Siemens Aktiengesellschaft

Rudolf Hauptmann

Harald Siegel

Rainer Peters

Guenter Beyer

Gerhard Foeller

A pulse Doppler radar system with variable pulse repetition frequency has a coherent integrator to which the reflected pulses are supplied in order to avoid deterioration of the indication of a moving target given over-the-horizon reception. The coherent integrator subjects the reflected pulses to a simplified vectorial addition by the use of a number of filters. A precondition for the modified coherent integration is a staggering of the pulse repetition periods such that their sums formed over successive pulse repetition periods are constant, and a phase reference for the signal amplitudes is obtained such that the phase difference is equal to zero after every second pulse repetition.

Pulse Doppler radar with variable pulse repetition frequency

A pulse doppler radar having variable repetition rates, noise pulses resulting from echos received from stationary multiple-time-around objects are removed by subjecting the reflected pulses to a coherent integration modified by means of a simplified vectorial addition of the reflected pulses, using an integration circuit consisting of a plurality of filters.The signal amplitude produced at the output of each filter is individually compared to the mean value of signals produced by all other filters, and a target indication is produced when the mean value is exceeded by the amplitude of a signal from an individual filter.

Pulse doppler radar with variable pulse repetition rate

A three-dimensional air space surveillance radar in which the radar receiver is connected to a target tracking means which stores target data and does extrapolation of target data for target trace formations, including a panoramic antenna which illuminates the entire elevation range to be covered and has a reception lobe at the elevation level which can be electronically or mechanically controlled such that a line air space scanning occurs during the course of normally sequence scanning programs. The line-shaped beam of the antenna is briefly interrupted in the invention from the normal reception lobe elevation angle when the tracker determines that a target echo is expected from a different elevation angle than that being scanned. During such scanning interrupt, the reception lobe is switched to the expected elevation angle of the target and in the invention, the data acquisition rate for the tracker is increased relative to known prior art three-dimensional surveillance radars which function on a strictly time sequential manner. The precision of the invention is retained and the invention is utilized in a tracker-equipped three-dimentional air space surveillance radar of high trace quality such as used, for example, in air defense radar.

Three-dimensional air space surveillance radar

A pulse Doppler radar receiver which continuously monitors successively obtained amplitude values Ao through An with the disrupted amplitude values which deviate by a prescribed value from an interpolation value obtained from adjacent undisturbed amplitude values are determined and are limited to a value obtained from the interpolation value or from the largest or smallest adjacent undisrupted amplitude values and are substituted for the disrupted values. The apparatus includes an interpolation circuit which includes the shift register and limiter with the memory for adjusting the output signal level of the limiter.

Pulse doppler radar receiver with a circuit for reducing spurious signals

A circuit arrangement for side lobe suppression in radar wherein the undesired signals which arrive at the radar receiver by way of the side lobes of the antenna are cancelled by using a compensation circuit formed as a loop. Additional circuit means for the formation of a weighting factor for the weighting multiplier are provided in the feedback of the loop between a correlator and a weighting amplifier. When the noise power at the output of the compensating circuit is greater than the noise power that the radar receiver supplies without the compensation circuit, the output will be switched from the compensation circuit to a direct output of the radar receiver. The comparison of the noise power in a comparator then supplies the control signal for the change-over. The change-over can also occur as a function of thermal noises when the amount of the weighting factor exceeds a predetermined value. The weighting factor is monitored by a control circuit. So as to make the response behaviour of the compensated loop independent of the noise signal power, a controlled amplifier is incorporated in the control circuit with the gain of the amplifier being inversely proportional to the square of the noise amplitude in the auxiliary channel. The controlled amplifier can be mounted in the feedback branch between the correlator and the weighting multiplier or can be inserted in front of one of the two inputs of the correlator.

Circuit arrangement for side lobe suppression in radar apparatuses

A moving window detector for a radar including adding circuits for automatic detection of moving targets wherein the components of prior art devices are substantially reduced by utilizing a digital integration circuit and a shift register with a number of storage locations and wherein the input echo signals are supplied to the input of the shift register and to the integration circuit and the output of the shift register and the integration circuit are supplied to a subtracting circuit which supplies an output to an adder of the integration circuit so as to substantially reduce the number of components over those of the prior art.

Growing community of inventors

Dachau, Germany

Rudolf Hauptmann