Polycom EF400 User Manual

CHOFREE

EF400

™

COUSTIC

CHO

ANCELLER

SER

ANUAL

Copyright © 1999 ASPI Digital. All rights reserved. Printed in the United States of America. Because of technical progress, specifications are subject to change without notice. EchoFree is a trademark and ASPI is a registered trademark of ASPI Digital.

ASPI Digital - The Sound of DSP 1720 Peachtree Street NW, Suite 220 Atlanta, GA 30309-2439 (404) 892-3200 www.echofree.com

Technical Support: (404) 892-3200 help@aspi.com

EF400UM-0100-99

EF400 U

SER MANUAL

Introduction.... ........ .............. .................... .............. ............. .............. ...........2

Product Features.......................... ............................................ ........ ........... ........... 3

Insta l lation.................. .............. .............. .................... ............. .............. .......4

Preparing................................................................................................................ 4

EF400 Front and Rear Panels................................................................................ 5

Prepar e th e Ro o m ............ .......... ................. .......... ................. ......... ................. ....... 6

Select a Mounting Location.................................................................................... 6

Connect Equipment.. ............................... .......... .................... ..................... .......... ... 6

Configuration..............................................................................................8

Setting the Bandwidth Switch ................................................................................. 8

Setting the Run/Setup Switch .................................................................................. 8

Setting the Phantom Power Switch......................................................................... 8

Calibration....................................................................................................9

Overview................................................................................................................. 9

About Signal Levels................................................................................................ 9

Calibra t io n St ep s ...... .. ... ......... .......... ................. .......... ................. .......... ................ 1 1

Calibra t io n Verifica ti o n ....... .. ... ................. .......... ................. ......... ................. ....... 16

Operati on. .. ........ .................... .............. .................... ............... .................... ..17

Traini n g ..... ... .. ................. .......... ................. .......... ................. ......... ................. ....... 17

The Mut e Bu tt o n .. .. .......... .......... ................. .......... ................. ......... ................. ....... 17

Record and Playback........................................ .......... .......... ............................... ... 17

General Conferencing Guidelines......................................................................... 18

Troubleshooting...........................................................................................19

No Output to Loudspeakers (you can’t hear them) ................................................ 19

No Output to Remote End (they can’t hear you) .................................................... 19

Residual Echo......................................................................................................... 20

Technical Support......................... ........ ................... .................................... ........ ... 22

Technical Specifications ..............................................................................23

Warran ty Informa ti o n . .......................... ........................... ..........................25

Appendix: About AEC ................................................................................27

NTRODUCTION

EF400 U

SER MANUAL

Congratulations!

About the EF400 User Manual

Product Description

Congratulat ions on your purchas e of the EchoF ree™ EF400 Acousti c Echo Ca ncell er (AEC). By ch oos ing the EF400, you have gained an exceptional communications system that delivers crisp, clear audio and efficient, comfortable conferencing.

This manual tell s you how to insta ll, conf igure , and calib rat e the EF400 to funct ion in a hands-free conferencing system. It also provides information about operating and troubleshooting the EF400.

The EchoFree™ EF400 AEC supports two-way conversations in hands-free communicati ons app lic at ion s. Th e EF4 00 el im ina te s ech oes an d ac ous ti c fe edba ck tha t oc cur when loudspeaker a udio is picked up by room microphones .

Whether you are using the EF400 in a small cubicle or a large confe rence room, all parties can communicate simult aneously without ec hoes , switching nois es , clipping of words, or dropout of speech. A patented state-logic algorithm ensures smooth and natural communications without typical speakerphone performance problems.

The EF400 employs a subband digital filtering architecture for ec ho ca ncellation. This architecture provides f aster convergence and b etter p erformance than o t her ec h o cancellers . It co ntinual ly adapts t o change s in t he envi ronment so tha t part ici pants can move about freely and volume levels may change during the conversation without adversely affecting communication quality.

