Recommendations and Guidelines
1. To provide a functional room layout that meets the objectives of the system. The flow into and out of the room, the placement of the equipment, tables and the location of the presenter to be laid out in such a way that all monitors are visible and the field of view of all cameras is taken into consideration.
2. To achieve minimum ambient noise levels by selecting a location which is relatively quiet (not near a major highway, above a subway, or next to an airport, for example). If there is no possibility of avoiding ambient noise, special construction techniques may have to be utilized in order to make the room acceptable as a videoconference facility. The amount of ambient noise present may be measured with a "sound-pressure level meter." The levels may then be correlated to an industry standard for acceptable ambient noise levels - "Noise Criteria." Videoconference rooms should be able to meet NC-35, or an SPL of 46db "A" weighted in order to ensure that speech is not masked by background noise, that the meeting flow is not interrupted by intrusive sounds, and that the audio equipment used for transmitting speech operates correctly.
3. To achieve a low reverberation time within the space, by providing the proper amount of sound absorbing materials such as acoustical panels, drapes, carpeting, or acoustic ceiling materials. The measurement for reverberation time is RT-60, which relates to the amount of time it takes for a pink noise signal which is suddenly interrupted to decay 60db. A proper videoconference room should not have an RT-60 of more than 500 milliseconds (approximately 1/2 second).
4. To minimize flutter echo and standing waves by proper design of the physical shape and dimensions of the room, which affects the way sound behaves in the room. Parallel surfaces (especially acoustically-reflective surfaces such as sheet rock or tiled floors) will cause flutter echo. This may be demonstrated by producing a sharp percussive sound (such as a hand clap), and listening for multiple, closely-spaced echoes. Standing waves are caused by the physical dimensions relating to the wavelength of audio frequencies. When the dimensions of the room are not properly selected, certain frequencies may be accentuated which will cause speech to sound "boomy" or "bassy" or "hollow".
5. To provide acceptable privacy and security by using appropriate construction techniques which give an acceptable amount of acoustic isolation, preventing someone outside the room from hearing what is being said within the room. The industry measurement used for determining isolation is STC (Sound Transmission Class). Double wall or "staggered-stud" construction, well-sealed door(s), caulking around any pipes / ducts / conduits, are all items typically needing careful attention in order to prevent "eavesdropping," as well as to prevent external noise from entering the room. An STC rating of 55 is recommended. Depending on the application, this may not be a concern. This should be decided for each facility.
6. When considering a room it will be helpful to keep in mind that high ambient or intermittent noise levels may make it difficult (if not impossible) to conduct a videoconference. Watch out for traffic noise, office or industrial machinery, poorly designed air-handling systems, and/or adjacent corridors which are heavily used. HVAC should have proper fan size, air velocity, size of ducts and vents, and/or mechanical isolation from the structure. Impact noise such as generated by footsteps, falling objects, rolling carts needs to be addressed. Impact noises generating 5db over the ambient noise level should be eliminated.
1. HVAC for rooms should be high volume, low velocity systems, with mechanical isolators and acoustical lining. Ducts should have turns to minimize sound transmission. Diffusers should meet NC-25, supply and return registers should not be located directly over the presenter’s table. One adequately sized return register/vent is recommended at the system rack location, maintain NC-35 rating.
2. HVAC is recommended one hour prior to system start-up and one after system shutdown, recommended HVAC availability would be 24 hours / 7 days a week (but not required).
3. Maintain relative humidity to minimize static electricity and general comfort.
4. Equipment and participant heat loads that need to be considered: *
Participants # x 330 BTU’s = total participant BTU rating
Lighting BTU’s = total wattage X 3.41
1. If walls can’t run deck to deck then add 12" high acoustical batts above ceiling tiles as code permits, and extend over perimeter walls into adjoining spaces: avoid all fire hazards.
2. If walls are to be treated with acoustical panels, VTEL IS can recommend suppliers and types.
3. Ceiling to have acoustical tiles with an STC. rating of 40-44.
4. Floor to have carpet over pad.
5. All doors opening into classroom should have acoustical seals, automatic drop bottoms and be fire rated as required by local code (optional).
Finishes and Colors
1. A wide variety of colors and finishes are available. Certain colors and finishes are better suited for the camera use. Cameras tend to prefer blue background; however, success can be achieved with warm beige, blue gray and rose colors in paint or acoustical panel. The color should provide adequate contrast on camera to the conference participants faces and clothing. The wall finishes should have a Light Reflective Value of 40-60%.
