Patent US5654816A successfully refreshed from Google Patents.
US5654816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Performance monitoring and fault location in optical transmission
Assignee: Nokia of America Corp
•
Filing: 1996-06-06
•
Granted: 1997-08-05
•
Expires: 2016-06-06
Abstract
Abstract Monitoring of optical amplifiers is accomplished, in accordance with the invention, by an apparatus and method for detecting a power level of a tone modulated upon a signal input to the amplifier, detecting an output power level of the amplifier, and comparing the power level of the tone to the output power level of the amplifier to determine an indication of the performance of the amplifier. In illustrative embodiments of the invention, each of the individual channels within a multiplexed optical signal are modulated with a specific low-frequency tone. The modulating is performed at the transmission site of the optical signal, and the specific tone frequencies are chosen to be lower than the low-frequency cut-off of any other information encoded upon the optical signal. The channel power of each channel is determined after each stage of optical amplification in the network by measuring the power of its respective unique low-frequency tone using a low-cost monitor. The total optical output power of the optical amplifier is also measured by the monitor. The ratio between the tone power and the optical amplifier output power after the first stage of optical amplification in the network is compared to the tone power/output power ratio at each subsequent optical amplification stage. Changes between the first and subsequent tone power/output power ratios reflect changes in network performance. The changes in tone power/output power ratio are strongly correlated to actual changes in optical signal-to-noise ratio. Advantageously, such a monitor may be built-in to each optical amplifier in the network, and no complex calibration of any components in the network is needed. Since each optical amplifier has a dedicated monitor which determines the status of each channel, faults in the network may be readily and quickly located to a specific optical amplifier and a specific channel.
Inventors
- 👤 Daniel A. Fishman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:46
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/29; H04B10/291; H04B10/293; H04B10/2933; H04B10/07; H04B10/075; H04B10/077; H04B10/0777; H04B2210/00; H04B2210/07; H04B2210/075; H04J; H04J14/00; H04J14/02; H04J14/0298
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
79 words
A method for monitoring the performance of an optical amplifier, the amplifier having an input port and an output port, the method comprising the steps of: detecting, at the output of the amplifier, a level of a tone modulated upon a signal input to the amplifier; detecting an output level of the amplifier; and determining a signal-to-noise ratio for said optical amplifier as a function of the level of said tone and the output level of the optical amplifier.
Claim 2
Independent Claim
79 words
A method for monitoring the performance of an optical amplifier, the amplifier having an input port and an output port, the method comprising the steps of: detecting, at the output of the amplifier, a level of a tone modulated upon a signal input to the amplifier; detecting an output level of the amplifier; and determining a signal-to-noise ratio for said optical amplifier as a function of the level of said tone and the output level of the optical amplifier.
Claim 3
Dependent Claim
15 words
The method of claim 1 in which the signal comprises a plurality of multiplexed channels.
Claim 4
Dependent Claim
20 words
The method of claim 2 in which a specific tone is modulated upon each of the plurality of multiplexed channels.
Claim 5
Dependent Claim
20 words
The method of claim 3 in which the tone detector detects a power level of each of the specific tones.
Claim 6
Dependent Claim
27 words
The method of claim 4 in which the comparing means compares the power level of each of the specific tones to the power level of the amplifier.
Claim 7
Dependent Claim
24 words
The method of claim 5 in which the performance includes the performance of the amplifier in amplifying each of the channels of the signal.
Claim 8
Dependent Claim
18 words
The method of claim 4 in which the indication of performance is a representation of optical signal-to-noise ratio.
Claim 9
Dependent Claim
20 words
The method of claim 2 in which the modulating is performed by frequency modulating selected ones of the multiplexed channels.
Claim 10
Dependent Claim
20 words
The method of claim 2 in which the modulating is performed by amplitude modulating selected ones of the multiplexed channels.
Claim 11
Dependent Claim
20 words
The method of claim 2 in which the modulating is performed by polarization modulating selected ones of the multiplexed channels.
Claim 12
Dependent Claim
20 words
The method of claim 1 in which the indication of performance is an indication of optical signal to noise ratio.
Claim 13
Dependent Claim
23 words
The method of claim 1 in which the performance monitoring steps are applied to at least one of a plurality of optical amplifiers.
Claim 14
Dependent Claim
24 words
The method of claim 12 in which the performance monitoring steps are applied to no more than one of the plurality of optical amplifiers.
Claim 15
Dependent Claim
72 words
The method of claim 12 further including the step of comparing a tone power level to an output power level ratio at a first optical amplifier in the plurality of optical amplifiers to a tone power level to output power level ratio at at least one other optical amplifier in the plurality of optical amplifiers to determine an indication of the performance of at least one of the plurality of optical amplifiers.
Claim 16
Dependent Claim
16 words
The method of claim 14 in which the plurality of optical amplifiers are arranged in stages.
Claim 17
Dependent Claim
25 words
The method of claim 15 in which the first optical amplifier in the plurality of optical amplifiers is coupled to at least one optical source.
Claim 18
Dependent Claim
29 words
The method of claim 1 in which the signal is modulated to carry information, the information modulation being independent of, and in addition to, the modulation with the tone.
Claim 19
Dependent Claim
31 words
The method of claim 1 in which selected ones of the specific tones are modulated at a frequency lower than a low-frequency cut-off of a receiver coupled to receive the signal.
