PeakTech 4025 User manual

PeakTech
®4025 / 4030
DDS Function Generator 20 mHz - 5 MHz
PeakTech®4025
DDS Function Generator 20 mHz - 20 MHz
PeakTech®4030
Operation Manual

2
Safety Precautions
This product complies with the requirements of the following European Community
Directives: 89/336/EC (Electromagnetic Compatibility) and 73/23/EEC (Low Voltage)
as amended by 93/68/EC (CE-marking).
To ensure safe operation of the equipment and eliminate the danger of serious injury
due to short-circuits (arcing), the following safety precautions must be observed.
Damages resulting from failure to observe the safety precautions are exempt from any
legal claims whatever.
• Prior to connection of the equipment to the main outlet, check that the
available mains voltage corresponds to the voltage setting of the equipment.
• Connect the main plugs of the equipment only to a mains outlet with earth
connection.
• Do not exceed the maximum permissible input rating
• Replace a defective fuse only with a fuse of the original rating. Never short-
circuit fuse or fuse holding
• Disconnect test leads or probe from the measuring circuit before switching
models or functions.
• Check the test leads and probes for faulty insulation or bare wires before
connection to the equipment
• Do not cover the ventilation slots of the cabinet to ensure that the air is able to
circulate freely inside
• Do not insert metal objects into the equipment by way of the ventilation slots
• Do not place water-filled containers on the equipment (danger of short-circuit
in case of know-over the container)
• To avoid electrical shock, do not operate this product in wet or damp
conditions. Conduct measuring works only in dry clothing and rubber shoes, i.
e. on isolating mats
• Never touch the tips of the test leads or probe
• Comply with warning labels and other info on the equipment
• Do not subject the equipment to direct sunlight or extreme temperatures,
humidity or dampness
• Do not subject the equipment to shocks or strong vibrations
• Do not operate the equipment near strong magnetic fields (motors,
transformers etc.)
• Keep hot soldering irons or guns away from the equipment
• Allow the equipment to stabilise at room temperature before taking up
measurement important for exact measurements)
• Periodically wipe the cabinet with a damp cloth and mid detergent. Do not
use abrasives or solvents
• The meter is for indoor use only.
• Do not operate the meter before the cabinet has been closed and screwed
safely as terminal can carry voltage.

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• Do not store the meter in a place of explosive, inflammable substances
• Do not modify the equipment in any way
• Opening the equipment and service- and repair work must only be performed
by qualified service personnel
• The instrument must be set up so that the power plug can removed from the
socket easily.
• Measuring instruments don´t belong to children hands
Introduction of PeakTech®DDS Function Generators
With Direct Digital Synthesis Technique（DDS）, PeakTech ®DDS function
generators are of the high performance indexes and numerous function characteristics
which are necessary for the fast completion of measuring. The simple and clear front
panel design and the display interface of number and indicator light are convenient
for the users to operate and observe. Moreover, the extended optional functions
enhance the system characteristics.
The generators are of the following advanced specifications and powerful
function characteristics.
 High frequency accuracy: up to the level of 10-5.
 High frequency resolution: 20mHz for the whole range.
 Unlimited measurement range: without limitation for the whole range, digital
setting directly.
 Non-intergraded process: up to the stable value immediately when switching,
continuous signal phase and amplitude without deflection.
 High waveform accuracy:the output waveform is synthesized by the computation
value of functions with higher waveform accuracy and less distortion.
 Multi-waveform: 16 types of waveforms can be output.
 Square characteristics: Accurate square duty cycle can be set.
 Output characteristics: Independent output for two channels, the phase
difference can be set accurately.
 Frequency sweeping: Be of the function of frequency sweeping and amplitude
sweeping. Start point and end point can be set arbitrarily.
 Frequency modulation: Frequency modulation signal (FM) can be output.
 Computation function: Frequency or period, amplitude virtual value or peak-
peak value can be selected.