Unlike most other echo cancellers, the EF400 requires no training sequence to lear n a room’s echo respons e. This means there are no annoying tone bursts at the beginning of the conversation. After the unit has been ins talled, all you have to do is turn it on. No further adjustments are requ ired.

You can move the spea ker or mi crophone or chang e rooms wit hout putt ing the EF 400 through a training sequence. This is possible becaus e of the EF400’s advanced acoustic echo cancellation techno logy. And it means the EF400 ada p ts to changes in room acoustics during conversations quickly for consistent performance throughout the conversation.

In addition to superior echo cancellation, the EF400 provides high-fidelity audio connections. Thi s allows low-noise, tr ouble-free interaction with professional or co nsumer quality audio equipment.

Warranty Registration

Please take a moment to fill out and return your warranty regis trati on card. This information will help us to provide you with better customer support.

NTRODUCTION

RODUCT FEATURES

• Full-duple x communications that sounds real and natural with no switching, dropouts, or speech clipping. All parties can be heard simultaneously.

• Based on proven, patented technology.

• Automatic tr aining does not require nois e burs ts or tones for setup.

• Continuous and quick adaptation to changes in room acoustics with a 30dB/s convergence rate.

• Howling rejection (feedback suppression).

• Long tail time (200 ms) for even difficult rooms.

• Operates with up to 10dB room gain.

• Supports 3.5kHz an d 7kHz speech and audio communications (switch selectable).

• Supports muting without disabling AEC adaptation.

• Balanced, professional line-level input and output permit direct connection to CODECs and other professional quality equipment.

• Connects to the EF200 Phone Add to make a complete teleconferencing unit.

• Accepts mic-level input (switch selectable).

• Unbalanced record input and playba ck output for connecting external equipment.

• Small footprint f its easily in rollabout carts or on rack tray.

• Easy set up. After input and output levels are calibrated, operation is completely automatic.

• Tamper proof. No external level controls f or unauthorized users to disturb.

• Continuous a nd quic k ad aptat ion to n ew envir onm ents. Doe s not requ ire memory to store room settings.

• Guaranteed superior workmanship backed by a full two-ye ar warranty.

• Extended warranty available.

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NSTALLATION

REPARING

EF400 U

SER MANUAL

The EF400 product packa ge includes the following items:

• EF400 User Manual (this manual)

• EF400 Acoustic Echo Canceller

• External power supply

• Warranty registra tion card

• Flat head trimpot adjuster.

You need the following tools to install and configure the EF400:

• EF400 User Manual (this manual)

• Small Phillips head screwdriver for opening the top of the EF400

• Hand-held SPL meter for measu r ing loudness (such as the Radio Shack 33-2050 Sound Level Meter)

• Small plastic trimpot adjuster for adjusting th e electrical signal levels (included).

RESPONSEWEIGHTING

-10

BATT

SOUND LEVEL METER

SCREWDRIVER

OFF

RANGE >

SLOW FAST

A C

You need the following additional equipment to create a completely functional system:

• Microphone(s)

• Speaker(s)

• Audio amplifie r (or am plified speaker)

• CODEC and/or EF200 Phone Add

• Audio cables

• Tape recorder or VCR (optional)

• Mute switch (optional)

• RS200 Rack Mount shelf (optional).

NSTALLATION

EF400 F

RONT AND REAR PANELS

MICROPHONE REMOTEPOWER

1 2

1(875,.

ROOM REMOTE

567891011 12

INPUTMIC INPUT SPEAKER OUTPUT OUTPUT

Figure 1. The front and rear pa nel of the EchoFree EF400.

MUTE

PLAY RECORD

TAPE

MUTE ROOM INPUT

T H E

S O U N D O F D S

EchoFree

EF400

+5,+/-

VDC

OWER INDICATOR

1. P

ICROPHONE INPUT LEVEL INDICATOR

2. M

. When LED is green, power is on.

. Displays micr ophone input signal le vel.

See page 12.

EMOTE INPUT LEVEL INDICATOR

3. R

. Displays remote input signal level. See

page 13.

