US6037993A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital BTSC compander system
Assignee: MIDDLESEX SAVINGS BANK
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Filing: 1998-03-11
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Granted: 2000-03-14
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Expires: 2018-03-11
Abstract
Abstract An apparatus for generating a broadcast television stereo signal has a left channel and a right channel. An analog-to-digital converter converts the right-channel signal to a right digital signal and the left-channel to a left digital signal. A circuit, which could include a digital signal processing chip, generates a first signal that includes the right digital signal added to the left digital signal and generates a second signal that includes the right digital signal subtracted from the left digital signal. The circuit also generates a digitally pre-emphasized first signal, which includes digital pre-emphasis, and a digitally pre-emphasized second signal, which also includes digital pre-emphasis. The circuit transforms the pre-emphasized first signal to a digital BTSC L+R signal and transforms the pre-emphasized second signal to a digital BTSC L-R signal. A digital-to-analog converter converts the digital BTSC L+R signal to an analog BTSC L+R signal and the digital BTSC L-R signal to an analog BTSC L-+R signal. The analog BTSC L+R and L-R signals are then modulated onto a carrier wave.
Inventors
- 👤 Matthew Frank Easley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:40
CPC Classifications
H; H03; H03G; H03G7/00; H03G7/007; H04; H04N; H04N21/00; H04N21/80; H04N21/81; H04N21/8106; H04N5/00; H04N5/44; H04N5/60; H04N5/607; H04N7/00; H04N7/06; H04R; H04R5/00; H04R5/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
191 words
A system for generating a broadcast television stereo signal from a left-channel signal and a right-channel signal, the system comprising: (a) an analog-to-digital converter for converting the right-channel signal to a right digital signal and for converting the left-channel to a left digital signal; (b) means coupled to the analog-to-digital converter for generating a summation signal comprising the sum of the right digital signal and the left digital signal, and for generating a difference signal comprising the difference between the right digital signal and the left digital signal; (c) means for generating a first digitally pre-emphasized signal corresponding to the summation signal, and for generating a second digitally pre-emphasized signal corresponding to the difference signal; (d) means for transforming the first pre-emphasized signal to a digital BTSC L+R signal and for transforming the pre-emphasized second signal to a digital BTSC L-R signal; (e) a digital-to-analog converter for converting the digital BTSC L+R signal to an analog BTSC L+R signal and for converting the digital BTSC L-R signal to an analog BTSC L-+R signal; and (f) means for modulating the analog L+R signal and the analog L-R signal onto a carrier wave.
Claim 2
Independent Claim
191 words
A system for generating a broadcast television stereo signal from a left-channel signal and a right-channel signal, the system comprising: (a) an analog-to-digital converter for converting the right-channel signal to a right digital signal and for converting the left-channel to a left digital signal; (b) means coupled to the analog-to-digital converter for generating a summation signal comprising the sum of the right digital signal and the left digital signal, and for generating a difference signal comprising the difference between the right digital signal and the left digital signal; (c) means for generating a first digitally pre-emphasized signal corresponding to the summation signal, and for generating a second digitally pre-emphasized signal corresponding to the difference signal; (d) means for transforming the first pre-emphasized signal to a digital BTSC L+R signal and for transforming the pre-emphasized second signal to a digital BTSC L-R signal; (e) a digital-to-analog converter for converting the digital BTSC L+R signal to an analog BTSC L+R signal and for converting the digital BTSC L-R signal to an analog BTSC L-+R signal; and (f) means for modulating the analog L+R signal and the analog L-R signal onto a carrier wave.
Claim 3
Dependent Claim
30 words
The system of claim 1, wherein the generating means comprises a digital signal processor circuit programmed to digitally add pre-emphasis to the first signal and to the second signal, respectively.
Claim 4
Dependent Claim
26 words
The system of claim 1, wherein the transforming means includes an L-R data path and an L+R data path, each path having a preselected sample rate.
Claim 5
Dependent Claim
71 words
The system of claim 3, wherein the L-R data path comprises: (a) means for interpolating the preselected sample rate to a second sample rate, the second sample rate being faster than the preselected sample rate, thereby generating a sample rate-interpolated L-R signal; (b) means for adding fixed pre-emphasis to the sample rate-interpolated L-R signal; and (c) second means for transforming the sample rate-interpolated L-R signal to the digital BTSC L-R signal.
