Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships

• US 8,340,618 B2
• Filed: 12/22/2010
• Issued: 12/25/2012
• Est. Priority Date: 10/21/1998
• Status: Expired due to Fees

• Current Assignee: ParkerVision, Inc.
• Original Assignee: ParkerVision, Inc.
• Inventors: Sorrells, David F., Bultman, Michael J., Cook, Robert W., Looke, Richard C., Moses, Charley D., Rawlins, Gregory S., Rawlins, Michael W.
• Primary Examiner(s): Bhattacharya, Sam
• Application Number:
  US12/976,839
• Publication Number:
  US 20110183640A1
• Time in Patent Office: 734 Days
• Field of Search: 455/413, 455/113, 455/118, 455/130, 455/131, 455/182.1, 455/190.1, 455/191.1, 455/313, 455/323, 455/343, 455/350, 375/130, 375/142, 375/143, 375/150, 375/152, 375/316, 375/343, 327/113
• US Class Current: 455/313
• CPC Class Codes: H03C 1/62 Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1475 Subharmonic mixer arrangements
• CPC Class Codes: H04B 1/0025 using a sampling rate lower than twice the highest frequency component of the sampled signal for demodulation of angle-modulated signals H03D3/006
• CPC Class Codes: H04B 1/16 Circuits
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 25/08 Modifications for reducing interference; Modifications for reducing effects due to line faults ; Receiver end arrangements for detecting or overcoming line faults
• CPC Class Codes: H04L 27/00 Modulated-carrier systems
• CPC Class Codes: H04L 27/06 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/14 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 27/148 using filters, including PLL-type filters
• CPC Class Codes: H04L 27/156 with demodulation using temporal properties of the received signal, e.g. detecting pulse width
• CPC Class Codes: H04L 27/2672 Frequency domain
• CPC Class Codes: H04L 27/3881 using sampling and digital processing, not including digital systems which imitate heterodyne or homodyne demodulation

Abstract

Methods, systems, and apparatuses, and combinations and sub-combinations thereof, for down-converting an electromagnetic (EM) signal are described herein. Briefly stated, in embodiments the invention operates by receiving an EM signal and recursively operating on approximate half cycles (½, 1½, 2½, etc.) of the carrier signal. The recursive operations can be performed at a sub-harmonic rate of the carrier signal. The invention accumulates the results of the recursive operations and uses the accumulated results to form a down-converted signal. In an embodiment, the EM signal is down-converted to an intermediate frequency (IF) signal. In another embodiment, the EM signal is down-converted to a baseband information signal. In another embodiment, the EM signal is a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal.

Claims

1. A method for down-converting an electromagnetic signal, comprising the steps of:

(1) performing a resistor-capacitor (RC) processing operation on a portion of a carrier signal, wherein the RC processing operation comprises operating on an approximate half cycle of the carrier signal with an RC filter and integrating the output of the RC filter,

(2) accumulating the result of the RC processing operation of step (1); and

(3) repeating steps (1) and (2) for additional portions of the carrier signal, whereby the accumulation results form a down-converted signal.

2. The method according to claim 1, where h(t) is an impulse response of an RC filter, R is an impedance, C is a capacitance, and u(t)-u(t-TA) is a windowing operator or aperture of duration TA, and wherein step (1) comprises the steps of:

(a) operating on an approximate half cycle of the carrier signal with an RC filter having an impulse response approximated by and

(b) integrating the output of the RC filter.

3. The method according to claim 1, wherein step (1) comprises the step of controlling a switch to pass an approximate half cycle of the carrier signal through the switch and integrating the output of the switch using a capacitive storage device.

4. The method according to claim 1, wherein step (2) comprises the step of transferring a portion of the energy contained in an approximate half cycle of the carrier signal to a capacitive storage device.

5. The method according to claim 1, where C is capacitance, RS is a source impedance, and TA is a time of an approximate half cycle of the carrier signal, and wherein step (2) comprises the step of accumulating a portion of the energy contained in the approximate half cycle of the carrier signal using a capacitive storage device chosen in accordance with:

C≧

(T_A/0.25R_S).

6. The method according to claim 1, further comprising the step of:

(4) passing on the accumulation result of step (2) to reconstruction filter.

7. The method according to claim 1, further comprising the step of:

(4) passing on the accumulation result of step (2) to an interpolation filter.

8. The method according to claim 1, wherein step (3) comprises the step of repeating steps (1) and (2) at a sub-harmonic rate of the carrier signal.

9. The method according to claim 1, wherein step (3) comprises the step of repeating steps (1) and (2) at an off-set of a sub-harmonic rate of the carrier signal.

10. The method according to claim 1, further comprising the step of:

(4) performing steps (1), and (3) for positive approximate half cycles of the carrier signal and for inverted negative approximate half cycles of the carrier signal.

11. A method for down-converting an electromagnetic signal, comprising the steps of:

(1) performing a resistor-capacitor (RC) processing operation on a portion of a carrier signal, wherein the RC processing operation includes controlling a switch to pass an approximate half cycle of the carrier signal through the switch and integrating the output of the switch using a capacitive storage device;

(2) accumulating the result of the RC processing operation of step (1); and

(3) repeating steps (1) and (2) for additional portions of the carrier signal, whereby the accumulation results form a down-converted signal.

12. The method according to claim 11, wherein step (2) comprises the step of transferring a portion of the energy contained in an approximate half cycle of the carrier signal to a capacitive storage device.

13. The method according to claim 11, where h(t) is an impulse response of an RC filter, R is an impedance, C is a capacitance, and u(t)-u(t-TA) is a windowing operator or aperture of duration TA, and wherein step (1) comprises the steps of:

(a) operating on an approximate half cycle of the carrier signal with an RC filter having an impulse response approximated by and

(b) integrating the output of the RC filter.

14. The method according to claim 11, further comprising the step of:

(4) passing on the accumulation result of step (2) to a reconstruction filter.

15. The method according to claim 11, further comprising the step of:

(4) passing on the accumulation result of step (2) to an interpolation filter.

16. The method according to claim 11, wherein step (3) comprises the step of repeating steps (1) and (2) at a sub-harmonic rate of the carrier signal.

17. The method according to claim 11, wherein step (3) comprises the step of repeating steps (1) and (2) at an off-set of a sub-harmonic rate of the carrier signal.

18. The method according to claim 11, further comprising the step of:

(4) performing steps (1), (2), and (3) for positive approximate half cycles of the carrier signal and for inverted negative approximate half cycles of the carrier signal.

19. A method for down-converting an electromagnetic signal, comprising the steps of:

(1) performing a resistor-capacitor (RC) processing operation on a portion of a carrier signal;

(2) accumulating the result of the RC processing operation of step (1), wherein the accumulating comprises the step of transferring a portion of the energy contained in an approximate half cycle of the carrier signal to a capacitive storage device; and

(3) repeating steps (1) and (2) for additional portions of the carrier signal, whereby the accumulation results form a down-converted signal.