AOR SDU-5500 Operating Manual

							31
Rotate the spin wheel dial to highlight “AR5000”
then press 
.
The message “AR5000 Connected” will be briefly
displayed on the SDU5500, if an error message “RX Disconnected” appears, re-check the connections
and the RS232 parameters of the AR5000 (the SDU5500 may try two or three times to connect to the
AR5000).
Other items such as  PLOT ,  CONT ,  B/W  can
be ignored unless necessary. The frequency sweep
direction  FDIR  is default and cannot be changed.
3)  Go to menu 2, use the  PREV   NEXT  keys or
press the numeric key 
. The  MODE ,  ATT
and  STEP  are automatically transferred from the
AR5000 to the SDU5500, however re-check the
attenuator setting.  Press  ATT  to toggle the
attenuator status, in this example switch the
attenuator off.  Push the  MODE  key to select
receive mode, in this example “WFM” followed by
.
Push  STEP  to enter the tuning step size in kHz
format, in this example of 100 kHz followed by 
.
The  GAIN  key accesses the SDU5500 gain
control, leave this in the default “Hi” (high) position.
The  SPAN  is set to the default of 10000 kHz
(10 MHz), if it is not, press  SPAN  then enter
        
4)  Go to menu 3, use the  PREV   NEXT  keys or
press the numeric key 
.  This menu dictates
the operating mode of the SDU5500:
SPECT = Spectrum display
STRES = Step Resolution
CHANL = Channel scope mode
Push  STRES  to select step resolution mode,  the
LCD legend “OP.MODE : STRES” confirms
selection.
5)  Go to menu 4, if necessary use the  PREV
NEXT  keys or press the numeric key 
.
This menu is used to input the centre frequency and resolution band width (RBW), note that the “SPAN”
key is replaced by “STEP”.
Section 5-3 
						

							32
Push the  CF  key and enter the required centre
frequency in MHz format.  In this example select
95 MHz followed by 
.
The LCD legend “CF : 95.00000MHz” confirms
entry.  Leave the RBW set to 30 kHz.
6)  Go to menu 5, if necessary use the  PREV
NEXT  keys or press the numeric key 
.
This menu is used to define the operation of the
frequency marker.
Now the LCD should be displaying a centre
frequency of 95 MHz with a spread either side (the
screen representing 90 MHz to 100 MHz from left to
right).  In step resolution mode, the radio step and
LCD-step are equal, in this example each step is
100 kHz.  Only a small area in the centre of the LCD
will be employed, as only wanted frequencies are
sampled, the refresh rate will be faster than
spectrum analyser mode.  Active signals will
populate the LCD.  The “CF” and “Marker”
frequencies are currently the same and the “CF” is
what the receiver is tuned to... what you are listening to.
Rotate the spin wheel dial to move the marker onto any active trace, the frequency may be read directly
in MHz format next to the legend “Marker” and the signal level will be displayed alongside in dBm.  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-CF where the marker is
moved to centre frequency so that activity traces may be monitored by a single key press.
Section 5-3 
						

							33
& Note:  In step resolution mode, the minimum displayed frequency will be the lower limit plus one
LCD-step/radio step, in the above example with a centre frequency of 95 MHz, 10000 kHz span and 30
kHz RBW this will be 90.10000 MHz with the top frequency being 100.00000 MHz.
7)  Go to menu 7, if necessary use the  PREV
NEXT  keys or press the numeric key 
.  This
menu is used in step resolution mode to move the
centre frequency.
  Moves the centre frequency up by half the span width, in this example the centre frequency moves
to 100.00000 MHz.
5-4  Channel scope mode
In ‘channel scope mode’, you may view a defined bandwidth up to a maximum span of 5 MHz minus one
step.  In particular, channel scope mode is very useful for viewing relatively narrow bands of a couple of
MHz.  ONLY the wanted steps are checked for activity and as a narrower span is specified, screen
refresh can be significantly faster than sweeping a whole 10 MHz bandwidth.  To achieve this, the
LCD-step is automatically forced to equal the tuning step of the companion radio.
As an example of usage, monitor a small section of the VHF airband using channel scope mode
with the AR5000.
1)  Connect the AR5000 with the SDU5500 referring to section 4-1 of this manual.  First switch on the
AR5000 then the SDU5500.  Unless the AR5000/SDU5500 combination has been previously configured,
the SDU5500 will default to “Other” companion radio.
Section 5-3, 5-4 
						

