能与使用说明
安捷伦函数信号发生器33120A 是数字式函数信号发生器。其内部永久存储着正弦波、方波、三角波、噪声、锯齿波、sin(x)/x 、负锯齿波、指数上升波、指数下降波、心电波，共10种函数信号。其中，正弦波、方波的频率范围为100μHz －15MHz ，幅值范围为100mV P-P －10V P-P 。函数信号发生器有一个HP-IB （IEEE-488）接口和一个RS-232接口，计算机通过接口可遥控函数信号发生器，在计算机中使用HP BASIC 语言程序或C 语言程序，能产生12bit 40Msa/s 的任意波形，通过接口写入函数信号发生器，函数信号发生器有四个可存储16000点的任意波形存储器。其具体的性能指标和基本操作方法见本节后摘录自“Agilent 33120A Function Generator User Guide ”的内容。要知道详细的内容应阅读该仪器的“用户手册”。
⒈ 信号源显示电压与实际输出电压
理想信号源的内阻应为零。若实际信号源的内阻为零，则
信号源输出端一旦短路或负载电阻过小，信号源就会因功率过
载而损坏。实际信号源一般都在其输出端串接一个电阻R s ，
使信号源既使短路，在短时间内也不会因功率过载而损坏，由
此使信号源的保护电路有时间实现对信号源输出电路进行保护，
同时发出过载警告。
称信号源输出端串接电阻R s 为信号源内阻。 安捷伦33120A （以下简称为信号源）的内阻为50Ω。 由于有了信号源内阻R s ，如图1，信号源输出端的电压，
即负载电阻R L 上的电压，是信号源的电源E s 在信号源内阻R s 和负载电阻R L 上的分压，即V o ≠E s 。信号源内设置了两个负载电阻值，开机时默认为R LD =50Ω，通过操作可修改为R LD →∞。
在信号源开机默认为R LD =50Ω时，信号源内部的电压源输出的电压为E s ，信号源显示屏上显示的电压是
s s LD s LD Display E 2
1E R R R V =+= （1） 若实际负载不是50Ω，那么负载上实际得到的电压V o 为
s s L s L o E 2
1E R R R V ≠+= （2） 即信号源显示屏上显示的电压与负载上得到的实际电压不一样，V o ≠V Display 。
在实际使用时，当信号源的负载电阻，即电路的输入电阻R L 与50Ω可比时，信号源宜取R LD =50Ω状态，这时V o ≠V Display ，但是V Display 比较接近V o 。信号源的负载电阻，即电路的输入电阻R L >>50Ω时，信号源宜取R LD →∞状态，这时V o ≠V Display ，但是V Display 比较接近V o 。V o 究竟为多少应使用电压表具体测量。
⒉ 关于本信号源的具体性能指标和基本操作使用方法
以下关于本信号源的具体性能指标和基本操作使用方法摘自“Agilent 33120A Function Generator User Guide ”。直接阅读原版用户手册，比阅读翻译后的用户手册更有利于了解关于本信号源的具体性能指标和基本操作使用方法。在使用本信号源前，
使用者必须阅读以下
的内容。
附录
Agilent 33120A Function Generator User Guide Specifications
1
18℃ to 28℃ range (1-year specification).
2100 mVpp – 20 Vpp amplitude into open-circuit load.
3Offset ≤2 X peak-to-peak amplitude.
4For square wave outputs, add 2% of output amplitude additional error.
5Trigger source ignored when External Gate is selected.
6Time to change parameter and output the new signal.
7Modulation or sweep off.
8Times For 5-digit and 12-digit numbers.
9For 4800 baud, multiply the download times by two; For 2400 baud, multiply the download times by four, etc.
10Time for 5-digit numbers. For 12-digit numbers, multiply the 5-digit numbers by two.
Operating Basics
The Front Panel
①Function/Modulation keys ②Menu operation keys
③WaveForm modify keys ④Single/Internal Trigger key(Burst and Sweep only) ⑤Recall/Store instrument state key ⑥Enter Number key
⑦Shift/Local key ⑧Enter Number “Units” key
Quick StART
One of the first things you will want to do with your function generator is to become acquainted with its front panel. We have written the exercises in this chapter to prepare the function generator For use and help you get familiar with some of the front-panel operations.
The front panel has two rows of keys to select various functions and operations. Most keys have a shifted function printed in blue above the key. To perForm a shifted function,
press
(the Shift
annunciator will turn on). Then, press the key that has the desired label above it. For example, to select the AM (amplitude modulation) function,
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press
(the shifted version of the
key).