2. In general, interior finishes should be flat and not be "saturated " colors. Saturated or strong colors can tend to "bleed" into faces, particularly when using video compression and when the camera is moving. Patterned finishes generally are not recommended. Highly reflective surfaces (chrome, glass etc.) should be avoided. The contrast ratio for the room finishes should be kept fairly low. Choose medium blue gray tones or medium oak rather than white or dark wood surfaces.
1. To provide cable access to all pieces of equipment to the main equipment.
2. To provide required AC power to all equipment for the system.
3. To define communication lines required for the system to function properly.
1. The location of the communication link and interface (demarc) should be close to the proposed location if possible.
2. Cables must be protected by code approved material.
3. All the conduits need to have measured pull tapes.
4. All conduits to be rigid EMT, thin wall type, except where noted, do not use flex conduit.
5. Conduit/cable way locations and sizes to be determined after physical site survey.
Electrical Circuits Required
Note: Exact number of circuits and outlets to be determined by physical site survey and final system configuration. Following notes are for generic reference only.
1. 1 -20 AMP, 120V, 60HZ circuit dedicated to the codec
2. 1 - 20AMP, 120V, 60HZ circuit dedicated to the equipment rack
3. 1 -20AMP, 120V, 60 HZ circuit dedicated to all other equipment. Special consideration must be taken with ceiling mounted monitors and cameras for power up. The outlets these items utilize must be switched.
4. Surge suppression to be provided by others (as necessary).
Communication Lines Required
The following conditions are required for the classroom or facility:
1. Communication line demarcation point to be behind the system equipment .
2. Communication line(s) to be tested and operational one week prior to installation.
3. 1 - Analog telephone line with handset for diagnostics, located within 4’ of the system equipment. (optional but highly recommended). 1 - Analog telephone line for "phone add" located within 4’ of the system equipment rack (if this option is purchased).
To be determined after physical site survey
The objectives identified in the following items, 1 through 16, might not be achieved in every case. For example, multiple tables will place some participants closer than others to the cameras and displays. This situation creates several problems, including light sources within the included angle of view of the participants farthest from the displays and increased difficulty in shielding the displays. One of the best approaches for distance learning seating arrangements is the use of fluorescent fixtures with parabolic louvers, which provide adequate shielding as well as some directional control of light due to the typical 45 degree "batwing" light output. Correct placement of the fixtures allows more conventional key, fill and backlight opportunities. Modifying factors to these "rules of thumb" are ceiling heights, use of video display monitors rather than projection displays and the use of architectural elements for shielding unwanted light from participants, displays or camera lenses.
1. To provide the proper light level required for the video camera(s), in order to provide a noise-free adequate depth-of-field.
2. To provide properly aimed lighting in order to avoid undesirable facial shadows caused by light sources directly overhead.
3. To minimize the "flatness" of images by intentionally creating shadows and highlights if possible (key light, fill light, back light).
4. To provide proper lighting contrast-ratio acceptable for video cameras.
5. To avoid creating a "TV-studio feel" that is uncomfortable to the participants.
6. To keep light sources in front of the participants and above their included angle of view, yet maintaining a low enough angle to avoid undesirable facial shadows (dark eye sockets, etc.).
7. To prevent the ceiling lights from shining into the cameras, possibly causing the automatic iris to close down, making the image appear dark (applies to both front and rear of room cameras).
8. To prevent light from falling on the display screens (video monitors), thereby significantly reducing the contrast of the displayed images.
9. To provide acceptable illumination of the background area of the room relative to the illumination of the conference participants (wall-wash, etc.).
10. To provide suitable and consistent color temperature of lighting in order to optimize TV camera performance.
11. To avoid an inadequate lighting plan, which would unnecessarily restrict participant seating or movement within the room.
12. To prevent or minimize unwanted reflections or glare off of the video monitors.
13. To minimize excessive heat generation caused by lighting which would result in user discomfort, or might require additional air conditioning system installation or operational costs (Note: larger air conditioning systems may generate more noise).
14. To properly light secondary areas such as lecterns, writing boards, graphic display areas, or participants and observers not seated at the tables.
15. To prevent or minimize unwanted glare off of writing boards, or graphic stages.
16. To achieve a light level of 40 foot candles minimum, measured vertically at seated eye height.