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 Operation mode: Keyboard operation, color large screen menu display, direct
digital setting or continuous adjusting by knobs.
 High reliability: The adopting of Large Scale Integration circuit, SMT and VFD
make the generator high reliability and long service life.
 Frequency measuring：Cymometer can be selected to measure the frequency of
external signal.
 Power amplification: Power amplifier can be selected and the output power can
reach to 7W.
PeakTech DDS function generators and accessories (package list)
PeakTech DDS function generator 1
3-core power supply 1
Q9 testing cable 1
Q9 bi-nip wire 1
《User’s guide》1
Options for PeakTech DDS function generators
 Frequency counter
 Power amplifier
Summary of the Book
Brief Introduction
The brief usage of the generator is introduced in chapter one.
Principle Summarize
The basic working principle of the generator is described in chapter two.
Handling Instruction
The function, the operation and the application of the generator are described in
detail in chapter three.

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Introduction of Optional Components
The functions and usages of the optional components are introduced in chapter four.
Specifications
The performances and technical specifications of the function generator are
introduced in detail in chapter six.
Notice: Please excuse any modification of the contents without special
notification. Besides, it is unavoidable for not-so-adequate description and
wrong printing. The present document will not warrant in any form
including, but not limited to, those for special aims.
Chapter One Brief Introduction
The front panel and Rear panel of PeakTech®DDS function generators are
described in this chapter so as to help users to master the usage as quickly s possible.
The main contents of the chapter are as follows.
 Prepare to use
 Front Panel and Rear Panel
 Screen description
 Keyboard description
 Basic operation
1.1 Prepare to use
1.1.1 To check the instrument and the accessories:
Check whether the instrument and the accessories are complete and unbroken. If
the package is badly damaged, please keep it until the instrument passes the
performance testing.

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1.1.2 Plug in and turn on the function generator
To guarantee the safe operation of the instrument, the following conditions
should be achieved.
Voltage：AC 100-240V
Frequency：50/60 Hz
Power：＜30VA
Temperature：0～40 Humidity：80％
Plug the power connector into power socket outlet on the rear panel with safe
earth- wire. Press the power switch on the front panel to switch on the power. Now
the initialization of the generator begins, and then the default parameters are
installed. The instrument will enter into the working state of single frequency of
channel A and output sine waveform and display the frequency value and amplitude
value of signal of channel A.
Warning: In order to ensure the security of the operator, triple- core
socket outlet with safe earth-wire must be used.
1.2 Description of Front Panel and Rear Panel
Front Panel
1. Display screen 2. Power switch 3. Waveform selection keys 4.option key
5. Output A 6. Output B 7. Synchronization 8. Direction keys 9. Adjusting knob
10. Function and numeric keys 11. USB interface connector
1
2
3
4
5
6
7
11
10 9
8

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Rear Panel
1. AC power socket 2. Fan 3. External Modulation Input Terminal 4. Input of frequency
measurement 5. Power Amplifier Input 6. Power Amplifier Output
1.3 Screen description
There are two rows of digisplay on the screen. The parameters of time such as
frequency, period, interval, gate time, frequency deviation modulation, duty cycle
and others are shown on the upper row. The parameters of voltage such as amplitude,
offset, attenuation, as well as other parameters such as harmonic times, phase
difference, waveform sequence number and so on are shown on the lower row. There
are 22 indicator lights on the screen indicating output channels, signal waveforms,
the current function and options as well as the units of the parameters. The
instrument has 5 functions with the following different options. The options with
shadow in the following table are the common ones which can be selected directly
by pressing the corresponding keys on the front panel and the instrument will enter
into the function of these options automatically. The options without shadow are
uncommon-used .So it is required to select the corresponding function firstly, and
then select different terms circularly by 【Menu】.
23 5 6
4
1

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Table of function option
function Frequency of
channel A
sine
Frequency of
channel B
sine
Frequency
sweeping Frequency modulation
Exterior
measuring
frequency
Frequency of
channel A
Frequency of
channel B
Start
frequency
Carrier
frequency
Exterior
measuring
frequency
Period of
channel A
Period of
channel B
End
frequency
Carrier
amplitude Gate time
Amplitude of
channel A
Amplitude of
channel B
Step
frequency
Frequency
modulation
Waveform of
channel A
Waveform of
channel B
Sweeping
mode
Offset of
Frequency
modulation
Duty cycle of
channel A
Duty cycle
of channel B
Interval
time
Modulation
waveform
Attenuation of
channel A
Harmonic
waveform of
channel B
Offset of
channel A
Phase shift
of channel B
Step frequency
option
Step amplitude
1.4 Keyboard description
There are 38 keys on the front panel of the instrument with the following
functions (see the layout of the front panel).
The keys of 【0】【1】【2】【3】【4】【5】【6】【7】【8】【9】：To
enter the numbers.
The key of【.】：To enter the Decimal point.
The key of【-】：To enter the minus in the option of “Offset”, and in other
circumstances, it is used to enable or disable the key-press sound circularly.
The keys of 【CHA 】【CHB 】【Sweep 】【FM 】【Count 】：Function
selection keys.
The key of 【Menu】：To select the options without shadow in the table of
function options circularly.

