assigment osiloskope
TRANSCRIPT
PENGENALAN KEPADA OSILOSKOP
Osiloskop adalah alat asas untuk mengkaji berbagai jenis bentuk gelombang . Ia
boleh digunakan untuk mengukur kuantiti seperti voltan puncak , frekuensi , beza fasa ,
lebar denyut,masa lengah , masa naik dan masa jatuh . Terdapat berbagai jenis
osiloskop daripada alatan asas yang mudah kepada alatan boleh aturcara yang canggih
dengan bacaan digit . Walau bagaimanapun,prinsip dan ciri-ciri asasnya tetap sama
KEGUNAAN OSILOSKOP
* Pengukuran Voltan Puncak-ke-puncak
Amplitud puncak ke puncak bentuk gelombang yang terpapar pada osiloskop
bolehdiukur dengan mudah .
Pastikan bahawa tombol vernier pusat pada kawalan VOLT/DIV pada kedudukan
tentukur (CAL) sebelum mengukur amplitud bentuk gelombang .
Vpp = (jumlah bahagian p ke p ) x ( volt/div )
Voltan Puncak , Vp = Vpp / 2
* Penentuan Frekuensi
Tempoh ialah masa yang dilalui oleh satu kitar gelombang . Tempoh
masa T boleh ditentukan
dengan mengukur masa bagi satu kitar mengikut bahagian mendatar dan
mendarab nilai tersebut
dengan nilai time/div yang disetkan pada osiloskop .
T = ( jumlah bahagian mendatar/kitar ) ( time/div )
- Frekuensi dikira sebagai songsangan tempoh masa , T .
* Pengukuran Arus
Osiloskop merupakan alatan bergalangan masukan tinggi . Oleh itu , ia tidak
boleh digunakan secara langsung untuk mengukur arus .
Arus diukur melalui jatuhan voltan pada satu perintang .
Untuk tujuan itu , perlu berhati-hati dengan sambungan osiloskop kepada
perintang kerana salah satu hujung perintang perlu berada pada keupayaan
bumi kecuali jika penguat masukan kebezaan digunakan .
* Pengukuran Fasa
* Pengukuran Denyut
OPERASI OSILOSKOP
* Alur elektron bergerak dan menghentam lapisan fosfor di skrin .
* Satu titik terbentuk di seluruh skrin dan kecerahannya ditentukan oleh banyaknya
electron yang terkena pada lapisan fosfor .
* Alur elektron dipesong pada paksi-x dan paksi-y untuk mempamerkan bentuk 2 dimensi
pada skrin .
* Paksi-x dipesong dengan satu kadar malar yang dirujuk kepada masa ( time/div ) .
* Paksi-y dipesong sebagai sambutan kepada masukan yang diberkan ( volt/div ).
PRINSIP KENDALIAN
* Osiloskop terdiri daripada tabung sinar katod (C.R.T.) dan litar-litar kawalan
dan masukan yang berkaitan .
* Dalam tabung sinar katod , elektron terjana oleh katod yang dipanaskan
dibentukkan kepada alur halus dan dipecutkan ke arah skrin pendarflour .
* Skrin tersebut mengeluarkan cahaya pada tempat yang terkena elektron .
* Alur elektron terpesong pada arah menegak dan mengufuk oleh voltan yang
dikenakan pada plat memesong .
BINAAN OSILOSKOP
ALAT-ALAT KAWALAN PADA OSILOSKOP
Litar Tegak
* Volt/div
- Memberikan skala yang tertentu pada gambaran isyarat di paksi-Y .
- Kalau isyarat terlalu besar , skala dinaikkan dan sebaliknya .
* Pembolehubah
- Jika skala Volt/div hendak digunakan ianya mesti dipusingkan ke kedudukan
CAL , sekiranya tidak dilakukan nilai yang ditunjukkan bukanlah nilai yang
sebenar .
* AC-GND-DC
- GND . membumikan isyarat supaya garis sifar dapat ditentukan di skrin .
- AC . memberikan gambaran isyarat ulang-alik .
- DC . memberikan isyarat terus .
* Position
- membolehkan isyarat dinaikkan dan diturunkan di skrin . * INV
- Menyongsangkan isyarat .
Litar Mendatar * Time/div
- memberikan skala masa isyarat dari kiri ke kanan skrin osiloskop .
- skala hanya boleh digunakan jika pembolehubah di bahagian tengah berada
pada kedudukan CAL .
* Position
- Membolehkan isyarat dibawa ke kiri atau ke kanan skrin osiloskop .
Litar Picu
* Trigger Source
- INT . isyarat diambil dari dalam
( salah satu bentuk gelombang atau isyarat masukan )
- EXT . isyarat diambil dari luar ( perlu masukan pada punca EXT TRIGGER )
- LINE . isyarat diambil dari talian atau frekuensi kuasa a.u.
* SYNC ( Penyegerakan )
- Selalu digunakan dalam keadaan biasa ( normal )
- Kedudukan TV digunakan jika bentuk gelombang adalah kompleks .
