IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0609196
(2012-09-10)
|
등록번호 |
US-9634878
(2017-04-25)
|
발명자
/ 주소 |
- Bench, Stephanie M.
- Shaffer, Roger B.
- Olsson, Mark S.
|
출원인 / 주소 |
|
대리인 / 주소 |
Tietsworth, Esq., Steven C.
|
인용정보 |
피인용 횟수 :
1 인용 특허 :
14 |
초록
Quadrature Amplitude Modulation (QAM) methods, apparatus, and systems including a QAM transmit modulator to generate an output signal using a two-dimensional (2-D) QAM symbol constellation is disclosed.
대표청구항
▼
1. A method for providing a self-synchronizing Quadrature Amplitude Modulation (QAM) signal in a video inspection system, comprising: generating, in a video camera module of a camera head coupled to a push-cable including two or more conductors, a digital video signal comprising a digital data strea
1. A method for providing a self-synchronizing Quadrature Amplitude Modulation (QAM) signal in a video inspection system, comprising: generating, in a video camera module of a camera head coupled to a push-cable including two or more conductors, a digital video signal comprising a digital data stream representing the interior of a pipe or conduit in which the camera head is deployed into;receiving, at a QAM transmitter module disposed in the video camera module, the digital data stream;mapping the digital data stream to ones of a plurality of symbol values corresponding solely to points on a circular symbol constellation, including orthogonal I and Q axes, to generate a mapped data stream; wherein the points defining the circular symbol array are spaced on the circumference of a first circle of the circular symbol array constellation so that the angular distance between a first pair of points in the circular array is different than the angular distance between a second pair of points of the circular array and such that the mapped data stream has substantially zero energy at a symbol clock frequency; andsending the mapped data stream to the wired communication conductors of the push-cable. 2. The method of claim 1, wherein the circular symbol constellation is a four or more point array defined on a circle, and two or more symbol pairs are non-uniformly spaced on the circle in a mirror symmetry configuration about the I and/or Q axes. 3. The method of claim 1, wherein the circular symbol constellation comprises two or more circles with four or more symbols disposed on each of the circles, wherein two or more symbol pairs are non-uniformly spaced on one or more of the two or more circles in a mirror symmetry configuration about the I and/or Q axes. 4. The method of claim 1, wherein the circular symbol constellation includes a first circle and a second circle, and wherein the digital data stream is mapped to points on the first circle and the second circle. 5. The method of claim 1, wherein a portion of the digital data is further mapped to ones of a plurality of symbol values corresponding to points on a rectangular symbol constellation. 6. The method of claim 1, further comprising: receiving the transmitted signal at a QAM receiver module operatively coupled to the push-cable conductors;applying the transmitted signal to a non-linearity module to recover the symbol clock by generating a squared version of the transmitted signal; anddecoding the received transmitted signal using the recovered symbol clock. 7. The method of claim 6, wherein the non-linear module is a square-law processing module configured to square the received transmitted signal. 8. The method of claim 6, wherein the recovering the symbol clock includes: narrowband filtering an output of the non-linearity device; andapplying the output of the narrowband filter to a phase-locked loop to generate the symbol clock. 9. The method of claim 1, wherein the digital data stream is a video data stream generated from a pipe inspection imaging element. 10. The method of claim 9, further including compressing the video data stream in a camera head before providing the video data stream to the QAM module. 11. The method of claim 1, wherein at least one symbol point in the circular constellation is on the in-phase (I) axis of the constellation. 12. A method for providing a self-synchronizing Quadrature Amplitude Modulation (QAM) signal from a QAM transmitter module, comprising: receiving a digital data stream corresponding to a video signal from a camera head disposed in a pipe or cavity;mapping the digital data stream to ones of a plurality of symbol values corresponding to points on a circular symbol constellation including orthogonal I and Q axes, to generate a mapped data stream; wherein the points defining the circular symbol array are spaced on the circumference of a first circle of the circular symbol array constellation so that the angular distance between a first pair of points in the circular array is different than the angular distance between a second pair of points of the circular array;wherein the points defining the circular symbol array are spaced such that the mapped data stream includes signal energy at a symbol clock frequency; andsending the mapped data stream in a wired push-cable communication channel. 13. A QAM transmitter, comprising: a memory; anda processor coupled to the memory, the processor configured to:receive a digital data stream corresponding to a video stream;map the digital data stream to ones of a plurality of symbol values corresponding solely to points on a circular symbol constellation, including orthogonal I and Q axes, to generate a mapped data stream; wherein the points defining the circular symbol array are spaced on the circumference of a first circle of the circular symbol array constellation so that the angular distance between a first pair of points in the circular array is different than the angular distance between a second pair of points of the circular array and such that the mapped data stream has substantially zero energy at a symbol clock frequency; andsend the mapped data stream as an output signal to a wired push-cable communication channel. 14. The QAM transmitter of claim 13, further comprising: a camera head for enclosing the memory and processor; anda video compression module in the camera head for compressing the digital data stream before the digital data stream is mapped to the ones of a plurality of symbol values. 15. The method of claim 12, wherein at least one symbol point in the circular constellation is on the in-phase (I) axis of the constellation. 16. The method of claim 12, wherein the circular symbol constellation is a four or more point array defined on a circle, and two or more symbol pairs are non-uniformly spaced on the circle. 17. The method of claim 12, wherein the circular symbol constellation comprises two or more circles with a plurality of symbols disposed thereon, wherein two or more symbol pairs are non-uniformly spaced on one or more of the two or more circles. 18. The method of claim 12, wherein the circular symbol constellation includes a first circle and a second circle, and wherein the digital data stream is mapped to points on the first circle and the second circle. 19. The method of claim 12, wherein a portion of the digital data is further mapped to ones of a plurality of symbol values corresponding to points on a rectangular symbol constellation. 20. The method of claim 12, further comprising: receiving the transmitted signal;recovering a symbol clock signal from the received transmitted signal; anddecoding the received transmitted signal using the recovered symbol clock. 21. The method of claim 20, wherein the recovering the symbol clock includes: narrowband filtering the received transmitted signal; andapplying the output of the narrowband filter to a phase-locked loop to generate the symbol clock. 22. A QAM Transmitter, comprising: a camera head housing;a memory disposed in the camera head housing; anda processor coupled to the memory and disposed in the camera head housing, the processor programmed to:receive a digital data stream from an imaging sensor in the camera head when the camera head is disposed in a pipe or cavity;map the digital data stream to ones of a plurality of symbol values corresponding solely to points on a circular symbol constellation including orthogonal I and Q axes, to generate a mapped data stream, where the mapped data stream includes energy at a symbol clock frequency for use in clock recovery at a corresponding receiver; andsend the mapped data stream through a wired push-cable communication channel. 23. A communications apparatus, comprising: an input for receiving digital data from a camera head disposed in a pipe or cavity;a Quadrature Amplitude Modulation (QAM) module coupled to the input configured to separate the digital data stream into in-phase (I) and quadrature (Q) data streams;a mapping module for mapping the I and Q data streams to a plurality of symbol values corresponding solely to points of a circular symbol constellation, wherein the points of the circular symbol constellation are non-uniformly spaced on the circular symbol constellation so as to facilitate symbol clock recovery by either squaring the received signal to generate a clock recovery signal or recovering the clock signal from energy at the symbol clock frequency in the QAM module output; anda transmitter module configured to send the symbol values as a transmitted signal through a wired push-cable communication channel. 24. The apparatus of claim 23, wherein at least one symbol point in the circular constellation is on the in-phase (I) axis of the constellation.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.