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Countermeasure for echo phenomenon

Countermeasure for echo phenomenon. （ Ver1.3 ：　 17 November 2010 ）. Echo Cancelation Setting. ECHO cancelation setting flow-chart. When you can hear ECHO on your extension …. START. Call Type ?. EXT-CO Call. EXT-DPH Call. EXT-EXT Call. EXT-Conference Call. EXT-TIE Call. 2. 3.

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Countermeasure for echo phenomenon

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  1. Countermeasure for echo phenomenon （Ver1.3 ：　17 November 2010 ）

  2. Echo Cancelation Setting

  3. ECHO cancelation setting flow-chart When you can hear ECHO on your extension….. START Call Type ? EXT-CO Call EXT-DPH Call EXT-EXT Call EXT-Conference Call EXT-TIE Call 2 3 4 1 5 Oh, do you !? I can hear ECHO of my voice ! EXT user PBX Talk pair

  4. ECHO cancelation setting in EXT-EXT call (1/6) 1 EXT-EXT Call You are… DPT, APT, SLT Legacy Extension Your EXT Type ? IP-PT (IP-EXT card) SIP-phone (V-SIPEXT) IP-PT (V-IPEXT) 11 12 13 14 You ECHO !

  5. ECHO cancelation setting in EXT-EXT call (2/6) You are… You DPT, APT, SLT, Legacy Extension ECHO ! IP-PT (IP-EXT card) 11 13 Other party is… DPT, APT, SLT Legacy Extension Other party’s ? IP-PT(IP-EXT card) SIP-phone (V-SIPEXT) IP-PT (V-IPEXT) 111 112 113 114 Oh,!? Other party

  6. ECHO cancelation setting in EXT-EXT call (3/6) You are… You SIP-phone (V-SIPEXT) ECHO ! 12 Other party is… DPT, APT, SLT Legacy Extension Other party’s ? IP-PT(IP-EXT card) IP-PT(V-IPEXT) SIP-phone (V-SIPEXT) 121 123 Can not control Echo ! Oh,!? NOTE!! For the intercom call between V-IPEXT / V-SIPEXT, the voice becomes P2P(peer to peer) communication without using the circuit of PBX main unit. Other party

  7. ECHO cancelation setting in EXT-EXT call (4/6) You are… You IP-PT (V-IPEXT) ECHO ! 14 Other party is… DPT, APT, SLT Legacy Extension Other party’s ? IP-PT(IP-EXT card) IP-PT(V-IPEXT) SIP-phone (V-SIPEXT) 141 143 Can not control Echo ! Oh,!? NOTE!! For the intercom call between V-IPEXT / V-SIPEXT, the voice becomes P2P(peer to peer) communication without using the circuit of PBX main unit. Other party

  8. ECHO cancelation setting in EXT-EXT call (5/6) 114 111 113 112 See Fig.2 See Fig.1 -3dB EXT Card Gain (Up and Down) down V-IPEXT/V-SIPEXT DSP Gain (Down) -3dB EC Gain -3dB Update MPR software TDE v3.0 or later NCP v2.0 or later Voice too low ! Voice too low ! See Fig.5 Volume OK ? Volume OK ? System option reserved (bits) 08-2 Disable Enable OK OK NG NG ECHO OK ? ECHO OK ? OK OK NG ECHO OK ? NOTE!! For EXT-EXT call, ECHO card on OPB3 can not work. Echo is cancelled ! Echo is cancelled ! OK Echo is cancelled ! +3dB EXT Card Gain (Up and Down) Up V-IPEXT/V-SIPEXT DSP Gain (Down) +3dB EC Gain +3dB Echo remains but Better then before

  9. ECHO cancelation setting in EXT-EXT call (6/6) 141 143 121 123 See Fig.2 See Fig.2 V-IPEXT/V-SIPEXT Echo Canceller ability 48m 128m V-IPEXT/V-SIPEXT NLP setting Weak Normal Strong Update MPR software TDE v3.0 or later NCP v2.0 or later Voice chopping ! NG ECHO OK ? Voice quality OK ? System option reserved (bits) 08-2 Disable Enable OK OK NG ECHO OK ? Echo is cancelled ! See Fig.5 OK Echo is cancelled ! Yes NG More NLP ? ECHO OK ? NLP one-step back OK No, MAX ! 111 113 Echo is cancelled !

