AOR SDU5600 Spectrum Display Unit Operating Manual

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5-7 Waterfall display facility
The SDU5600 is equipped with a waterfall facility which can display the variation of signal strengths in
conjunction with the time lapsed (as sweeps progress). Sixteen different colours are employed
dependant on signal strength, in the shape of a waterfall.
Press the FUNC + ˜ to start the waterfall display. The bottom half of the screen will be allocated to
the waterfall display and will build-up with time.
The waterfall display continues to operate being unaffected by change of the monitoring mode,
calculation mode, the RBW, centre frequency, frequency span, start frequency and end frequency.
Section 5-7
To exit from the waterfall display, repeat the key sequence FUNC + ˜
Signal strength is represented by sixteen different colours, corresponding to the height of each signal
in the vertical scale. Therefore the colour will vary when the input sensitivity (AMPLITUDE) has been
altered in the course of monitoring.
While the waterfall display is in operation, the only parameter of the companion receiver which can be
altered is the receive frequency.
To exit from the waterfall display, repeat the key sequence FUNC + ˜ or press CLR 
						

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5-8  On/off of the displayed information
The companion receiver parameters
are usually displayed on the left side of
the LCD graticule.  The key sequence
FUNC + 5 (DISP) will toggle the display
of the companion receiver’s parameter
on / off.
When the calculation mode is in use,
the calculation data will be turned on or
off by the same key-in sequence.
By effective use of this facility, you can
view the signal activities easier on the
much less cluttered display area.
5-9  Beep alert
To toggle the keypad confirmation beep on / off, use the key sequence
FUNC + 6 (BEEP).
5-10 Factory default/reset
If you wish to revert the SDU5600 to
default status, power-on the SDU5600
via the main power switch while
holding-in the 3 and 6 keys together
until the opening message EEPROM
initialized is displayed.
Section 5-8, 5-9, 5-10    
						

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6.  Operating the SDU5600
This section will provide examples of operating the SDU5600 using the AR5000A+3 as companion
receiver. Refer to pages 10 to 12 of this manual for connection to the receiver.
Section 6, 6-1
6-1 Operate the SDU5600 with
the AR5000A+3.
Turn the SDU5600 on, which
is followed by the opening
message to confirm for
readiness.
Access the configuration menu by pressing the
FUNC + 4 to select the companion receiver.
Press the RX key, which displays the current
companion radio type above the key on the LCD
in reverse contrast. Select the AR5000 (in this
example) via the main dial followed by ENT.
The communication between the two should be
correctly established so that you can start
monitoring.
At this stage the SDU5600 is operating in the
spectrum analyser mode with the centre
frequency (CF) corresponding to the receive
frequency of the AR5000A+3. The frequency
span (visible bandwidth) is 10MHz.
Setup of the companion receiver
Continue to operate the AR5000A+3 via the
SDU5600 referring to the following example:
RX.FREQ. = 80.00000MHz
RX.MODE = AUTO
RX.STEP =  100.000kHz
RX.ATT = OFF
The SDU5600 can remotely operate the
following functions of the companion receiver.
ê Receive frequency
ê Receive mode
ê Frequency step
ê Attenuator on/off
Other functions such as the antenna
switching are not possible.
Access the conflagration menu
 
Selection of the companion receiver soft key
Rotate the main dial to select the
companion receiver
Confirm the selection of the companion receiver
 or 
Enter the centre frequency CF (80MHz)
  
Press the MODE key to access the receive
mode menu. Select the receive mode by
rotating the main dial to AUTO followed by MHz
  
In this example, the AUTO mode will select a
receive mode of FM and frequency step of
100kHz.
To toggle the attenuator on/off, press the
attenuator key      
						

