IEC TR 61292-3:2020

Optical amplifiers - Part 3: Classification, characteristics and applications

IEC TR 61292-3:2020 which is a Technical Report, establishes the classification of optical amplifiers (OAs). It also includes a brief description of each amplifier, its general properties, performance, configurations and applications. This second edition cancels and replaces the first edition published in 2003. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:  
document architecture now focuses on EDFA, FRA and SOA;
the description of PDFA and TDFA has been moved to the annexes;
the EDWA description has been deleted;
information on single channel amplification, multi-channel amplification, configuration and control method for EDFA, FRA and SOA has been added;
information on future amplifiers, arrayed amplifiers and SDM amplifiers has been added.

General Information

• Status: Published
• Publication Date: 24-Mar-2020
• ICS: 33.160.10 - Amplifiers
• ICS: 33.180.30 - Optic amplifiers
• Technical Committee: SC 86C - Fibre optic systems, sensing and active devices
• Drafting Committee: WG 3 - TC 86/SC 86C/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 25-Mar-2020
• Completion Date: 01-Apr-2020

Relations

• Revises: IEC TR 61292-3:2003 - Optical amplifiers - Part 3: Classification, characteristics and applications
• Effective Date: 05-Sep-2023

Overview

IEC TR 61292-3:2020 - Optical amplifiers: Part 3: Classification, characteristics and applications is a Technical Report from the International Electrotechnical Commission (IEC) that establishes a clear classification and descriptive framework for optical amplifiers (OAs). This second edition (2020) updates the 2003 edition and focuses on the most widely used amplifier types - EDFA (erbium-doped fibre amplifiers), FRA (fibre Raman amplifiers) and SOA (semiconductor optical amplifiers) - while moving rarer types (PDFA, TDFA) to annexes and removing EDWA. The report describes each amplifier’s general properties, performance, typical configurations and applications, and adds material on single‑channel vs. multi‑channel operation, control schemes, arrayed amplifiers and future SDM (space division multiplexing) amplifiers.

Key Topics and Technical Highlights

• Classification of optical amplifiers: taxonomy by gain medium, amplification form and application role.
• Amplification forms: lumped (discrete) vs. distributed amplification; single‑channel vs. multichannel; fixed vs. variable gain.
• Detailed profiles for EDFA, FRA and SOA:
  • General properties and operational principles
  • Typical performance characteristics (noise, gain behaviour, ASE considerations)
  • Pumping and configuration options (including remote optically pumped amplifiers, ROPA)
  • Control schemes and product configurations (gain control, level control, multi‑stage arrangements)
• Advanced and future amplifier topics:
  • Arrayed amplifiers (parallel arrangements of SOAs/EDFAs)
  • SDM amplifiers (multi‑core and few‑mode EDFAs)
  • Annex coverage for PDFA and TDFA
• Informative content: figures and terminology clarifying energy levels, pump configurations, ROADM and network integration.

Note: IEC TR 61292-3 is a technical report (informative), synthesizing state‑of‑the‑art descriptions rather than setting prescriptive normative requirements.

Practical Applications and Who Uses This Standard

IEC TR 61292-3 is useful to professionals involved in optical communications and photonics, including:

• Network architects and system designers selecting and deploying amplification solutions for WDM, long‑haul, metro and ROADM networks.
• Equipment manufacturers developing EDFA, FRA, SOA modules, ROPA subsystems, arrayed and SDM amplifiers.
• System integrators and operators assessing amplifier configurations, gain control strategies and network planning trade‑offs (OSNR, noise figure, multichannel performance).
• Test laboratories and researchers needing a consolidated reference on amplifier types, characteristics and future developments.

Related Standards

• IEC 61291-1 - Optical amplifiers: Generic specification
• IEC TR 61931 - Fibre optic terminology
• IEC 60050-731 - Electropedia vocabulary for optical fibre communication

This IEC TR is an authoritative, SEO‑relevant resource for anyone researching “optical amplifiers,” “EDFA vs FRA vs SOA,” “amplifier classification,” “SDM amplifiers” and practical amplifier selection for optical networks.

