47
a. Field strengths from fixed transmitters, such as base stations
for radio (cellular/cordless) telephones and land mobile radios,
amateur radio, AM and FM radio broadcast and TV broadcast
cannot be predicted theoretically with accuracy. To assess the
electromagnetic environment due to fixed RF transmitters, an
electromagnetic site survey should be considered. If the mea-
sured field strength in the location in which the Melodia™ series
hearing aid is used exceeds the applicable RF compliance level
above, the Melodia™ series hearing aid should be observed to
verify normal operation. If abnormal performance is observed,
additional measures may be necessary, such as re-orienting or
re-locating the Melodia™ series hearing aid.
b. Over the frequency range 150 kHz to 80 MHz, field strengths
should be less than 3 V/m.
Recommended separation distances
Recommended separation distances between portable and
mobile RF communication equipment and the Melodia™ series
hearing aids.
The Melodia™ series hearing aids are intended for use in the
electromagnetic environment in which RF disturbances are con-
trolled. The customer or the user of the Melodia™ series hearing
aid can help prevent electromagnetic interference by maintaining
a minimum distance between portable and mobile RF communica-
tions equipment (transmitters) and the Melodia™ hearing aids as
recommended below, according to the maximum output power of
the communications equipment.
Rated maximum
output power of
transmitter
(W)
Separation distance according to frequency
of transmitter (m)
150 kHz to
80 MHz
d = 1.2
√
P
80 MHz to
800 MHz
d = 1.2
√
P
800 MHz to
2.5 GHz
d = 2.3
√
P
0.01
0.12
0.12
0.23
0.1
0.38
0.38
0.73
1
1.2
1.2
2.3
10
3.8
3.8
7.3
100
12
12
23
For transmitters rated at a maximum output power not listed
above, the recommended separation distance
d
in meters (m) can
be estimated using the equation applicable to the frequency of
the transmitter, where
P
is the maximum output power rating of
the transmitter in watts (W) according to the transmitter manu-
facturer.
NOTE 1 At 80 MHz and 800 MHz, the higher frequency range ap-
plies.
NOTE 2 These guidelines may not apply in all situations. Electro-
magnetic propagation is affected by absorption and reflection
from structures, objects and people.
This Melodia™ hearing aid may be interfered with by other equip-
ment even if that other equipment complies with CISPR emission
requirements.