If you accidentally press Shift
annunciator. Most keys also have a number printed in green next to the key. To enable the number
mode, press (the
Num annunciator will turn on). Then, press the keys that have the desired numbers printed next to them. For example, to select the number “10”, press
(next to the
and keys).
If you accidentally press
to turn off
the
Num annunciator. To set the output frequency
At power-on, the function generator outputs a sine wave at 1 kHz with amplitude of
100 mV peak-to-peak (into a 50Ω termination).
The following steps show you how to change the frequency to 1.2 MHz. 1 Enable the frequency modify mode.
Press The displayed frequency is either the power-on value or the previous frequency selected.
When you change functions, the same frequency is used if the present value is valid For the new function.
2 Enter the magnitude of the desired frequency.
Press
or use the knob
and arrow keys to change the number.
Notice that the Num
annunciator turns on and “ENTER
NUM” flashes on the display, indicating that the number mode is enabled.
To cancel the number mode, press 3 Set the units to the desired value.
Press (MHz/mVpp)
The units are selected using the arrow keys on the right side of the front panel. As soon as you select the units, the function generator outputs the waveform with the displayed frequency. To turn off the flashing digit, move the cursor to the left of the display using the arrow keys.
To set the output amplitude
At power-on, the function generator outputs a sine wave with amplitude of 100 mV peak-to-peak (into a 50_ termination).
The following steps show you how to change the amplitude to 50 mVrms.
1 Enable the amplitude modify mode.
Press
The displayed amplitude is either the power-on value or the previous amplitude selected. When you change functions, the same amplitude is used if the present value is valid For the new function.
2 Enter the magnitude of the desired amplitude.
Press
or use
the knob
and arrow keys to
change the
number.
Notice that the Num annunciator
turns on and
“ENTER NUM” flashes on
the display, indicating that the number mode is enabled.
To cancel the number mode, press
3 Set the units to the desired value. Press
(kHz/mVrms)
The units are selected using the arrow keys on the right side of the front panel. As soon as you select
the units, the function
generator outputs the
waveForm with the displayed amplitude.
To turn off the flashing digit, move the cursor to the left of the display using the arrow keys.
To set a dc offset voltage
At power-on, the function generator outputs a sine wave with a dc offset voltage of 0 volts (into a 50Ω termination). The following steps show you how to change the offset to
–1.5 mVdc.
1 Enable the offset modify mode.
Press The displayed offset voltage is either the power-on value or the previous offset selected. When you change functions, the same offset is used if the present value is valid for the new function.
2 Enter the magnitude of the desired offset.
Press or use the knob and arrow keys to change the number.
Notice that the Num annunciator turns on and “ENTER NUM” flashes on the display, indicating that the number mode is enabled. Notice that toggles the displayed value between + and – .
To cancel the number mode, press
3 Set the units to the desired value.
Press
(kHz/mVrms)
At this point, the function generator outputs the waveForm with the displayed offset. Notice that the Offset annunciator turns on, indicating that the waveForm is being output with an
offset. The annunciator will turn on when the offset is any value other than 0 volts. To turn off the flashing digit, move the cursor to the left of the display using the arrow keys.
To set the duty cycle
Applies only to square waves. At power-on, the duty cycle for square waves is 50%. You can adjust the duty cycle for a square waveform from 20% to 80%, in increments of
1% (for frequencies above 5 MHz, the range is 40% to 60%). The following steps show you how to change the duty cycle to 45%.
1 Select the square wave function.
Press
Notice that the
annunciator turns
on, indicating that the square
wave function is enabled.
2 Enable the duty cycle modify mode.
Press The displayed duty cycle is either the power-on value or the previous value selected.
This message appears on the display for approximately 10 seconds. Repeat this step as needed.
3 Enter the desired duty cycle.
Press
or use the knob
and arrow keys to change the
number.
Notice that the Num annunciator turns on and “ENTER NUM” flashes on the display, indicating that the number mode is enabled.
To cancel the number mode, press 4 Output the waveform with the displayed duty cycle.
Press
To output a stored arbitrary waveform
There are five built-in arbitrary waveforms stored in non-volatile memory for your use. You can output these waveforms directly from non-volatile memory. The following steps show you how to output an “exponential rise” waveform from memory.
Shift Arb List 1 Display the list of arbitrary waveforms.
Press
The list contains the five built-in arbitrary waveForms (sinc, negative ramp, exponential rise, exponential fall, and cardiac). The list may also contain up to four user-defined arbitrary waveForm names. The first choice on this level is “SINC”.
