Radar for ground speed measurement

Abstract

A radar transducer has a planar array antenna mounted on a plate portion of a housing with the microwave transceiver mounted on the opposite side of the plate and carrying a PCB defining the processing section for supplying an output to a cable. The plate portion slides into a plastic receptacle defining the radome for the antenna with a potting compound sealing the open face of the receptacle. The electrical processing section is shielded from extraneous electromagnetic waves without additional metallic shielding elements. The processor is programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change the output to the output cable for different end use controllers and for compatibility with communications protocols. The processor is programmed to carry out a test of the operation of the transceiver and to provide a failure output signal to the cable in the event that the operation is found to be outside predetermined parameters.

1 . A radar transducer comprising: 
 an antenna for transmitting electromagnetic waves at a predetermined frequency and for receiving reflected waves at a second frequency Doppler shifted from the predetermined frequency;    a microwave transceiver for supplying to and receiving from the antenna the electromagnetic waves and detecting a Doppler frequency;    an output cable;    an electrical processing section for processing the Doppler frequency and for communicating with the output cable, the electrical processing section including: 
 an analogue section arranged for receiving and amplifying the Doppler frequency having at least an amplifier and a threshold comparator for comparing a sine wave amplitude with a predetermined threshold for generation of an output pulse only when the amplified amplitude exceeds the predetermined threshold;  
 and a processor for processing the sequence of digital pulses generated by the analogue section in accordance with a processing program and for generating an output to the output cable in response to the processing of the digital pulses;  
   and a housing for containing the antenna, the microwave transceiver and the electrical processing section and for receiving and locating an inner end of the output cable;    wherein the processor is programmed to carry out a test of the operation of the microwave transceiver and to provide a failure output signal to the cable in the event that the operation is found to be outside predetermined parameters.    
   
   
       2 . The transducer according to  claim 1  wherein the processor is programmed to carry out the test on power up of the transducer.  
   
   
       3 . The transducer according to  claim 1  wherein the processor is programmed to carry out the test when no movement, with the antenna arranged to receive reflected signals, to detect the presence of pulses at the comparator output and to provide the failure output signal in response to the detection thereof.  
   
   
       4 . The transducer according to  claim 1  wherein the processor is programmed to carry out the test when no movement, with the antenna arranged to receive reflected signals, to detect the presence of noise signals on output of the amplifier having an amplitude greater than a predetermined level lower than the threshold and to provide the failure output signal in response to the detection thereof.  
   
   
       5 . The transducer according to  claim 1  wherein the output cable includes four leads including a power lead, a ground lead, a signal lead and a “radar present” lead and wherein the processor is programmed to carry out a test and to supply the output to the “radar present” lead by generating a modulated signal on the “radar present” lead.  
   
   
       6 . The transducer according to  claim 1  wherein the processor is programmed on power up of the transducer to carry out a first test to detect the presence of pulses at the comparator and a second test to detect the presence of noise signals at the amplifier having an amplitude greater than a predetermined level lower than the threshold, and to provide the failure output signal in response to the failure of ether tests.  
   
   
       7 . The transducer according to  claim 6  wherein the output cable includes four leads including a power lead, a ground lead, a signal lead and a “radar present” lead and wherein the processor is programmed to carry out a test and to supply the output to the “radar present” lead by generating a modulated signal on the “radar present” lead.  
   
   
       8 . A radar transducer comprising: 
 an antenna for transmitting electromagnetic waves at a predetermined frequency and for receiving reflected waves at a second frequency Doppler shifted from the predetermined frequency;    a microwave transceiver for supplying to and receiving from the antenna the electromagnetic waves and detecting a Doppler frequency;    an output cable;    an electrical processing section for processing the Doppler frequency and for communicating with the output cable, the electrical processing section including: 
 an analogue section arranged for receiving and amplifying the Doppler frequency having at least an amplifier and a threshold comparator for comparing a sine wave amplitude with a predetermined threshold for generation of an output pulse only when the amplified amplitude exceeds the predetermined threshold;  
 and a processor for processing the sequence of digital pulses generated by the analogue section in accordance with a processing program and for generating an output to the output cable in response to the processing of the digital pulses;  
   and a housing for containing the antenna, the microwave transceiver and the electrical processing section and for receiving and locating an inner end of the output cable;    wherein the processor is arranged to be programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change the output to the output cable which is generated in response to specific reflected waves.    
   
   
       9 . The transducer according to  claim 8  wherein the output to the output cable comprises a series of pulses at a frequency which is related to the Doppler frequency from the microwave transceiver and wherein the processor is arranged to be programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change an offset value of the output signals.  
   
   
       10 . The transducer according to  claim 8  wherein the output to the output cable comprises a series of pulses at a frequency which is related to the Doppler frequency from the microwave transceiver and wherein the processor is arranged to be programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change a scaling factor of the output signals.  
   
   
       11 . The transducer according to  claim 8  wherein the output to the output cable comprises a series of pulses at a frequency which is related to the Doppler frequency from the microwave transceiver and wherein the processor is arranged to be programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change a polarity of the of the output signals.  
   
   
       12 . The transducer according to  claim 8  wherein the processor is arranged to be programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change a transducer response time by changing acquisition and processing time for the Doppler signals.  
   