Claim 20
Independent Claim
133 words
A method for monitoring the performance of an amplifier having an input port and an output port and amplifying a wavelength division multiplexed signal having a plurality of optical channels, the method comprising the steps of: detecting, at the output port of the amplifier, levels of individual ones of tones of different frequencies modulated upon respective ones of the plurality of channels of the wavelength division multiplexed signal; summing each of said levels to determine a total signal level at the output of said amplifier; detecting an output level of the amplifier and determining a noise level for said amplifier as a function of said sum and the output level of the amplifier; and determining a signal-to-noise ratio of each said optical channels as a function of said levels and said noise level.
Claim 21
Independent Claim
133 words
A method for monitoring the performance of an amplifier having an input port and an output port and amplifying a wavelength division multiplexed signal having a plurality of optical channels, the method comprising the steps of: detecting, at the output port of the amplifier, levels of individual ones of tones of different frequencies modulated upon respective ones of the plurality of channels of the wavelength division multiplexed signal; summing each of said levels to determine a total signal level at the output of said amplifier; detecting an output level of the amplifier and determining a noise level for said amplifier as a function of said sum and the output level of the amplifier; and determining a signal-to-noise ratio of each said optical channels as a function of said levels and said noise level.
Claim 22
Dependent Claim
38 words
A method for monitoring the performance of a transmission system including a plurality of amplifiers comprising the step of: employing the method of performance monitoring as defined in claim 31 for predetermined ones of the plurality of amplifiers.
Claim 23
Dependent Claim
30 words
The method of claim 20 in which the tone is modulated at a frequency lower than a low-frequency cut-off of a receiver coupled to receive the wavelength division multiplexed signal.
Claim 24
Dependent Claim
24 words
The method of claim 20 in which the modulating is performed by frequency modulating each of the channels of the wavelength division multiplexed signal.
Claim 25
Dependent Claim
24 words
The method of claim 20 in which the modulating is performed by amplitude modulating each of the channels of the wavelength division multiplexed signal.
Claim 26
Dependent Claim
24 words
The method of claim 20 in which the modulating is performed by polarization modulating each of the channels of the wavelength division multiplexed signal.
Claim 27
Dependent Claim
31 words
The method of claim 20 in which the wavelength division multiplexed signal is modulated to carry information, the modulation being independent of, and in addition to, the modulating with the tones.
Claim 28
Dependent Claim
27 words
The method of claim 19 in which the step of comparing includes comparing a power level of selected specific tones to a power level of the amplifier.
Claim 29
Independent Claim
116 words
A method for monitoring performance of an optical transmission system including a plurality of amplifiers arranged in stages, each of the plurality of amplifiers having an input port and an output port, the method comprising the steps of: modulating a signal transmitted on the transmission system with a tone; monitoring a level of the tone at predetermined amplifiers in the stages of amplification, whereas said monitoring is performed at the output port of the predetermined amplifiers; monitoring an output level of selected ones of the predetermined amplifiers; and determining a signal-to-noise ratio for each of the selected ones of the predetermined optical amplifiers as a function of the respective level of tone and respective output level.
Claim 30
Independent Claim
116 words
A method for monitoring performance of an optical transmission system including a plurality of amplifiers arranged in stages, each of the plurality of amplifiers having an input port and an output port, the method comprising the steps of: modulating a signal transmitted on the transmission system with a tone; monitoring a level of the tone at predetermined amplifiers in the stages of amplification, whereas said monitoring is performed at the output port of the predetermined amplifiers; monitoring an output level of selected ones of the predetermined amplifiers; and determining a signal-to-noise ratio for each of the selected ones of the predetermined optical amplifiers as a function of the respective level of tone and respective output level.
Claim 31
Dependent Claim
33 words
The method as claimed in claim 27 in which the signal is an wavelength division multiplexed optical signal having a plurality of channels, each of the channels being modulated with a specific tone.
Claim 32
Dependent Claim
34 words
The method of claim 28 in which selected ones of the specific tones are modulated at a frequency lower than a low-frequency cut-off of a receiver coupled to receive the wavelength-division multiplexed optical signal.
Claim 33
Dependent Claim
26 words
The method of claim 28 in which the modulating is performed by frequency modulating selected ones of the channels of the wavelength division multiplexed optical signal.
Claim 34
Dependent Claim
26 words
The method of claim 28 in which the modulating is performed by amplitude modulating selected ones of the channels of the wavelength division multiplexed optical signal.
Claim 35
Dependent Claim
26 words
The method of claim 28 in which the modulating is performed by polarization modulating selected ones of the channels of the wavelength division multiplexed optical signal.
Claim 36
Dependent Claim
32 words
The method of claim 28 in which the wavelength division multiplexed signal is modulated to carry information, the information modulation being independent of, and in addition to, the modulation with the tones.
Claim 37
Dependent Claim
15 words
The method as claimed in claim 27 in which the amplifier is an optical amplifier.
Claim 38
Dependent Claim
17 words
The method as claimed in claim 34 in which the optical amplifier is an erbium-doped fiber amplifier.
References Cited (Backward Citations)
US5313657A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-04 | 2001-02-03 | 2001-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-04 | 2005-02-03 | 2005-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-04 | 2009-02-03 | 2009-08-05 | $7700.00 | Window Closed / Lapsed |