Operating instructions

AVIONICS SYSTEM
B-8
RF frequency and level
The RF frequency and RF level for each of the Avionics modes is set in the same way as for the
RX test and Dx test modes. After selecting the parameter to be changed, a new value can be
entered using the data input keys or the current value can be adjusted using the variable control.
The RF level can be displayed in dBm, in Volt (V, mV or µV) or in dBµV by using the
appropriate terminator key.
When displayed in volts or dBµV, the RF level can be given as PD or EMF by making the
appropriate setting on Help/Setup page 1. The EMF or PD flag will be shown against the RF
Level setting.
ILS
Selecting [ILS] displays the screen and menu shown in Fig. B-1.
The ILS localizer transmitters and glideslope transmitters are similar, but independent, devices and
the on-board receivers associated with them can be tested individually.
The Service Monitor
ILS GENERATOR menu provides instant selection of test signals for either
receiver.
Modulation signal output
The modulation signal applied to the ILS carrier is available at the AF OUTPUT connector. The
signal level at the connector cannot be set independently of the modulation settings on the screen.
The output level is in the order of 200 mV when the modulation levels are at the default settings.
Selecting localizer or glideslope testing
Press the [Loc] key to select the Localizer screen and menu shown in Fig. B-1; press the [G.S.] key
to select the
Glideslope screen and menu.
The similarities of the two functions are obvious from the screens.
For localizer receiver testing:-
• Deviations from track, left and right.
• Carrier frequency in the band 108.10 to 111.95 MHz.
• Voice/ident signal facility.
For glideslope receiver testing:-
• Deviations from glideslope; above and below
• Carrier frequency in the band 329.15 to 335.00 MHz.
• No voice/ident facility.
Setting the RF frequency
The RF frequency of the localizer test signal can be set to any of the allocated frequencies within
the range 108.10 to 111.95 MHz. The RF frequency of the glideslope test signal can be set to any
of the allocated frequencies within the range 329.15 to 335.00 MHz.
Pressing the [RF freq] key will highlight the 'RF Freq:' legend on the display and allow the
indicated frequency to be changed by using the variable control, or by using the data keys to enter
a new value.
If the entered frequency is not an allocated frequency, the test set will select the nearest frequency
to it from the table.
The FREQ [⇑] or [⇓] increment keys can be used to change the RF frequency without selecting
[RF freq].
Each localizer frequency increment is paired with a specific glideslope frequency. See
ILS
frequency pairing, on page B-4.