Standards Content (Sample)

IEC TR 61292-3 ®
Edition 2.0 2020-03
TECHNICAL
REPORT
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Optical amplifiers –
Part 3: Classification, characteristics and applications
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IEC TR 61292-3 ®
Edition 2.0 2020-03
TECHNICAL
REPORT
colour
inside
Optical amplifiers –
Part 3: Classification, characteristics and applications

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.160.10; 33.180.30 ISBN 978-2-8322-8014-0

– 2 – IEC TR 61292-3:2020 © IEC:2020
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 7
4 Classification . 8
4.1 Types of OA . 8
4.2 Amplification forms . 10
4.2.1 Lumped (or discrete) amplification and distributed amplification . 10
4.2.2 Single channel and multichannel amplification . 10
4.2.3 Fixed and variable gain amplification . 10
4.3 Application of optical amplifiers . 11
5 General properties, performance and configurations . 12
5.1 Erbium-doped fibre amplifiers (EDFAs) . 12
5.1.1 General properties . 12
5.1.2 Typical performance . 13
5.1.3 Configurations . 14
5.1.4 Control scheme . 16
5.1.5 Product configurations and application . 17
5.2 Fibre Raman amplifiers (FRAs) . 18
5.2.1 General properties . 18
5.2.2 Typical performance . 19
5.2.3 Configuration . 20
5.2.4 Control scheme . 20
5.2.5 Product configurations and application . 20
5.3 Semiconductor amplifiers (SOAs). 20
5.3.1 General properties . 20
5.3.2 Typical performance . 21
5.3.3 Configurations . 21
5.3.4 Product configurations and applications . 22
Annex A (informative) Other rare earth-doped fibre amplifiers . 23
A.1 General . 23
A.2 Praseodymium-doped fibre amplifier (PDFA) . 23
A.3 Thulium-doped fibre amplifier (TDFA) . 24
Annex B (informative) SDM amplifiers . 26
Bibliography . 27

Figure 1 – Classification of optical amplifiers . 9
Figure 2 – Amplification bandwidth of each type of amplifier . 10
Figure 3 – Application forms of optical amplifiers in an optical transmission system . 11
Figure 4 – Application forms of optical amplifiers in optical network (ROADM with
colourless, directionless and contention-less function and arrayed amplifier) . 12
Figure 5 – Abridged and primary energy levels for erbium ion . 13
Figure 6 – Pumping configurations of optical fibre amplifier . 14

Figure 7 – Core and cladding pumping configurations . 15
Figure 8 – Configuration of ROPA . 15
Figure 9 – Single stage and double stage configurations . 16
Figure 10 – Control schemes of EDFA . 17
Figure 11 – Product configurations . 18
Figure A.1 – Abridged and primary energy levels for praseodymium ion . 23
Figure A.2 – Abridged and primary energy levels for thulium ion . 25
Figure B.1 – Space division multiplexing amplifiers . 26

– 4 – IEC TR 61292-3:2020 © IEC:2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL AMPLIFIERS –
Part 3: Classification, characteristics and applications

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61292-3, which is a technical report, has been prepared by subcommittee 86C: Fibre
optic systems and active devices, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2003. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) document architecture now focuses on EDFA, FRA and SOA;
b) the description of PDFA and TDFA has been moved to the annexes;
c) the EDWA description has been deleted;

d) information on single channel amplification, multi-channel amplification, configuration and
control method for EDFA, FRA and SOA has been added;
e) information on future amplifiers, arrayed amplifiers and SDM amplifiers has been added.
The text of this document is based on the following documents:
Draft TR Report on voting
86C/1597/DTR 86C/1630/RVDTR
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61292 series, published under the general title Optical amplifiers,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC TR 61292-3:2020 © IEC:2020
OPTICAL AMPLIFIERS –
Part 3: Classification, characteristics and applications

1 Scope
This part of IEC 61292, which is a Technical Report, establishes the classification of optical
amplifiers (OAs). It also includes a brief description of each amplifier, its general properties,
performance, configurations and applications.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-731, International Electrotechnical Vocabulary – Part 731: Optical fibre
communication (available at www.electropedia.org)
IEC 61291-1, Optical amplifiers – Part 1: Generic specification
IEC TR 61931, Fibre optic – Terminology
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-731,
IEC 61291-1, IEC TR 61931, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
erbium-doped fibre amplifier
EDFA
rare earth-doped fibre amplifier, where the core of the fibre is doped with erbium ions
3.1.2
semiconductor optical amplifier
SOA
optical amplifier that uses a semiconductor to provide the gain medium
Note 1 to entry: These amplifiers have a similar structure to Fabry-Pérot laser diodes but with anti-reflection design
elements at the end faces. The signal is amplified through the stimulated emission phenomenon of gain medium.
3.1.3
single channel amplifier
optical amplifier amplifying one signal