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6-2  Monitor the VHF FM band in the spectrum analyser mode
Continue to operate the SDU5600 from section 6-1 where the SDU5600 / AR5000A+3  has been set
in the spectrum monitoring mode.
The example to the right is the actual
result which was obtained after
monitoring the signal spectrum at the
AOR headquarters in Tokyo. It indicates
the input signal being saturated,
resulting in some weak ghost signals
appearing at regular intervals close to
the floor level of the spectrum trace.
Adjust the input sensitivity
(from -30 to -20)
Press the AMPLITUDE key to display
the reference level on the LCD, which
appears in reverse contrast (-30dBm).
Rotate the main dial to select -20dBm
which lowers the input sensitivity by
10dB followed by ENT
 (MHz or kHz)
  
Adjust the resolution bandwidth
(from 4kHz to 128kHz)
Press the RBW key to display the
resolution bandwidth value on the LCD,
which appears in reverse contrast
(4kHz). Rotate the main dial to select
128kHz followed by ENT
 (MHz or kHz)
  
The example on the right now shows the
same result with the RBW set to
128kHz, this bandwidth is far more
suitable for monitoring FM broadcast
signals with wider band occupancy.
Refer to page 23, section 5-4-1
should you wish to operate the
CF, frequency span, etc in the
spectrum analyser mode.
Section 6-2    
						

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6-3 Monitor the FM broadcast band in the step
resolution mode
The following information explains how to change the monitoring mode from
the default of spectrum analyser mode to the step resolution mode.
Press the FUNC + 2 (STEP), the SDU5600 will shift to Step Resolution mode
with the legend 
StepReso. appearing on the LCD. The display step will be
unchanged at this stage.
 
You may wish to change the display step to a 25kHz in order to make the task
of monitoring easier. Press the SPAN/STEP key, which results in the step
display appearing in reverse contrast on the LCD. Type in the required step
size via the ten-keys, in this example 2 5 followed by kHz
   
Rotate the main dial to move the marker sideways. It should be
immediately noticeable that the frequencies on active signals can be
found in 25kHz steps, which is much more suitable for monitoring
channelised bands such as FM broadcast.
In the step resolution mode the rule is:
1 displayed dot = 1 displayed step
The horizontal x-axis of the SDU5600 provides 320 dots.
Therefore in the above example, one displayed dot represents one 25kHz
increment. The step resolution mode provides a kind of operating convenience
where the operator can almost instinctively view activity on the band and
how the activity is
distributed.
The example on the
right shows the signal
activities observed at
the AOR headquarters
in Tokyo over the FM
broadcast band in the
step resolution mode.
Refer to page 24,
section 5-4-2 should
you wish to operate the
CF, display step, etc.
Section 6-3  
						

							36
6-4 Monitor the VHF air band in the channel scope mode.
The VHF airband is allocated over the wide frequency band, It is therefore impossible to display the
entire VHF airband on the SDU5600 at once. The channel scope mode however provides a very
convenient method of monitoring the channelised frequency band through the use of both the marker
and receive marker. Using this method, you can split the airband into small sections for quick
inspection.
Change of the monitoring mode
To change to Channel Scope mode press FUNC + 3 (CHANL). The LCD legend 
OP.MODE:Channel confirms that
channel scope mode has been engaged.
 
The LCD legend above [Ch.START] will display a frequency in revers contrast, this
is inviting you to key in a new start frequency via the ten-keys.
Enter a start frequency of 118MHz, if you make a mistake, press CLR to return to
the start entry position.
   