* Trigger Level ( aras picuan )
- menjana gelombang mata gergaji yang diperlukan oleh plat pesongan datar jika
mod ' Time ' digunakan ( asas masa ) .
- Penguat datar menguatkan isyarat tadi sebelum dihantar ke plat pesongan datar
pada CRT
* Litar Picu
- Mengawal pergerakan antara isyarat mata gergaji dan isyarat masukan yang
diberikan pada litar tegak .
- Memastikan pesongan tegak dan datar bermula pada masa yang sama .
- Boleh disambungkan kepada ' internal ', ' external ' dan ' line ' .
* Bekalan Kuasa
- Membekalkan voltan tinggi kepada CRT .
- Membekalkan voltan kendalian kepada lain-lain litar .
Skrin
* Focus
- Memfokuskan paparan kepada garisan yang lebih halus .
* Intensity
- Mengawal kecerahan paparan .
* Beam Finder
- Untuk mendapatkan semula paparan yang teranjak keluar dari skrin .
* Power On/Off
- Menghidup atau mematikan osiloskop .
MULTICHANNEL OCILOSCOPE
All TiePie engineering measuring instruments can be used as a USB oscilloscope. An
oscilloscope is an instrument to display signal voltages, plotted against time (Yt) or against
another signal voltage (XY). A benefit of graphically showing signals is that an oscilloscope will
show what is actually happening. The precise shape of the signal and time relations in the
signal or between signals can be seen.
WHEN TO USE THE OSCILOSCOPE
A scope has many applications, in many different areas. An important application of the
oscilloscope is to troubleshoot circuits that do not function properly. Another possible application
is using the labscope as signal monitor when adjusting a circuit under test.
An instrument toolbar is created for each detected instrument. The instrument toolbar is fully
configurable through the program settings. It shows the current settings of the instrument and
allows to change all settings.
USING THE INSTRUMENTS TOOLBAR
In the default setup, the instrument toolbar contains the following items:
Start/Stop button
The Start button is used to start continuous measurements.
When the measurement is running, it will change into a Stop button to stop the running measurement.
Both actions can also be executed by hotkey S.
One shot button
When no measurement is running, the One shot button is enabled. It can be used start a single shot measurement (hotkey O).
Auto setup button
The Auto setup button can be used to let the software quickly change several
instrument settings, to acquire stable measurements. Use it by clicking the button or
pressing its hotkey Q (quick auto setup). When the CTRL key is pressed while starting
the auto setup, the instrument will stay in auto setup mode. This can be used to track
changing signals. Choose which instrument settings may be changed by auto setup
in Settings->Instruments->Auto setup.
Measure mode button
The measure mode button can be used to switch between block- and streaming
mode. Switching the measure mode requires the instrument to be stopped measuring.
Instrument identification
This item displays the instrument name as well as its serial number,
which is a unique number in your measuring instrument. By using the serial numbers as
the instrument ID, it is clear which of the instruments you are controlling. Clicking the
instrument ID will show a popup menu with all instrument settings.
Record length + Sample frequency + Resolution
In this item, information concerning the current sample frequency, record
length and the resolution is shown. Settings can be adjusted through popup menus by
clicking on the text labels.
Time out + Trigger source
When using an instrument that supports triggering, the trigger
timeout and trigger source of the measuring instrument are also shown. Settings can be
adjusted through popup menus by clicking on the text labels.
Presamples knob
The pre samples turning knob controls the pre and post samples ratio. By default, no
pre samples are used and it is set to 0%. Dragging it up and down adjusts the knob, a
hovering readout displays the current setting. Right clicking it shows a popup menu with
predefined settings and a user defined setting.
Other controls that can be placed on the instrument toolbar are:
Sample frequency
The sample frequency readout shows the current sampling frequency. Clicking
the readout shows a popup menu with available sample frequencies.
Increase/decrease sampling frequency
Two buttons are available to increase or decrease the sample frequency:
Decrease the sample frequency one step (hotkey F3).
Increase the sample frequency one step (hotkey F4).
The steps that are taken are the sample frequencies that are available in the sample
frequency menu of the instrument. When a user defined sample frequency was
selected, each subsequent click on one of these buttons will double or halve the sample
frequency.
Record length
The record length readout shows the current record length. Clicking the readout
shows a popup menu with available record lengths.
Increase/decrease record length
Two buttons are available to increase or decrease the record length:
Decrease the record length one step (hotkey F11).
Increase the record length one step (hotkey F12).
The steps that are taken are the record lengths that are available in the record length
menu of the instrument. When a user defined record length was selected, each
subsequent click on one of these buttons will double or half the record length.
Resolution
The resolution readout shows the current resolution. Clicking the readout shows a
popup menu with available resolutions.
Increase/decrease resolution
Two buttons are available to increase or decrease the resolution:
Decrease the resolution one step.
Increase the resolution one step.
The steps that are taken are the resolutions that are available in the resolution menu of
the instrument.
