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Telecommunications Industry Association TR41.3.9-09-02-006-L. Investigation of TIA-1083-A Digital Signal Input Level. 2009.1.21 Panasonic Corporation Co., Ltd. Panasonic’s Analysis of Digital Signal Input Level.
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Telecommunications Industry Association TR41.3.9-09-02-006-L
Investigation of TIA-1083-A Digital Signal Input Level 2009.1.21 Panasonic Corporation Co., Ltd
Panasonic’s Analysis of Digital Signal Input Level • Panasonic has investigated this new requirement from perspective that digital telephone output Level is equivalent to the Analog telephone output Level • Panasonic still thinks that 3dB difference is not enough from our experience • Following table is a summary of Panasonic’s proposal with analysis following: [Conclusion] The digital signal input level for digital telephone should be -7.5dBV, instead of the current -15dBV. (10.5dB higher than PSTN input level)
New Requirement Overview (TR41.3.9) The Signal Input Level for Digital Telephone is -15dBV (3dB higher than PSTN input level) [The Back Ground to lead this value] (1)RLR Requirement Difference between PSTN (according to TIA-470C) and VoIP (according to TIA-810B) (2)Signal Level conversion factor from RLR value between PSTN and VoIP (3)Actual Input level in HAC simulator
Panasonic’s Opinion of current new requirement • There are three (3) reasons that TR41.3.9 decides HAC input level of digital telephone: • (1) RLR Requirement Difference between PSTN (according to TIA-470C) and VoIP (according to TIA-810B) • (2) Signal level conversion factor from RLR value between PSTN and VoIP • (3) Actual Input Level in HAC simulator • Panasonic agrees with above reasons: (2) and (3) • But Panasonic thinks above reason (1) does not meet actual situation • The reason is explained from the next slide
Actual Output Level for PSTN Telephone PSTN telephone output level has been decided from the following requirement in Part 68 This table is equivalent to TIA-470C table8 • Panasonic thinks the “volume setting” of a normal unamplified level is the minimum position • The gain between max position and min position is 15dB (12-18dB) • Ideal gain setting is • min RLR = -3dB @2.7km • mid RLR = -10.5dB @2.7km • max RLR = -18dB @2.7km • (When number of volume setting is 3)
Actual Output Level for VoIP Telephone PSTN telephone output level have been decided following requirement in TIA-810 • Panasonic thinks the “Nominal Volume Control setting” is the medium volume position • (for example “volume 2 of 3 steps volume setting” or “volume 2 of 4 steps volume setting” Assuming that VoIP have 3 step volume control setting See Annex: RLR values of IP and PSTN telephones in the market • Ideal gain setting is • min RLR = +9.5dB • mid RLR = +2dB • max RLR = -5.5dB
Conclusion • RLR = -3dB@2.7km for PSTN(accoridng to TIA-470C) is when volume is set to minimum position. • RLR = 2dB for IP(according to TIA-810B) is when volume is set to medium position. • assuming that just half level between VOL=HI and VOL = Low • RLR difference is 12.5dB(VOIP mid RLR = +2dB, PSTN mid RLR@2.7km = -10.5dB.) • The difference input Level is 10.5dB from impedance correlation point of view HAC input level for Digital telephone is -7.5dBV (-18dBV + 10.5dB = -7.5dBV)
Annex: RLR values of IP and PSTN telephones in the market • We researched the actual RLR values of several IP and PSTN telephones in the market to verify our analysis: • Panasonic thinks the “volume setting of normal unamplified” level is the minimum position • Panasonic thinks the “Nominal Volume Control setting” is the medium position.
Annex: RLR values of IP and PSTN telephones in the market PSTN IP • Based on this market trend, we believe; • “Volume setting of normal unamplified level” is Minimum volume position • “Nominal Volume Control setting” is Medium volume position