US 2006/0067686 A1Published application

Preemphasis of an optical wavelength multiplex signal

AssigneeSiemens Aktiengesellschaft

InventorsErich Gottwald, Lutz Rapp

Life of this patent

Estimating the term…

Loading patent…

Abstract

Methods are described for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, which are transmitted by a transmitter to a receiver. Power levels for the signals are set at the transmitter and measured at the receiver. A mean power level for the transmit-side signals is ascertained. New signal power level values are ascertained from the current power levels of the signals at the transmitter and at the receiver and set on the transmit side such that signal-to-noise ratios for all signal are approximately equalized at the receiver. In order to make more precise settings for the preemphasis, mean gain values and mean attenuations are ascertained from the sum power levels for the multiplex signal measured at the input and at the output of each amplification section and incorporated together with an effective noise figure into the process of ascertaining the new signal power level values. The preemphasis is thus performed autonomously without there being any need for further planning resources for control purposes.

Claims16

Dependent claims

A method for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, which are transmitted by a transmitter by way of a large number of approximately identical amplification sections to a receiver, the method comprising the following steps:

determining on the transmit side a mean power level (<P_Tx(λ)Beginn>) and an optical power level spectrum (P_Tx(λ)Beginn) for the optical multiplex signal;
determining on the receive side an optical power level spectrum (P_Rx(λ)Beginn) for the optical multiplex signal;
the sum power levels for the multiplex signal are determined at the input to and output from each amplification section and mean gain values (<Gi(λ)>) and mean attenuations (<ai(λ)>) are determined for each amplification section from the measured values for the sum power levels of the multiplex signal;
a gain function (Glink(λ)) which characterizes the overall gain of the transmission path is calculated from the relationship between optical power level spectra (P_Tx(λ)Beginn, P_Rx(λ)Beginn) determined on the transmit side and the receive side;
using the values <Gi(λ)> and <ai(λ)>, a wavelength-dependent function (Q(λ)) is calculated according to the specification
Q
⁡
(
λ
)
=
∑
i
=
0
N
⁢
G
link
-
i
/
(
N
+
1
)
⁡
(
λ
)
·
〈
G
i
⁡
(
λ
)
〉
·
∏
j
=
i
+
1
N
⁢
〈
G
j
⁡
(
λ
)
〉
·
〈
a
j
⁡
(
λ
)
〉
which serves to correct the new signal power level values (P_Tx(λ)) to be set on the transmit side, and where j represents an auxiliary variable;
and
using the correction function Q(λ) and an effective noise figure (Feff(λ)) the new signal power level values (P_Tx(λ)) to be set on the transmit side are calculated according to the formula
P_Tx
⁢
(
λ
)
=
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〈
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〉
·
〈
P_Tx
⁢
(
λ
)
Beginn
〉
so that signal-to-noise ratios for all signals of the multiplex signal can be matched to one another at the receiver, wherein the angle brackets always represent a mean value for the value entered within them.

108 more elements

ascertaining on the transmit side a mean power level (<P_Tx(λ)Beginn>) and an optical power level spectrum (P_Tx(λ)Beginn) for the optical multiplex signal;
ascertaining on the receive side an optical power level spectrum (P_Rx(λ)Beginn) for the optical multiplex signal;
the sum power levels for the multiplex signal are ascertained at the input to and output from each amplification section and mean gain values (<Gi(λ)>) and mean attenuations (<ai(λ)>) are ascertained for each amplification section from the measured values for the sum power levels of the multiplex signal;
a gain function (Glink(λ)) which characterizes the overall gain of the transmission path is calculated from the relationship between optical power level spectra (P_Tx(λ)Beginn, P_Rx(λ)Beginn) ascertained on the transmit side and the receive side;
a relative code number (ki) which characterizes the difference between the gain value (Gi(λ)) and the mean value (<Gi(λ)>) for each amplification section i is ascertained for each optical amplifier;
using the relative code numbers (ki), a wavelength-dependent function (Q(λ)) is calculated according to the specification
Q
⁡
(
λ
)
=
∑
i
=
0
N
⁢
G
link
⁡
(
λ
)
-
(
∑
j
=
0
i
-
1
⁢
k
j
)
/
(
∑
j
=
0
N
⁢
k
j
)
·
〈
G
i
⁡
(
λ
)
〉
·
∏
j
=
i
+
1
N
⁢
〈
G
j
⁡
(
λ
)
〉
·
〈
a
j
⁡
(
λ
)
〉
which serves to correct the new signal power level values (P_Tx(λ)) to be set on the transmit side, and wherein j represents an auxiliary variable;
and
using the correction function Q(λ) and an effective noise figure (Feff(λ)), the new signal power level values (P_Tx(λ)) to be set on the transmit side are calculated according to the formula
P_Tx
⁢
(
λ
)
=
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〈
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〉
·
〈
P_Tx
⁢
(
λ
)
Beginn
〉
so that signal-to-noise ratios for all signals of the multiplex signal can be matched to one another at the receiver, wherein the angle brackets always represent a mean value for the value entered within them.