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The keys of 【Freq 】【Perd 】【Ampl 】【Atten 】【Offs 】【Duty 】
【Harmo】【Phase】：To select the options with shadow in the table of function
options directly.
The key of【pp/rms】：To select the Peak-peak value and Virtual value of the
amplitude circularly.
The waveform selection keys of 【Sine 】【Square 】【Triang 】【Ramp 】
【Arb】: Press the former four keys to select the four common waveforms. Press
【Arb】key to select one of the 16 waveforms using the waveform sequence number.
The above five keys are bi-functional keys. They also have the functions of
units 【MHz 】【kHz 】【Hz 】【mHz 】【%】and waveform sequence number
【n】. If pressing the five keys after data input, the units of the data will be selected
so as to be the end of the data input.
The keys of【∧】【∨】：To increase or decrease the frequency or the
amplitude stepping of channel A.
The keys of【＜】【＞】：To move the cursor leftwards or rightwards.
The key of 【Cal.】:To calibrate the parameters.
The key of 【Reset】: To restore the system.
1.5 Basic operation
The following description will explain the basic operation to meet the usual need
of the users. Every user whoever has questions should read the corresponding
contents in the chapter three of the instruction.
1.5.1 Setting of parameters of channel A：Press the key of 【CHA】to light the
indicator lights of “CHA” and “Tone” and the instrument will enter into the single
frequency function of channel A.
Setting of frequency of channel A：Set the frequency to be 3.5kHz
【Freq】【3】【.】【5】【kHz】
Adjusting of frequency of channel A：Press the key of 【＜】 or 【＞】to move
the cursor. In order to adjust the frequency finely or crudely, turn the knob clockwise
or anticlockwise to decrease or increase the number with continuous carry or borrow.

10
In this way, other option data can also be adjusted by the knob ,which will not
restated again.
Setting of period of channel A ：Set the period to be 25ms
【Perd】【2】【5】【ms】
Setting of amplitude of channel A ：Set the amplitude to be 3.2V
【Ampl】【3】【.】【2】【V】
Selecting of amplitude format of channel A ：Virtual value or peak-peak value
【pp/rms】. The indicator light of Vpp means the selection of peak-peak value
of amplitude. The indicator light of Vrms means the selection of virtual value of
amplitude.
Selecting of common-used waveforms of channel A ：Select sine, square, triangle,
ramp for channel A
【Sine】【Square】【Triang】【Ramp】
Selecting of waveform of channel A：Select exponential for channel A（waveform
no.12，see the table of 16 waveform sequence numbers on page 19）
【Wave】【1】【2】【n】
Setting of duty cycle of channel A：Set the duty cycle of channel A to be 65％
【Duty】【6】【5】【%】
Setting of attenuation of channel A：Set the fixed attenuation to be 0dB（select
auto attenuation, AU, after start-up or reset）
【Atten】【0】【dB】
Setting of offset of channel A ：Set the DC offset to be -1V when the attenuation is
0dB.
【Offs】【-】【1】【V】
Step frequency of channel A：Set the step frequency of channel A to be 12.5Hz
Press the key of 【Menu】and then press the keys of【1】【2】【•】【5】【Hz】.
The frequency of channel A will be added by 12.5Hz at each pressing of the key of
【∧】; the frequency of channel A will be reduced by 12.5Hz at each pressing of
the key of【∨】.
1.5.2 Setting of parameters of channel B：Press the key of【CHB】and the
indicator lights of “CHB” and “Tone” will be on and select the function of “Single

