4
DETECTING AND AVOIDING
RADIO FREQUENCY INTERFERENCE:
When any electronic device is adversely affected by radio waves, Radio
Frequency Interference (RFI) is said to have occurred. All electronic
devices like the SEMS PDA distress alarm may be subject to the ef-
fects of RFI. Radio transmissions from the antennas of radios includ-
ing those used by fire fighters, police and other public safety related
personnel may produce RFI in the SEMS PDA distress alarm. RFI
may occur while the radio is transmitting if the respirator equipped
with the SEMS PDA distress alarm is in close proximity to a base
station or high-powered vehicle mounted radio, or if the antenna of a
personal portable hand held radio is touching or within six (6) inches
of the Control Console or Sensor Module of the SEMS PDA distress
alarm (See FIGURE 4).
Be aware of the symptoms of RFI. A SEMS PDA distress alarm af-
fected by RFI may temporarily give false indications such as the sud-
den sounding of the loud continuous three-tone chirp of the full alarm.
In some instances the lights on the Control Console may flash without
sounding the alarm. In rare circumstances, an alarm which was sound-
ing may stop.
If the SEMS PDA exhibits any of the symptoms of RFI, identify the
source of the RFI and do the following:
· If the symptoms of RFI occur when standing near a base sta-
tion transmitting antenna or a truck mounted radio antenna,
move away from the antenna until the symptoms stop.
· If the symptoms of RFI occur while transmitting on a hand-
held radio, move the radio away from the SEMS PDA.
CHECK THE CONTROL CONSOLE AND BE CERTAIN THE GREEN
LIGHT IS FLASHING NORMALLY WHEN THE INTERFERENCE
STOPS, REGARDLESS OF THE SOURCE.
In normal usage with the air cylinder open, the SEMS PDA distress
alarm will typically resume normal operation after experiencing RFI.
In some circumstances after experiencing RFI, it may be necessary to
remove the unit from service. Remove and reinstall the battery to re-
set the unit (see BATTERY REPLACEMENT section of this instruc-
tion). Then inspect and return the unit to service.
WARNING
KEEP THE ANTENNAS OF HAND-HELD
RADIOS AT LEAST SIX (6) INCHES AWAY
FROM THE CONTROL CONSOLE AND THE
SENSOR MODULE OF THE SEMS PDA
DISTRESS ALARM WHEN TRANSMITTING.
Close proximity of RADIO EQUIPMENT to the
SEMS PDA DISTRESS ALARM during radio
transmission may cause the unit to MAL-
FUNCTION. FAILURE TO RECOGNIZE A MAL-
FUNCTION OF THE SEMS PDA DISTRESS
ALARM AND TAKE THE PROPER CORRECTIVE
ACTION MAY RESULT A NONWORKING DIS-
TRESS ALARM WHICH WILL NOT SOUND IF
THE USER STOPS MOVING AND LEAD TO SE-
RIOUS INJURY OR DEATH.
WARNING
USERS OF RESPIRATORS EQUIPPED WITH
THE SEMS PORTABLE UNIT MUST BE AWARE
OF THE PROPER OPERATION OF THE
EQUIPMENT. FAILURE TO RECOGNIZE A
MALFUNCTION OF THE SEMS PORTABLE
UNIT AND TAKE PROPER CORRECTIVE ACTION
MAY RESULT IN SERIOUS INJURY OR DEATH.