Senin, 23 November 2009

Electrical Engineering

Oscilloscope

Examples of some use oscilloscope:
1. Large measure the electric voltage and its relationship with time.
2. Measuring the frequency of the oscillating signal.
3. Checking the course of a signal on an electrical circuit.
4. Distinguishes the current AC DC.
5. Check the noise in an electrical circuit and its relationship with time.

Oscilloscope are grouped into two sections based on how it works, namely: the analog oscilloscope and a digital oscilloscope.
a. Analog oscilloscope using the measured voltage to move the electron beam in a picture tube upwards or downwards in accordance with the measured waveform. On the oscilloscope screen can be instantly displayed the wave forms.

b. Digital oscilloscope waveform mencuplik measured and by using ADC (Analog to Digital Converter) to convert the sampled voltage magnitude into a digital scale.

PART oscilloscope
1. Cable connecting the probe is a tip given a brace, with the conductor kerkualitas, can reduce interference signals, such as radio signals or noise is strong. There are two connecting terminals on the probe, the probe tip and ground wires are usually fitted with alligator claws. In practice the crocodile claw is connected to the ground on the circuit, such as the metal chassis and touch the tip of the probe at a point on the circuit tested

2. Calibration of probes
In general, each oscilloscope is equipped with a reference signal source for calibration. For example, certain types of oscilloscope GW has a reference square wave with an amplitude of 2V peak to peak with a frequency of 1 KHz. Suppose channel 1 to be calibrated, the probe is connected to the BNC input of channel 1, as shown in the following figure:

3. Controller is used to adjust the intensity of the light intensity wave image displayed on the monitor oscilloscope. When you add the speed sweep (sweep speed) on an analog oscilloscope, then you should also increase the intensity level.

4. The controller is used to adjust the focus of the sharpness of the image wave. The controller is only found in analog oscilloscope:

5. The controller is used to change the vertical position and vertical wave scale. Oscilloscope has also set the controller to input coupling and other signal conditions discussed in this section. Figure 1 shows the front panel display and on-screen menu to control the vertical.

6. Controller vertical (cont.)
Vertical position of the button used to move the image on the screen waves upwards or downwards. Button Volts / div scale the display in the vertical direction. Selection position. Suppose the Volts / Div diputarpada position 5 Volt / Div, and the screen is divided into 8 boxes (division) vertical direction. Meaning, each division (the box) will describe the size of the voltage 5 volts and the entire screen can show 40 volts from bottom to top. If the button is on the position of 0.5 Volts / dDiv, the screen can display 4 volts from bottom to top, and so on. The maximum voltage that can be displayed on the screen is the scale value shown in the Volts / Div multiplied by the number of vertical boxes. If the reply is used probes using dilution factor of 10x, then reads the voltage to be multiplied 10.
Coupling is the method used to connect electrical signals from one circuit to another circuit. In this case, the input coupling is the link from the circuit being tested with the oscilloscope. Coupling can be defined / set to DC, AC, or ground. AC coupling prevents the DC component of the signal waveform is then seen centered at 0 volts.

Displays signal waves simultaneously. Alternating mode (alternate) to draw each channel in turn. This mode is used with the speed signal from the medium to high speed, when the scale of times / div is set at 0.5 ms or faster. Chop mode to draw small parts of each signal during the turn of the canal. Since the turn of the canal was too quick to note, that was a continuous waveform. For this mode is usually used to slow the speed signal sweep 1ms per section or less.

Osilioskop also has working system for adding two wave functions together, thus creating a new waveform display. Combining analog oscilloscope signals forming a digital oscilloscope while a new signal mathematically.

7. Horizontal Steering
Use the horizontal controls to adjust the position and scale on the horizontal part of the wave.

? Button Position
Button to move the horizontal position of the wave image from the left side to right or vice versa according to our wishes on the screen.
? Button Time / Div (time base control)
Time control buttons / span allows to adjust the horizontal scale. For example, if the scale of 1 ms is selected, then each box (division) indicates 1 ms and the total screen
indicates 10 ms (10 horizontal box). If one wave consists of 10 boxes, means periodanya is 10 ms or the wave frequency is 100 Hz. Changing Time / td enables us to see the signal intervals greater or smaller than the original, on the oscilloscope screen, the image will appear more waves meeting or tenuous

8. Trigger Controller
? Trigger is used to create a display image appear stationary. Trigger controller, allowing us to stabilize the repetition of the signal / wave and catch a wave of walking.
? Actual trigger voltage level can not be seen. Trigger button is used to adjust the voltage level, in this case is shown with scrollbar.
? Pemicuan techniques can be done in several ways. Pemicuan edge (edge triggering) is the basic and common type in pemicuan techniques.
? Trigger circuit behaves like a comparator. When matched with a trigger signal that is setting the oscilloscope to trigger