Claim 6
Dependent Claim
16 words
The system of claim 4, wherein the second transforming means comprises a digital wide-band feedback loop.
Claim 7
Dependent Claim
127 words
The system of claim 4, wherein the second transforming means comprises: a. a digital multiplier having a first input and a second input and an output, the output generating a value equal to the first input multiplied by the second input, the first input being responsive to the sample rate-interpolated L-R signal; b. a variable spectral pre-emphasis feed-back loop responsive to the output of the digital multiplier, for generating the digital BTSC L-R signal; c. a gain control filter, having an output, responsive to the BTSC L-R signal; d. an RMS detector, responsive to the output of the gain control; and e. a 1/x inverter, responsive to the output of the RMS detector, for generating a signal for input to the second input of the digital multiplier.
Claim 8
Dependent Claim
125 words
The system of claim 6, wherein the variable spectral pre-emphasis feed-back loop comprises: a. means, responsive to a first input and a feedback input, for generating variable pre-emphasis signal based on a signal from the first input and a signal from the feedback input, the first input being responsive to the output of the digital multiplier; b. a band limited low pass filter, responsive to the variable preemphasis signal, for generating the digital BTSC L-R signal; c. a gain control band pass filter, responsive to the BTSC L-R signal, for generating a gain control filtered signal; and d. a root-mean-square detector, responsive to the gain control filtered signal, for generating an RMS signal input to the feedback input of the variable pre-emphasis signal generating means.
Claim 9
Dependent Claim
110 words
The system of claim 3, wherein the L+R data path comprises: a. means for interpolating the preselected sample rate to a second sample rate, the second sample rate being faster than the preselected sample rate, thereby generating a sample rate-interpolated L+R signal; b. means for adding 75 micro-second pre-emphasis to the sample rate-interpolated L+R signal to generate a pre-emphasized L+R signal; c. a digital band limited low pass filter, responsive to the pre-emphasized L+R signal, for generating a band limited L+R signal; and d. means for compensating for gain and phase differences between the BTSC L-R signal and the band limited L+R signal and for generating a BTSC L+R signal.
Claim 10
Dependent Claim
165 words
A process for generating a broadcast television stereo signal from a left-channel signal and a right-channel signal, the process comprising: (a) converting the right-channel signal to a right digital signal; (b) converting the left-channel to a left digital signal; (c) generating a summation signal comprising the sum of the right digital signal and the left digital signal; (d) generating a difference signal comprising the difference between the right digital signal and the left digital signal; (e) generating a first digitally pre-emphasized signal corresponding to the summation signal; (f) generating a second digitally pre-emphasized signal corresponding to the difference signal; (g) transforming the first pre-emphasized signal to a digital BTSC L+R signal; (h) transforming the pre-emphasized second signal to a digital BTSC L-R signal; (i) converting the digital BTSC L+R signal to an analog BTSC L+R signal; (j) converting the digital BTSC L-R signal to an analog BTSC L-+R signal; and (k) modulating the analog L+R signal and the analog L-R signal onto a carrier wave.
Claim 11
Dependent Claim
165 words
A process for generating a broadcast television stereo signal from a left-channel signal and a right-channel signal, the process comprising: (a) converting the right-channel signal to a right digital signal; (b) converting the left-channel to a left digital signal; (c) generating a summation signal comprising the sum of the right digital signal and the left digital signal; (d) generating a difference signal comprising the difference between the right digital signal and the left digital signal; (e) generating a first digitally pre-emphasized signal corresponding to the summation signal; (f) generating a second digitally pre-emphasized signal corresponding to the difference signal; (g) transforming the first pre-emphasized signal to a digital BTSC L+R signal; (h) transforming the pre-emphasized second signal to a digital BTSC L-R signal; (i) converting the digital BTSC L+R signal to an analog BTSC L+R signal; (j) converting the digital BTSC L-R signal to an analog BTSC L-+R signal; and (k) modulating the analog L+R signal and the analog L-R signal onto a carrier wave.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-03-14 | 2003-09-13 | 2004-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-03-14 | 2007-09-13 | 2008-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-03-14 | 2011-09-13 | 2012-03-14 | $7700.00 | Window Closed / Lapsed |