RF slipring receiver for a computerized tomography system

• US 6,433,631 B2
• Filed: 08/13/2001
• Issued: 08/13/2002
• Est. Priority Date: 03/31/1999
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Pearson, Phil E. Jr., Harris, Michael H.
• Primary Examiner(s): MIS, DAVID C
• Application Number:
  US09/928,620
• Publication Number:
  US 20020003450A1
• Time in Patent Office: 365 Days
• Field of Search: 329/311-314, 329/347, 329/349, 329/350, 455/63, 455/66, 455/234.1, 455/249.1, 455/250.1, 375/268-270, 375/285, 375/320-321, 375/338-339, 375/340, 375/345, 375/346, 375/350
• US Class Current: 329/311
• CPC Class Codes: H04L 27/06 Demodulator circuits; Receiver circuits

Abstract

A computerized tomography (CT) system having an apparatus and method for receiving high data rate communication is disclosed herein. The apparatus includes a controlled variable attenuator for attenuating an encoded digital data signal having a wide range of power levels, a digital envelope detector for de-encoding the encoded digital data signal, a noise filtering circuit for filtering out the residual undesirable encoded signal components, and a feedback loop for maintaining a desired signal level such that the encoded digital data signal is converted to its pre-encoded state suitable for processing to generate a CT image.

Claims

1. An apparatus for demodulating and digitizing a modulated data signal possibly having a wide range of power levels, comprising:

a variable attenuation circuit configured to attenuate an amplitude of the modulated data signal in response to a feedback signal to generate an amplitude stabilized signal;

a conversion circuit coupled to the variable attenuation circuit and configured to remove a modulation component from the amplitude stabilized signal to generate a digitized signal;

a circuit coupled to the conversion circuit and configured to generate a reconstructed digital data signal and an amplitude signal from the digitized signal, wherein the reconstructed digital data signal is representative of the modulated data signal in a pre-modulated state and the amplitude signal is representative of an amplitude of the digitized signal; and

an attenuation controller coupled to the circuit and the variable attenuation circuit, wherein the attenuation controller is configured to generate the feedback control signal from the amplitude signal.

2. The apparatus of claim 1, further comprising:

a bandwidth filter coupled to the variable attenuation circuit and configured to filter the modulated data signal; and

an amplifier coupled to the variable attenuation circuit and the conversion circuit, wherein the amplifier is configured to provide a gain of up to 45 dB to the amplitude stabilized signal.

3. The apparatus of claim 2, wherein the bandwidth filter has a bandwidth range of 500 MHz to 1 GHz.

4. The apparatus of claim 1, wherein the circuit comprises a digital hysteresis circuit configured to add hysteresis to the digitized signal.

5. The apparatus of claim 1, wherein the conversion circuit comprises a radio frequency (RF) amplitude modulation digital envelope detector.

6. The apparatus of claim 1, wherein the modulated data signal comprises a signal having a power level range of up to 50 dBm around a center operating power level.

7. The apparatus of claim 1, wherein the modulated data signal comprises a signal having a power level range of up to 40 dBm around a center operating power level.

8. The apparatus of claim 1, wherein the feedback signal applied to the variable attenuation circuit is configured from a previous modulated data signal.

9. The apparatus of claim 1, wherein the modulated data signal comprises a signal having a center operating power level of approximately −

13.6 dBm.

10. The apparatus of claim 1, wherein the modulated data signal comprises a series digital bit data signal that is amplitude modulated with a radio frequency (RF) carrier signal.

11. An apparatus for demodulating and digitizing a modulated data signal possibly having a wide range of power levels, comprising:

means for variably attenuating the modulated data signal in response to a feedback signal to generate an amplitude stabilized signal;

means for digitizing the amplitude stabilized signal to generate a digitized signal;

means for filtering the digitized signal to generate a reconstructed digital data signal representative of the modulated data signal in a pre-modulated state; and

means for generating the feedback signal in response to the digitized signal, wherein the feedback signal is representative of an amplitude of the digitized signal.

12. The apparatus of claim 11, further comprising means for bandwidth filtering the modulated data signal, wherein the means for bandwidth filtering has a bandwidth range of 500 MHz to 1 GHz.

13. The apparatus of claim 11, further comprising means for amplifying the amplitude stabilized signal, wherein the means for amplifying is configured to provide a gain of up to approximately 45 dB.

14. The apparatus of claim 11, wherein the means for filtering comprises a digital hysteresis circuit, a digital buffer circuit, a digital noise filter circuit, or an NRZI data screen.

15. The apparatus of claim 11, wherein the means for digitizing comprises a radio frequency (RF) amplitude modulation digital envelope detector.

16. The apparatus of claim 11, wherein the means for generating comprises a digital hysteresis circuit and a digital signal level detector.

17. The apparatus of claim 11, wherein the modulated data signal comprises a signal having a power level range of up to 50 dBm around a center operating power level.

18. The apparatus of claim 17, wherein the center operating power level is approximately −

13.6 dBm.

19. The apparatus of claim 11, wherein the means for variably attenuating provides an attenuation range of −

40 dB to 0 dB.

20. The apparatus of claim 11, wherein the feedback signal applied to the means for variably attenuating is configured from a previous modulated data signal.

21. A method for demodulating and digitizing a modulated data signal possibly having a wide range of power levels, the method comprising the steps of:

transmitting the modulated data signal from a first location;

receiving the modulated data signal at a second location, wherein the first and second locations are remote from each other;

attenuating an amplitude of the modulated data signal in response to a previous modulated data signal via a feedback loop; and

converting the modulated data signal into a reconstructed digital data signal, wherein the reconstructed digital data signal is representative of the modulated data signal in a pre-modulated state, the attenuating and converting steps are carried out at the second location, and the modulated data signal comprises a signal having a power level range of up to 50 dBm around a center operating power level.

22. The method of claim 21, wherein the attenuating step includes attenuating the amplitude in a range of −

40 dB to 0 dB.

23. The method of claim 21, wherein the converting step includes demodulating the modulated data signal and filtering the modulated data signal.

24. The method of claim 23, wherein filtering the modulated data signal includes introducing a hysteresis to the modulated data signal.

25. The method of claim 21, wherein the center operating power level is approximately −

13.6 dBm.