초록 ▼

A radar or sonar system amplifies the signal received by an antenna of the radar system or a transducer of the sonar system is amplified and then subject to linear demodulation by a linear receiver. There may be an anti-aliasing filter and an analog-to-digital converter between the amplifier and the

A radar or sonar system amplifies the signal received by an antenna of the radar system or a transducer of the sonar system is amplified and then subject to linear demodulation by a linear receiver. There may be an anti-aliasing filter and an analog-to-digital converter between the amplifier and the linear receiver. The system may also have a digital signal processor with a network stack running in the processor. That processor may also have a network interface media access controller, where the system operates at different ranges, the modulator may produce pulses of two pulse patterns differing in pulse duration and inter-pulse spacing, those pulse patterns are introduced and used to form two radar images with the two images being derived from data acquired in a duration not more than twenty times larger than the larger inter-pulse spacing, or for a radar system, larger than one half of the antenna resolution time. One or more look-up tables may be used to control the amplifier. The radar system may generate digital output which comprises greater than eight levels of radar video.

대표청구항 ▼

1. An apparatus comprising: a modulator for generating a sequence of pulse signals;a transmitter for converting the sequence of pulse signals to ranging signals;an antenna for emitting the ranging signals and receiving return signals;an amplifier for amplifying the return signals;a switching device

1. An apparatus comprising: a modulator for generating a sequence of pulse signals;a transmitter for converting the sequence of pulse signals to ranging signals;an antenna for emitting the ranging signals and receiving return signals;an amplifier for amplifying the return signals;a switching device for switchedly interconnecting the transmitter to the antenna and the antenna to the amplifier;a signal processor for processing the amplified return signals for display and/or analysis, wherein the apparatus comprises either a radar apparatus that provides the ranging signals as radar signals or a sonar apparatus that provides the ranging signals as sonar signals;an analog-to-digital converter for converting the amplified return signals to digital signals; anda linear receiver comprising a linear demodulator for generating a digital output in response to the digital signals for processing by the signal processor. 2. An apparatus according to claim 1 wherein said linear receiver comprises a plurality of linear amplifiers. 3. An apparatus according to claim 1, further comprising an anti-aliasing filter connected to the amplifier for filtering the amplified return signals, wherein the analog-to-digital converter is a sub-sampling analog-to-digital converter for converting the filtered digital signals to the digital signals. 4. An apparatus according to claim 3, wherein said anti-aliasing filter is arranged to restrict the bandwidth of the amplified return signals to satisfy the Shanon-Nyquist-Kotelnikov sampling theorem. 5. An apparatus according to claim 3, further comprising a digital filter for filtering said digital signals from said sub-sampling analog to digital converter. 6. An apparatus according to claim 1, further comprising a display arranged to show a pseudo-colour representation of the amplitude of said return signals from the output of said signal processor. 7. An apparatus according to claim 1, further comprising an anti-aliasing filter connected to the amplifier for filtering the amplified return signals, wherein the analog-to-digital converter is an analog-to-digital converter for converting the filtered signals to the digital signals, wherein the signal processor is a digital processor comprising a network stack running in the digital processor. 8. An apparatus according to claim 1, further comprising: an anti-aliasing filter connected to the amplifier for filtering the amplified return signals, wherein the analog-to-digital converter is an analog-to-digital converter for converting the filtered signals to the digital signals, wherein the signal processor is a digital signal processor; anda network interface media access controller and a physical layer interface that are connected to a digital signal processing bus. 9. An apparatus according to claim 1, wherein said apparatus is a radar apparatus and said radar apparatus further comprises an antenna drive for rotating the antenna with a predetermined revolution duration; wherein the modulator is arranged to generate the sequence of pulse signals such that the sequence comprises pulses of a first pulse pattern and pulses of a second pulse pattern, the first and second pulse patterns differing in pulse duration and inter-pulse spacing, the first and second pulse patterns being interleaved such that within said predetermined revolution duration there are a plurality of pulses of each pulse type; andwherein the signal processor is arranged to generate first radar image from the amplified return signals associated with said pulses of said first pulse type and a second radar image from the amplified return signals associated with said pulses of said second pulse type, such that the pulses of the first and second pulse types at any time are within a time not greater than one half of the predetermined revolution duration. 10. An apparatus according to claim 1, wherein said apparatus is a radar apparatus and said radar apparatus further comprises an antenna drive for rotating the antenna with a predetermined revolution duration; wherein the modulator is arranged to generate the sequence of pulse signals such that the sequence comprises pulses of a first pulse pattern and pulses of a second pulse pattern, the first and second pulse patterns differing in pulse duration and inter-pulse spacing, the first and second pulse patterns being interleaved such that within said predetermined revolution duration there are a plurality of pulses of each pulse type; andwherein the signal processor is arranged to generate a first radar image from the amplified return signals associated with said pulses of said first pulse type and a second radar image from the amplified return signals associated with said pulses of said second pulse type, such that the pulses of the first and second pulse types at any time are within a time not greater than twenty times whichever is larger of the pulse spacing of the first and second pulse patterns. 11. An apparatus according to claim 1, wherein said apparatus is a sonar apparatus and the modulator is arranged to generate the sequence of pulses and that the sequence comprises pulses of a first pulse pattern and pulses of a second pulse pattern, the first and second pulse patterns differing in pulse duration, pulse spacing, and being interleaved; and wherein the signal processor is arranged to generate a first sonar image from the amplified return signals associated with said pulses of said first pulse type and a second sonar image from the amplified return signals associated with said pulses of said second pulse type, and that the pulses of the first and second pulse types at any time are within a time not greater than twenty times whichever is longer of the pulse spacing of the first and second pulse patterns. 12. An apparatus according to claim 1, further comprising a controller for controlling the gain of the amplifier, the controller comprising at least one look-up table containing data for compensating for any range-dependent variation of said return signals. 13. An apparatus according to claim 12, wherein the apparatus is configured to operate at multiple ranges and wherein there are multiple look-up tables, each range having a corresponding look-up table. 14. An apparatus according to claim 12, wherein the apparatus is configured to operate at multiple ranges and wherein said at least one look-up table has multiple table regions, each range having a corresponding table region. 15. An apparatus according to claim 6, wherein said amplifier has a plurality of gain stages, and wherein there are a plurality of said look-up tables, each table corresponding to one of said gain stages. 16. An apparatus according to claim 12, wherein said amplifier has a plurality of gain stages, and wherein said at least one look-up table has a plurality of table regions, each table region corresponding to one of said gain stages. 17. An apparatus according to claim 15, further comprising an adder configured to add together outputs from said plurality of look-up tables for said plurality of table regions and saturation logic arranged to be applied to the added-together outputs, wherein an appropriate gain stage of said amplifier is determined on the basis of the saturation logic. 18. An apparatus according to claim 1, wherein said apparatus is a radar apparatus and said signal processor is a digital signal processor arranged to generate a digital output which comprises greater than eight levels of radar video. 19. A radar apparatus according to claim 18, further comprising means for subjecting said digital output of said digital signal processor to non-linear dynamic range matching. 20. A radar apparatus according to claim 1, wherein the ranging signals and the received return signals are X-hand signals;the radar apparatus further comprises a converter for converting the X-band return signals to intermediate frequency return signals;wherein the amplifier operates on the intermediate frequency return signals;wherein the filter operates on the amplified intermediate frequency return signals; andwherein the sub-sampling analog-to-digital converter samples the filtered amplified intermediate frequency return signals at a sample rate less than the intermediate frequency.