  10. ECHO cancelation setting in EXT-CO call (1/6) 2 EXT-CO Call You are… DPT, APT, SLT Legacy Extension Your EXT Type ? IP-PT(IP-EXT card) SIP-phone (V-SIPEXT) IP-PT (V-IPEXT) 21 22 23 24 You ECHO !

  11. ECHO cancelation setting in EXT-CO call (2/6) You are… You SIP-phone (V-SIPEXT) ECHO ! 22 LCOT, ISDN Legacy Trunk Trunk type ? V-SIPGW 221 222 Oh,!? Other party

  12. ECHO cancelation setting in EXT-CO call (3/6) You are… You IP-PT (V-IPEXT) ECHO ! 24 LCOT, ISDN Legacy Trunk Trunk type ? V-SIPGW 241 242 Oh,!? Other party

  13. ECHO cancelation setting in EXT-CO call (4/6) 21 23 See Fig.1 See Fig.4 -3dB Trunk Card Gain (Up and Down) down Install OPB3(ECHO) + System Option “Echo Cancel” setting - Extension to Digital (case of ISDN/E1/T1) - Extension to Analog (case of LCOT) Voice too low ! Volume OK ? OK NG ECHO OK ? NG ECHO OK ? Echo remains but Better then before OK Echo is cancelled ! OK Echo is cancelled ! +3dB Trunk Card Gain (Up and Down) Up

  14. ECHO cancelation setting in EXT-CO call (5/6) 241 221 See Fig.2 See Fig.2 V-IPEXT/V-SIPEXT Echo Canceller ability 48m 128m V-IPEXT/V-SIPEXT NLP setting Weak Normal Strong Update MPR software TDE v3.0 or later NCP v2.0 or later Voice chopping ! NG ECHO OK ? Voice quality OK ? System option reserved (bits) 08-2 Disable Enable OK OK NG ECHO OK ? Echo is cancelled ! See Fig.5 OK Echo is cancelled ! Yes NG More NLP ? ECHO OK ? NLP one-step back OK No, MAX ! 21 23 Echo is cancelled !

  15. ECHO cancelation setting in EXT-CO call (6/6) 142 222 See Fig.3 V-SIPGW DSP Gain (Down) -3dB EC Gain -3dB Update MPR software TDE v3.0 or later NCP v2.0 or later Voice too low ! Volume OK ? System option reserved (bits) 08-2 Disable Enable OK NG ECHO OK ? See Fig.5 OK Echo is cancelled ! NOTE!! For V-IPGW/V-SIPGW, ECHO card on OPB3 can not work. NG ECHO OK ? V-SIPGW DSP Gain (Down) +3dB EC Gain +3dB OK Echo is cancelled ! Echo remains but Better then before

  16. ECHO cancelation setting in EXT-TIE call (1/6) 3 EXT-TIE Call You are… DPT, APT, SLT Legacy Extension Your EXT Type ? IP-PT(IP-EXT card) SIP-phone (V-SIPEXT) IP-PT (V-IPEXT) 31 32 33 34 You ECHO !

  17. ECHO cancelation setting in EXT-TIE call (2/6) You are… You DPT, APT, SLT, Legacy Extension ECHO ! IP-PT (IP-EXT card) 31 33 E&M, ISDN Legacy Trunk TIE Trunk ? IPGW cards V-IPGW 311 312 313 Oh,!? Other party

  18. ECHO cancelation setting in EXT-TIE call (3/6) ECHO ! Oh,!? 313 311 See Fig.1 You Other party Network PBX PBX IPGW IPGW See Fig.4 ECHO ECHO -3dB Trunk Card Gain (Up and Down) down No Install OPB3(ECHO) + System Option “Echo Cancel” setting - Extension to Digital (case of ISDN/E1/T1 & IPGW card) - Extension to Analog (case of E&M) Voice too low ! In this adjustment, you must program same way for both side of the network simultaneously !! Volume OK ? OK NG ECHO OK ? OK Echo is cancelled ! NG ECHO OK ? Echo remains but Better then before OK +3dB Trunk Card Gain (Up and Down) Up Echo is cancelled !

