There are two main types of
simultaneous interpretation equipment:
infrared (also
called IR) and radio frequency (also called RF or FM). Both
are used for assistive listening and simultaneous interpretation systems.
Infrared
Infrared (IR) is electromagnetic radiation
with wavelengths longer than visible light but shorter than radio waves.
This equipment is best suited for meetings where
their restricted range of transmission is an advantage, typically, where
industrial espionage or national security is a major concern. They are also the
system of choice in areas of the world where poor regulation of the radio
frequency spectrum allows interference with FM equipment.
The main advantage
of infrared equipment is its immunity to radio interference. The main
drawbacks are restricted range, susceptibility to light, and the fact that
it requires professional installation.
Radio frequency
Radio Frequency (RF) is a frequency in the range within which radio waves may be
transmitted, from about 3 kilohertz to about 300,000 megahertz.
FM radio frequency systems are the most widely
used in meetings and conventions because of their superior range, ease of
operation, mobility, and reliability. They are also very user-friendly and
can be installed by anyone with a basic knowledge of sound equipment. This
equipment is also available in several frequencies, of which the most popular
are 72 MHz and 216 MHz.
Choose a 72 MHz system:
-
For shorter range application
requirements up to 1,500 feet
-
For exceptional sound quality
-
For compatibility with
existing FM assistive listening equipment
Choose a 216 MHz system:
-
For longer range application
requirements up to 3,000 feet
-
For areas where interference
is a problem
-
For good sound quality
-
For expanded applications
including language interpretation, tour group communications,
medical/dental, and law enforcement.
Use
this chart to help you choose between 72 MHz and 216 MHz:
| |
72MHz |
216MHz |
|
To Meet ADA
Requirements
|
Meets ADA guidelines for the hard of
hearing at both 72 and 216MHz. Listen is compatible with all existing major
brand systems. No special license is required. |
|
ADA Frequency Use
Designation
|
Designated for hearing impaired and
assistive listening transmissions. |
Designated for assistive listening, tour
group, language interpretation, medical, and law enforcement transmissions. |
|
Simultaneous Channels
|
Offers 6 simultaneous channels within the
72-76MHz spectrum range.* |
Offers 3 simultaneous channels within the
216-217MHz spectrum range.* |
|
Sound Quality
|
Exceptional sound quality (SNR 80db, 50Hz
to 15KHZ)** |
Excellent sound quality (SNR 80 dB, 50Hz
to 10KHZ)** |
|
Transmission Range
|
Good Range -- stationary transmitters
have a 500-1,500 foot range, and mobile transmitters have a 100-150 foot
range. |
Greater Range -- stationary transmitters
have a 1,000-3,000 foot range, and mobile transmitters have a 100-150 foot
range. |
|
Reduction of
Interference
|
Expect more interference from outside
sources. |
Because 216MHz is an exclusive band to
assistive listening, it may offer less transmission interference. |
|
72MHz |
216MHz |
|
For More Simultaneous
Channels
|
72MHz offers twice the number of
simultaneous channels. |
 |
|
For Better Transmission
Range
|
|
216MHz offers almost twice the
transmission range as 72MHz (from a stationary transmitter). |
|
For Less Interference
|
|
As an exclusive band, 216MHz is not
licensed for other uses and may offer less transmission interference.
|
|
RECOMMENDED
APPLICATIONS FOR:
|
72MHz |
216MHz |
|
Places of Worship
|
Recommended: Clearer signals with
twice the number of simultaneous channels for multiple language
interpretation or different meetings. |
Suggested for when greater range is
necessary. |
|
Language Interpretation
|
Benefits: Use 6 channels* for
simultaneous interpretation to multiple languages. |
Benefits: Greater range with stationary
transmitter. Use 3 channels* for simultaneous interpretation. |
|
Tour Groups
|
Benefits: Use 6 channels* for
simultaneous groups touring the same facility without interference and
overlap. |
Benefits: Because 216MHz is an exclusive
band to tour groups, it may offer less transmission interference. 72MHz and
216MHz transmitters have similar transmission ranges. |
|
Schools
|
Recommended: Compatible with most
existing systems at 72MHz systems. |
Suggested for when greater range is
necessary. Compatible with Phonak MicrolinkTM. |
|
Meeting Rooms, Hotels
and Convention Centers
|
Recommended: More simultaneous
channels means multiple meetings can use different FM systems at the same
time without interference from each other. |
Suggested for when greater range is
necessary, such as large rooms or for remote speakers in foyers and overflow
areas, however SNR may be objectionable in low noise environments. |
|
Stadiums/Arenas
|
Suggested when adding to or upgrading an
existing 72MHz system (compatible with all major brands). |
Recommended: Greater range for
larger venues, particularly stadiums and arenas. |
|
Live Theatre
|
Suggested when more simultaneous
transmissions are necessary (such as simultaneous interpretation). |
Suggested when greater range is
necessary. |
*
Number of available simultaneous channels vary by proximity of transmitters,
transmitter output power level area interface, etc.
