US-12621019-B1 - Fast hopping correlator-based transceiver

US12621019B1US 12621019 B1US12621019 B1US 12621019B1US-12621019-B1

Abstract

An example frequency hopping transceiver includes one or more antennas, a transmitter digital oscillator, transmitter correlation circuitry, a receiver digital oscillator, and receiver correlation circuitry. The transmitter correlation circuitry is communicatively coupled to the transmitter digital oscillator and to the antennas, and is configured to spread, based on transmitter oscillation signals, transmit signals over transmit channels to create frequency-hopped transmit signals that are provided to the antennas. The receiver correlation circuitry is communicatively coupled to the receiver digital oscillator and to the antennas, and is configured to: de-spread the frequency-hopped data signals; spread, based on the receiver oscillation signals, one or more narrow-band interference signals included in received signals over a group of receive channels to create frequency-hopped interference signals, where the receive channels are orthogonal to the transmit channels; and filter out the frequency-hopped interference signals from the de-spread data signals.

Inventors

Ramesh Harjani
Seyednaser Mousavi
Zhiheng Wang

Assignees

REGENTS OF THE UNIVERSITY OF MINNESOTA

Dates

Publication Date: 20260505
Application Date: 20190830

Claims (20)

1 . A frequency hopping transceiver, comprising: one or more antennas that are configured to receive and transmit wireless signals; a transmitter digital oscillator that is configured to provide transmitter oscillation signals at one or more frequencies as a function of a transmit hopping code; transmitter correlation circuitry that is communicatively coupled to the transmitter digital oscillator and to the one or more antennas, wherein the transmitter correlation circuitry is configured to spread, based on the transmitter oscillation signals, one or more transmit signals over a plurality of transmit channels to create frequency-hopped transmit signals that are provided to the one or more antennas; a receiver digital oscillator that is configured to provide receiver oscillation signals at one or more frequencies as a function of a receive hopping code, wherein the receive hopping code is orthogonal to the transmit hopping code; and receiver correlation circuitry that is communicatively coupled to the receiver digital oscillator and to the one or more antennas, wherein the receiver correlation circuitry is configured to: de-spread one or more frequency-hopped data signals included in incoming wireless signals received by the one or more antennas to generate de-spread data signals, wherein the incoming wireless signals further include one or more narrow-band interference signals; spread, based on the receiver oscillation signals, the one or more narrow-band interference signals over a plurality of receive channels to create frequency-hopped interference signals, wherein the plurality of receive channels are orthogonal to the plurality of transmit channels; and filter out the frequency-hopped interference signals from the de-spread data signals.
2 . The frequency hopping transceiver of claim 1 , wherein the one or more narrow-band interference signals comprise one or more in-band jamming signals, and wherein the receiver correlation circuitry is configured to filter out the frequency-hopped interference signals at least by suppressing the one or more in-band jamming signals.
3 . The frequency hopping transceiver of claim 1 , wherein the transmitter digital oscillator comprises transmission digital oscillation circuitry that includes exactly one digital multiplier, exactly one digital adder, and exactly two registers, the transmit hopping code being provided as input to the exactly one digital multiplier of the transmission digital oscillation circuitry, and wherein the receiver digital oscillator comprises receiver digital oscillation circuitry that includes exactly one digital multiplier, exactly one digital adder, and exactly two registers, the receive hopping code being provided as input to the exactly one digital multiplier of the receiver digital oscillation circuitry.
4 . The frequency hopping transceiver of claim 3 , further comprising: a first digital-to-analog converter (DAC) that is configured to convert the transmitter oscillation signals from the transmitter digital oscillator into transmitter analog oscillation signals; a second DAC that is configured to convert the receiver oscillation signals from the receiver digital oscillator into receiver analog oscillation signals; a first injection-locked oscillator communicatively coupled to the first DAC, wherein the first injection-locked oscillator functions as a first bandpass filter with respect to the transmitter analog oscillation signals; and a second injection-locked oscillator communicatively coupled to the second DAC, wherein the second injection-locked oscillator functions as a second bandpass filter with respect to the receiver analog oscillation signals.
5 . The frequency hopping transceiver of claim 3 , wherein the transmitter digital oscillator provides the transmitter oscillation signals at the one or more frequencies in a range from 0 to fst/2 based on the transmit hopping code, where fst is a sampling clock frequency for the transmission digital oscillation circuitry, and wherein the receiver digital oscillator provides the receiver oscillation signals at the one or more frequencies in a range from 0 to fsr/2 based on the receive hopping code, where fsr is a sampling clock frequency for the receiver digital oscillation circuitry.
6 . The frequency hopping transceiver of claim 1 , further comprising: band selection circuitry that is communicatively coupled to the one or more antennas, wherein the band selection circuitry is configured to suppress at least a portion of out-of-band interference outside of a defined bandwidth for the incoming wireless signals received by the one or more antennas.
