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 Introduction to Simultaneous Interpretation Equipment |
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| FM or Infrared? |
| FM |
IR |
Use FM systems for ease of operation, flexibility, and transportability.
FM systems can transmit through solid objects
FM systems operate indoors or outdoors.
FM systems are user-friendly and can be installed easily by almost anyone.
FM transmitters can be positioned anywhere and hidden from view.
FM systems can suffer from radio interference. |
Use IR systems for confidentiality and sound reliability.
IR systems cannot transmit thought solid objects
IR systems operate indoors only
IR is complex to install and requires precise and painstaking positioning.
IR emitters must be within a direct line of sight of the receivers and can be unsightly.
IR systems are immune to radio interference. | |
| FM Wideband or Narrowband? |
| WIDEBAND |
NARROWBAND |
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Use wideband for economical, reliable transmission in most environments
Wideband channels have less noise
Wideband channels have better frequency response
Wideband receivers cost less. |
Use narrowband in high radio traffic environments or when you need up to 40 simultaneous channels
Narrowband channels have more noise
Narrowband channels have poorer frequency response
Narrowband receivers cost more | |
| 72 MHz or 216 MHz? |
| 72 MHz |
216 MHz |
72 MHz has a transmission range of up to 1,500 feet
72 MHz has exceptional sound quality
2 MHz is compatible with existing FM assistive listening equipment
72 MHz can operate in up to 8 simultaneous channels. |
216 MHz has a transmission range of up to 3,000 feet
216 MHz has good sound quality
216 MHz avoids interference from existing FM listening equipment
216 MHz can operate in up to 3 simultaneous channels | |
| Below is a side-by-side comparison of features and functionality of our most popular RF and IR systems. |
| Feature |
Listen Radiofrequency |
Williams Sound Radiofrequency |
Williams Sound Infrared |
Bosch Integrus Infrared |
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Frequency Response
+/- 3 db |
50 Hz-15 KHz |
22 Hz-16 KHz |
30 Hz-16 KHz |
20 Hz-20 kHz |
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Frequency Bands |
72 MHz
216 MHz |
72 MHz |
2.3-3.8 MHz |
2-8 MHz |
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Signal to Noise Ratio |
80 dB |
74 dB |
> 60 dB |
> 80 dB |
| Number of channels |
56 |
6 |
4 |
32 |
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Nominal range |
72 MHz: 1,500 ft. (457 m)
216 MHz: 3,000 ft. (914 m) |
72 MHz: 1000 ft. (304 m) |
18,000 ft2
(1,700 m2) per emitter (2-channel mode)
28,000 ft2 (2,600 m2) per emitter (1-channel mode) |
1000 m2 per medium-power emitter (4-channel mode)
2000 m2 per high-power emitter (4-channel mode) |
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Transmits through walls? |
yes |
yes |
no |
no |
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Works well outdoors? |
yes |
yes |
no |
no |
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Performance affected by light fixtures, camera flashes, shadowed areas or sunlight? |
no |
no |
yes |
yes |
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Susceptible to RF interference? |
yes |
yes |
no |
no |
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Transmission security? |
no |
no |
yes |
yes |
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Stereo Transmitters / Receivers? |
no |
no |
yes |
yes |
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Multiple channels simultaneously? |
yes |
yes |
yes |
yes |
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Portable systems? |
yes |
yes |
no |
yes | |
| Other articles in this series: |
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