US4816783A
Expired / Lapsed
US
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Method and apparatus for quadrature modulation
Assignee: Motorola Solutions Inc
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Filing: 1988-01-11
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Granted: 1989-03-28
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Expires: 2008-01-11
Abstract
Abstract A quadrature amplitude modulation system utilizes two subcarrier signals, each quadrature modulated with information signals which are quadrature modulated onto the RF carrier. This provides a hole in the center of frequency spectrum, permitting carrier and bit sync signals can be provided in the center area of the signal spectrum.
Inventors
- 👤 Clifford D. Leitch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:09
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/36; H04L27/362; H03; H03C; H03C3/00; H03C3/38; H03C3/40; H03C3/403; H04L27/345; H04L27/3455; H04L27/365; H03C2200/00; H03C2200/0004; H03C2200/0029; H03C2200/0037; H03C2200/0058; H03D; H03D7/00; H03D7/16; H03D7/161; H03D7/165
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
51 words
A method of transmitting a quadrature amplitude modulated signal comprising the steps of: quadrature modulating first and second signals onto a first subcarrier, quadrature modulating third and fourth signals onto a second subcarrier, quadrature modulating said first and second quadrature modulated subcarriers onto a carrier, and transmitting said quadrature modulated carrier,
Claim 2
Independent Claim
51 words
A method of transmitting a quadrature amplitude modulated signal comprising the steps of: quadrature modulating first and second signals onto a first subcarrier, quadrature modulating third and fourth signals onto a second subcarrier, quadrature modulating said first and second quadrature modulated subcarriers onto a carrier, and transmitting said quadrature modulated carrier,
Claim 3
Independent Claim
68 words
A method of transmitting a quadrature amplitude modulated signal comprising the steps of; quadrature modulating first and second signals onto a first subcarrier quadrature modulating third and fourth signals onto a second subcarrier, providing a DC component with one of said quadrature modulated subcarriers for producing a pilot carrier, quadrature modulating said quadrature first and second quadrature modulated subcarriers onto a carrier, and transmitting said quadrature modulated carrier.
Claim 4
Independent Claim
68 words
A method of transmitting a quadrature amplitude modulated signal comprising the steps of; quadrature modulating first and second signals onto a first subcarrier quadrature modulating third and fourth signals onto a second subcarrier, providing a DC component with one of said quadrature modulated subcarriers for producing a pilot carrier, quadrature modulating said quadrature first and second quadrature modulated subcarriers onto a carrier, and transmitting said quadrature modulated carrier.
Claim 5
Dependent Claim
30 words
A method of transmitting quadrature amplitude modulated signal as defined in claim 1, comprising the further step of providing a bit sync signal with one of said quadrature modulated subcarriers.
Claim 6
Dependent Claim
36 words
A method as defined in claim 3, in which the signals are digital signals having a predetermined bit rate and the bit sync signal has a frequency that is an integral multiple of said bit rate.
Claim 7
Independent Claim
82 words
A method of transmitting a quadrature amplitude modulated signal, comprising: reading from memory first and second prototype pulses each including a subcarrier component, summing said first and second prototype pulses to produce a first quadrature modulated subcarrier, reading from memory third and fourth prototype pulses each including a subcarrier component, summing said third and fourth prototype pulses to produce a second quadrature modulated subcarrier, quadrature modulating a carrier with said first and second quadrature modulated subcarriers, and transmitting said quadrature modulated carrier.
Claim 8
Independent Claim
82 words
A method of transmitting a quadrature amplitude modulated signal, comprising: reading from memory first and second prototype pulses each including a subcarrier component, summing said first and second prototype pulses to produce a first quadrature modulated subcarrier, reading from memory third and fourth prototype pulses each including a subcarrier component, summing said third and fourth prototype pulses to produce a second quadrature modulated subcarrier, quadrature modulating a carrier with said first and second quadrature modulated subcarriers, and transmitting said quadrature modulated carrier.
Claim 9
Independent Claim
97 words
A method of transmitting a quadrature amplitude modulated signal comprising: reading from memory first and second prototype pulses each including a subcarrier component, summing said first and second prototype pulses to produce a first quadrature modulated subcarrier, reading form memory third and fourth prototype pulses each including a subcarrier component, summing said third and fourth prototype pulses to produce a second quadrature modulated subcarrier, quadrature modulating a carrier with said first and second quadrature modulated subcarriers, summing an offset with one of said summed pulses prior to quadrature modulating said carrier, and transmitting said quadrature modulated carrier,
Claim 10
Independent Claim
97 words
A method of transmitting a quadrature amplitude modulated signal comprising: reading from memory first and second prototype pulses each including a subcarrier component, summing said first and second prototype pulses to produce a first quadrature modulated subcarrier, reading form memory third and fourth prototype pulses each including a subcarrier component, summing said third and fourth prototype pulses to produce a second quadrature modulated subcarrier, quadrature modulating a carrier with said first and second quadrature modulated subcarriers, summing an offset with one of said summed pulses prior to quadrature modulating said carrier, and transmitting said quadrature modulated carrier,
Claim 11
Dependent Claim
34 words
A method of transmitting a quadrature amplitude modulated signals defined in claim 5 including the further step of summing a sync signal with one of said summed pulses prior to quadrature modulating said carrier.
Claim 12
Independent Claim
52 words
An apparatus for transmitting quadrature modulated signals comprising: means for quadrature modulating first and second signals on a first subcarrier, means for quadrature modulating third and fourth signals onto a second subcarrier, means for quadrature modulating said first and second subcarriers onto a carrier, and means for transmitting said quadrature modulated carrier.
Claim 13
Independent Claim
52 words
An apparatus for transmitting quadrature modulated signals comprising: means for quadrature modulating first and second signals on a first subcarrier, means for quadrature modulating third and fourth signals onto a second subcarrier, means for quadrature modulating said first and second subcarriers onto a carrier, and means for transmitting said quadrature modulated carrier.
Claim 14
Independent Claim
63 words
An apparatus for transmitting quadrature modulated signals comprising: means for quadrature modulating first and second signals on a first subcarrier, means for quadrature modulating third and fourth signals onto a second subcarrier, means for summing a sync signal with one of said subcarriers, means for quadrature modulating said first and second subcarriers onto a carrier, and means for transmitting said quadrature modulated carrier.
Claim 15
Independent Claim
63 words
An apparatus for transmitting quadrature modulated signals comprising: means for quadrature modulating first and second signals on a first subcarrier, means for quadrature modulating third and fourth signals onto a second subcarrier, means for summing a sync signal with one of said subcarriers, means for quadrature modulating said first and second subcarriers onto a carrier, and means for transmitting said quadrature modulated carrier.
Claim 16
Dependent Claim
28 words
An apparatus as defined in claim 9, in which a processor means is used for quadrature modulating said first and second signals and said third and fourth signals.
Claim 17
Dependent Claim
39 words
An apparatus as defined in claim 10, in which said processor means includes a memory means containing a prototype pulse having a subcarrier component, and said first and second subcarriers produced by summing prototype pulses in said microprocessor means.
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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) | 1992-03-27 | 1992-09-26 | 1993-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-27 | 1996-09-26 | 1997-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-27 | 2000-09-26 | 2001-03-28 | $7700.00 | Window Closed / Lapsed |