Zoom is a show software that expands the view of the chosen waveform. The supply hint could be expanded horizontally and vertically for detailed visible evaluation or additional processing. Every zoom hint can have its personal horizontal and vertical scale setting, enabling views of the supply hint utilizing a number of horizontal and vertical scales. All digital oscilloscopes provide zoom performance.
Zoom is vital as a result of oscilloscopes can purchase gigasamples of information per acquisition, with a vertical decision of 12 or extra bits. This information have to be displayed on a display screen with a decision of roughly 1920 x 1080 pixels. If a full acquisition is displayed, the information needs to be compacted to suit on the display screen. Increasing the information with a zoom hint in order that it suits throughout the display screen decision permits a view of all of the acquired information.
Zoom demo
Zoom could be invoked from this oscilloscope’s entrance panel utilizing the Zoom button. It may also be evoked interactively by touching the touchscreen and dragging the ensuing field over the realm to be expanded. Zoom traces may also be managed from the Zoom Hint dialog packing containers (Determine 1).
Determine 1 An instance of a number of zoom cases used to investigate a distant keyless entry system waveform. The Zoom dialog field is used to manage every zoom hint. Supply: Artwork Pini
The supply waveform from a distant keyless entry (RKE) system seems as hint M1 within the prime grid. The waveform includes an amplitude-modulated RF service. The modulation encodes the instructions to lock a automobile door. Zoom is used to broaden the fifth pulse within the acquired waveform horizontally. Observe that the zoomed space is highlighted by elevated depth on the supply hint. The expanded model seems in hint Z1 (second down from the highest). The Z1 hint is managed utilizing the Z1 zoom dialog field on the backside of the show.
The hint’s horizontal and vertical scale and offset could be adjusted interactively whereas observing the consequences on the display screen. The hint annotation field for the Z1 hint reveals the vertical and horizontal scaling for the zoom hint. Hint Z1 has a horizontal scale of 150 seconds per division, in comparison with the 5 milliseconds per division scale of the M1 supply hint, representing an growth of thirty-three instances.
The zoom hint reveals variations within the RF service amplitude at first and finish of the burst. These keying transitions have an effect on the technology of spurious indicators that may intrude with different RF providers. The zoom hint Z2 expands the view of the trailing fringe of the primary zoom hint and shows it intimately within the third grid from the highest. Right here, we now have an instance of Zoom on Zoom.
The evaluation continues by demodulating the sign in Z2 by low-pass filtering absolutely the worth of the waveform. The demodulated sign could be measured to acquire the sign amplitude’s slew fee and the decaying amplitude’s time fixed. That is an instance of a math operation on Zoom. The maths hint F1 performs demodulation; the result’s displayed within the backside grid. This instance used two zooms, every with a special horizontal scale.
Horizontal and vertical scale components
Zoom, within the oscilloscope used for this text, could be utilized to any waveform, acquired indicators, math, reminiscence, and even different zoom traces. Zoom traces are waveforms like every other. They are often expanded additional utilizing one other zoom hint, permitting the identical sign to be seen with a number of horizontal or vertical scale components.
Math operators could be utilized, permitting arithmetic, filtering, or FFTs to be carried out on them. The variety of out there zoom traces typically matches the variety of acquisition traces; nonetheless, all non-acquisition traces, like math or reminiscence traces, have zoom performance on this household of oscilloscopes.
Determine 2 supplies an instance of zoom getting used to broaden a sign vertically.
Determine 2 The echo in an ultrasonic vary finder sign is expanded vertically to see the main points of a double sign return. Supply: Artwork Pini
A double echo in an ultrasonic vary finder is zoomed vertically to see the element of the waveform that’s not simply discerned on the acquired waveform. The vertical decision of this waveform is twelve bits or 4096 ranges. Not less than a four-to-one vertical zoom is required to render the complete decision on a show with 1080-pixel vertical decision. A ten-to-one vertical growth reveals the echo at 5 mV per division, offering an in depth view of the waveform construction.
Multi-Zoom
Some purposes use a number of zoom traces with the identical growth issue for comparability functions. Contemplate the measurement of an I2C information sign and clock indicators proven in Determine 3.