   
       13 . The transducer according to  claim 8  wherein the processor is arranged to be programmable in response to signals received through the output cable so as to re-configure the program thereof so as to change the output to the output cable so as to be compatible with a bus communication protocol.  
   
   
       14 . A radar transducer comprising: 
 an antenna for transmitting electromagnetic waves at a predetermined frequency and for receiving reflected waves at a second frequency Doppler shifted from the predetermined frequency;    a microwave transceiver for supplying to and receiving from the antenna the electromagnetic waves and detecting a Doppler frequency;    an output cable;    an electrical processing section for processing the Doppler frequency and for communicating with the output cable, the electrical processing section including: 
 an analogue section arranged for receiving and amplifying the Doppler frequency having at least an amplifier and a threshold comparator for comparing a sine wave amplitude with a predetermined threshold for generation of an output pulse only when the amplified amplitude exceeds the predetermined threshold;  
 and a processor for processing the sequence of digital pulses generated by the analogue section in accordance with a processing program and for generating an output to the output cable in response to the processing of the digital pulses;  
   and a housing for containing the antenna, the microwave transceiver and the electrical processing section and for receiving and locating an inner end of the output cable;    wherein the microwave transceiver and the electrical processing section are shielded from extraneous electromagnetic waves substantially without metallic shielding elements.    
   
   
       15 . The transducer according to  claim 14  wherein the microwave transceiver and the electrical processing section are shielded from extraneous electromagnetic waves completely without metallic shielding elements.  
   
   
       16 . The transducer according to  claim 14  wherein the microwave transceiver and the electrical processing section are arranged to have a high immunity to extraneous electromagnetic waves by arranging the power supply such that a 5V voltage regulator powers the analogue section directly and the processor through a pi-RC filter.  
   
   
       17 . The transducer according to  claim 14  wherein the microwave transceiver and the electrical processing section are arranged to have a high immunity to extraneous electromagnetic waves by providing a power supply conductor and a ground return conductor as parallel plates on a printed circuit board on which the electrical processing section is mounted.  
   
   
       18 . The transducer according to  claim 14  wherein the microwave transceiver and the electrical processing section are arranged to have a high immunity to extraneous electromagnetic waves by arranging no more than one resistive element in the power supply conductor to decrease impedance and avoid resonant sensitivity.  
   
   
       19 . The transducer according to  claim 14  wherein the microwave transceiver and the electrical processing section are arranged to have a high immunity to extraneous electromagnetic waves by arranging that the signals from the extraneous electromagnetic waves are filtered in the processor controlled digital processing of the signals.  
   
   
       20 . A radar transducer comprising: 
 an antenna for transmitting electromagnetic waves at a predetermined frequency and for receiving reflected waves at a second frequency Doppler shifted from the predetermined frequency;    a microwave transceiver for supplying to and receiving from the antenna the electromagnetic waves and detecting a Doppler frequency;    an output cable;    an electrical processing section for processing the Doppler frequency and for communicating with the output cable, the electrical processing section including: 
 an analogue section arranged for receiving and amplifying the Doppler frequency having at least an amplifier and a threshold comparator for comparing a sine wave amplitude with a predetermined threshold for generation of an output pulse only when the amplified amplitude exceeds the predetermined threshold;  
 and a processor for processing the sequence of digital pulses generated by the analogue section in accordance with a processing program and for generating an output to the output cable in response to the processing of the digital pulses;  
   and a housing for containing the antenna, the microwave transceiver and the electrical processing section and for receiving and locating an inner end of the output cable;    wherein the housing comprises 
 a mounting element providing mountings thereon for the antenna, the microwave transceiver, the electrical processing section and an inner end of the cable;  
 a receptacle element having an open end face into which the mounting element carrying the antenna, the microwave transceiver, the electrical processing section and an inner end of the cable can be inserted;  
 and a potting compound closing the open end face and enclosing the mounting element, the antenna, the microwave transceiver, the electrical processing section and an inner end of the cable within the receptacle.  
   
   
   
       21 . The transducer according to  claim 20  wherein the receptacle element is substantially wholly formed from a plastic material.  
   
   
       22 . The transducer according to  claim 20  wherein the receptacle element defines a radome for the antenna.  
   
   
       23 . The transducer according to  claim 20  wherein the mounting element includes a plate portion on which the antenna is mounted as a planar array.  
   
   
       24 . The transducer according to  claim 23  wherein the plate portion on which the antenna is mounted as a planar array has a peripheral sealing member for engaging a sealing surface of the receptacle element so prevent the entry of the potting compound into the area between the plate portion and the sealing surface.  
   
   
       25 . The transducer according to  claim 24  wherein the sealing surface is arranged substantially at right angles to the open mouth such that the plate portion slides into the receptacle element in a direction substantially parallel to the plate portion and to the sealing surface.  
   
   
       26 . The transducer according to  claim 23  wherein the microwave transceiver and the electrical processing section are mounted on a rear of the plate portion opposite to the antenna array.  
   
   
       27 . The transducer according to  claim 26  wherein the microwave transceiver and the electrical processing section are mounted on a single printed circuit board.  
   
   
       28 . The transducer according to  claim 27  wherein the single printed circuit board extends substantially at right angles to the plate portion.  
   
   
       29 . The transducer according to  claim 26  wherein the single printed circuit board is attached to and carried by the microwave transceiver.