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frequency of channel B”. The setting method of frequency, period, amplitude, Vpp,
Vrms, waveform, duty cycle of channel B is the same as those of channel A.
Setting of harmonic waveform of channel B：Set the frequency of channel B is the
once harmonic waveform of channel A.
【Harmo】【1】【n】
Phase shift of channel B：Set the phase difference between the two channels is 90°
【Phase】【9】【0】【°】
1.5.3 Frequency sweeping of channel A：Press the key of 【Sweep】. Sweeping
signal is output from channel A. Use default parameters.
Setting of sweeping mode：Set the sweeping mode to be to-and-fro.
Press the key of【Menu】to light the indicator light of “Sweep” and then press
【2】【n】
Setting of other parameters is described in 3.4.
1.5.4 Frequency modulation of channel A
Pressing the key of【FM】，the signal of frequency modulation（FM）is
output from channel A. The default parameters are used.
Setting of frequency deviation modulation ：Set the frequency deviation
modulation to be 5％
Press the key of 【Menu】to light the indicator light of “Devia”. Press the keys
of 【5】【%】.
The setting of other frequency deviation modulation parameters will be described
in 3.5.
1.5.5 Initialization or reset state
The initial working state after start-up or resetting by pressing the key of
【reset】is as follows：
Waveform of channel A and channel B：sine
Frequency of channel A and channel B：1kHz
Amplitude of channel A and channel B：1Vpp
Duty cycle of channel A and channel B：50%
Attenuation of channel A：AU (automatic)
Offset of channel A：0V
Harmonic waveform of channel B：1.0

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Phase shift of channel B：0°
Start frequency：500Hz
End frequency：5kHz
Step frequency：10Hz
Interval time：10ms
Sweeping mode：0 (positive)
Carrier frequency：50kHz
Carrier amplitude：1Vpp
Frequency modulation：1kHz
Frequency deviation modulation：5.0%
Modulating waveform：sine
Gate time：1000ms
Chapter Two Principle summarize
In the present chapter, users will acquaint with the basic concept of the signal forming and
the interior operation of the generator so as to know more about the specifications and use the
generator in the best way.
 Principle frame
 Working principle of DDS
 Working principle of operation control

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2.1 Principle frame
2.2 Working principle of DDS
To generate a voltage signal, the traditional analog signal source adopts electronic
components as oscillator in different ways. So both frequency accuracy and stability are not
high enough. Besides, it is of the disadvantages of complicated technique, low resolution and
inconvenient frequency setting and realization of computer control. Direct Digital
Synthesize（DDS）technique is a new developing method of generating signals without any
oscillator components, by which a series of data stream are generated using digital synthesizing
method and then a pre-established analog signal is generated from digital-analog converter.
To generate a sine signal, for example, the function of y＝sinxshould be digitally
quantized first, and then taking x as the address and y as the quantized data to store them into
DDS
Digital circuit
Lowpass Comparator TTL output
FM
Voltage
amplification
Amplitude
control
and AM
Power
amplification
Offset setting
Modulation input
Output
attenuation
20-60dB
Output
protection
Output A
Lowpass Amplitude
control
Power
amplification
Output B
Keyboard
MCU
DDS
Knob
Displayer
Clock

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waveform memorizer. DDS uses phase adding technique to control the address of waveform
memorizer. Add a phase increment on the present result of phase accumulator in each sampling
clock period so as to change the output frequency value by change phase increment. According
to the address from the phase accumulator, take the quantized data out from the wave
memorizer and then convert it into analog voltage via digit-analog converter and operation
amplifier. Since the waveform data are discontinuous sampling, stair sine waveform is output
from DDS generator. The included high-level harmonic wave should be filtered by lowpass
filter so to output a continuous sine wave. With high accurate reference voltage source in digit-
analog converter, the output waveform is if high amplitude accuracy and stability.
Amplitude controller is a digit-analog converter. Based on the amplitude value preset by
user, it generates a corresponding analog voltage and then multiplied by the output signal so to
guarantee the amplitude of output signal to be the preset value. Offset controller is a digit-
analog converter. Based on the offset value preset by user, it generates a corresponding analog
voltage and then added with the output signal so to guarantee the offset of output signal to be
the preset value. The synthesized signal from amplitude and offset controllers is amplified by
the power amplifier and then is output from output end A.
2.3 Working principle of operation control
MPU controls keyboard and display parts by interface circuit. When the key is pressed,
MPU identifies the code of pressed key and then executes the corresponding commands.
Display circuit displays the working state and parameters of the generator using menu
characters.
The knob on the panel can be used to change the number in the position of cursor. A
trigger pulse will be generated for each rotating of 15°. MPU can judge whether the rotation is
left or right. If it is left, the number in the position of cursor will be subtracted by 1; if it is right,
the number in the position of cursor will be added by 1 with continuous carry or borrow.
Chapter 3 Handling instruction
 General operation rule
 Frequency of channel A
 Frequency of channel B
 Frequency sweeping