Determine 3 Utilizing time-locked multi-zoom to confirm the timing between an I2C information and its related clock sign. Supply: Artwork Pini
The sign within the prime grid is an I2C information sign. The grid instantly under that’s the related I2C clock. These waveforms are expanded synchronously utilizing a function referred to as multi-zoom. Multi-zoom locks the chosen zoom traces collectively. This function permits frequent horizontal management of all zoom traces. They are often expanded or contracted synchronously, locked in time, or offset by a user-defined time offset.
Within the instance, the zoom traces Z1 and Z2 are the expansions of the information and clock sign, respectively. They’re locked in time with no offset. The expanded view makes it simpler to see the relative timing of the indicators. So, the beginning situation, the place the information sign is compelled to a low state, adopted by the clock sign being compelled low, is simple to discern. The zoom traces incorporate the deal with area of the I2C packet. The expanded view afforded by the zoom shows is helpful in evaluating bodily layer points like sign ranges, interval, with, transition instances, and timing.
The multi-zoom function additionally contains an auto-scroll mode to mechanically scan via the whole waveform at a user-set fee (Determine 4).
Determine 4 The zoom auto-scroll controls permit computerized scrolling of the zoom horizontal location of the zoom hint to scan via lengthy information. Supply: Artwork Pini
Computerized scrolling could be very useful when shifting slender zoom home windows via very lengthy acquisitions which may require an excessive variety of turns of a knob. It presents two scan charges and the power to leap to the intense values.
Evaluating waveform segments
Zoom shows might help evaluate waveforms. For example, an acquired I2C information sign comprises a number of information packets; Zoom can be utilized to show these packets on the identical expanded timescale for comparability (Determine 5).
Determine 5 Utilizing zoom traces to separate and evaluate I2C information packets on the identical expanded time scale. Supply: Artwork Pini
Packets 1, 2, and 4 from the acquired I2C information bus acquisition are separated and in contrast utilizing three zoom traces with the identical scale components however with completely different offsets. It’s simple to see the distinction within the size of packet 2; the information content material of the three packets differs within the final half millisecond of the waveforms.
Utilizing Zoom to window indicators
Zoom can choose, or window, particular areas of an acquired sign for additional processing. This enables the examination of chosen components of a sign individually. Contemplate analyzing an RKE system that makes use of frequency shift keying (FSK) to encode instructions (Determine 6).
Determine 6 Utilizing zoom traces to isolate the one and nil state frequencies in an RKE system utilizing FSK modulation. Supply: Artwork Pini
The hint within the higher left grid represents 10 ms of a 260-ms-long RKE command. The RKE fob makes use of FSK to encode the digital one and nil states. The hint under the acquired hint reveals that the demodulated FSK information is an NRZ serial sign. The upper-right grid reveals the FFT of the acquired RKE sign. The sign has a frequency-modulated 434-MHz service. The FFT reveals two peaks attribute of frequency hopping, one similar to the frequency of the one state and the opposite to the frequency similar to the zero state.
Zoom can be utilized to separate the components of the acquired sign similar to the sign’s 0 and 1 states. Zoom hint Z1 (third grid down on the left) reveals the a part of the RKE sign matching the zero state proven within the demodulated sign. The period of the zoom hint is adjusted to suit throughout the period of the digital state.
Equally, the zoom hint Z2 (backside left) has been used to pick the a part of the sign within the one-state. The intensified segments on the acquired waveform correspond to the chosen areas. FFTs of the zoom traces present that every digital state contributes a particular frequency to the sign.
Measurement parameters determine the zero frequency as 433.888 MHz and the one state as 433.964 MHz. The magnitude of the frequency shift between the 2 digital states is decided by taking the distinction between the 2 measured frequencies, which is 76 kHz. Zoom has separated the frequencies related to every digital state.
Observe that the FFT’s frequency decision is proportional to its enter’s file size and that the zoom traces are shorter than the acquired waveform and thus could have poorer decision. This doesn’t matter on this instance, the place the objective is to find out the frequencies of the 2 digital states.
Increasing waveforms with zoom
Zoom is a great tool for finding out and analyzing acquired waveforms by offering an expanded view of the sign vertically or horizontally. These traces present enhanced visible acuity, permitting the instrument’s full amplitude and time decision to be displayed on the display screen. In addition they choose particular components of a sign, permitting for the evaluation of solely these parts of the sign which can be of curiosity.
Arthur Pini is a technical assist specialist and electrical engineer with over 50 years of expertise in electronics check and measurement.
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