3.1.4
multichannel amplifier
optical amplifier amplifying two or more signals whose wavelengths differ
3.1.5
remote optically pumped amplifier
ROPA
optical fibre amplifier in which pumping light(s) is transmitted remotely to active fibre through a
transmission fibre
3.1.6
space division multiplexing amplifier
SDM amplifier
optical fibre amplifier that uses space division multiplexing (SDM) transmission system
Note 1 to entry: There are two types of SDM amplifier: one is a multi-core fibre amplifier, and the other is a few-
mode fibre amplifier.
3.1.7
multi-core erbium-doped fibre amplifier
multi-core EDFA
space division multiplexing EDFA for multi-core transmission
3.1.8
few-mode erbium-doped fibre amplifier
few-mode EDFA
space division multiplexing EDFA for few-mode transmissions
3.1.9
arrayed amplifier
optical amplifier formed by arranging several semiconductor amplifiers and EDFAs in parallel
3.2 Abbreviated terms
ACC automatic current control
AGC automatic gain control
ALC automatic level control
APC automatic power control
ASE amplified spontaneous emission
DRA distributed Raman amplifier
EDF erbium-doped fibre
EDFA erbium-doped fibre amplifier
EDFFA erbium-doped fluoride fibre amplifier
EDSFA erbium-doped silica fibre amplifier (commonly known as EDFA)
EDTFA erbium-doped tellurite fibre amplifier
EDWA erbium-doped waveguide amplifier
EYDFA erbium ytterbium-doped fibre amplifier
EYDSFA erbium ytterbium-doped silica fibre amplifier (commonly known as EYDFA)
FMF few-mode fibre
FRA fibre Raman amplifier
GFF gain flattening filter
LD laser diode
MCF multi-core fibre
– 8 – IEC TR 61292-3:2020 © IEC:2020
MQW multiple quantum well
NF noise figure
OA optical amplifier
OFA optical fibre amplifier
OSNR optical signal-to-noise ratio
OWGA optical waveguide amplifier
PD photo diode
PDFA praseodymium-doped fibre amplifier
PDFFA praseodymium-doped fluoride fibre amplifier (also known as PDFA)
PDG polarization-dependent gain
ROADM reconfigurable optical add/drop multiplexer
ROPA remote optically pumped amplifier
SDM space division multiplexing
SMF single-mode fibre
SOA semiconductor optical amplifier
TEC thermo-electric cooler
TDFA thulium-doped fibre amplifier
TDFFA thulium-doped fluoride fibre amplifier (also known as TDFA)
VOA variable optical attenuator
WDM wavelength division multiplexing
WSS wavelength selective switch
4 Classification
4.1 Types of OA
Figure 1 shows the classification of optical amplifiers. Optical amplifiers (OAs) are classified as
optical fibre amplifiers (OFAs), semiconductor amplifiers (SOAs) and others (e.g. optical wave
guide amplifiers (OWGA) such as Erbium doped waveguide amplifiers (EDWA)). Furthermore,
OFAs are classified as rare earth-doped optical fibre amplifiers and fibre Raman amplifiers
(FRAs), and rare earth-doped optical fibre amplifiers are classified as erbium-doped optical
fibre amplifiers (EDFAs) and rare earth-doped optical fibre amplifiers with alternative dopants.
From these various OAs, the OAs which are practically used are EDFAs, FRAs and SOAs.
General properties, performance and configurations of EDFAs, FRAs and SOAs are described
in Clause 5. OAs are also classified according to amplification form, application, etc., in addition
to those in Figure 1. The various amplification forms and the application of optical amplifiers
are explained in 4.2 and 4.3, respectively.

Figure 1 – Classification of optical amplifiers
Rare earth-doped optical fibre amplifiers other than erbium-doped ones have also been
developed. Various rare earth-doped fibre amplifiers are often expressed as an abbreviation:
X-Y-DFA. "X" indicates the type of rare earth, i.e., E, T, P, and "Y" represent erbium, thulium,
praseodymium, and ytterbium, respectively. "Y" indicates the fibre type, i.e., S, F and T
represent silica fibre, fluoride fibre and tellurite fibre, respectively. So, EDSFA, which is
commonly known as EDFA, EDFFA and EDTFA indicate an erbium-doped silica fibre amplifier,
an erbium-doped fluoride fibre amplifier and an erbium-doped tellurite fibre amplifier,
1 2
respectively. When two kinds of rare earths are added, the notation X -X -Y-DFA is used. For
example, EYSDFA (commonly known as EYDFA) indicates an erbium ytterbium-doped silica
fibre amplifier. Although many rare earth-doped fibres have been developed, EDFA is the rare
earth-doped fibre that is generally commercialized today. In addition, EYDFA is described as
an EDFA that has high output characteristics in this classification. Furthermore, since
praseodymium-doped fluoride fibre amplifiers (PDFFA, also known as PDFA) and thulium-
doped fluoride fibre amplifiers (TDFFA, also known as TDFA) are used in special fields, they
are introduced in Annex A. Furthermore, Annex B introduces SDM amplifiers that have recently
appeared.
Figure 2 shows the amplification bandwidth of each type of amplifier. EDFA is used for
amplification of C-band (amplification bandwidth: approximately 30 nm) and L-band
(amplification bandwidth: approximately 30 nm) optical signals, and it is also applicable to
amplification of a part of the S-band (amplification bandwidth: approximately 20 nm) optical
signal. Rare earth-doped optical fibre amplifiers other than erbium-doped ones can achieve O-
band, S-band and U-band amplification by using praseodymium and thulium as the dopant.
NOTE Spectral bands of O-band, S-band, C-band, L-band and U-band are defined in ITU-T G.Sup39.
FRAs and SOAs can realize amplification in the required band over the whole wavelength region
by selecting the wavelength of the pump source and semiconductor composition. The
amplification bandwidth of FRAs and SOAs is about 100 nm.