							34
2)  Go to menu 1, use the  PREV   NEXT  keys or
press the numeric key 
.  Push the  RX  key to
access the companion radio configuration menu.
Rotate the spin wheel dial to highlight “AR5000”
then press 
.  The message “AR5000 Connected”
will be briefly displayed on the SDU5500, if an error
message “RX Disconnected” appears, re-check the
connections and the RS232 parameters of the
AR5000 (the SDU5500 may try two or three times to
connect to the AR5000).
Other items such as  PLOT ,  CONT ,  B/W  can be
ignored unless necessary. The frequency sweep
direction  FDIR  is default and cannot be changed.
3)  Go to menu 2, use the  PREV   NEXT  keys or
press the numeric key 
. The  MODE ,  ATT  and
STEP  are automatically transferred from the
AR5000 to the SDU5500, however re-check the
attenuator setting.  Press  ATT  to toggle the
attenuator status, in this example switch the
attenuator off.  Push the  MODE  key to select
receive mode, in this example “AM” followed by 
.
& Note:  There is no need to define the channel
step at this point.
The  GAIN  key accesses the SDU5500 gain control,
leave this in the default “Hi” (high) position.
4)  Go to menu 3, use the  PREV   NEXT  keys or
press the numeric key 
.  This menu dictates the
operating mode of the SDU5500:
SPECT = Spectrum display
STRES = Step Resolution
CHANL = Channel scope mode
Push  CHANL  to select channel scope mode, the LCD legend “OP.MODE : CHANL” will later confirm
selection.
5)  A new menu will appear “Channel Scope Start
Freq(MHz)” inviting you to enter the lower frequency
limit in MHz format.  In this example input 120 MHz
   
Section 5-4 
						

							35
Another menu will appear “Channel Scope Step
Freq(kHz)” inviting you to enter the channel step size
using kHz format.  In this example input 25 kHz
  
A third menu will appear “Channel Scope End
Freq(MHz)” inviting you to enter the upper frequency
limit in MHz format.  In this example input 124 MHz
   
The maximum span width (difference between upper and lower frequency limit) is 5000 kHz minus one
channel step.
& Note: Should you wish to later change the start / end frequency or channel step, use the “FREQ”
key which is displayed on menu 4 while in channel scope mode.
6)  Go to menu 4, use the  PREV   NEXT  keys or
press the numeric key 
.  Press the  RBW  key to
select 5 kHz resolution (the default is 30 kHz... as the
channel step in this example is 25 kHz, it is best to
select a ‘RBW’ sampling rate which is smaller).
In place of “CF”, the legend “RF” RECEIVE
FREQUENCY is displayed.  The receiver will monitor
“RF” which is default to the lower frequency of 120
MHz in this example.  The span is automatically set
by the SDU5500 with the spectrum trace displayed
either side of the centre point, in this example the
span width is 4050 kHz (4.05 MHz).
In channel scope mode, the radio step and LCD-step are equal, in this example each step is 25 kHz.
Only a small area in the centre of the LCD will be employed, as only wanted frequencies are sampled,
active signals will populate the LCD.  The “RF” and “Marker” frequencies are currently the same and the
“RF” is what the companion radio is tuned to... what you are listening to.  The “RF” marker will be
displayed as an outline pair of triangle markers above & below the graticule, this is to remind you of the
receive frequency which is NOT the centre frequency.
Rotate the spin wheel dial to move the marker onto any active trace, the frequency may be read directly
in MHz format next to the legend “Marker” and the signal level will be displayed alongside in dBm.
Section 5-4 
						

							36
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 
.  This menu
is used in channel step mode to move the “RF” marker (effectively tune the receive frequency.
 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).
Section 5-4, 5-5 
						

