Technical information

EMS SYSTEM 7000

7703 INSTALLATION, ISSUE V2.2 – 13/04/10

(g) RADIO INTERFERENCE: KEY IN CLEAR. 30 seconds of an unrecognisable signal will

cause the RED RFI LED to turn on. The LED will flash if the signal ceases. Thereafter, the

LED will light steadily for any RF interference signal which exceeds one second. Turn the

key to reset to clear the display. With the KEY IN TEST, the RFI LED will follow any RF

signal. It is possible to receive a valid alarm with no Carrier Detect occurring, as the

receiver can decode valid data where the carrier is 10DB below the Carrier Detect level.

5.5 Tamper Aerial

5.5.1 The aerial supplied with the 7703 is special and should not be substituted for any other

aerial, unless it has been recommended by E.M.S Limited. Should the aerial be cut or

removed from its BNC connector a LOCAL ALARM will be signalled. If the buzzer option is

selected the audible warning will operate continuously, see Buzzer Option table 4. The

LOCAL ALARM can only be cleared by installing a serviceable aerial of the same type.

5.6 Radio Interference LED

5.6.1 With TEST mode selected the Red RADIO INTERFERENCE LED will light if any radio signal

tuned to the channel used by the 7703 is received. This includes the transmitters assigned

to the 7703. With CLEAR mode selected the RADIO INTERFERENCE LED will light if an

interfering radio signal is received for a period exceeding 30 seconds. This only applies to

signals not recognised by the 7703.

5.7 Anti-false Alarm

5.7.1 Should an ALARM or LOCAL signal be received at the same time as CLEAR mode is

selected, the Anti-false alarm routine will take control and hold the 7703 in the TEST

routine until the signal terminates. During the waiting period the Green CLEAR LED will

remain OFF, the Red TEST LED will be ON and the Red RADIO INTERFERENCE will be ON

announcing the presence of an unwanted signal. Providing the CLEAR mode remains

selected, when the signal terminates the 7703 will then automatically release the TEST

routine and change to CLEAR mode. Only the green CLEAR LED and Amber POWER LED

will remain ON.