This message appears on the display for approximately 10 seconds. Repeat this step as
needed.
2 Move across to the EXP_RISE choice.
Press
3 Select and output the displayed arbitrary waveform.
Press
Notice
that the Arb
annunciator turns on, indicating
that the output
is an arbitrary waveform. The waveform is output using the present settings for frequency, amplitude, and offset unless you change them.
The selected waveform is now assigned to the key. Whenever you press this
key, the selected arbitrary waveform is output. To output a dc voltage
In addition to generating waveforms, you can also output a dc voltage in the range ±5
Vdc (into a 50Ω termination). The following steps show you how to output +155 mVdc. 1 Press the
key and hold it down for more than 2 seconds
. To enter the dc voltage mode, press the key or any key in the top row of function keys and hold it down for more than 2 seconds . The displayed voltage is either the power-on value or the previous offset voltage selected.
2 Enter the magnitude of the desired voltage.
Press or use the knob
and arrow keys to change the number.
Notice that the Num annunciator turns on and “ENTER NUM” flashes on the display, indicating that the number mode is enabled.
To cancel the number mode, press 3 Set the units to the desired value.
Press (kHz/mVrms)
At this point, the function generator outputs the displayed dc voltage. Notice that the Offset annunciator turns on (all other annunciators are off), indicating that a dc voltage is
being output. The annunciator will turn on when the offset is any value other than 0 volts.
To store the instrument state
You can
store up to
three different instrument states in
non-volatile memory. This enables you to recall the entire instrument configuration with just a few key presses from
the front panel. The following steps show you how to store and recall a state.
1 Set up the function generator to the desired configuration.
The state storage feature “remembers” the function, frequency,
amplitude, dc offset, duty cycle, as well as any modulation parameters.
2 Turn on the state storage mode.
Press
Three memory
locations (numbered 1, 2,
and 3) are
available to store instrument
configurations. The instrument configuration
is stored in non-volatile memory and is remembered when power has been off.
This message appears on the display For approximately 10 seconds. Repeat this step as needed.
3 Store the instrument state in memory location “2”.
Press or use the knob and arrow keys to change the number.
Use the up and down arrow keys to select the memory location.
To cancel the store operation, press again or let the display time-out after 10 seconds.
4 Save the instrument state.
Press
The instrument state is now stored. To recall the stored state, turn to the next page.
To verify that the state was stored properly, you can turn the power off beFore recalling the state.
5 Recall the stored instrument state.
Press
To recall the stored state, you must use the same memory location used previously to store the state. Use the up and down arrow keys to change the displayed storage location.
To cancel the restore operation, press again.
This message appears on the display for approximately 10 seconds. Repeat this step as needed.
6 Restore the instrument state.
Press The function generator should now be configured in the same state as when you stored
the setup on the previous page.
When power is turned off, the function generator automatically stores its state in memory location “0”. You can rec all the power-down state, but you cannot store the state to location “0” from the front panel.
Use the POWER ON ENABLE command in the SYS MENU to automatically recall the power-down state when power is turned on. See chapter 3 For more information on using the front-panel menus.
MENU
A: Modulation MENU
1: AM SHAPE → 2: AM SOURCE → 3: FM SHAPE → 4: BURST CNT → 5: BURST RATE → 6: BURST PHAS → 7: BURST SRC → 8: FSK FREQ → 9: FSK RATE → 10: FSK SRC 1: AM SHAPE Selects the shape of the AM modulating waveform.
2: AM SOURCE Enables or disables the internal AM modulating source.
3: FM SHAPE Selects the shape of the FM modulating waveform.
4: BURST CNT Sets the number of cycles per burst (1 to 50,000 cycles).
5: BURST RATE Sets the burst rate in Hz for an internal burst source.
6: BURST PHAS Sets the stARTing phase angle of a burst (-360 to +360 degrees).
7: BURST SRQ Selects an internal or external gate source for burst modulation.
8: FSK FREQ Sets the FSK “hop” frequency.
9: FSK RATE Selects the internal FSK rate between the carrier and FSK frequency.
10: FSK SRC Selects an internal or external source for the FSK rate.
B: SWP (Sweep) MENU
1: START F → 2: STOP F → 3: SWP TIME → 4: SWP MODE
1: START F Sets the start frequency in Hz for sweeping.
2: STOP F Sets the stop frequency in Hz for sweeping.
3: SWP TIME Sets the repetition rate in seconds for sweeping.
