Telecommunications Industry Association
TR41.3.3-09-10-008-M
Document Cover Sheet
Project Number
PN-3-4705.110-RV1
Document Title
Automatic Level Enhancement section to Receive Assistive Features proposal.
Source
Texas Instruments Inc.
Contact
Distribution
Intended
Purpose of
Document
(Select one)
Name:
Warren Karapetian
Phone:
301-407-9307
Complete
Address:
20450 Century Blvd.
Germantown, MD. 20874
Fax:
301-515-7954
Email:
wkarapetian@ti.com
TR-41.3.3
X
For Incorporation Into TIA Publication
For Information
Other (describe) -
The document to which this cover statement is attached is submitted to a Formulating Group or
sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the
provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of
which provisions are hereby incorporated by reference.
The following contribution is adding a the Automatic Level Enhancement function (see section 1.1.1.5) to Mr.
Don McKinnon’s contribution discussed on 08-10-2009 web echo meeting (see the original document listed
below).
TR41.3.3-09-10-006-ReceiveAssistiveFeatures,dmckinnon,AST.doc
To simplify editorial efforts, the original text submitted by Mr. McKinnon’s (AST Technology Labs. Inc.) has
been preserved and the new section added for ALE function is highlighted in BLUE.
Abstract
The current TIA handset acoustics documents, TIA-470.110-C, TIA-810-B and TIA920.110-A draft do not contain any specifics regarding features other than volume
control for hard of hearing people. The upcoming TIA-470.110-D revision in TR41.3.5
will be addressing additional receive enhanced features.
This contribution is provided as a proposal to TR41.3.3 and TR41.3.5 to establish
continuity for such receive enhanced requirements. The section may be a part of the
technical body or a normative annex.
Telecommunications Industry Association
TR41.3.3-09-10-008
Table of Contents
1.1.
RECEIVE ASSISTIVE FEATURES........................................................................................ 2
1.1.1. Handset Receive Volume Control (VC) ....................................................................... 2
1.1.2. Handset Amplified Receive Gain Levels ...................................................................... 3
1.1.3. Handset Receive Tone Control ..................................................................................... 3
1.1.4. Handset Receive Automatic Gain Control (AGC) ........................................................ 3
1.1.5. Handset Receive Automatic Level Enhancement (ALE) ............................................. 3
1.1.6. Handset Receive Maximum Output .............................................................................. 3
1.1.7. Magnetic Field for Hearing Aid Coupling .................................................................... 3
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Telecommunications Industry Association
TR41.3.3-09-10-008
Note, the following section can be part of the technical requirements or be a normative annex.
It was agreed in principle during the August TR41.3.5 living list review that a normative annex
would be acceptable for FCC to reference.
1.1.
Receive Assistive Features
The Americans with Disabilities Act requires telephone with amplified handsets. Other receive
features may be available on CPE such as additional amplification, tone control, automatic gain
control, etc.
1.1.1.
1.1.1.1.
Handset Receive Volume Control (VC)
General
The regulatory volume control requirements are specified in 47 CFR Part 68.317. The wideband
RLR measurements in this document use the HATS (Head and Torso Simulator) while the current 47
CFR Part 68.317 references narrowband ROLR measurements in ANSI/EIA/TIA-579-1991, which
specifies the Type 1 ear (ITU-T Recommendation P.57). TSB-31-C-1 contains the test procedures
for 47 CFR Part 68.317 and specifies HATS testing using the high leak condition when handsets do
not seal on the Type 1 ear.
1.1.1.2.
Requirement
1. With the receiver at the high leak position the RLR at the maximum volume control setting shall
be at least 12 dB louder than the RLR at the Reference Volume Control Setting (see definitions
clause 3.1.12), or the manufacturer defined reference volume setting (also measured at the high
leak position).