UTE INDICATOR

4. M

. When the LED is blue , local audio is not sent to the remote

connection.

5. M

IC INPUT

. Connects to a mic, mic preamplifier, or mixer. Provides phantom power to condenser microphones. Configured via the internal phantom power switch. See page 8.

PEAKER OUTPUT

6. S

. Connects to an audio amplifier or powered speaker. (Line

level output cannot drive a speaker without an amplifier.)

EMOTE INPUT

7. R

EMOTE OUTPUT

8. R

APE PLAYBACK INPUT

9. T

. Connects to the output of a CODEC or EF200 Phone Add.

. Connects to the input of a CODEC or EF200 Phone Add.

. Connects to the output of a tape recorde r, VCR, or other recording device. This signal is sent to the remote output as well as the speaker output. See Figure 5 on page 17.

APE RECORD OUTPUT

10. T

. Connects to a recording device. Signals from the remote and mic inputs (both ends of the conversation) go to the recording device. See Figure 5 on page 17.

UTE ROOM INPUT

11. M

. Connects to the mute switch (not included but an example circuit is sh own in Figu re 4 on page 17). Th e mute swit ch turns off the REMOTE OUTPUT while still allowing adap tation. It prevents local conversations from being sent to the remote site.

OWER SUPPLY INPUT

12. P

HASSIS LID SCREW

13. C

. Connects to the external power supply.

. Loosen this screw to lower the L

OCK BAR

, open t h e chas-

sis, and make adjustments to the EF400.

14. L

OCK BAR

. Latch es o n to th e C

HASSIS LID SCREW

to keep the lid on.

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REPARE THE ROOM

To ensure good acoustics in the room, add carpeting, curtains, or acoustic tiles to the conferenci ng r oom . Imp roving room acoustics enhances the performanc e of the EF400 and the sound qualit y and int ellig ibi lit y of local sp eech. Keep ing micr ophone s near people and away from loud speakers and noise sources (fans, air vents, and projectors for e xample) also improves the performance of the EF400.

ELECT A MOUNTING LOCATION

After verifying that you have all the equipment and m aterial required for th e installation, select a moun ting location for the sy st em . You can mount the EF400 on a table top or an ASPI Digital RS200 Shelf. The RS200 Shelf can suppor t two EF400s mounted side-by-side, or an EF400 and an EF200 Phone Add for usin g the E F4 00 with a telephone line.

Assemble your too ls and all required and optional equipment in an area that is convenient to the mounting locati on.

ONNECT EQUIPMENT

EF400 U

SER MANUAL

Required Connections

microphone

ICROPHONE INPUTSPEAKER OUTPUT

1(875,.

OOM

POWER LOW HIGH VOLUME MIC

POWERED SPEAKER

CODEC/hybrid

NPUT

EMOTE

TX RX

UTPUT

LAYRECORD

auto-reverse

VCR

APE

TAPE RECORDER



UTE OOM

NPUT

Figure 2. Connection of typical external equipmen t to the EF400.

Certain equi pment and c onnect ions a re requir ed for the EF400 to be fully op era tional . (Figure 2 depicts typical connections.) Complete the following steps to ma ke all the required connections:

1. Connect the M plifier. The M

IC INPUT

to a microphone or to the output of a microphone pream-

accepts balanced XLR-type or balanced Phone (TRS)

connectors.

2. Connect the S

PEAKER OUTPUT

to the input of an audio amplifier or powered speaker. This output cannot dri ve an unampl ifi ed speake r. The S accepts a balanced XLR-type connector.

3. Connect the R CODEC, or the F

NPUT

accepts a balanced XLR-type connector.

4. Connect the R

EMOTE INPUT

ROM

EMOTE OUTPUT

to the output of your terminal equipment, usually a

AEC connection on the EF200 Phone Add. The R

to the input of your terminal equipment, usually a

+5,+/-15

VDC

PEAKER OUTPUT

EMOTE

NSTALLATION

Important!

