EP0300491A2
Expired / Lapsed
EP
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An optical apparatus for pulling an intermediate frequency in a predetermined frequency range
Assignee: NEC Corp
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Filing: 1988-07-22
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Granted: —
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Expires: 2008-07-22
Abstract
Abstract In an optical apparatus for pulling an intermediate frequency in a predetermined frequency range, a local oscillation light source (15) is swept in an oscillation frequency thereof in accordance with a signal applied to a frequency adjusting terminal thereof. The signal is of a counted value of a counter (9) which counts pulse signals of an oscillator (18). When an intermediate frequency is pulled in a predetermined frequency range including a predetermined intermediate frequency, the counter (9) is stopped to count the pulse signals, and is controlled to hold a then counted value which will be a fixed driving signal for the local oscillation light source (15).
Inventors
- 👤 Shuntaro C/O Nec Corporation Yamazaki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 16:26
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/60; H03; H03J; H03J7/00; H03J7/18; H03J7/20; H03J7/24; H03J7/26; H03J7/28; H04B10/61; H04B10/64
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
136 words
An optical apparatus for pulling an intermediate frequency in a predetermined frequency range comprising, a sweep circuit for supplying a sweep signal to a local oscillation light source which is thereby driven to produce local oscillation light, said local oscillation light being combined to signal light received in an optical heterodyne receiver to produce an intermediate frequency signal, and a control circuit for supplying a control signal to said sweep circuit which is thereby stopped to produce said sweep signal when a frequency of said intermediate frequency signal is pulled in a frequency range thereof whereby a fixed driving signal is supplied to said local oscillation light source, wherein said sweep circuit includes a counter for counting output pulses of an oscillator, and means for converting a counted value of said counter to said sweep signal.
Claim 2
Dependent Claim
136 words
An optical apparatus for pulling an intermediate frequency in a predetermined frequency range comprising, a sweep circuit for supplying a sweep signal to a local oscillation light source which is thereby driven to produce local oscillation light, said local oscillation light being combined to signal light received in an optical heterodyne receiver to produce an intermediate frequency signal, and a control circuit for supplying a control signal to said sweep circuit which is thereby stopped to produce said sweep signal when a frequency of said intermediate frequency signal is pulled in a frequency range thereof whereby a fixed driving signal is supplied to said local oscillation light source, wherein said sweep circuit includes a counter for counting output pulses of an oscillator, and means for converting a counted value of said counter to said sweep signal.
Claim 3
Dependent Claim
101 words
An optical apparatus for pulling an intermediate frequency in a predetermined frequency range according to claim 1, wherein said control circuit includes an intermediate frequency monitor circuit for producing an automatic frequency control request signal and an intermediate frequency stabilizing signal when said frequency is pulled in said predetermined frequency range whereby said counter is stopped to count said output pulses, said means converts said counted value to said fixed driving signal, and said intermediate frequency stabilizing signal is added to said fixed driving signal so that said frequency of said intermediate frequency signal is stabilized on a predetermined center frequency.
Claim 4
Dependent Claim
100 words
An optical apparatus for pulling an intermediate frequency in a predetermined frequency range according to claim 2, wherein said intermediate frequency monitor circuit includes high and low pass filters for passing signal components of high and low frequency bands in regard to said predetermined center frequency of said intermediate frequency signal, means for detecting levels of outputs of said high and low pass filters, and means for dividing a subtracting value between said levels by an adding value of said levels whereby said intermediate frequency stabilizing signal is controlled such that an output of said means for dividing becomes zero.
Claim 5
Dependent Claim
55 words
An optical apparatus for pulling an intermediate frequency in a predetermined frequency range according to claim 3 further comprising, a polarization control device for adjusting a polarization of said local oscillation light, said polarization control device being positioned in front of said local oscillation light source such that said adding value becomes the maximum value.
References Cited (Backward Citations)
No citation records indexed.
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