Increase/decrease pre trigger percentage
Two buttons are available to increase or decrease the pre trigger percentage:
Decrease the pre trigger percentage with 2.5% (hotkey SHIFT + ←)
Increase the pre trigger percentage with 2.5% (hotkey SHIFT + →)
Oscilloscope time/div
The oscilloscope time/div readout shows the current time/div setting as if the
instrument is used as oscilloscope. Clicking the readout shows a popup menu with
available time/div settings.
Increase/decrease oscilloscope time/div
Two buttons are available to increase or decrease the oscilloscope time/div:
Decrease the time/div one step.
Increase the time/div one step.
The steps that are taken are the time/div settings that are available in the time/div
menu.
Increase/decrease oscilloscope time resolution
Two buttons are available to increase or decrease the oscilloscope time resolution:
Decrease the time resolution one step.
Increase the time/div one step.
An oscilloscope measurement has a record length and a sample frequency. This gives
a total measuring time. With each subsequent click on one of these buttons, the record
length and sample frequency are respectively halved or doubled. The total measuring
time remains equal, but the time resolution will decrease or increase.
Trigger now!
Force the instrument to trigger now (hotkey space bar).
Predefined trigger time out settings
Three buttons are available to set the trigger time out:
Set the trigger time out to zero (hotkey 0)
Set the trigger time out to 1 second (hotkey 1)
Set the trigger time out to infinite (hotkey w)
OSCILLOSCOPE GRAPH
The oscilloscope can have one or more graphs, each displaying one or more signals, where each graph can display different parts of a signal. Graphs can display the signal(s) in Yt mode or in XY mode, with or without interpolation. Colors of all items in a graph can be set to any required value. Graph dimensions can be adjusted to any required size, graphs can be located in one single window or in separate windows, which can be located anywhere on the desktop.
Cursors are available to make on screen measurements, as well as a t=0 line to indicate the trigger moment. Signals can be given descriptive names and a legend is available to simplify identifying the displayed signals. Text labels can be placed to mark interesting parts of the signal(s).
To reveal all details of the measured signals, unlimited zooming is available in both vertical and horizontal direction. All zoom actions can be undone with an undo zoom function.
OSCILLOSCOPE CONTROL
Controlling the oscilloscope is done through customizable toolbars, through popup menus and by hotkeys. A quick function toolbar is available for often used functions.
STORAGE OSCILLOSCOPEStorage oscilloscope An instrument that is used to measure fast nonrepetitive signals. It does
this by capturing the signal on demand and continuing to display it until reset. This can be
achieved in two ways: a digital storage oscilloscope samples the incoming signal, stores these
samples, and displays them; other storage oscilloscopes use a special storage cathode-ray
tube that retains the image by mapping it as a charge pattern on an electrode behind the
screen; the pattern then modulates the electron beam to give a picture of the captured signal.
Trace storage is an extra feature available on some analog oscilloscopes; they used
direct-view storage CRTs. Storage allows the trace pattern that normally decays in a fraction of
a second to remain on the screen for several minutes or longer. An electrical circuit can then be
deliberately activated to store and erase the trace on the screen.
The storage is accomplished using the principle of secondary emission. When the
ordinary writing electron beam passes a point on the phosphor surface, not only does it
momentarily cause the phosphor to illuminate, but the kinetic energy of the electron beam
knocks other electrons loose from the phosphor surface. This can leave a net positive charge.
Storage oscilloscopes then provide one or more secondary electron guns (called the "flood
guns") that provide a steady flood of low-energy electrons traveling towards the phosphor
screen. Flood guns cover the entire screen, ideally uniformly. The electrons from the flood guns
are more strongly drawn to the areas of the phosphor screen where the writing gun has left a
net positive charge; in this way, the electrons from the flood guns re-illuminate the phosphor in
these positively-charged areas of the phosphor screen.
If the energy of the flood gun electrons is properly balanced, each impinging flood gun
electron knocks out one secondary electron from the phosphor screen, thus preserving the net
positive charge in the illuminated areas of the phosphor screen. In this way, the image originally
written by the writing gun can be maintained for a long time — many seconds to a few minutes.
Eventually, small imbalances in the secondary emission ratio cause the entire screen to "fade
positive" (light up) or cause the originally-written trace to "fade negative" (extinguish). It is these
imbalances that limit the ultimate storage time possible.
Storage oscilloscopes (and large-screen storage CRT displays) of this type, with storage
at the phosphor, were made by Tektronix. Other companies, notably Hughes, earlier made
storage oscilloscopes with a more-elaborate and costly internal storage structure.
Some oscilloscopes used a strictly binary (on/off) form of storage known as "bistable
storage". Others permitted a constant series of short, incomplete erasure cycles which created
the impression of a phosphor with "variable persistence". Certain oscilloscopes also allowed the
partial or complete shutdown of the flood guns, allowing the preservation (albeit invisibly) of the
latent stored image for later viewing. (Fading positive or fading negative only occurs when the
flood guns are "on"; with the flood guns off, only leakage of the charges on the phosphor screen
degrades the stored image.
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