							37
(6)  Special considerations
Electrical performance:  The SDU5500 is designed to operate in conjunction with a companion radio
as a complete system unlike an all-in-one spectrum analyser.  You are reminded of the following points:
Displayed signal level
The signal level which the SDU5500 provides is always at the RF input of the SDU5500, not the signal
level at the companion radio aerial input.
AGC
The signal level of the SDU5500 may fluctuate when the companion radio is tuned or the received signal
may appear to change in level.  This is because the AGC circuit of the companion radio reacts to varying
incoming signals.  When the companion radio is tuned to a very weak signal or to a frequency with no
activity at all, the radio’s RF gain is set to a maximum.  Under such circumstances, when a strong signal
is received the AGC reacts to reduce the input level to the SDU5500.  Some radios have an AGC OFF
position which can prevent such fluctuations, however this will inevitably increase the distortion / noise in
recovered audio when a strong signal is encountered.
Frequency characteristics
While multiple active signals are simultaneously displayed, you may notice that the received signals
change positions in signal level (i.e. a strong signal is displayed weaker and a weaker signal is displayed
stronger in comparison), particularly when the companion radio is tuned around multiple strong signals.
This is caused by a disparity in the companion radio’s RF filters, IF filters, etc which result in non-linear
amplification in the wider frequency range.  This is particularly noticeable when a wide span is selected
(such as 10MHz) the extreme edge of the screen may show a reduced signal level by as much as 10dB
(when AR3000A is used), this is not a fault.  This has to be taken into account when a comparison of
signal level is required.
Frequency Resolution Band Width (RBW)
The displayed signal level may be affected depending on the choice of narrow or wide filter as a result of
different losses in each filter applied.  In addition the signals which use a wider bandwidth (i.e. WFM,
television / high speed digital signals) may also affect the displayed signal level.  When a signal of wide
bandwidth passes through a narrow filter, only partial energy will be measured, resulting in reduced
signal level on the display when compared to the same signal measured after passing through a wide
filter.  Similar phenomena may be noticed when the sweeping rate is too fast for the narrow filter path.
Image reception
You may find stray signals on the screen, like meteors or ghosts, moving in the opposite direction to
tuning or moving faster / slower randomly compared to genuine active signals.  Such ghost signals are
the result of images or cross-modulation / inter-modulation caused by design characteristics of the
companion radio.
Overload from the companion radio
While monitoring a crowded band with lots of strong signals (particularly with a long wire aerial con-
nected) the noise floor of the SDU5500 may rise due to the AGC action of the companion radio.
Overloading the radio may cause a distortion within the receiver’s amplifier circuits which then affects
the SDU5500 noise floor.  Turn the radio attenuator ON if such phenomena are observed.
Section 6 
						

							38
(7)  Computer control information
The SDU5500 is fully controllable by PC via the RS232 socket, no specific hardware interface is
required, just a straight RS232 cable.  All keyboard operations may be mimicked via a PC and display
data may be downloaded for reconstruction in the PC enabling recording of activity and historic analysis.
The SDU5500 is equipped with an RS232 port in addition to the connection port for a companion radio.
The two connectors are the same, please refer to section 2-2 of this manual to assist with identification.
DO NOT CONNECT TO THE WRONG PORT. The RS232 port uses a 9-pin D-type female socket, this
requires an RS232 lead terminated in a 9-pin D-type male plug.  The wiring of the cable is straight
through:
SDU5500 PC 9 pin PC 25 pin
22 3
33 2
77 4
88 5
5 5 7  GND
The SDU5500 RS232 specification is as follows:
Data bits: 8
Stop bits: 2
Parity: None
Baud rate: 9600bps
Flow control: X flow
Command list
Commands are divided into four categories:
S = Spectrum  analysis
V = Visual  command
U = User  interface
I = Information
The following format is used for tabular presentation, Windows terminal / HyperTerminal may be used to
enable experimentation (+ indicates that a carriage return is sent by the SDU5500):
Function Read/Write Command category Type of command Parameter Example Response
CENT FREQ. R S CF RSCF [CR]    SCF84.3 +
In this example, the centre frequency is read
Command = read (not write)
Category = Spectrum
Type of command (abbreviation) = CF
Parameter (variable), in this example none used
Example of input = RSCF [CR]
Response from SDU5500 = SCF84.3 +  (Centre frequency is 84.3 MHz carriage return)
A correct WRITE command results in the action being carried out and a (CR) being returned.  An
incorrect command results in a question make “?” being returned.
Section 7 
						