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 Frequency modulation(FM）
 Exterior measurement
 Parameter calibration
3.1 General operation rule
3.1.1 Data input：If an item is selected, the parameter value can be entered by ten
numeric keys writing from left to right. If there are more than one decimal point
entered in a parameter, only the first one is valid. For the function of “Offset”,
minus can be entered. To make the data come into effect, unit key must be entered
after data input. For wrong data input, there are two ways to modify. If the output
end permits wrong output signal, press any unit key to end and then re-enter data. If
the output end does not permit wrong output signal, re-select the same item and
enter correct data, and then press unit key to end it.
The input of data can use any assorted decimal point and unit, but the generator
will display it in fixed format. For example, the data 1.5kHz or 1500Hz entered will
be effective displayed as 1500.00Hz.
Take the unit key as the ending of a data entering. The corresponding unit,
Hz ，V ，ms ，％ or dB, will be displayed. No display for other units.
3.1.2 Step entering method：In practice, a group of equidistant frequencies or
amplitudes is needed. It will be a messy job to use numeric key entering method.
Using knob will be also inconvenient as the distant value is multi-digit. It can be
easily reached by step entering method. To simplify the operation, the step function
for the frequency and amplitude of channel A is set. By the simple step key, the
frequency or the amplitude can be added or subtracted a step. Besides, the changed
frequency will come into effect at once without pressing the unit key.
To generate a series of frequencies with the distant of 12.5kHz, for example, the
sequence of pressing is as follows:
Press the key of 【Menu】to select “Step frequency”; press the keys of【1】
【2】【.】【5】【kHz】; The frequency of channel A will be added by 12.5Hz at
each pressing of the key of 【∧】and the frequency of channel A will be reduced by
12.5Hz at each pressing of the key of【∨】. Now a series of increasing-by-distant
or decreasing-by-distant frequencies with the step of 12.5kHz are obtained in fast and

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accurate way. The Step entering method can only be used in the frequency of channel
A or the amplitude of channel A.
3.1.3 Knob adjusting ：In practice, signal needs to be adjusted sequentially
sometimes, so number adjusting knob will be used. There is a blink position of cursor
in the numeric display. Press the key of 【＜】 or 【＞】 to move the blink cursor
leftwards or rightwards. Rotate the knob on the panel can adjust the number
sequentially with increasing 1 by turning it clockwise or decreasing 1 by turning it
anticlockwise, even carry or barrow from high-order digit. By the knob, data come
into effect after entering and do not need enter unit key. When the blink cursor
moves leftwards, the data can be adjusted crudely and when it moves rightwards, the
data can be adjusted finely.
3.1.4 Selecting of input way：For known data, it is the most convenient to use
numeric keys as it can be gotten easily without the generating of transient data no
matter how big the change of the data is, which is so important. For the modifying of
the entered data or for entering sequence data, it will be more convenient to use the
knob. But for a series of equidistant data, using step key will be much more
convenient. So user should select neatly according to the different applications.
3.2 Frequency of channel A
Press the key of 【CHA】to light the indicator lights of “CHA” and “Tone”.
The frequency value and the amplitude value of signal of channel A will be displayed
and the waveform indicator light will display the waveform of channel A.
3.2.1 Setting of frequency of channel A: Press the key of 【Freq】to display the
current frequency value. The frequency value can be entered either by the numeric
keys or by the knob. The signal of the frequency will be output at the end of “Output
A”.
3.2.2 Setting of period of channel A: The signal of channel A can also be set and
displayed in the form of period. Press the key of 【Perd】. The current period value
will be displayed. Then use the numeric keys or the knob to enter the period value.
But frequency synthesizing way is still used in the interior of the generator. It is only
a conversion when entering and displaying the data. Limited by the low-end
resolution of frequency, only those frequency points with large distant period can be
entered for longer periods. Although the setting and display of the period are