  19. ECHO cancelation setting in EXT-TIE call (4/6) ECHO ! Oh,!? See Fig.2 You Other party See Fig.2 Network 312 PBX PBX V-IPGW V-IPGW V-IPGW Echo Canceller ability 48m 128m V-IPGW NLP setting Weak Normal Strong In this adjustment, you must program same way for both side of the network simultaneously !! Voice chopping ! NG ECHO OK ? Voice quality OK ? OK OK NG ECHO OK ? Echo is cancelled ! OK Echo is cancelled ! Yes More NLP ? NLP one-step back No, MAX ! 314

  20. ECHO cancelation setting in EXT-TIE call (5/6) Oh,!? ECHO ! 314 You Other party Network PBX PBX See Fig.2 V-IPGW V-IPGW V-IPGW DSP Gain (Down) -3dB EC Gain -3dB In this adjustment, you must program same way for both side of the network simultaneously !! Voice too low ! Volume OK ? OK NG ECHO OK ? OK Echo is cancelled ! NOTE!! For V-IPGW/V-SIPGW, ECHO card on OPB3 can not work. V-IPGW DSP Gain (Down) +3dB EC Gain +3dB Echo remains but Better then before

  21. ECHO cancelation setting in EXT-TIE call (6/6) ECHO ! You Other party Network PBX PBX See Fig.2 34 32 See Fig.2 V-IPEXT V-IPEXT Oh,!? In this adjustment, you must program same way for both side of the network simultaneously !! V-IPEXT/V-SIPEXT Echo Canceller ability 48m 128m V-IPEXT/V-SIPEXT NLP setting Weak Normal Strong Update MPR software TDE v3.0 or later NCP v2.0 or later Voice chopping ! NG ECHO OK ? Voice quality OK ? System option reserved (bits) 08-2 Disable Enable OK OK NG ECHO OK ? Echo is cancelled ! See Fig.5 OK Echo is cancelled ! Yes NG More NLP ? ECHO OK ? NLP one-step back OK No, MAX ! 31 33 Echo is cancelled !

  22. ECHO cancelation setting in EXT-DPH call (1/3) 4 EXT-DPH Call You are… DPT, APT, SLT Legacy Extension Your EXT Type ? IP-PT(IP-EXT card) SIP-phone (V-SIPEXT) IP-PT (V-IPEXT) 41 42 43 44 You ECHO !

  23. ECHO cancelation setting in EXT-DPH call (2/3) 41 43 See Fig.1 -3dB DPH Card Gain (Up and Down) down Voice too low ! Volume OK ? OK NG ECHO OK ? OK Echo is cancelled ! NOTE!! For DPH card, ECHO card on OPB3 can not work. +3dB DPH Card Gain (Up and Down) Up Echo remains but Better then before

  24. ECHO cancelation setting in EXT-DPH call (3/3) See Fig.2 See Fig.2 44 42 V-IPEXT/V-SIPEXT Echo Canceller ability 48m 128m V-IPEXT/V-SIPEXT NLP setting Weak Normal Strong Update MPR software TDE v3.0 or later NCP v2.0 or later Voice chopping ! NG ECHO OK ? Voice quality OK ? System option reserved (bits) 08-2 Disable Enable OK OK NG ECHO OK ? Echo is cancelled ! See Fig.5 OK Echo is cancelled ! Yes NG More NLP ? ECHO OK ? NLP one-step back OK No, MAX ! 41 43 Echo is cancelled !

  25. ECHO cancelation setting in EXT-Conference call (1/3) 5 EXT-Conference Call You are… DPT, APT, SLT Legacy Extension Your EXT Type ? IP-PT(IP-EXT card) SIP-phone (V-SIPEXT) IP-PT (V-IPEXT) 51 52 53 54 You ECHO !

  26. ECHO cancelation setting in EXT-Conference call (2/3) 51 53 See Fig.4 Install OPB3(ECHO) + System Option “Echo Cancel” setting - Conference NG ECHO OK ? Echo remains but Better then before OK Echo is cancelled !