							39
The second example uses Windows HyperTerminal, Plot mode is set to outline “WVPM2”, plot mode is
read to confirm the command “RVPM” and the response to the request is displayed “VPM2”:
S = Spectrum analysis
Function Read/Write Command category Type of command Parameter Example Response
CENT FREQ SET W S CF Min - Max WSCF10.7 [CR] + or ?
CENT FREQ READ R S CF N/A RSCF [CR] SCF84.3 +
SPAN SET W S SP Min - Max WSSP1000 [CR] + or ?
SPAN READ R S SP N/A RSSP [CR] SSP1000 +
RBW SET W S BW 1=5kHz
2=30kHz WSBW2 [CR] + or ?
RBW READ R S BW N/A RSBW [CR]            SBW2 +
GAIN SET W S GN 1-LOW
2=HIGH WSGN2 [CR] + or ?
GAIN READ R S GN N/A RSGN [CR] SGN2 +
SET CURSOR W S CM 1=MKR
2=PEAK
3=CPEAK WSCM1 [CR] + or ?
READ CURSOR R S CM N/A RSCM [CR] SCM1  +
DATA MODE SET W S DM 1=NORMAL
2=AVR
3=MAX WSDM1 [CR] + or ?
DATA MODE READ R S DM N/A RSDM [CR] SDM1 +
AVR SAMPLE SET W S AV 2 - 32 WSAV16 [CR] + or ?
AVR SAMPLE READ R S AV N/A RSAV [CR] SAV16 +
RSCF
SCF84.30000WVPM2
RVPM
VPM2
Section 7 
						

							40
V = Visual command
Function Read/Write Command category Type of command Parameter Example Response
PLOT MODE SET W V PM 1=PAINT
2=OUTLINE WVPM1 [CR] + or ?
PLOT MODE READ R V PM N/A RVPM [CR] VPM1 +
FDIR SET W V DD 1=NORMAL
2=REVERSEWVDD1 [CR] + or ?
FDIR READ R V DD N/A RVDD [CR] VDD1 +
LCD CONTRAST SET W V CL 0 - 160 WVCL50 [CR] + or ?
LCD CONTRAST READ R V CL N/A RVCL [CR] VCL50 +
LCD DISPLAY MODE W V RV 1=NORMAL
2=REVERSE WVRV1 [CR] + or ?
LCD DISPLAY MODE R V RV N/A RVRV [CR] VRV1 +
SEND VISUAL IMAGE R V IM N/A RVIM [CR] VIM +
FOLLOWED BY
IMAGE AND +
U = User interface
Function Read/Write Command category Type of command Parameter Example Response
RECEIVE MODE SET W U MD 1=WFM WUMD3 [CR]   + or ?
2=NFM
3=AM
4= LSB
5=USB
6=CW
7=AUTO
RECEIVE MODE READ R U MD N/A RUMD [CR UMD3 +
ATTENUATOR SET W U AT 1=ON
2=OFF WUAT2 [CR] + or ?
ATTENUATOR READ R U AT 1=ON
2=OFF RUAT [CR] UAT2 +
STEP SIZE SET W U ST SIZE IN kHz WUST25 [CR] + or ?
STEP SIZE READ R U ST N/A RUST [CR] UST25.00 +
(FOR 25 kHz
STEP)
COMPANION RX SET W U RX 1=AR5000 WURX1 [CR] + or ?
2=AR3000A
3=IC-R7100
4=IC-R8500
5=IC-R9000
6=OTHER
COMPANION RX READ R U RX N/A RURX [CR] URX1 +
MK-CF W U MC N/A WUMC [CR] + or ?
STEP-UP W U SU N/A WUSU [CR] + or ?
STEP-DOWN W U SD N/A WUSD [CR] + or ?
Section 7