– 10 – IEC TR 61292-3:2020 © IEC:2020

Figure 2 – Amplification bandwidth of each type of amplifier
4.2 Amplification forms
4.2.1 Lumped (or discrete) amplification and distributed amplification
In a transmission system, there are two amplification types: lumped (or discrete) amplification,
which performs optical amplification between transmission fibres, and distributed amplification,
which uses the transmission fibre itself as the amplification medium. EDFAs, other rare earth-
doped optical fibre amplifiers and SOAs are applied to the former, and FRAs are used for both
applications. However, an FRA is used as a distributed Raman amplifier (DRA) rather than a
lumped (or discrete) amplifier because of its advantages and drawbacks. In addition,
amplification in which an EDFA and Raman are combined is also applied in the system.
4.2.2 Single channel and multichannel amplification
OAs are classified according to the number of signals to be amplified with a single channel
amplifier and a multichannel amplifier. The single channel amplifier amplifies only one signal,
and the multichannel amplifier amplifies two or more signals whose wavelengths differ (that is,
the WDM signal). EDFAs, other rare earth-doped optical fibre amplifiers and FRAs are applied
as both amplifiers, and SOAs are generally used as single channel amplifiers due to the four
wave-mixing effect.
4.2.3 Fixed and variable gain amplification
Normally, since the gain characteristic of an OA is fixed, it may be called a fixed gain type OA.
However, depending on the application, the OA may change its gain characteristics as
necessary, and it may be called a variable gain type OA. An EDFA that can operate variable
gain functions (this may be called a variable gain EDFA or gain switchable EDFA) can be
achieved by changing EDF length that is used in the EDFA, or by using a multistage
configuration (see 5.1.3.3).
4.3 Application of optical amplifiers
There are three application forms of the lumped amplifier for use in a transmission system:
booster, repeater (sometimes called line amplifier) and preamplifier, as shown in Figure 3 a).
The booster amplifies a transmitted signal that is sent out to a transmission fibre. The repeater
enlarges the signal intensity that became weak by fibre transmission and sends it out to the
next transmission fibre. The preamplifier is installed in front of a receiver and amplifies the
signal that became weak by transmission to a receiving level. When distributing a signal to two
or more receiving points, the power amplifier acts as one of the lumped amplifiers and is
installed in front of a branching point, as shown in Figure 3 b).

a) Booster amplifier, repeater (line) amplifier and preamplifier

b) Power amplifier
Figure 3 – Application forms of optical amplifiers in an optical transmission system
Recently, reconfigurable optical add/drop multiplexer (ROADM) technology for combining
wavelength multiplexing and path management technology and successfully operating the ultra-
high-speed/large-capacity optical network requires colourless, directionless and contention-
less function. Details of ROADM are in IEC TR 62343-6-4.
To realize the function, it is necessary to construct a ROADM using a multi-port wavelength
selective switch (WSS) and a multi-cast switch, as shown in Figure 4.
An arrayed amplifier, which is formed by arranging several semiconductor amplifiers and EDFAs
in parallel, is used for loss compensation of WSS and multicast switches. The performance
specification template of the multicast switch is standardized in IEC 62343-3-4.