Optional Connections

CODEC, or the TO AEC connection on the EF20 0 Phon e Add. The R

UTPUT

Verify that the EF400 R the EF400 R

accepts a balanced XLR-type connector.

EMOTE INPUT

EMOTE OUTPUT

is connected to the input of the CODEC.

is connected to the output of the CODEC and

EMOTE

5. Connect the power supply connector to the exte rnal power supply included with the EF400.

You may find these connections useful, but they are not required for proper operation of the EF400.

• Record. To record with a tape recorder or VCR, connect the T

PUT

on the EF400 to the audio input on the recording devi ce. This is an unbal-

APE RECORD OUT

anced RCA connector.

• Playback. To play back through a tape recorder or VCR, connect the T

BACK INPUT

on the EF400 to the audio output on the playback device . This is an

APE PLAY

unbalanced RCA connector.

• Mute. To add mute capability, connect th e M

UTE ROOM INPUT

on the EF400 to a mute button or ot her swi tching circui t. Thi s is a two-c onducto r mini co nnecto r. If the switch is closed (that is, the two conductors of the M shorted), the R

PUT

is not muted. If you do not connect the mute button to the M

NPUT

, the EF400 is not capable of muting audio.

EMOTE OUTPUT

is muted. If the switch is ope n, the R

UTE ROOM INPUT

UTE ROOM

are

EMOTE OUT

Important!

You can build a mute button using the schema tic in Figure 4 on page 17.

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ONFIGURATION

EF400 U

You must configure s everal options using the DIP switch S7. These options are described bel ow. Refe r to the EF400 Circ uit Board Layou t on pa ge 12 for t he l ocati on of DIP switch S7. (You must open the EF400 chassi s to acces s the DIP switches.)

SER MANUAL

NOTE

Important!

ETTING THE BANDWIDTH SWITCH

Wide Bandwidth

Narrow Bandwidth

The side of the switch that is down is the side that is selected. For instance, if the

7.0kHz/3.5kHz switch is down on t he 7.0kHz side, the EF400 is operating in 7.0 kHz mode. The switches rock up a nd down rather than sliding from si de to side.

Switches 1 through 3 are reserved. Keep them in the factory default positions. The factory default positi ons are ON (1), OFF (2), and OFF (3). A switch is of f if the left side is presse d down.

Keep this switch in the 7kHz position for most applications.

If you use a wide bandwidth (7kHz) CODE C, set the bandwidth switch to the 7kHz position. If you connect to wideband and narrowband connections (that is, if yo ur system connects to a wideband video CODEC or a narrowba nd telephone connection through the EF200 for different calls), set the bandwidth switch to 7kHz.

If you connect only to na rrowband terminals, set the ba ndwidth switch to the 3.5kHz position. In extreme conditions, you may find that the EF400 works better in the 3.5 kHz mode.

ETTING THE RUN/SETUP SWITCH

Whenever you calibrat e the EF400, set the RUN/S ing normal operation, set the R

Setup mode is active only if the EF400 is reset when the R

ETUP

position. The EF400 may be rese t by chang ing the ba ndwidth s witch bac k and

S forth. Setup mode is exi ted and normal operation restored when the R switc h is set to R

ETTING THE PHANTOM POWER SWITCH

Condenser and electret microphones need phantom power. Dynamic microphones do not. Phantom power may damage a dynamic mi crophone. If you are not sure whether the microphone needs phantom power, check the microphone spec ifications.

Power Required

Power Not Required

If a micropho ne is connected to the MIC I power, set the P

If a microphone preamplifier or a microphone is connected to the MIC I ther device requires pha ntom power, set the P

HANTOM POWER

ETUP

switch to S

UN/SETUP

switch to P

switch to the RUN position.

NPUT

and the microphone requires phantom

HANTOM

HANTOM POWER

ETUP

UN/SETUP

switch to OFF.

position. Dur-

switch is in the

UN/SETUP

NPUT

and nei-

+ 22 hidden pages