**
With Listen SQ Technology implemented
Below is a side-by-side comparison of features and functionality for our most
popular RF and IR systems. Use this chart to help you choose between
radiofrequency and infrared:
|
Feature |
Listen Radiofrequency |
Williams Sound Radiofrequency |
Williams Sound Infrared |
Bosch Integrus Infrared |
|
Frequency Response
+/- 3 db |
50 Hz-15 KHz |
22 Hz-16 KHz |
30 Hz-16 KHz |
20 Hz-20 kHz |
|
Frequency Bands |
72 MHz
216 MHz |
72 MHz |
2.3-3.8 MHz |
2-8 MHz |
|
Signal to Noise Ratio |
80 dB |
74 dB |
> 60 dB |
> 80 dB |
|
Number of channels |
56 |
6 |
4 |
32 |
|
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) |
|
Transmits through walls? |
yes |
yes |
no |
no |
|
Works well outdoors? |
yes |
yes |
no |
no |
|
Performance affected by light
fixtures, camera flashes, shadowed areas or sunlight? |
no |
no |
yes |
yes |
|
Susceptible to RF
interference? |
yes |
yes |
no |
no |
|
Transmission security? |
no |
no |
yes |
yes |
|
Stereo Transmitters /
Receivers? |
no |
no |
yes |
yes |
|
Multiple channels
simultaneously? |
yes |
yes |
yes |
yes |
|
Portable systems? |
yes |
yes |
no |
yes |
Use the following chart to compare the different
radio frequency simultaneous equipment offerings on the market. The
systems we carry, Listen and Williams Sound, are highlighted.
Radio
Frequency Simultaneous Interpretation Equipment Comparison Chart
| |
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Stationary Transmitters |
|
Model
Number |
|
PPA-T35
|
PE
560T
|
ST-300
|
TX-37A
|
ALT1000
|
BST-50b
|
|
Number
of Channels |
57
|
87
|
50
|
17
|
37
|
17
|
50
|
|
Frequency Bands Available |
72 & 216 MHz
|
72MHz only
|
72MHz
only
|
72MHz
only
|
72 &
216 MHz
|
72MHz
only
|
72MHz
only
|
|
Number
of Audio Inputs |
2
|
1
|
2
|
2
|
2
|
1
|
1
|
|
Maximum
range in linear feet on 72MHz/216MHz |
1,500/ 3,000
|
1,000
|
1,000
|
1500
|
1,000
|
1,000
|
1,500
|
|
List
Price |
$660.00
|
$649.00
|
$610.00
|
$600.00
|
$620.00
|
$699.00
|
$1,425.00
|
|
|
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Wireless
Transmitters |
|
Model
Number |
|
T16/T1-216
|
PE
300T
|
PST-170
|
PTX
|
NA
|
M72
|
|
LCD
Display |
Yes
|
No
|
No
|
Yes
|
Yes
|
No
|
|
Number
of Channels |
57
|
8/10
|
40
|
17
|
37
|
1
|
|
Frequency Bands Available |
72 & 216 MHz
|
72 & 216 MHz
|
72MHz
only
|
72MHz
only
|
72 MHz
|
72MHz
only
|
|
Number
of Audio Inputs |
2
|
1
|
2
|
1
|
2
|
1
|
|
Maximum
range in linear feet on 72MHz/216MHz |
150
|
150
|
100
|
NA
|
10/50
|
300
|
Battery
Life (Alkaline/ Rechargeable)