17
accurate, the period values of real output signal will be greatly different. The user
should know fairly well.
3.2.3 Setting of amplitude of channel A：Press the key of 【Ampl】and the
current amplitude will be displayed. Then use the numeric keys or the knob to enter
the amplitude value. The amplitude will be output at the end of “Output A”.
3.2.4 Format of amplitude value：There are two ways to display and to enter the
amplitude of channel A. Press the key of 【pp/rms】to circularly select peak-peak
value or virtual value and the corresponding indicator light will be on. The displayed
value of the amplitude will vary with the different format.
Although there are two formats for amplitude values, the working way inside the
generator is Vpp. Limited by the amplitude resolution, a little difference will be
produced between the former and the latter after exchanging. Entering 1Vpp for sine
wave, for example, the virtual value after changing is 0.353Vrms. But entering
virtual value of 0.353Vrms, the Vpp after changing is 0.998Vpp. Of course, the
difference is within the error range. If the waveform is square, the conversion
coefficient is 2. Vrms is used only in the function of “Frequency of channel A” and
the waveform is sine or square. For other functions or other waveforms, only Vpp but
not Vrms will be used.
3.2.5 Amplitude attenuator：The generator is set to “Auto” when startup or reset.
Press the keys of【Atten】and “AU” will be displayed. Then the generator selects
the attenuation proportion automatically according to the magnitude of the set
amplitude. The attenuation switches when the output amplitudes are 2Vpp，0.2Vpp
and 0.02Vpp. Now, higher amplitude resolution and signal-to-noise can be obtained
regardless of the magnitude of amplitude. The distortion of waveform is smaller. But
a little instant jumping will occur for output signal when attenuation switching,
which is not allowed in some cases. So the fixed attenuation way is set for the
generator. Pressing the key of 【Atten】, the attenuation value can be entered by the
numeric keys. The attenuation is 0dB when the data entered＜20, 20dB when the data
entered ≥20, 40dB when the data entered≥40, 60dB when the data entered≥6 and auto
when the data entered≥80. The knob can also be used to adjust the attenuation. The
attenuation will change one gear for each step. If the fixed attenuation way is
selected, the attenuation step will not be changed when the amplitude of signal
changes So that the output signal within the whole amplitude range will be changed

18
continually. But if the amplitude of signal is small in the attenuation of 0dB, the
distortion of waveform will be larger and the signal-to-noise ratio is worse.
3.2.6 Output load：The setting value of amplitude is calibrated when the output
end is open. The real voltage of output load is the setting value of amplitude
multiplied by the assignment ratio of load resistance and output resistance. The
output resistance is about 50Ω. When the load resistance is big enough, the assignment ratio
approaches to 1. The voltage loss of output resistance can be neglected. The real
voltage approaches to the setting value of amplitude. But when the load resistance is
smaller, the voltage loss of output resistance cannot be neglected. It should be paid
more attention that the real voltage does not accord with the setting value of
amplitude.
Output of channel A has over-voltage protection and over-current protection. Several-
minute short circuit or reverse voltage of less than 30V will not lead to any obvious damage.
Nevertheless, the above cases should be avoided in case of potential damage for the generator.
3.2.7 Flatness of amplitude：For the output frequency less than 1MHz, the
amplitude of output signal is very flat. For the output frequency greater than 10MHz,
the matching characteristics of output amplitude and load will lead to the worse
flatness. The maximum output flatness will be limited too. Generally speaking, the
maximum output flatness is only 15Vpp if the output frequency is greater than
15MHz and the maximum output flatness is just reach to 8Vpp if the output
frequency is greater than 20MHz. The larger the output amplitude is, the bigger the
distortion of the waveform is.
3.2.8 Setting of offset of channel A：In some cases, certain DC component should
be contained in the AC signal to be output so as to produce DC offset. Press the key
of【Offs 】and select “ Offset of channel A”. The present offset value will be
displayed. Use the numeric keys or the knob to enter the offset value. The preset DC
offset will be produced from the output of channel A.
It must be paid attention that the summation of the half of the output amplitude
of signal and the absolute offset value should be less than 10V to guarantee the peak
value of signal less than ±10V. Otherwise, the amplitude-limited distortion will be
induced. Besides, when the attenuation of channel A is selected auto, the output
offset will attenuate with the attenuation of amplitude. For the Vpp of amplitude
greater than 2V, the real output offset is the set offset value. For the Vpp of
amplitude greater than 0.2V but less than 2V, the real output offset is tenth of the set

