Digital frequency modulated continuous wave radar using handcrafted constant envelope modulation
A radar system for mobile applications includes transmitters and receivers. The transmitters are configured for installation and use in a mobile application. Each of the transmitters is configured to generate a radio signal. The receivers are configured for installation and use in the mobile application. Each of the receivers is configured to receive radio signals that include transmitted radio signals transmitted by the transmitters and reflected from objects in the environment. A first transmitter of the transmitters is configured to frequency modulate the transmitted radio signal using a shaped frequency pulse which is defined by a sequence of chips. The sequence of chips is selected to realize a selected frequency pulse shape.
1. A radar system configured for mobile applications, the radar system comprising:
a transmitter configured to transmit radio signals; and
a receiver configured to receive radio signals that include transmitted radio signals transmitted by the transmitter and reflected from objects in the environment;
wherein the transmitter is configured to frequency modulate the transmitted radio signal using a selected shaped frequency pulse, wherein the shaped frequency pulse is defined by a selected sequence of chips, and wherein each chip of the selected sequence of chips comprises a selected quantity of predetermined samples.
2. The radar system of claim 1 , wherein the transmitter comprises a code generator configured to generate the selected sequence of chips at a selected chiprate, wherein a modulation interval between successive chips is a reciprocal of the chiprate.
3. The radar system of claim 1 , wherein the transmitter comprises a modulator configured to perform the frequency modulation, and wherein the modulator is further configured to select a particular sequence of chips to realize a desired waveform.
4. The radar system of claim 3 , wherein the transmitter further comprises a memory, and wherein the selected sequence of chips is selected from a plurality of chip sequences stored in the memory.
5. The radar system of claim 4 , wherein the shaped frequency pulse is selected from a plurality of shaped frequency pulses, and wherein each chip sequence of the plurality of chip sequences defines a corresponding shaped frequency pulse.
6. The radar system of claim 3 , wherein the plurality of chip sequences is configured such that the selection of different sequences of chips selectively realizes eight different waveforms.
7. The radar system of claim 3 , wherein the desired waveform is defined by no more than three successive chips, wherein the desired waveform is defined by a selected quantity of I,Q sample values per chip, and wherein the selected quantity of I,Q sample values comprises one of 4, 8, and 16 samples per chip.
8. The radar system of claim 7 , wherein the modulator comprises I and Q digital-to-analog converters, and wherein the I and Q digital-to-analog converters are configured to convert the corresponding I and Q sample values to I and Q analog signals.
9. The radar system of claim 8 , wherein the modulator is configured to low-pass filter the I and Q analog signals and then modulate a carrier signal at a desired center frequency.
10. The radar system of claim 1 , wherein the shaped frequency pulses correspond to a first signal, the frequency of which deviates from a desired center frequency during each of the modulation intervals according to a selected pulse shape.
11. A radar system configured for mobile applications, the radar system comprising:
a plurality of transmitters configured for installation and use in a mobile application, wherein each transmitter of the plurality of transmitters is configured to generate a radio signal;
a plurality of receivers configured for installation and use in the mobile application, wherein each receiver of the plurality of receivers is configured to receive radio signals that include transmitted radio signals transmitted by the transmitters and reflected from objects in the environment;
wherein a first transmitter of the plurality of transmitters is configured to frequency modulate the transmitted radio signal using a shaped frequency pulse which is defined by a sequence of chips, wherein the sequence of chips is selected to realize a selected frequency pulse shape, and wherein each chip of the sequence of chips comprises a selected quantity of predetermined samples.
12. The radar system of claim 11 , wherein the mobile application is a motor vehicle.
13. The radar system of claim 12 , wherein transmitters of the plurality of transmitters are arranged within the motor vehicle.
14. The radar system of claim 11 , wherein the first transmitter comprises a modulator configured to perform the frequency modulation, and wherein the modulator is configured to select a particular sequence of chips to realize a desired waveform.
15. The radar system of claim 14 , wherein the first transmitter comprises a memory, and wherein the selected sequence of chips is selected from a plurality of chip sequences stored in the memory.
16. The radar system of claim 14 , wherein the plurality of chip sequences is configured such that the selection of different sequences of chips selectively realizes eight different waveforms.
17. The radar system of claim 11 , wherein the selected frequency pulse shape is selected from a plurality of shaped frequency pulses, and wherein each chip sequence of the plurality of chip sequences defines a corresponding shaped frequency pulse.
18. A radar system for a vehicle, the radar system comprising:
a transmitter configured for installation and use on a vehicle, and configured to transmit a radio signal; and
a receiver configured for installation and use on the vehicle, and configured to receive radio signals that include radio signals transmitted by the transmitter and reflected from objects in the environment;
wherein the transmitter comprises a modulator configured to frequency modulate the transmitted radio signal, wherein the modulator is configured to generate a selected sequence of chips, wherein the selected sequence of chips is selected to realize a desired waveform, and wherein each chip of the selected sequence of chips comprises a selected quantity of predetermined samples.
19. The radar system of claim 18 , wherein the transmitter comprises a memory configured to store a plurality of chip sequences, and wherein the modulator is configured to select a sequence of chips from the memory to realize the desired waveform.
20. The radar system of claim 18 , wherein the frequency modulation is defined by a selected shaped frequency pulse which is a frequency deviation pulse shape defined by the selected sequence of chips, and wherein the limited quantity of samples comprises one of 4, 8, and 16 samples per chip.