable connectors to define a loop and are electrically connected by a wire. By adjusting a length of the wire, easy tuning of the resonance frequency of the antenna unit can be obtained. The deformation of the connector absorbs shock given to the antenna unit by road obstacles such as stones or mud and guards it against impact damage.

Antenna unit for vehicle

A bar-type antenna unit is installed at a normally non-visible point on the lower side of a vehicle body. The unit includes an antenna element, a metal plate, and noise shielding means. The metal plate functions to adjust the reactance of the antenna to obtain a desired sensitivity and protects the antenna from water, mud, or snow splashed from the vehicle's wheels to ensure good insulation between the vehicular body and the antenna element. By selecting capacitance of the metal plate, the length of the antenna can be shortened without reducing sensitivity of the unit. The shielding means shields the antenna from noise generated by for example an engine or electrical equipment which would otherwise interfere with radio broadcasts.

Antenna unit for a vehicle

A Loran-C signal receiving apparatus which achieves accurate measurement of the location of the apparatus without error due to a well-known cycle slip phenomenon. In the Loran-C signal receiving apparatus, a pulse tracking a particular cycle of a carrier wave of the received Loran-C signal is generated, a frequency at which the tracking pulse is generated by a pulse generator (in a PLL circuitry) is monitored and when a frequency error of the generator is derived on the basis of a tracking error of the tracking pulse with respect to the received Loran-C signal, the frequency of the pulse generator is corrected on the basis of the derived frequency error. The apparatus can thus assure a phase tracking of the received Loran-C signal and assure accurate measurement of the location.

Loran-C signal receiving apparatus

An apparatus receives Loran-C pulses and tracks the phase of each received Loran-C pulse received from master and secondary stations. The apparatus comprises: (a) a phase comparator (12) for comparing the phase of the Loran-C pulse received from each transmitting station with that of a comparison signal; (b) a phase locked loop circuitry (16) for generating the comparison signal at a given integral multiple of the repetition rate of the Loran-C signal; (c) an S/N ratio detection circuit (14) for measuring the signal-to-noise ratio of the received signal; (d) a loop filter (13) for correcting the timing at which the comparison signal is generated toward coincidence with the phase of the received Loran-C pulse when a given number of phase comparisons by the phase comparator (12) produce results of the same polarity; and (e) a sample number control circuit (15) for adjusting at least one of the given integral multiple and the given number according to the measured signal-to-noise ratio. The phase tracking can thus be achieved with high accuracy even at low signal-to-noise ratios and with far higher accuracy at higher signal-to-noise ratios.

Loran-C signal phase tracking apparatus

An improved positioning system for a vehicle is shown. In the system, when radio wave can be received from only one satellite, the current position of the vehicle is computed based on a pair of navigational data, which are brought by radio wave received at the current time and by radio wave received at an earlier time.

Positioning system for a vehicle

An improved position measuring system for determining a vehicle's position by receiving radio waves emitted from satellites is shown. The system adopts successive approximation using a convergent computation, in which initially estimated values are computed.

Position measuring system

An automatic Loran-C signal detecting apparatus samples a received signal at a constant high sampling frequency of which the Loran-C carrier frequency is a harmonic. The polarity of the sampled signal at each sampling frequency cycle is stored in a corresponding memory cell for every two successive periods of the Loran-C signal. All of memory cells are previously loaded with a value m. A control unit determines whether the polarity of the sampled signal is positive or negative and adds +1 to the value m of the memory cell when the sampled signal is positive and adds -1 to the value m of the memory cell when the sampled signal is non-positive. After a given number of Loran-C signal cycles, the accumulated polarity totals are compared to a range around the original value m to detect which memory cells, i.e. which sampling times, coincide with Loran-C pulses. The polarity of the Loran-C pulses thus detected can then be checked to identify the sending station of each group of Loran-C pulses.

Automatic Loran-C signal detecting apparatus

A system for detecting a particular cycle of a received Loran-C signal in a Loran-C receiving apparatus, recognizes the envelope of a carrier wave in each Loran-C pulse for a predetermined duration after the onset of the Loran-C pulse. The system compares the detected envelope to reference envelope data so as to identify where on the actual Loran-C envelope the measured envelope lies in order to identify the particular cycle of the received Loran-C pulse.

The signal-to-noise ratio of a signal having positive and negative components is determined by periodically sampling polarity values of the signal. The numbers of the sampled values of each polarity are accumulated. A quantitative measure of the relative accumulated numbers of the sampled values of each polarity is determined. A stored function of signal-to-noise ratio as a function of the quantitative measure and the number of samples is correlated with the derived quantitative measure.

S/N ratio determining method and apparatus for a receiver

A received signal containing a loran-C signal is periodically sampled. The sampled data values in two successive periods of the loran-C signal are stored in corresponding first and second period areas of a memory. The sampled data values for the next successive pair of periods of the loran-C signal are added to corresponding sampled data values stored in the memory. Such adding operation is repeated for a plurality of subsequent first and second periods of the loran-C signal. First and second groups each including a fixed number of totalled values are read from the first and second period areas, respectively, of the memory. The fixed number matches the number of pulses in each loran pulse group. The totalled values are read from memory addresses separated in coincidence with the separation of pulses in each loran pulse group. Each of the first and second groups of read values are processed in accordance with the known phase coding of each group of loran pulses. These processed values of the first and second groups are added and stored in corresponding memory address. The reading, processing, adding and storing steps are repeated until every possible combination of totalled values satisfying the separation criterion has been processed. Each of the loran pulse groups within each pair of successive loran-C signal periods is located according to which groups of values exactly match the known phase coding of each loran-C pulse group.

Loran signal receiver

In a loran-C radio receiver, tracking of the loran-C signal is initiated by sampling the carrier wave intensity of the loran-C signal at a high frequency over two pulse modulation cycles of the loran-C signal and storing the values recorded in each cycle of the sampling frequency in a corresponding memory cell. The sampled values are stored by adding one to the corresponding memory cell if the sampled signal polarity is positive and subtracting one from the given cell, which is initialized to a known value, when the sample has a negative polarity. This sampling over two loran-C cycles is then repeated numerous times, so that after such repetion, each memory cell, corresponding to a specific phase of the loran-C signal, will either have the known value, indicating no carrier wave peak, or a value significantly greater than the known value, indicating a carrier wave peak and so a loran-C pulse. Coordination between the carrier wave and the sampling process is achieved by a multiple sample pulse with a period matching that of the carrier wave, each pulse of the multiple sample pulse being separate from others by 1/4-or 1/8-of the carrier wave period and the first of the multiple pulses being synchronized with a zero-crossing point of the carrier wave.

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Yokosuka, Japan

Hiroshige Fukuhara