SUPPLEMENT TEST & MEASUREMENT SCOPE OF THE ART


With optional logic and protocol analyser, signal waveform and pattern generator and digital voltmeter, the latest entry class oscilloscopes from Rohde & Schwarz are an attractive option for the discerning user. Here Dr. Philipp Weigell gives us the low-down on this latest range of instruments


A


s far as oscilloscopes go they are an essential bit of kit but often the mire


of options can leave the onlooker rather weary with the abundance of choice. But if you are looking for something that features dedicated operating modes for spectrum analysis, mask tests and long data acquisitions then perhaps this is your answer. The R&SRTB2000 series oscilloscopes make debugging of all types of electronic systems easy and cost effective.


HIGH-RESOLUTION WITH GESTURE SUPPORT The high-resolution, capacitive 10.1" touchscreen makes working with the R&SRTB2000 a visual experience. At more than twice the size offered by other oscilloscopes in this class and with a resolution of 1280 × 800 pixels, the screen provides a richly detailed waveform display. Users also want fast and easy operation. This instrument offers touch gestures for easy scaling, zooming and moving waveforms – familiar features from smartphones. Now even customers with a limited budget can enjoy such convenience features. The user interface is the result of


extensive usability studies. Based on higher-class models, it eases the transition from third-party products. A toolbar provides fast access to frequently used functions and the R&S SmartGrid function makes optimal use of the screen for waveform display. All axes are labelled for quick recognition of signal characteristics. An annotation tool allows users to make notes directly on the screen or to highlight areas of interest (Fig. 1).


10-BIT VERTICAL RESOLUTION FOR VISIBLY MORE SIGNAL DETAILS Oscilloscopes measure voltage over time. The analogue-to-digital converter performs a key function in this process. Its characteristics determine how well an instrument can resolve the amplitude of measured signals. For decades, the standard has been an 8-bit ADC with 256 levels. The 10-bit ADC used here offers 1024 levels – four times that of other


S4 JULY/AUGUST 2017 | ELECTRONICS


Fig. 1: The annotation tool allows users to draw directly on the screen – convenient for commenting and reports


Fig. 2: Signal details of a decaying sine wave Above is an R&SRTB2000 oscilloscope with its standard 10-bit resolution. Below is the same signal with the ADC artificially limited to 8 bit


Fig. 3: The deep memory permits the acquisition of long signal sequences. This is especially useful when analysing data telegrams and serial protocols


oscilloscopes in this segment. The higher resolution permits more


precise measurements and helps users detect very small among very large signals. Fig. 2 illustrates the advantage of the higher resolution at the end of an exponentially damped sine function. A large vertical scaling factor is required to fully display the initially high signal level of the sine waveform. The screenshot shows the portion of the time axis in which the amplitude has dropped sharply. Shown underneath is the same


waveform displayed while artificially limiting the ADC to 8 bit. The 10-bit resolution is much richer in details. The display can be improved by using averaging and special decimation with lowpass filtering. This significantly higher resolution can be the key to finding a problem within a circuit.


10 MSAMPLE STANDARD MEMORY After the bandwidth and the sampling rate, the memory depth is the most important characteristic of an oscilloscope. It is the decisive factor in determining how well an instrument can be used for debugging. At 10 Msample per channel, this oscilloscope series has the largest acquisition memory in this class – up to ten times more than other instruments in this segment. In interleaved mode, the memory even increases to 20 Msample per channel. As a result, signal errors and important events are more reliably detected and the high sampling rate is retained even over long data acquisition times. Long acquisition times are essential for


analysing serial protocols. The standard memory in this machine provides sufficient record length for the data telegrams of most buses (Fig. 3). The memory can be optionally expanded to a 160 Msample segmented memory. This mode records only the periods containing signals, such as protocol communications data or signal pulses. For example, protocol-based signals with communications gaps such as I2


C or SPI


can be captured over several seconds or minutes. Thanks to the variable segment size ranging from 10 ksample to 10 Msample, the 160 Msample memory can be optimally utilised; more than 13,000 cohesive individual recordings are possible. Segmented memory in line with the


protocol trigger and decoding option turns this instrument into a protocol analyser capable of handling all the information in analogue or digital signal sources.


OFFERS ADAPTABILITY This series of oscilloscopes can be purchased as 2-channel or 4-channel instruments with bandwidths of 70MHz, 100MHz, 200MHz or 300MHz. Licence keys are available to unlock upgrades up to 300MHz bandwidth. The 4-bit pattern generator and the logic analyser are also enabled using licenced keys.


Rohde & Schwarz www.rohde-schwarz.com T: 01252 818888


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