125 more elements

A method for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, which are transmitted by a transmitter by way of a large number of different amplification sections (i=0, 1, 2, . . . N) having amplifiers with known gain factors Gi(λ)=gityp(λ)·<G0(λ)>, ∀i=1, 2, . . . , N to a receiver, the method comprising the following steps:

ascertaining on the transmit side a mean power level (<P_Tx(λ)Beginn>) and an optical power level spectrum (P_Tx(λ)Beginn) for the optical multiplex signal;
ascertaining on the receive side an optical power level spectrum (P_Rx(λ)Beginn) for the optical multiplex signal;
the sum power levels for the multiplex signal are ascertained at the input to and output from each amplification section and mean gain values (<Gi(λ)>) and mean attenuations (<ai(λ)>) are ascertained for each amplification section from the measured values for the sum power levels of the multiplex signal;
an overall gain (Gges(λ)) between transmitter and receiver is calculated according the equation
G
ges
⁡
(
λ
)
=
〈
G
0
⁡
(
λ
)
〉
·
[
∏
j
=
1
N
⁢
〈
G
j
⁡
(
λ
)
〉
·
〈
a
j
⁡
(
λ
)
〉
]
·
∏
i
=
0
N
⁢
(
g
i
typ
)
m
i
wherein (mi) is chosen as an exponent of gain factors (gjtyp(λ)) such that characteristic differences between the overall gain (Gges(λ)) and the measured gain (Glink(λ)) are minimized and wherein (G0(λ)) is the mean gain of the first amplifier on the transmit side;
a wavelength-dependent function (Q(λ)) is calculated according to the specification
Q
⁡
(
λ
)
=
∑
i
=
0
N
⁢
⁣
〈
G
i
⁡
(
λ
)
〉
·
[
∏
j
=
i
+
1
N
⁢
〈
G
j
⁡
(
λ
)
〉
·
〈
a
j
⁡
(
λ
)
〉
]
·
∏
j
=
i
N
⁢
(
g
j
typ
)
m
j
∏
i
=
0
N
⁢
(
g
i
typ
)
m
i
,
which serves to correct the new signal power level values (P_Tx(λ)) to be set on the transmit side, and where j represents an auxiliary variable;
and
using the correction function Q(λ) and an effective noise figure (Feff(λ)), the new signal power level values (P_Tx(λ)) to be set on the transmit side are calculated according to the formula
P_Tx
⁢
(
λ
)
=
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〈
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〉
·
〈
P_Tx
⁢
(
λ
)
Beginn
〉
so that signal-to-noise ratios for all signals of the multiplex signal can be matched to one another at the receiver, wherein the angle brackets always represent a mean value for the value entered within them.

180 more elements

A method for preemphasizing an optical multiplex signal comprising a plurality of signals having different wavelengths, which are transmitted by a transmitter by way of a large number of amplification sections (i=0, 1, 2, . . . N) to a receiver, and the partial transmission function g(λ)k:m is known for a group of 1<m−k+1<N of the N amplification sections, the method comprising the following steps:

ascertaining on the transmit side a mean power level (<P_Tx(λ)Beginn>) and an optical power level spectrum (P_Tx(λ)Beginn) for the optical multiplex signal;
ascertaining on the receive side an optical power level spectrum (P_Rx(λ)Beginn) for the optical multiplex signal;
the sum power levels for the multiplex signal are ascertained at the input to and output from each amplification section and mean gain values (>Gi(λ)>) and mean attenuations (<ai(λ)>) are ascertained for each amplification section from the measured values for the sum power levels of the multiplex signal;
a partial transmission function
g
⁡
(
λ
)
k
:
m
=
∏
j
=
k
m
⁢
G
j
⁡
(
λ
)
·
a
j
⁡
(
λ
)
defined for the group of 1<m−k+1<N of the N amplification sections and the assumption is made that the gain or form factors gj(λ) of the gain profile are the same for all amplification sections jε[k:m] of the partial path and are calculated in accordance with
g(λ)j=g(λ)k:m1/(m−k+1)
where j, k and m are auxiliary variables;
a wavelength-dependent function (Q(λ)) is calculated, taking Gj(λ)=g(λ)j·<Gj(λ)>∀jε[k:m] into consideration, according to the specification
Q
⁡
(
λ
)
=
∑
i
=
0
N
⁢
∏
l
=
0
i
⁢
G
l
-
1
⁡
(
λ
)
·
〈
G
i
⁡
(
λ
)
〉
·
∏
j
=
i
+
1
N
⁢
〈
G
j
⁡
(
λ
)
〉
·
〈
a
j
⁡
(
λ
)
〉
,
which serves to correct the new signal power level values (P_Tx(λ)) to be set on the transmit side, and where 1 represents an auxiliary variable;
and
using the correction function Q(λ) and an effective noise figure (Feff(λ), the new signal power level values (P_Tx(λ)) to be set on the transmit side are calculated according to the formula
P_Tx
⁢
(
λ
)
=
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〈
Q
⁡
(
λ
)
·
F
eff
⁡
(
λ
)
〉
·
〈
P_Tx
⁢
(
λ
)
Beginn
〉
so that signal-to-noise ratios for all signals of the multiplex signal can be matched to one another at the receiver, wherein the angle brackets always represent a mean value for the value entered within them.

140 more elements

Dependencies are inferred from the claim text.