  27. ECHO cancelation setting in EXT-Conference call (3/3) See Fig.2 See Fig.2 54 52 V-IPEXT/V-SIPEXT Echo Canceller ability 48m 128m V-IPEXT/V-SIPEXT NLP setting Weak Normal Strong Update MPR software TDE v3.0 or later NCP v2.0 or later Voice chopping ! NG ECHO OK ? Voice quality OK ? System option reserved (bits) 08-2 Disable Enable OK OK NG ECHO OK ? Echo is cancelled ! See Fig.5 OK Echo is cancelled ! Yes NG More NLP ? ECHO OK ? NLP one-step back OK No, MAX ! Echo is cancelled ! Echo remains but Better then before

  28. Echo Canceller setting of UPCMC Fig.1 Gain Control Analog(LCOT8/16) card T1 card PRI card IP-GW4/16 card DPH2/4 card IP-GW4 card

  29. Echo Canceller setting of UPCMC Fig.2 DSP Gain (down) and EC gain - Virtual IP Extension - Virtual SIP Extension - Virtual IPGW Echo Canceller Ability - Virtual IP Extension - Virtual SIP Extension - Virtual IPGW NLP Setting - Virtual IP Extension - Virtual SIP Extension - Virtual IPGW

  30. Echo Canceller setting of UPCMC Fig.3 DSP Gain (down) and EC gain - Virtual SIPGW Echo Canceller Ability - Virtual SIPGW NLP Setting - Virtual SIPGW

  31. Echo Canceller setting of UPCMC Fig.4

  32. Echo Canceller setting of UPCMC Fig.5 This reserve bit is effective only on the following MPR software. TDE v3.0 or later NCP v2.0 or later Reserved (bits) 08-2 : Optimization of V-IPEXT built-in echo canceller studying

  33. The mechanism of Echo Canceller

  34. 4 wire 2 wire 4 wire D/A Sx echo H H A/D Rx Echo The cause of Echo and work of Echo canceller (1/4) 1. Cause of echo-1: Hybrid echo by 2wire - 4wire conversion This echo occurs by the mismatch of impedance in hybrid line such as interfaces from 2-wire to 4-wire. A part of the signal of Sx on 4-wire appears on the Rx side and this signal returns as echo.

  35. SP D/A Sx Echo Mic A/D Rx Echo The cause of Echo and work of Echo canceller (2/4) 2. Cause of echo-2: Acoustic echo by speaker & microphone This echo occurs by the sound returning from the speaker to the microphone at the same handset.

  36. Echo canceller Sx Digital Filter echo Y(t) Rx Y(t) Y(t)－Y(t) NLP Echo Echo cancel The cause of Echo and work of Echo canceller (3/4) 3. Theory of Echo canceller Linear adaptive“Digital filter" removes this echo by adding the recorded Sx signal with applying proper delay-time/minus-factor on it. (the best value of these parameters are automatically obtained by the studying activity at the starting of Echo Canceller) But this linear filtering can not remove the actual distorted echo sound completely. So, for the better echo cancellation, Echo Canceller has another block called as NLP (Non-Linear Processing). This block removes the remaining echo by non-Linear mathematical calculation.

  37. The cause of Echo and work of Echo canceller (4/4) 4. Notes of Echo canceller - The echo might remain for a few seconds at beginning of the conversation because there is study (processing) time even if the echo canceller works. - By the side-effect of NLP, the sound can be interrupted (chopped) at the double-talk situation (simultaneous speaking from both parties) if the setting of NLP is too strong.

  38. Echo Canceller devices in TDE/NCP system design. 1) DSPon IPCMPR（TDE/NCP） - This works for suppressing of echo which is caused at virtual IP extension and virtual IP trunk on IPCMPR card. 2) DSP on ECHO Card This works for suppressing of echooccurred by the following pattern. - Echo which is caused atconference call of 6 to 8 parties or CO to CO call. - Echo which is caused at legacy extension and trunk card. 3) DSP on IP-GW/IP-EXT - This works for suppressing of echo which is caused atIP-GW card and IP-EXT card. 4) DSP on IP-PT - This works for suppressing of echo which is caused by using IP-PT. (Note) By call constitution, the plural echo cancellers are used at the same time. For each echo canceller device, we cannot basically expect more effect of echo-canceling than the designing purpose of each echo canceller although the effect may not be 0(zero).