7 . The frequency hopping transceiver of claim 1 , wherein the receiver correlation circuitry comprises first N-path switch-capacitor circuitry, wherein the transmitter correlation circuitry comprises second N-path switch-capacitor circuitry, and wherein N is an integer greater than 1.
8 . The frequency hopping transceiver of claim 1 , further comprising self-interference cancellation circuitry that is communicatively coupled to the transmitter correlation circuitry and also to the receiver correlation circuitry, wherein the self-interference cancellation circuitry is configured to suppress transmit channel interference on one or more channels of the plurality of transmit channels at least by performing narrow-band flat fading per each of the one or more channels.
9 . The frequency hopping transceiver of claim 8 , further comprising: a power amplifier; a directional coupler that is communicatively coupled to the power amplifier and to the self-interference cancellation circuitry; and an analog-to-digital converter communicatively coupled to the directional coupler, wherein the analog-to-digital converter is included in an auxiliary path that is configured to suppress broadband noise signals that are output from the power amplifier.
10 . A frequency hopping receiver, comprising: one or more antennas that are configured to receive incoming wireless signals that include one or more frequency-hopped data signals and one or more narrow-band interference signals; a receiver digital oscillator that is configured to provide receiver oscillation signals at one or more frequencies as a function of a receive hopping code; and receiver correlation circuitry that is communicatively coupled to the receiver digital oscillator and to the one or more antennas, wherein the receiver correlation circuitry is configured to: de-spread the one or more frequency-hopped data signals to generate de-spread data signals; spread, based on the receiver oscillation signals, the one or more narrow-band interference signals over a plurality of receive channels to create frequency-hopped interference signals; and filter out the frequency-hopped interference signals from the de-spread data signals.
11 . The frequency hopping receiver of claim 10 , wherein the one or more narrow-band interference signals comprise one or more in-band jamming signals, and wherein the receiver correlation circuitry is configured to filter out the frequency-hopped interference signals at least by suppressing the one or more in-band jamming signals.
12 . The frequency hopping receiver of claim 10 , wherein the receiver digital oscillator comprises receiver digital oscillation circuitry that includes exactly one digital multiplier, exactly one digital adder, and exactly two registers, the receive hopping code being provided as input to the exactly one digital multiplier of the receiver digital oscillation circuitry.
13 . The frequency hopping receiver of claim 12 , further comprising: a digital-to-analog converter (DAC) that is configured to convert the receiver oscillation signals from the receiver digital oscillator into receiver analog oscillation signals; and an injection-locked oscillator communicatively coupled to the DAC, wherein the injection-locked oscillator functions as a bandpass filter with respect to the receiver analog oscillation signals.
14 . A method of providing in-band rejection of interference signals, the method comprising: receiving, by one or more antennas, incoming wireless signals that include one or more frequency-hopped data signals and one or more narrow-band interference signals; providing, by a receiver digital oscillator, receiver oscillation signals at one or more frequencies as a function of a receive hopping code; receiving, by receiver correlation circuitry that is communicatively coupled to the receiver digital oscillator and to the one or more antennas, the receiver oscillation signals provided by the receiver digital oscillator; de-spreading the one or more frequency-hopped data signals to generate de-spread data signals; spreading, based on the receiver oscillation signals, the one or more narrow-band interference signals over a plurality of receive channels to create frequency-hopped interference signals; and filtering out the frequency-hopped interference signals from the de-spread data signals.
15 . The method of claim 14 , wherein de-spreading the one or more frequency-hopped data signals comprises providing a processing gain to the one or more frequency-hopped data signals.
16 . The method of claim 14 , wherein the one or more narrow-band interference signals comprise one or more in-band jamming signals, and wherein filtering out the frequency-hopped interference signals comprises suppressing the one or more in-band jamming signals.
17 . The method of claim 14 , wherein the receiver digital oscillator comprises receiver digital oscillation circuitry that includes exactly one digital multiplier, exactly one digital adder, and exactly two registers, the receive hopping code being provided as input to the exactly one digital multiplier of the receiver digital oscillation circuitry.
18 . The method of claim 14 , further comprising: converting, by a digital-to-analog converter (DAC), the receiver oscillation signals from the receiver digital oscillator into receiver analog oscillation signals; and implementing, by an injection-locked oscillator communicatively coupled to the DAC, a bandpass filter with respect to the receiver analog oscillation signals.
19 . The method of claim 14 , further comprising: suppressing, by band selection circuitry that is communicatively coupled to the one or more antennas, at least a portion of out-of-band interference outside of a defined bandwidth for the incoming wireless signals.
20 . The method of claim 14 , further comprising: suppressing, by self-interference cancellation circuitry that is communicatively coupled to transmitter correlation circuitry and also to the receiver correlation circuitry, transmit channel interference on one or more channels of a plurality of transmit channels at least by performing narrow-band flat fading per each of the one or more channels.