The LCD entry point will move to [Ch.STEP], enter a step frequency of 25kHz
  
The LCD entry point will move to [Ch. END], enter an end frequency of 122MHz
   
Note, the end frequency is always restricted under the rules:
(CH.START) + [(CH.STEP) x 160]
and
(CH.START) + 5MHz
Any incorrect entry of the end frequency will be alerted with the beep, and it will be automatically corrected to the
nearest possible frequency.
Upon the successful entry of the end frequency the companion receiver will commence receiving on the start
frequency. Change the receive mode to AM for air band if required (or use AUTO mode), use the MODE key, main
dial or SDU5600 and MHz key.
Rotate the main dial, which moves the marker
sideways. The 
receive marker legend appears
(yellow outline triangle on the LCD) to indicate the
frequency which the companion receiver is actually
receiving.
Press the MK.F key to move the receive marker to
the marker position, this will move the companion
receive to the new frequency where monitoring will
continue.
East time you press the MK.F key, the companion
receiver will shift to the marker position, as you move
the marker by rotating the SDU5600 main dial, two
markers will be displayed on the LCD. You can
change the parameters at any time by pressing the
corresponding soft key under the LCD.
Section 6-4  
						

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6-5  Suitable applications of each monitoring mode
A summary of the three monitoring modes and suitable applications is given
here:
Spectrum analyser mode
This mode is the DEFAULT and most common monitoring mode among the
three. It is suited to the monitoring of permanent or intermittent signals or
noise.  The CF (centre frequency) and SPAN (visible bandwidth) are the main
criteria to be specified.
Step resolution mode
This mode is suited best to monitor signals which are allocated with certain
intervals over the band spectrum. The STEP is the criteria to be specified in
place of the SPAN,  so that one dot is equal to one step on the display.
Channel scope mode
This mode is best suited to monitor known channelised frequency spectrums
such as VHF airband and FM sections or broadcast and ham radio bands.
The start frequency, end frequency and step have to be specified. There is no
concept of CF applied to this mode.  It is most convenient to follow and listen
to the various signals by using both marker and receive markers.
Section 6-5 
						

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7. Useful Information
The SDU5600 has been designed to operate with a wide-band companion receiver such as the
AR5000A. Therefore, there are some differences in operating characteristics with the unit when
compared with the spectrum analysers which are designed for more general testing / measuring
applications. It is advisable that you take into account the following information while making yourself
familiar with the SDU5600.
Signal strength
The signal strength which the SDU5600 indicates is measured at the RF input of the SDU (not the signal strength of the companion
receiver at the antenna terminal). If the radio provides a gain / loss from the aerial input to IF output, the calibration of displayed signal
strength will be affected. Most receivers provide a POSITIVE gain of +10dB or so. The receivers AGC and attenuator will also affect
results.
Frequency characteristics of the companion receiver
The SDU5600 operates with a wide span of frequency (up to 10MHz band span). It must be noted that the companion receiver’s RF
circuit and / or IF filter configuration may affect the spectrum monitoring with some interference being observed. In particular, when the
wider band span has been selected such as a 10MHz, the far ends of the band edges are most affected depending on characteristics
of the receiver in use. The AR5000A is usable over 10MHz bandwidth, as is the AR3000A, however the output level of the AR8600/
MK2 drops beyond 4MHz or so.
Excessive input from the receiver
While receiving strong signals (e.g. broadcast station) with an external aerial connected to the companion receiver, the noise floor
may appear to be incorrectly lifted due to distortion from the receiver. Use of the attenuator of the receiver may help reduce these
phenomena... however, generally speaking the front end selectivity of the companion receiver is beneficial compared to a directly fed
spectrum analyser.
Selection of RBW
When monitoring the signals of broader bandwidth with the narrower RBW selected, the displayed signal strength may appear
reduced (less accurate) due to the fact that only part of the energy from the broader bandwidth can pass through the narrower
sampling filter, resulting in loss of signal strength to some extent. When monitoring wider signals (such as FM broadcast), use a wider
RBW such as 128kHz.
AGC action of the companion receiver
It must be noted that the AGC action of the companion receiver may affect the spectrum monitoring by the SDU5600. It may be
observed that the overall signal strength has dropped when abrupt changes in receiving conditions have occurred (for example, when
quickly tuning from a weak signal to a strong signal). This is because the input from the receiver’s IF is significantly reduced by AGC
action. Switching the companion receivers AGC off may eliminate this effect but the reception will become unstable and distorted with
AGC off.
Image signal
Occasionally false signals (spurious image signal) can be spotted on the display, sometimes moving at random, sometimes to the
opposite direction while monitoring the spectrum. This is due to the image signals which are generated by characteristics of the
companion receivers superheterodyne circuit design or intermodulation products, ALL receivers will present this affect to some
degree.
With the SDU5600 operating at its widest sweep range (10MHz) when coupled to an AR5000A, an unwanted spurious signal can be
observed approximately 4.8MHz away from the centre frequency (moves slightly with AR5000A frequency).  This is present at all
frequencies although it will jump to the other side of the screen when the AR5000 is tuned above 1.4GHz.
The spurii appears to be leakage of the 2nd local oscillator DDS signal at 5.8MHz to 6.7MHz (hence when viewed from the IF
frequency of 10.7MHz becomes 4.9 to 4.0MHz away). This is not a problem during normal receive with the AR5000A as the 10.7MHz
filter removes any signal but is present at the IF output taken before the filter. It is also not a problem if the sweep width on the
SDU5600 is reduced slightly.
To address this, select a bandwidth of about 9.8MHz rather than 10MHz, so the spurii drops off the edge of the display.  The spurii is
usually in the area of -70dBm to -60dBm.
The AR8600/MK2 produces a 455kHz image, its a compromise of design and has to be worked around.
RF earth
Of course all electrical equipment produces some noise, especially where large displays are involved. Connecting a good RF earth to
the equipment can help with general low level spurii... the AC adapter is not earthed, avoid earth loops.
Minimum frequency span
The SDU5600 has a minimum frequency span of 160kHz (0.160MHz). It is not possible to set the frequency span narrower than
160kHz.
Section 7 
						