  39. Filter Filter Filter Filter Filter Echo Canceller Type DSP(IPCMPR) Echo Canceller Legacy EXT/CO/Door/Page IPEXT16/IPGW16/ IP V-IPEXT,V-SIPEXT V-IPGW,V-SIPGW PCM ECHO CANCEL IP V-IPEXT,V-SIPEXT V-IPGW,V-SIPGW IP V-IPEXT,V-SIPEXT V-IPGW,V-SIPGW ECHO CANCEL ECHO CANCEL DSP(ECHO) Echo Canceller Legacy EXT/CO/Door/Page IPEXT16/IPGW16/ Legacy EXT/CO/Door/Page IPEXT16/IPGW16/ PCM PCM ECHO CANCEL ECHO CANCEL

  40. Filter Filter Echo Canceller Type DSP(IPEXT/GW) Echo Canceller Legacy EXT/CO/Door/Page IPEXT16/IPGW16/ IP PCM IP-PT,IP-GW ECHO CANCEL DSP(IPPT) Echo Canceller IP Handset IP-PT,V-IPEXT PCM ECHO CANCEL

  41. Echo CancellerCombination System Option-Option3 ECHO Cancel (1)Conference (Enable/Disable) (2)CO to CO (Enable/Disable) (3)Extension to Analog line (Enable/Disable) (4)Extension to Digital line (Enable/Disable)

  42. Filter Filter Echo Canceller Function (IP-EXT) PBX DSP(IPCMPR) Echo Canceller IP-PT LCOT Analog CO Analog IP PCM ECHO (Return by 2line -4line conversion) ECHO CANCELLER ECHO by acoustic Analog CO Digital CO IP network Behind PBX NLP Setting Analog ECHO (Return by 2line -4line conversion) ECHO (Return by 2line -4line conversion) IP-EXT card Echo Canceller IP-PT Terminal Digital CO IP network IP Analog ECHO (Return by 2line -4line conversion) ECHO (Return by 2line -4line conversion) ECHO by acoustic ECHO CANCELLER Gain Control Setting Gain Control Setting Indoor Outdoor Fig.1 Factor of echo and working by eco-canceller during outgoing call or conversation

  43. Filter Filter Echo Canceller Function (IP-GW) PBX DSP(IPCMPR) Echo Canceller DPT opposite side PBX DLC/DHLC PCM PCM IP ECHO by acoustic ECHO CANCELLER NLP Setting SLT SLC/DHLC Analog ECHO (Return by 2line -4line conversion) ECHO by acoustic IP-GW card Echo Canceller LCOT Analog Analog CO IP ECHO (Return by 2line -4line conversion) ECHO CANCELLER Gain Control Setting Fig.2 Factor of echo and working by eco-canceller during conversation

  44. Filter Echo Canceller Function (Conference) DPT PBX DLC/DHLC PCM PCM Echo Canceller Card ECHO by acoustic Conference Trunk SLT SLC/DHLC Analog ECHO CANCELLER Gain Control Setting ECHO (Return by 2line -4line conversion) ECHO by acoustic Conference call of 6 to 8 parties LCOT Analog Analog CO ECHO (Return by 2line -4line conversion) Others Others ECHO (Return by 2line -4line conversion) Fig.3 Factor of echo and working by eco-canceller during conference

  45. Filter Filter Echo Canceller Function (EXT-Digital CO) In case of Echo return from CO PBX Echo Canceller Card DPT CO DLC/DHLC PCM PCM PRI/T1 PCM ECHO ECHO by acoustic ECHO CANCELLER In case of install Echo card Gain Control Setting SLT SLC/DHLC Analog ECHO (Return by 2line -4line conversion) ECHO by acoustic Fig.4 Factor of echo and working by eco-canceller during conversation

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