2. If the RLR at the maximum volume control setting is more than 18 dB louder than the RLR at the
Reference Volume Control Setting or the manufacturer’s defined reference volume setting, then
the CPE shall automatically reset to either the Nominal Volume Control Setting, Reference
Volume Control Setting, or the manufacturer’s defined reference volume setting, after ending the
call.
3. To ensure that there is no significant clipping, the receive signal to total distortion and noise
ratio:
a. Shall be Greater than 20 dB with a 800 Hz, -16 dBm0 input at the Reference Volume +12
dB Control Setting.
b. Should be greater than 20 dB with a 800 Hz, -16 dBm0 input at the maximum volume
control setting if the maximum volume control is not the Reference Volume +12 dB Control
Setting.
1.1.1.3.
Measurement Method
1. The RLR is be calculated from the receive frequency response measured with the receiver at the
high leak position. The measurement is performed with the volume control at either the
Reference Volume Control Setting or the manufacturer’s defined reference volume setting, the
Reference Volume +12 dB Control Setting, and the maximum volume setting. Use Equation A-2
of Annex A and bands 1 to 20 of Table A.1.
2. Measure the receive distortion and noise (see clause 5.2.6) with a 1004 Hz sine wave at -16
dBm0 input at the Reference Volume +12 dB Control Setting (see definitions clause 3.1.13).
Repeat at the maximum volume control setting.
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Telecommunications Industry Association
1.1.2.
TR41.3.3-09-10-008
Handset Amplified Receive Gain Levels
This standard does not contain the requirements for receive sound pressure level amplified gain
performance. This issue may be considered for a future revision.
1.1.3.
Handset Receive Tone Control
This standard does not contain the requirements for receive tone control performance. This issue
may be considered for a future revision.
If a CPE with tone controls is to be tested, the default position(s) shall meet the frequency response
requirements of this standard.
1.1.4.
Handset Receive Automatic Gain Control (AGC)
This standard does not contain requirements for receive AGC performance. This issue may be
considered for a future revision.
If a CPE with receive signal AGC is to be tested, subjective testing should be performed to verify
there are no undesirable effects from the AGC processing.
1.1.5.
Handset Receive Automatic Level Enhancement (ALE)
This standard does not contain requirements for receive ALE performance. This issue may be
considered for a future revision.
Brief ALE functionality description
1. ALE boosts the received signal in the RECEIVE direction (toward the handset) if high noise
is observed coming from the SEND direction (in noisy environments).
2. ALE is applicable only in the RECEIVE direction (toward the handset)
3. Boost is be applied to target depending on noise level coming from the mobile:
4. For examples:
If the SEND noise level is > -30 dBm0, a 9 dB boost in the RECEIVE direction
If the SEND noise level is > -33 dBm0, a 6 dB boost in the RECEIVE direction
If the SEND noise level is > -36 dBm0, a 3 dB boost in the RECEIVE direction
If a CPE with receive signal ALE is to be tested, subjective testing using various ambient noise levels
and various noise types should be performed to verify there are no undesirable effects from the ALE
processing.
1.1.6.
Handset Receive Maximum Output
This standard does not contain the requirements for receive Maximum Output performance. This
issue may be considered for a future revision.
NOTE:
UL/CSA 60950 contains requirements for long duration and short duration
maximum acoustic pressure.
1.1.7.
Magnetic Field for Hearing Aid Coupling
1. This standard does not contain requirements for Magnetic Field for Hearing Aid Coupling. The
current regulatory hearing aid compatibility magnetic output requirements are specified in 47
CFR Part 68.316.
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Telecommunications Industry Association
TR41.3.3-09-10-008
NOTE:
Part 68.316 does not provide suitable references for testing Digital Telephones.
Suitable test procedures are currently in TSB-31-C-1, Part 68 Rationale and
Measurement Guidelines.
2. An additional criterion is provided in TIA-1083-A for ensuring that a handset does not create
undesired magnetic noise that results in interference to hearing aid coupling.
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