– 12 – IEC TR 61292-3:2020 © IEC:2020

Figure 4 – Application forms of optical amplifiers in optical network (ROADM with
colourless, directionless and contention-less function and arrayed amplifier)
5 General properties, performance and configurations
5.1 Erbium-doped fibre amplifiers (EDFAs)
5.1.1 General properties
The concept of the optical fibre amplifier was proposed by Dr Snitzer in 1961. The EDFA
concept was first demonstrated in 1985. Just when conventional un-repeated systems were
approaching their peak performance, a research group at the University of Southampton
showed that optical fibres could exhibit optical gain at wavelengths near 1 550 nm. These fibres
were doped with a rare earth element, erbium, and were activated or pumped with low powers
of visible light. EDFAs have since attracted considerable attention in the field of optical fibre
communications because they conveniently operate in the preferred, i.e. low-loss,
telecommunications spectral window at around 1 550 nm. EDFAs are the most widely used
optical amplifiers today.
An EDFA can be optically pumped at several wavelengths, with optimum performances
achieved at wavelengths of 980 nm and 1 480 nm. They provide gain at wavelengths from
approximately 1 520 nm to 1 625 nm.
In its most basic configuration, a typical EDFA consists of a section of single-mode erbium-
doped fibre, a pump laser, a WDM coupler for combining the signal and the pump power into
the erbium fibre, input and output isolators and tap couplers and control electronics, as
described in IEC TR 61292-1.
There are many energy levels for the erbium ion. However, only a small set of these energy
levels is of interest to optical amplification in telecommunication systems. These include the
ground state and a few of the lowest level states. The higher energy states represent transitions
in the visible and ultra-violet part of the spectrum, and these states are essentially unoccupied
in EDFA applications. Figure 5 shows the abridged energy levels for EDFAs and primary energy
levels used in EDFAs.
Figure 5 – Abridged and primary energy levels for erbium ion
EDFAs have been shown to exhibit low polarization-sensitive gain, immunity to inter-channel
cross-talk, a high saturation output power and low noise close to the quantum limit. EDFAs can
simultaneously amplify weak signals at wavelengths across the operating range of 1 520 nm to
1 625 nm. This operating range varies with amplifier design, but this capability is crucial for
wavelength division multiplexing (WDM). EDFAs provide all optical amplification in the 1 550-
nm region, where silica transmission fibre has its minimum loss. Erbium has excellent
spectroscopic properties, including a radiative decay limited metastable lifetime and
conveniently located auxiliary energy levels. As a result, it has been possible to produce
amplifiers that operate within fractions of a dB of the quantum limits of noise figure and power
conversion efficiency. Erbium-doped fibre amplifiers have made it possible to increase the
capacity of optical transmission systems dramatically while reducing system costs. Capacity
increases are possible because the high output powers afforded by EDFAs can be used to
support a higher number of channels, while their broad bandwidth and slow gain dynamics allow
transparent multichannel operation. A variety of host glasses, dopants and fibre designs
continue to be investigated with the aim of optimizing amplifier characteristics such as pump
efficiency and spectral bandwidth.
5.1.2 Typical performance
EDFAs have been demonstrated to provide about 50 dB or more gain, noise figures a few tenths
of a dB above the quantum limit, output powers of > 1 W, and gain variations of under 0,2 dB
on bandwidths greater than 40 nm by applying gain band flattening technology. Gain, noise
figure, output power, power conversion efficiency and gain variation over the required operating
band constitute the primary optical parameters that describe the performance of an EDFA. The
above parameters, however, tend to require different operating conditions for their respective
optimization. Good noise performance requires a high average inversion, while the best power
conversion efficiency is available at lower inversions in highly saturated amplifiers. High gain
can interfere with noise performance if the backward propagating amplified spontaneous
emission (ASE) begins to significantly deplete the inversion in the front end of the EDFA. Many
gain-flattening techniques reduce noise performance and/or power conversion efficiency.
Commercial systems, however, typically require strong performance on all the essential
parameters, but some amount of compromise is needed to achieve this. Any amplifier design
will still require some trade-off between parameters of interest. The final design decisions
naturally are made in the context of the transmission system in which the amplifier is to be used.

– 14 – IEC TR 61292-3:2020 © IEC:2020
5.1.3 Configurations
5.1.3.1 General
In 5.1.3.2 and 5.1.3.3, the typical pumping method is explained. Furthermore, the multistage
configuration that is used to realize the desired characteristic and the style of business dealings
is described.
5.1.3.2 Pumping method
5.1.3.2.1 Pumping direction
Basic EDFA components are a pump source, an EDF, optical isolators and a WDM coupler. To
realize the EDFAs, how the pumping light is launched into the EDF combining those
components is important. There are three pumping directions: forward pumping, backward
pumping and bidirectional pumping, as shown in Figures 6 a), b) and c). In general, forward
pumping is superior in noise characteristic, and backward pumping is superior in high output
characteristic. Bidirectional pumping can realize both characteristics.

a) Forward pumping
b) Backward pumping
c) Bidirectional pumping
Figure 6 – Pumping configurations of optical fibre amplifier
5.1.3.2.2 Core and c
...