Ultra wide band coherent radar system optimising the radio interference discrimination capability
First Claim
1. A coherent radar system assessing Doppler shift of returned radar echoes, which uses a radar signal having a relative bandwidth of more than one octave and which has a control unit by which the transmit-receive process is partitioned into a number of consecutive sub-processes, each of which includes transmission followed by reception of a signal having a relative bandwidth of a fraction of an octave and where received signals from different narrow band transmissions are used to reconstruct broad band radar data by pulse compression techniques, wherein the control unit sets a recurrence time, defined as a time lapse between two consecutive transmissions, of a narrow band signal for a certain frequency step such that said recurrence time is approximately inversely proportional to a frequency of the step and is at least equal to the Nyquist rate with respect to a Doppler bandwidth at the frequency, whereby the recurrence time is larger at lower frequencies than at higher frequencies.
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Abstract
The present invention relates to an ultra wide band coherent radar system assessing the Doppler shift of the returned radar echoes, which radar system optimises the radio interference discrimination capability. The radar system comprises a control unit by which the transmit-receive process is partitioned into a number of consecutive sub-processes each of which consists of transmission followed by reception of a signal having a relative bandwidth of a fraction of an octave and where the received signals from the different narrow band transmissions are used to reconstruct broad band radar data by pulse compression techniques. Further, the control unit is arranged to determine the recurrence time, i.e. the time lapse between two consecutive transmissions, of a narrow band signal for a certain frequency step to be approximately inversely proportional to the frequency of this step and higher or equal to the Nyquist rate with respect to the Doppler bandwidth at this frequency.
18 Citations
12 Claims
- 1. A coherent radar system assessing Doppler shift of returned radar echoes, which uses a radar signal having a relative bandwidth of more than one octave and which has a control unit by which the transmit-receive process is partitioned into a number of consecutive sub-processes, each of which includes transmission followed by reception of a signal having a relative bandwidth of a fraction of an octave and where received signals from different narrow band transmissions are used to reconstruct broad band radar data by pulse compression techniques, wherein the control unit sets a recurrence time, defined as a time lapse between two consecutive transmissions, of a narrow band signal for a certain frequency step such that said recurrence time is approximately inversely proportional to a frequency of the step and is at least equal to the Nyquist rate with respect to a Doppler bandwidth at the frequency, whereby the recurrence time is larger at lower frequencies than at higher frequencies.
- 7. A coherent radar system for assessing Doppler shift of returned radar echoes, which uses a radar signal having a relative bandwidth of more than one octave and which has a control unit by which the transmit-receive process is partitioned into a number of consecutive sub-processes, each having a relative bandwidth of a fraction of an octave and where received signals from different narrow band transmissions within a frequency step sequence are used to reconstruct broad band radar data, wherein for each narrowband signal frequency within the frequency step sequence the control unit sets a time lapse between two consecutive transmissions as a recurrence time, said recurrence time being approximately inversely proportional to the narrowband signal frequency and at least equal to the Nyquist rate with respect to a Doppler bandwidth at the narrowband signal frequency, such that the recurrence time is larger at lower frequencies than at higher frequencies within the frequency step sequence.
Specification