Passive Bandscope Operation - AOR SDU5500 Manual

Section 5-4, 5-5
If the incoming signal is greater than -40dBm, switch-on the companion radio's attenuator (in the case of
the AR5000 this is via menu 2).
Additional facilities are provided by menu 5 and menu 6, these include MK-RF where the marker is
moved to receive frequency so that activity traces may be monitored by a single key press.
7) Go to menu 7, if necessary use the PREV NEXT keys or press the numeric key
is used in channel step mode to move the "RF" marker (effectively tune the receive frequency.
<-
Moves the receive frequency down by one step, in this example by 25 kHz.
->
Moves the receive frequency up by one step, in this example by 25 kHz.

5-5 Passive bandscope operation

When the companion radio is set to "Other", the range of facilities is reduced and the method of
frequency readout is different. Refer to section 4-4 of this manual for details on how to configure "Other"
radio.
You cannot change the receive mode or attenuator,
the legend "- - -" will be displayed next to the LCD
status lines. The centre frequency always displays
as 10.7 MHz (unless you reprogram the IF
frequency to suit the companion radio). Channel
scope mode is not available.
The 'Marker' is displayed in kHz format, initially in
the centre position as "0.00 kHz". As the spin wheel
dial is rotated, the OFFSET FROM CENTRE will
become more positive (up to + 5000.00 kHz) or more
negative (to a minimum of - 5000.00 kHz minus one
LCD-step, with a 25 kHz LCD-step and 10000 kHz
span this will be - 4967.10 kHz).
The STEP control does not affect the companion radio tuning increment, instead it sets the LCD-step
resolution.
Note: The "MK-CF" facility cannot place the companion receiver onto the active frequency, instead
this is used to assist the programming of IF frequency when the exact IF of the companion radio is
unknown.
FREQUENCY DIRECTION "FDIR" of menu 4, reverses the direction of display processing to ensure that
'+' and '-' are correctly implemented.
To correctly set FDIR, tune the companion radio 1 MHz below a known transmission (such as a strong
VHF Band-II transmission), look for a peak "+1000.00kHz" above the centre frequency, if the peak is on
the other side of the LCD, press FDIR . For example, if using the AR5000 in band scope mode, FDIR
should be set to REVERSE.
To measure active frequencies, simply add or subtract the marker offset from the frequency displayed
on the companion radio. For example: If the companion radio display is 88.300 MHz and the SDU5500
offset is displaying +4407.89kHz, the actual frequency will be 88.300 + 4.40789 = 92.70789 MHz
As VHF Band-II is allocated in 100kHz increments, the true frequency is 92.700 MHz... this slight
discrepancy is a characteristic of the horizontal resolution of the LCD (304 dots).
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