By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Lapat, Ronald (Sudbury, MA); Patrizi, Michael R. (McKinney, TX); Blair, Shane D. (Woburn, MA), filed on December 4, 2013, was published online on February 2, 2016.
The assignee for this patent, patent number 9250313, is RAYTHEON COMPANY (Waltham, MA).
Reporters obtained the following quote from the background information supplied by the inventors: "Aspects of the present invention relate generally to a multi-mode radar system, and more particularly to an analog-to-digital converter circuit for a radar system that is reconfigurable to operate in a multi-channel, narrow/medium bandwidth mode or a single-channel, wide bandwidth mode, and method of operating the same.
"Radars generally operate in a narrow to-medium instantaneous bandwidth mode for search and track operations by using waveforms that may be sampled with lower-cost, higher fidelity and higher-bit-resolution, narrow/medium band analog-to-digital converters (ADCs). However, high instantaneous bandwidth capability is often used in radars for wideband tracking, threat discrimination, and clutter mitigation, for example. Accordingly, a radar apparatus capable of operating in both narrow/medium band and wide band with similar performance specifications, at both bandwidths, in terms of number of bits of resolution and signal fidelity, is desired.
"Ultra-wideband ADCs may meet overall sampling requirements (i.e., capable of narrow to medium or wide band sampling), but generally compromise on dynamic range, spurious-free dynamic range (SFDR), and signal-to-noise ratio (SNR), and have high power consumption, processing, and cost requirements compared to lower bandwidth ADCs.
"Alternatively, physically separate narrow/medium band and wideband channels configured in parallel may provide the desired sampling requirements and measurement fidelity for each mode, but providing these separate channels comes at higher cost, lower wideband signal fidelity, and greater real estate, and does not aid in reducing size, weight, and power (SWaP) of the system, which is also desirable.
"Stretch Processing and Frequency Jump Burst methods may also provide some wideband capability while using lower-cost narrow/medium band ADCs, but these methods have well-known shortcomings. For example, Stretch Processing must trade-off range extent to achieve the high bandwidth imaging, and Frequency Jump Burst gives up waveform flexibility.
"The challenges of the existing wideband or multi-mode radar technology motivate developing an architecture that reconfigurably supports both wideband and narrowband radar functions, in order to mitigate cost and component redundancies, and ideally mitigate fidelity degradation typical of stand-alone ultrawideband ADCs."
In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "Aspects of the present invention are directed toward providing an analog-to-digital converter circuit for a radar system that is electronically reconfigurable to operate in multi-channel, narrow/medium band mode, or single-channel, time-interleaved, instantaneous wideband mode that mitigates costs, performance degradation, and component redundancies.
"Aspects of the present invention relate to analog-to-digital converters (ADCs) for radar devices that switchably operate in either a normal (e.g., multi-channel, narrow/medium band) mode or a time-interleaved (e.g., single-channel, instantaneous, wideband) mode. In the time-interleaved mode, each ADC may continue operating at its nominal sampling rate, but by clocking each ADC out of phase with respect to every other ADC and then multiplexing each of their outputs together, the ADCs may be effectively combined into a single wideband ADC. This eliminates circuit redundancies, and capitalizes on the lower cost and higher signal fidelity performance of the individual lower sampling rate ADCs.
"According to an embodiment of the present invention, there is provided an analog-to-digital converter circuit for a radar apparatus, the analog-to-digital converter circuit including: a plurality of analog-to-digital converters. Here, the analog-to-digital converters are dynamically configurable to operate in a multi-channel mode with a first instantaneous bandwidth and a single-channel mode with a second instantaneous bandwidth higher than the first instantaneous bandwidth.
"The analog-to-digital converters may be configured to be operated in phase with one another when in the multi-channel mode, and the analog-to-digital converters may be configured to be operated out of phase with one another when in the single-channel mode.
"When in the multi-channel mode, each of the analog-to-digital converters may be configured to receive a corresponding one of a plurality of analog input signals and may be configured to sample the corresponding one of the analog input signals at a first sample rate to generate a corresponding one of a plurality of digital output signals. When in the single-channel mode, at least two of the analog-to-digital converters may be configured to receive a same one of the analog input signals and may be configured to collectively sample the same one of the analog input signals at a second sample rate to generate at least two of the digital output signals, the at least two of the digital output signals being configured to collectively digitally represent the same one of the analog input signals. The second sample rate is higher than the first sample rate.
"According to one embodiment, the analog-to-digital converter circuit is included in a receiver of a radar apparatus, which may further include a frequency converter configured to receive the radar signals from the radar antenna and electronically reconfigurable to dynamically center at least one of the radar signals according to whether the receiver is in the multi-channel mode or the single channel mode to generate at least one analog input signal provided to the analog-to-digital converter circuit.
"The frequency converter may include a first mixer configured to receive a first radar signal of the radar signals, to receive a center signal, and to mix the first radar signal with the center signal to generate a centered first radar signal. The center signal may be dynamically adjustable according to whether the receiver is in the multi-channel mode or the single channel mode. Here, the at least one analog input signal provided to the analog digital converter circuit corresponds to the centered first radar signal.
"According to another embodiment of the present invention, there is provided a method of operating a multi-mode analog-to-digital converter circuit including a plurality of digital to analog converters, the method including: receiving a plurality of analog signals; determining whether the multi-mode analog-to-digital converter circuit is in a single channel mode or a multi-channel mode. Here, when the multi-mode analog-to-digital converter circuit is in the multi-channel mode: provide the analog signals to the analog-to-digital circuits to generate a plurality of digital signals corresponding to the analog signals, the digital signals having been sampled at a first sampling rate; and drive the analog-to-digital converters in phase with one another. Also, when the multimode analog-to-digital converter circuit is in the single channel mode: provide the same one of the analog signals to the analog-to-digital converters to generate the digital signals corresponding to the same one of the analog signals; consolidate the digital signals to generate a consolidated digital signal corresponding to the same one of the analog signals, the consolidated digital signal having an effective sampling rate that is higher than the first sampling rate; and driving the analog-to-digital converters out of phase with one another.
"When in single channel mode, a phase spacing for driving the analog-to-digital converters may be set according to 360.degree./N, N being a number of the analog-to-digital converters. When in the single-channel mode, the effective sampling rate of the analog-to-digital converters may correspond to N.times.F, F being a nominal sampling rate of one of the analog-to-digital converters."
For more information, see this patent: Lapat, Ronald; Patrizi, Michael R.; Blair, Shane D.. Electronically Reconfigurable Bandwidth and Channel Number Analog-To-Digital Converter Circuit for Radar Systems. U.S. Patent Number 9250313, filed December 4, 2013, and published online on February 2, 2016. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9250313.PN.&OS=PN/9250313RS=PN/9250313
Keywords for this news article include: RAYTHEON COMPANY.
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