Wideband frequency hopping spread spectrum transmitters and related methods

• US 20090161730A1
• Filed: 10/28/2008
• Published: 06/25/2009
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Inventors: Fudge, Gerald L.
• Granted Patent: US 8,249,129 B2
• Time in Patent Office: Days
• US Class Current: 375/135
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 7/285 Receivers
• CPC Class Codes: H04B 1/7136 Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform
• CPC Class Codes: H04B 1/71635 Transmitter aspects H04B1/7174 takes precedence
• CPC Class Codes: H04B 1/71637 Receiver aspects H04B1/7183 takes precedence
• CPC Class Codes: H04B 2001/71362 using a bank of frequency sources

Abstract

Systems and methods are disclosed that provide ultra-wideband frequency hopping spread spectrum (UWB-FHSS) solutions for transmit and receive architectures. These UWB-FHSS transmit and receive architectures can transmit signals over an extremely wide bandwidth while using a relatively slow analog-to-digital converter (ADC) without suffering from unacceptable performance degradation. For example, ADCs can be used having sample rates lower than standard Nyquist criteria would require for the bandwidth of the spread spectrum utilized.

Claims

1. A wideband frequency hopping spread spectrum transmitter, comprising:

sampling circuitry configured to receive a transmit signal at an intermediate frequency (f_IF) and to receive sampling signals at a sample clock frequency (f_S) and configured to generate sampled output signals having a plurality of frequency components, the frequency components including frequencies at two or, more harmonics of f_S plus and minus f_IF;

frequency select filter circuitry configured to receive the sampled output signals and to receive a frequency selection signal, the frequency select filter circuitry configured to provide a plurality of different selectable filter passband frequency ranges across a bandwidth that includes at least two harmonics of the sample clock frequency (f_S), the frequency select filter circuitry further having an output signal within a selected filter passband frequency range that includes one frequency component of the sampled output signals; and

frequency hopping control circuitry configured to output the frequency selection signal and to adjust the frequency selection signal over time so that the output signal hops to different frequency components depending upon the selected filter passband frequency range.

2. The wideband frequency hopping spread spectrum transmitter of claim 1, wherein the plurality of frequency components for the sampled output signals comprises a DC harmonic frequency component, having frequencies at DC plus and minus f_IF, and a 1f_S frequency component, having frequencies at 1f_S plus and minus f_IF.

3. The wideband frequency hopping spread spectrum transmitter of claim 1, further comprising amplifier circuitry configured to receive the output signal from the frequency select filter circuitry and to provide an amplified output signal to an antenna.

4. The wideband frequency hopping spread spectrum transmitter of claim 1, wherein the frequency select filter circuitry comprises a plurality of different selectable filters, wherein each selectable filter having a passband frequency range configured to pass one frequency component of the sampled output signals, and wherein the frequency selection signal is configured to select one of the different selectable filters.

5. The wideband frequency hopping spread spectrum transmitter of claim 1, wherein the frequency select filter circuitry comprises a tunable filter configured to be tuned to a passband frequency range to pass one frequency component of the sampled output signals, and wherein the frequency selection signal is configured to tune the tunable filter to a selected passband frequency range.

6. The wideband frequency hopping spread spectrum transmitter of claim 1, wherein the sample clock frequency (f_S) is about 1 GHz or greater and the intermediate frequency (f_IF) is about 200 MHz or less.

7. The wideband frequency hopping spread spectrum transmitter of claim 6, wherein the bandwidth spanned by the minimum and maximum frequencies of the frequency select filter circuitry is about 10 GHz or more.

8. The wideband frequency hopping spread spectrum transmitter of claim 1, wherein the sampling clock signal comprises a modulated sampling clock signal.

9. The wideband frequency hopping spread spectrum transmitter of claim 1, wherein the sampling clock signal comprises a tuned sampling clock signal.

10. The wideband frequency hopping spread spectrum transmitter of claim 1, further comprising a digital signal processor (DSP) configured to output a digital transmit signal, a digital-to-analog converter (DAC) configured to receive the digital transmit signal and output an analog transmit signal, and mixer circuitry configured to receive the analog transmit signal and output the transmit signal at an intermediate frequency (f_IF).

11. A method for transmitting wideband frequency hopping spread spectrum signals, comprising:

sampling a transmit signal at an intermediate frequency (f_IF) using sampling signals at a sample clock frequency (f_S) to generate sampled output signals having a plurality of frequency components, the frequency components including frequencies at two or more harmonics of f_S plus and minus f_IF;

selecting one of the frequency components using frequency select filter circuitry;

transmitting the selected frequency component as an output signal; and

repeating the sampling, selecting and transmitting steps to select and transmit different frequency components so that the output signals hop to different frequency components over time.

12. The method of claim 11, wherein the sampling step comprises generating a plurality of frequency components for the sampled output signals including a DC harmonic frequency component, having frequencies at DC plus and minus f_IF, and a 1f_S frequency component, having frequencies at 1f_S plus and minus f_IF.

13. The method of claim 11, wherein the selecting step comprises providing a plurality of selectable filters each having a passband frequency range configured to pass one frequency component of the sampled output signals and selecting one of the plurality of different selectable filters to pass one of the frequency components.

14. The method of claim 11, wherein selecting step comprises providing a tunable filter configured to be tuned to a passband frequency range to pass one frequency component of the sampled output signals, and tuning the tunable filter to pass one of the frequency components.

15. The method of claim 11, wherein the sampling step comprises using a sample clock frequency (f_S) of about 1 GHz or greater and an intermediate frequency (f_IF) of about 200 MHz or less.

16. The method of claim 15, wherein the bandwidth spanned by the minimum and maximum frequencies of the frequency select filter circuitry is about 10 GHz or more.

17. The method of claim 11, wherein the sampling step comprises using a sampling clock signal comprising a modulated sampling clock signal.

18. The method of claim 11, wherein the sampling step comprises using a sampling clock signal comprising a tuned sampling clock signal.

19. The method of claim 11, further comprising generating the transmit signal at an intermediate frequency (f_IF) by digitally processing signals to produce digital transmit signals, converting the digital transmit signals to analog transmit signals, and mixing the analog transmit signals to produce the transmit signal at an intermediate frequency (f_IF).