US4069398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for pilot signal cancellation in an FM multiplex demodulator
Assignee: Pioneer Corp
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Filing: 1976-09-01
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Granted: 1978-01-17
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Expires: 1996-09-01
Abstract
Abstract Unwanted pilot signal components in the "L" and "R" outputs of a stereophonic FM multiplex demodulator are cancelled by inverting the 19KHz pilot signal, separately multiplying or gating it with the opposite phase 38KHz subcarrier signals, and adding the multiplier or gate outputs to the "L" and "R" demodulator outputs. The multiplication produces signals equal in amplitude but opposite in phase to the contaminating pilot signal components, whereby the latter are effectively cancelled by the addition function.
Inventors
- 👤 Seijiro Fujie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:29
CPC Classifications
H; H04; H04H; H04H40/00; H04H40/18; H04H40/27; H04H40/36; H04H40/45; H04H40/72; H03; H03D; H03D1/00; H03D1/22; H03D1/2209; H03D1/2227; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/1646; H03D2200/00; H03D2200/0041; H03D2200/0086
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
115 words
In an FM multiplex demodulator including means for providing left (L) and right (R) channel output signals from a composite input signal in response to opposite phase switching signals derived from a pilot signal, means for removing unwanted pilot signal components from the L and R output signals, comprising: a. means for inverting the pilot signal, b. means for individually multiplying the inverted pilot signal by each of the opposite phase switching signals to produce signals equal in amplitude but opposite in phase to the unwanted pilot signal components, and c. means for individually adding the multiplication signals to the respective L and R output signals, whereby the unwanted pilot signal components are effectively cancelled.
Claim 2
Dependent Claim
115 words
In an FM multiplex demodulator including means for providing left (L) and right (R) channel output signals from a composite input signal in response to opposite phase switching signals derived from a pilot signal, means for removing unwanted pilot signal components from the L and R output signals, comprising: a. means for inverting the pilot signal, b. means for individually multiplying the inverted pilot signal by each of the opposite phase switching signals to produce signals equal in amplitude but opposite in phase to the unwanted pilot signal components, and c. means for individually adding the multiplication signals to the respective L and R output signals, whereby the unwanted pilot signal components are effectively cancelled.
Claim 3
Dependent Claim
59 words
A multiplex demodulator as defined in claim 1 further comprising a phase lock loop for deriving the pilot signal and the opposite phase switching signals from the composite input signal, and wherein the means for inverting comprises an inverter, the means for multiplying comprises a pair of multipliers and the means for adding comprises a pair of nodal adders.
Claim 4
Dependent Claim
112 words
In an FM multiplex demodulator wherein left (L) and right (R) channel output signals are derived from a composite input signal in response to opposite phase switching signals derived from a pilot signal, a method for removing unwanted pilot signal components from the L and R output signals, comprising the steps of: a. inverting the pilot signal, b. individually multiplying the inverted pilot signal by each of the opposite phase switching signals to produce signals equal in amplitude but opposite in phase to the unwanted pilot signal components, and c. individually adding the multiplication signals to the respective L and R output signals, whereby the unwanted pilot signal components are effectively cancelled.
Claim 5
Dependent Claim
112 words
In an FM multiplex demodulator wherein left (L) and right (R) channel output signals are derived from a composite input signal in response to opposite phase switching signals derived from a pilot signal, a method for removing unwanted pilot signal components from the L and R output signals, comprising the steps of: a. inverting the pilot signal, b. individually multiplying the inverted pilot signal by each of the opposite phase switching signals to produce signals equal in amplitude but opposite in phase to the unwanted pilot signal components, and c. individually adding the multiplication signals to the respective L and R output signals, whereby the unwanted pilot signal components are effectively cancelled.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-01-16 | 1981-07-18 | 1982-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-16 | 1985-07-18 | 1986-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-16 | 1989-07-18 | 1990-01-17 | $7700.00 | Window Closed / Lapsed |