19
offset value. For the Vpp of amplitude less than 0.2V, the real output offset is one
percent of the set offset value.
It will be more convenient using the numeric keys than the knob when adjusting
DC offset for output signal. In general case, whether DC offset is positive or
negative, DC level will rise if turning right and fall if turning left. Sign of positive
and negative will change automatically when passing through zero point.
3.2.9 Output of DC voltage：If amplitude attenuation of channel A is set to be 0
dB, the output offset value is equal to the preset offset value and it is independent of
the amplitude. If the amplitude is set to be 0V, the offset can be set arbitrarily within
the range of ±10V. The apparatus will be a DC voltage source and preset DC voltage
signal can be output.
3.2.10 Selection of waveform of channel A：There are 16 waveforms in channel A.
Press the key of 【Wave】and the sequence number of the present waveform will be
displayed. The sequence number can be entered by the numeric keys and press the
key of 【n】to select the required waveform. It can also be changed by the knob
conveniently. For the four common-used waveforms, press the keys of 【Sine】
【Square】【Triang】【Ramp】to select directly. The sequence numbers and names
of the 16 waveforms are shown in the following table.
List of names and sequence numbers of 16 waveforms
sequence
number waveform name sequence
number waveform name
00 sine Sine
08 positive DC Pos-DC
01 square Square
09 negative DC Neg-DC
02 triangle Triang 10 all sine
commuting All sine
03 up ramp Up ramp 11 limit sine Limit sine
04 down ramp Down
ramp 12 square-root function Exponent
05 positive
pulse Pos-pulse 13 logarithm
function Logarithm
06 negative
pulse Neg-pulse 14 Half round
function Half round
07 Stair Stair 15 sine function Sin(x)/x

20
3.2.11 Setting of duty cycle of channel A：Press the key of 【Duty】and the
channel selects square automatically. The duty cycle is displayed. The value can be
entered by the numeric keys or by the knob. The square with set duty cycle will be
output. The adjusting range of duty cycle is 1％～99％.
3.3 Frequency of channel B
Press the key of 【CHB】to select the function of“Frequency of channel B”. The
sequence number and name of waveform of channel B will be displayed on the top
left of the screen.
The setting method of frequency, period, amplitude, Vpp, Vrms, waveform, duty
cycle of channel B is the same as those of channel A. the difference is that no
amplitude attenuation and no DC offset for channel B.
3.3.1 Setting of harmonic wave of channel B：The frequency of channel B can be
set and displayed at the multiple of the frequency of channel A. That is to say, the
signal of channel B is the N-grade harmonic wave of the signal of channel A. Press
the key of【harmo】and selected “Harmonic wave of channel B”. The grade of
harmonic wave can be entered by the numeric keys or by the knob. The phases of the
two channels can get the stable synchronously.
If “Harmonic wave of channel B” is not selected, the signals of two channels
will not keep harmonic relation at all. Even the frequency of channel B is set to be
the multiple of that of channel A, the signals between the two channels cannot
always reach the phase synchronization. So to keep the harmonic relation between
the signals of two channels, set the frequency of channel A; select “Harmonic wave
of channel A” and set harmonic grade. The frequency of channel B can be changed
automatically. Do not use the frequency of channel B.
3.3.2 Setting of phase shift of channel B If the harmonic wave of channel B has
been set, press the key of【Phase】and select “Phase shift of channel B”. Now the
signals of two channels are completely synchronous with the phase difference of 0.
The phase difference of the signals of two channels can be entered by the numeric
keys or by the knob. The maximum resolution of time difference of the signals of two
channels is 80ns, so the resolution of phase difference is higher when the frequency
is lower. For example, the resolution of the phase difference is 1°when the frequency
is lower than 34KHz. The higher the frequency is, the lower the resolution of the