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8. SDU5600 Command List
The SDU5600 can be operated via PC using the RS232 port.
8-1 Communication parameter and connecting lead
The SDU5600 and a PC should be connected using a straight cable between
the [PC I/F] socket and the serial port of the PC. The SDU5600 port is MALE,
so the PC lead must have a female connector or a gender changer will have to
be employed.
Communications parameters of the SDU5600
Baud rate 9600bps
Data length 8 bit
Parity None
Stop bit 2 bit
Flow control RTS/CTS
8-2  Delimiter
A brief description of delimeter and response format is given here.
Delimiter
Each command from the PC to SDU5600 is defined by:
 0x0d in 16-bit form
or
 0x0d,0x0a in hexadecimal format
Note:  will be ignored
Response when the command has been correct:
  0x20,0x0d,0x0a   in hexadecimal format
Response when the command has been incorrect:
?   0x3f,0x0d,0x0a in hexadecimal format
Response to the read command:
Following the output of the parameter, the correct response should read
 0x20,0x0d,0x0a in hexadecimal format
Section 8, 8-1, 8-2  
						

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8-3  Basic format of the command
Each command to be sent to the SDU5600 consists of 4 letters (upper case) in
ASCII code with appropriate parameters followed by .
Each letter represents the following:
(1) First letter Either W for write or R for read
(2) Second letter Line of command such as S for
spectrum analysis, V for visual
set-up, U for user interface and
I for information
(3 & 4) Third and Fourth letter Categories of each line of command
8-4 RS232 command list
Commands are divided into four categories:
S = Spectrum analysis
V = Visual command
U = User Interface
I = Information
Microsoft Windows® Hyper Terminal® may be used to control the SDU5600 or you may write your
own software.
An example of command format is given here:
RSCF Response: SCF79.5
In this example, the centre frequency is read.
Command = Read
Category = Spectrum analysis
Type of command (abbreviation) = CF
Parameter (variable) = Not used in this example
Example of input = RSCF Response from SDU5600 = SCF79.5
A correct WRITE command results in the action being carried out and  being
returned. An incorrect command results in a question mark “?” followed by  being
returned.
Section 8-3, 8-4