Description

This application claims the benefit of U.S. Provisional Application No. 62/725,912 filed Aug. 31, 2018, which is incorporated herein by reference in its entirety. GOVERNMENT INTEREST This invention was made with government support under HR0011-17-2-0001 awarded by the Defense Advanced Research Projects Agency (DARPA). The government has certain rights in the invention. TECHNICAL FIELD The present disclosure relates to antenna systems. BACKGROUND In-band resilience with respect to jamming or interference signals is an area of concern for proper operations of certain equipment, such as, e.g., military communication equipment. In a simple receiver coupled to an antenna, for example, many in-band jammers can easily saturate or, at the very least, limit the receiver gain of the receiver, resulting in significant communication link degradation due to decreased signal-to-interference-plus-noise ratio (SINR). As a countermeasure, frequency hopping has traditionally been used to improve robustness of a communication link by regularly changing the frequency of operation and avoiding jammers at a particular frequency. SUMMARY The present disclosure describes techniques for implementing an ultra-fast hopping, correlator-based spread spectrum transceiver that enables in-band rejection of jamming or interference signals in frequency hopping systems. These techniques may provide, e.g., 20 dB of processing gain at radio frequencies, while enabling a receiver front-end to suppress any in-band interference by, e.g., 20 dB. The disclosed transceiver circuitry includes passive mixers and agile oscillator/digital-to-analog converter engines that are capable of quickly moving in the frequency domain with very low power. An achieved hopping speed of, e.g., 47 Mhops/second is orders of magnitude faster than prior frequency-hopping systems. The disclosed transceiver may prevent in-band blocking (e.g., jamming) signals from jamming the receiver, and may also make it harder for jamming systems to follow the frequency hopping system, which may be very useful for, e.g., secure military applications, radar applications, and mobile communication systems, to name a few non-limiting examples. Multiple blockers can be suppressed without potentially any a priori knowledge of their frequency content. The disclosed techniques may also eliminate multi-path propagation effect in wireless channels. In one example, a frequency hopping transceiver includes one or more antennas, a transmitter digital oscillator, transmitter correlation circuitry, a receiver digital oscillator, and receiver correlation circuitry. The one or more antennas are configured to receive and transmit wireless signals. The transmitter digital oscillator is configured to provide transmitter oscillation signals at one or more frequencies as a function of a transmit hopping code. The transmitter correlation circuitry is communicatively coupled to the transmitter digital oscillator and to the one or more antennas, and is configured to spread, based on the transmitter oscillation signals, one or more transmit signals over a plurality of transmit channels to create frequency-hopped transmit signals that are provided to the one or more antennas. The receiver digital oscillator is configured to provide receiver oscillation signals at one or more frequencies as a function of a receive hopping code, where the receive hopping code is orthogonal to the transmit hopping code. The receiver correlation circuitry is communicatively coupled to the receiver digital oscillator and to the one or more antennas, and is configured to: de-spread one or more frequency-hopped data signals included in incoming wireless signals received by the one or more antennas, wherein the incoming wireless signals further include one or more narrow-band interference signals; spread, based on the receiver oscillation signals, the one or more narrow-band interference signals over a plurality of receive channels to create frequency-hopped interference signals, wherein the receive channels are orthogonal to the transmit channels; and filter out the frequency-hopped interference signals from the de-spread data signals. In one example, a method of providing in-band rejection of interference signals includes receiving, by one or more antennas, incoming wireless signals that include one or more frequency-hopped data signals and one or more narrow-band interference signals, providing, by a receiver digital oscillator, receiver oscillation signals at one or more frequencies as a function of a receive hopping code, and receiving, by receiver correlation circuitry that is communicatively coupled to the receiver digital oscillator and to the one or more antennas, the receiver oscillation signals provided by the receiver digital oscillator. The example method further includes de-spreading the one or more frequency-hopped data signals, spreading, based on the receiver oscillation signals, the one or more narrow-band interference