in Hours |
15/8
|
15/8
|
40/10
|
8/4
|
4/2
|
30/5
|
|
List
Price |
$450.00
|
$400.00 / 389.00
|
$275.00
|
$505.00
|
$410.00
|
$535.00
|
|
|
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Lowest Cost Receivers |
|
Model
Number |
|
PPA R7N
|
PE
500R
|
SR-50
|
RX-1A
|
MR306
|
PR-72b
|
|
LCD
Display |
No
|
No
|
No
|
No
|
No
|
Yes
|
No
|
|
Number
of Channels |
17
|
1
|
1
|
1
|
1
|
17
|
1
|
|
Frequency Bands Available |
72 & 216 MHz
|
72 & 216 MHz
|
72MHz
only
|
72MHz
only
|
72 MHz
|
72MHz
only
|
60-216MHz
|
|
Tuning
Method |
Digital
|
Trim Pot / Coil
|
Auto
Freq Control
|
Crystal
|
Trim
Pot / Coil
|
Digital
|
Crystal
|
|
Battery
Life (Alkaline/
Rechargeable) in Hours |
30
/15
|
32/6
|
60/30
|
20/14
|
60/30
|
30/NA
|
40/NA
|
|
List
Price |
$82.00
|
$79.00
|
$97.00
|
$85.00
|
$77.00
|
$99.00
|
$235.00
|
|
|
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Multichannel Receivers |
|
Model
Number |
|
PPAR7-4N
|
PPAR7-6N
|
PE
506R
|
SR-400
|
Digital 6
|
MR306
|
NA
|
|
LCD
Display |
Yes
|
No
|
No
|
No
|
Yes
|
No
|
Yes
|
|
Number
of Channels |
57
|
4
|
6
|
6
|
17
|
6
|
17
|
|
Frequency Bands Available |
72 & 216 MHz
|
72 MHz
|
72 MHz
|
72MHz
only
|
72MHz
only
|
72 MHz
|
72MHz
only
|
|
Tuning
Method |
Digital
|
4 Position Dial
|
6 Position Dial
|
6
Position Switch
|
Digital
|
Digital
|
Digital
|
|
Battery
Life (Alkaline/ Rechargeable) in Hours |
30/15
|
32/6
|
32/6
|
60/30
|
20/14
|
40/20
|
30/NA
|
|
Programmability |
Yes
|
No
|
No
|
No
|
No
|
No
|
No
|
|
List
Price |
$189.00
|
$127.00
|
$155.00
|
$97.00
|
$232.00
|
$150.00
|
$99.00
|
|
|
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Audio Specifications (end-to-end): |
|
Frequency Response |
50-15KHz
|
100-10KHz
|
100-10KHz
|
80-8KHz
|
100-10KHz
|
100-10KHz
|
50-15KHz
|
100-10KHz
|
|
Signal
to Noise Ratio |
80dB
|
55dB
|
65dB
|
55dB
|
58dB
|
55dB
|
60dB
|
65dB
|
|
Distortion |
<2%
|
NA
|
NA
|
<2%
|
<2%
|
<2%
|
NA
|
NA
|
|
|
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Batteries and Chargers: |
|
Battery
Size and Quality |
2 x AA
|
1 x 9V
|
1 x 9V
|
2 x AA
|
2 x AA
|
2 x AA
|
2 x AA
|
1 x 9V
|
|
Types of
Rechargeable Batteries |
NiMH
|
NiMH
|
NiMH
|
NiCAD
|
NiCAD
|
NiCAD
|
NA
|
NiCAD
|
|
Battery
Compartment Can Be Locked |
Yes
|
No
|
No
|
No
|
No
|
No
|
No
|
No
|
|
Drop-in
Charging |
Yes
|
No
|
No
|
No
|
No
|
No
|
NA
|
No
|
|
Charging
Case Sizes |
4, 8, 16
|
12
|
12
|
12
|
2, 4
|
10
|
NA
|
10
|
|
|
Listen
|
Williams
|
Phonic
Ear
|
Telex
|
Starlin/ Gentner
|
Drake
|
Comtek
|
|
Other: |
|
Warranty |
Lifetime
|
5 Years
| |