Digital oscilloscope TO WORK

If the analog oscilloscope waves are shown directly attributed to a series of vertical so memorable "taken" just like that (real time), then in a digital oscilloscope, a wave that is displayed first disampling (sampled) and digitized. Oscilloscope and then save the values of this voltage with the same wave time scale in memory. In principle, a digital oscilloscope and store mencuplik only so much value and then stops. He repeats this process again and again until stopped.
DSO has two ways to "catch" or mencuplik waves, ie with single shot techniques or real-time sampling. With both these techniques, get all the footage oscilloscope with an event trigger. In theory (according to the Nyquist sampling theorema), digital oscilloscope input with sekurangkurangnya require two trailers per period waves to reconstruct a waveform. In practice, three or more fragments per period to ensure the accuracy of the acquisition. If the sample can not be as quick with the input signal, oscilloscope will not be able
collect a sufficient amount to produce a result in another demonstration of the original waveform. the oscilloscope will describe the overall structure of the input signal at a frequency much lower than the actual signal frequency
When catching a wave form of single (single shot waveform) with real-time footage, digital oscilloscope to accurately capture the signal frequency
input. Digital oscilloscope is usually specifies two broad bands; real time and analog. Analog bandwidth expressed the highest frequency input channels that can escape without serious defects in the signal. Bandwidth real-time showing the maximum frequency of
oscilloscope that can accurately mencuplik using a trigger event.
With the alternative method that uses sampling equivalenttime DSO can accurately capture signals up to the osiloskopnya bandwidth, but only on the signals repetitive nature. With this technique, digital oscilloscope receives footage on many trigger events that then gradually constructing the entire waveform. Only the analog bandwidth oscilloscope at a frequency limit how many can accept this technique.

1. Left Active vs. Left Dead on the DSO
Sedangdiukurnya signal. Said oscilloscope sweep is active when the signal along the screen displays. At the end of each stroke, oscilloscope signals in sistempenyangga acquisitions (buffer) data. To enable the next menangkapsinyal DSO, this buffer must be emptied, moved to buffer the data in peraganya or to other places. And the trigger must ditimbulkanlagi. The time required to form these functions is called dead time.
At this dead time, after the acquisition, DSO to processing danmemperagakan-cuplikannya footage. While this was happening, something that happens on the input signal will be ignored by the oscilloscope DSO tersebut.Dengan other words can not meragakannya

2. Real-time Sampling
In real-time method of sampling, the digitizer memory DSOakanmengisi in one event from the signal stored danmenggunakan seperangkatdata demonstration tersebutuntuk create waves. Waktuwaktudiantara footage in yangdigunakan memory for the tuner show menciptakankembali said to be the real time in antaracuplikan-cuplikannya when needed. Therefore, real-time sampling, can be used for signals or recurrent nature bentuktunggal (single shot). However it is important to understand that denganrealtime sampling, will not get a display bentukgelombang similar to that of the analog oscilloscope (for signal-sinyalyang complex), but the signal shape of a simple sine or square berupagelombang.

3. Equvalent-time Sampling
Equivalent-time-sampling is a method used DSO to retrieve data from the frequency repetitive gelombanggelombang technique tinggi.Ini is real footage. Equivalent-time sampling provides an equivalent time resolution (horizontal) for a digitizeryang work at speeds much higher. He worked with mengambilcuplikan-trailers through a few incidents of the signal to semuamemori filled. For example, in a DSO with the ability to show 50 horizontal divisions cuplikantiap working on a time basis (time base) 5 nano seconds / division, the time between each sample is 5 / 50 nano detikatau 100 pico seconds. This would be equivalent to a speed of real-timesampling 10 gigabytes per second cuplik

4. Random and sequential
Random sampling (random) and sequential are two types of dariequivalent-time sampling. In random sampling, sample-cuplikandiambil random manner and the wave reconstructed with menggunakanpewaktuan of footage in front of the relative trigger point. Sampling Sementarasequential footage taken at the time the trigger on sesudahtitik signals that are repetitive. Thus, in random sampling, can be obtained the information before the trigger (pre-trigger), but the sequential sampling, the trigger that started it so it will not prosesakuisisinya obtained information about the shape was observed before gelombangyang happening pemicuan.

5. Oversampling
Each DSO real-time sampling of actual oversample. Istilahoversampling associated with the wave frequency on the rate cuplikanreal time. Oversampling means that decision-cuplikanpada footage of a higher frequency than the frequency signal sedangdiukur. An oscilloscope with a maximum sample rate of only 1 mega cuplik per second is still a far oversampling DSO menyangkutsinyal 100 kHz. An example of an oscilloscope oversamplingdengan only real-time technique is only 500 mega digitize cuplikper seconds (interval 2 nano seconds), will take five perperiode footage on 100 MHz signal is the same, which is used in the sample-equivalent above timesampling

6. Voltage Measurement
Voltage is greater electrical potential difference, expressed in Volts, between two points on rngkaian. Usually one is the point titikny ground, but not always. Voltage is also measured from peak to peak, ie from the point of maximum peak to minimum muncak point. Dankita must specify voltage hatihati what is meant.
Oscilloscope is basically a voltage meter. Once you measure the voltage, then the other quantities can be known through calculation. For example current measurement by applying Ohm's law can be known current through the voltage measurement and dividing by the use of barriers. The application can also be done calculations for AC circuit but certainly will be more complicated, but the point is that by measuring the voltage as a first step, then the other quantities can be known through calculation
Voltage measurement is done by counting the number of distributors that covers the face of the waves on the vertical scale. Set the signal by varying the vertical control and to better choose the best measurement scale volts / div is most appropriate.

7. Time and Frequency Measurement
Take the time measurement by using the horizontal scale on the oscilloscope. Measurements included the time period, pulse width (pulse width), and the time of the pulse. Frequency is a form of resiprok period, so by measuring the frequency period will be known, ie one per period.

8. Phase Measurement
starting from one loop to the beginning of the next loop. Measured in degrees. Phase shift describes the difference in timing between two or more identical periodic signals. One way of measuring the phase difference is to use the XY mode. Ie by plotting one signal in the vertical (Y axis) and other signals on the horizontal axis (X axis). This method will work effectively if the second signal is the signal used sinusiodal. The resulting waveform is called the image of the pattern