4: SWP MODE Selects linear or logarithmic sweeping.
C: EDIT MENU *
1: NEW ARB → 2: POINTS → [3: LINE EDIT] → [4: POINT EDIT] → [5: INVERT] → [6: SAVE AS] → 7:DELETE
1: NEW ARB Initiates a new arb waveform or loads the selected arb waveform.
2: POINTS Sets the number of points in a new arb waveform (8 to 16,000 points).
3: LINE EDIT Performs a linear interpolation between two points in the arb waveform. 4: POINT EDIT Edits the individual points of the selected arb waveform.
5: INVERT Inverts the selected arb waveform by changing the sign of each point.
6: SAVE AS Saves the current arb waveform in non-volatile memory.
7: DELETE Deletes the selected arb waveform from non-volatile memory.
* The commands enclosed in square brackets ( [ ] ) are “hidden” until you make a selection from the NEW ARB command to initiate a new edit session.
3D: System MENU
1: OUT TERM _ 2: POWER ON _ 3: ERROR _ 4: TEST _ 5: COMMA _ 6:REVISION
1: OUT TERM Selects the output termination (50_ or high impedance).
2: POWER ON Enables or disables automatic power-up in power-down state “0”.
3: ERROR Retrieves errors from the error queue (up to 20 errors).
4: TEST PerForms a complete self-test.
5: COMMA Enables or disables a comma separator between digits on the display.
6: REVISion Displays the function generator’s firmware revision codes.
E: Input / Output MENU
1: HPIB ADDR _ 2: INTERFACE _ 3: BAUD RATE _ 4: PARITY _ 5: LANGUAGE
1: HPIB ADDR Sets the GPIB bus address (0 to 30).
2: INTERFACE Selects the GPIB or RS-232 interface.
3: BAUD RATE Selects the baud rate for RS-232 operation.
4: PARITY Selects even, odd, or no parity for RS-232 operation.
5: LANGUAGE Verifies the interface language: SCPI.
F: Calibration MENU *
1: SECURED →[1: UNSECURED] →[2: CALIBRATE] →3: CAL COUNT →4: MESSAGE
1: SECURED The function generator is secured against calibration; enter code to unsecure.
1: UNSECURED The function generator is unsecured for calibration; enter code to secure.
2: CALIBRATE Performs individual calibrations; must be UNSECURED.
3: CAL COUNT Reads the total number of times the function generator has been calibrated.
4: MESSAGE Reads the calibration string (up to 11 characters) entered from remote.
* The co mmands enclosed in square brackets ( [ ] ) are “hidden” unless the function generator is UNSECURED for calibration.
Three Step During Menu Use
This section is a step-by-step tutorial which shows you how to use the front-panel menu. We recommend that you spend a few minutes with this tutorial to get comfortable with the structure and operation of the menu before attempting verification, calibration, or adjustments.
The menu is organized in a top-down tree structure with three levels (menus, commands,
and parameters). You move down or up the menu tree to get from one level to the next. Each of the three levels has several horizontal choices which you can view by
moving left or right .
The menu is organized in a top-down tree structure with three levels.
* To turn on
* To turn off * To exECUte
*
To recall
* To
turn off
3
Messages Displayed During Menu Use
TOP OF MENU You pressed while on the “MENUS” level; this is the top level of the menu and you cannot go any higher.
To turn off the menu, press
To move across the choices on
a level, press or .
To move down a level, press
.
MENUS You are on the “MENUS” level. Press
or to view the choices.
COMMANDS
You are on the
“COMMANDS” level. P
ress
or to view
the command choices within the selected menu group.
PARAMETER
You are on the “PARAMETER” level. Press or
to view and edit the parameter For the selected command.
MENU BOTTOM
You pressed
while on the “PARAMETER” level; this is the bottom level of the menu and you cannot go any lower. To turn off the menu, press . ENTERED The change made on the “PARAMETER” level is saved. This is displayed after you press (Menu Enter) to execute the command.
MIN VALUE The value you specified on the “PARAMETER” level is too small for the selected command. The minimum value allowed is displayed for you to edit.
MAX VALUE The value you spe cified on the “PARAMETER” level is too large for the selected command. The maximum value allowed is displayed for you to edit.
EXITING You will see this message if you turn off the menu by pressing or
. You did not edit any values on the “PARAMETER” level and changes were NOT saved.
NOT ENTERED You will see this message if you turn off the menu by pressing or
changes were NOT saved. Press (Menu Enter) to save changes made on the
“PARAMETER” level.
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