Telecommunications Industry Association TR41.3.5-09-11-006-L Document Cover Sheet Project Number PN-3-4705.110-RV4 Document Title Receive Assistive Features proposal Source AST Technology Labs. Inc Contact Distribution Intended Purpose of Document (Select one) Name: Don McKinnon Phone: 321-473-6950 Complete Address: 1430 Sarno Rd Melbourne, FL 32935 Fax: 321-254-9511 Email: dmckinnon@asttechlabs.com TR-41.3.5 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. 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 TIA-470.110-D revision will be addressing the addition of receive enhanced features. This contribution was originally submitted to TR41.3.3 in August 2009 and is provided as a proposal to TR41.3.5 for a possible receive enhanced section(s). Receive Automatic Level Enhancement (ALE) was added per a contribution from Warren Karapetian of TI. Telecommunications Industry Association TR41.3.5-09-11-006-L 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 i Telecommunications Industry Association TR41.3.5-09-11-006-L 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 for Receive Volume Control. 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 1000 Hz, -16 dBm0 input at the Reference Volume +12 dB Control Setting. b. Should be greater than 20 dB with a 1000 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. 2 Telecommunications Industry Association 1.1.2. TR41.3.5-09-11-006-L Handset Amplified Receive Gain Levels Note, if a CPE with amplified receive gain is to be tested, the send loudness should be tested for verification of loudness (level) changes. 1.1.3. Handset Receive Tone Control Note, 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) Note, 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) ALE functionality description 1. ALE is applicable only in the Receive direction (toward the handset) 2. 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). 3. For example: a. If the SEND noise level is > -30 dBm0, a 9 dB boost in the RECEIVE direction b. If the SEND noise level is > -33 dBm0, a 6 dB boost in the RECEIVE direction c. If the SEND noise level is > -36 dBm0, a 3 dB boost in the RECEIVE direction Note, 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 NOTE: 1.1.7. UL/CSA 60950 contains requirements for long duration and short duration maximum acoustic pressure. 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. 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. 3