AOR SDU5500 Manual page 8

Section 3-1
(2) SPAN Total displayed bandwidth
The centre frequency appears in the middle of the display with frequency extending to the left and right.
The total frequency spread from the left through centre to the right is referred to as the total SPAN and is
indicated in kHz. The maximum span is 10000 kHz (10 MHz) and minimum is 1 kHz.
(3) RBW Resolution Band Width
Two input filters may be toggled for sampling, 5 kHz and 30 kHz. Greater detail is obtained by 5 kHz,
often with a lower baseline while 30 kHz provides faster refresh rates.
(4) GAIN SDU5500 input gain
The input stage of the SDU5500 has two gain settings Hi / Low, this is selectable from menu 2. Input
gain is measured at the input of the SDU5500, not at the companion radio aerial socket. The difference
between high and low gain setting is about 30dB.
(5) RX Companion radio type
The type of companion radio is displayed (selected from those available in RX configuration menu).
When no specific companion radio is connected "Other" is automatically indicated.
(6) FDIR Frequency Direction
This function enables the SDU5500 to display the frequency in normal (left is lower frequency from the
centre cursor) or reverse (left is higher frequency from the centre cursor). This is useful depending the
type of superheterodyne receiver configured while in "Other" operation. The direction is automatically
determined when using one of the supported radio receivers (so the menu item is not available, but
selection is automatically displayed).
(7) PLOT Plot mode
Plot type can be PAINT or OUTLINE. Outline appears closer to the representation of a high priced
dedicated spectrum analyser while paint is often easier to view.
(8) STEP Step frequency
Tuning step size of the companion radio is displayed in kHz format with a resolution of tens of Hz.
(This is not the same as the LCD-step which is based upon the LCD resolution of 304 dots).
(9) MODE Receive mode
The companion radio receive mode is displayed. Not applicable when the radio type is set to "Other".
(10) ATT Attenuator
Indicates whether the attenuator of the companion radio is ON or OFF. Not applicable when the radio
type is set to "Other" nor with certain radio models.
(11) OP.MODE SDU5500 Operating mode
Three operating modes are provided and may be selected from menu 3:
•
SPECT: Spectrum analyser mode
•
STRES: Step resolution mode
•
CHANL: Channel scope mode
(12) AVR / MAX Averaging and maximum level
Averaging and Maximum level may be selected from menu 6. When "MAX" is selected, the traces on
the LCD are frozen to indicate the strongest signals encountered (if you look very carefully, you will see
that the trace is still updating). To cancel MAX press the [MAX] key a second time. When "AVR" is
selected, the sampling rate is indicated and signals will be averaged over a number of sweeps.
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