3 Frequency resolution Spectrum analyzers sweep the frequency range in discrete steps. In Figure 2, the sweep time is 5. 6 RBW and Sweep Time A signal displayed with the proper sweep time is shown in the 1st wave. Suppose one configures the signal analyzer to perform a High Resolution Audio Spectrum Analyzer: TrueRTA 's audio spectrum analyzer software shows you a detailed picture of what you're hearing in real-time, that is, as it happens. The figure-1 depicts filters used for RBW and VBW tuning in spectrum analyzer. This may be simplified and another way of looking at it is; The Spectrum Analyzer Local Osc, LO Sweep rate = span/sweep time= RBW²/k. Interference hunting and spectrum clearing – fast sweep speeds a low distortion front-end and the Real Time spectrum analyzer combine to quickly identify interfering signals. The SP145 is a high-performance, 14. 90 KHz the instrument is in Swept mode Spectrum analyzer for multiple SDR platforms (PyQtGraph based GUI for soapy_power, hackrf_sweep, rtl_power, rx_power and other backends) - xmikos/qspectrumanalyzer There are two broad categories of spectrum analyzers: swept-tuned analyzers and real-time analyzers. NSN 6625-01-656-1527 (Standard, not Opt 1) 4. The IF is the final mixer Intermediate freq. Unlike an oscilloscope, however, the spectrum analyzer has only one function-to produce a display of the frequency content of an input signal. Refer to the text for a discussion of the various circuit functions. Real-Time Spectrum Analyzers bring the dimension of time to RF Analysis making it easier to monitor and characterize these complex RF systems. com Spectrum Analysis Basics (AN150) | Keysight Compare the display of a traditional swept spectrum analyzer (Figure 3) and that of a real-time spectrum analyzer with a DPX spectrum display (Figure 4). From Speeding up Spectrum Analyzer Measurements Application Note Products: ı R&S®FPS ı R&S®FSW ı R&S®FSV ı R&S®SGT100A ı R&S®SMW200A ı R&S®SMBV100A Test time is a critical parameter when it comes to evaluating the cost of test. Previously only Linux software such as QSpectrumAnalyzer was compatible with hackrf_sweep, but now over on GitHub user pavsa has released Nov 22, 2013 · In other applications, such as a fast spectrum sweep, the instantaneous bandwidth of the signal analyzer directly affects measurement speed. This application note describes typical spectrum analyzer measurements in production environments Jul 8, 2014 · The Signal Hound series of spectrum analyzers are about as small as three large-size Hershey chocolate bars stacked on top of each other. Using the real-time spectrum analysis mode, you can trigger signals with a mask and even view signals in the time domain. • DC coupling applied if center frequency is < 20 MHz. (But it is possible to display the time waveform on the spectrum analyzer screen with the proper settings. But what's the difference between a network analyzer and a spectrum analyzer? swept spectrum analyzer architecture. The audio spectrum analyzer shows the changing spectrum of live input signals up to 48kHz (half the maximum sampling frequency). While the spectrum analyzer is used to show the frequency domain representation of the RF signals. The PSA Series Spectrum Analyzers Specification Guide can be obtained on the web through: 2 Choosing the Right Spectrum Analyzer Figure 2. Like an oscilloscope, a spectrum analyzer produces a visible display on a screen. The basic function is to represent the signals in a graphical display as amplitude—or power level—on the y-axis, against frequency on the x-axis; the amplitudes of detected signals are represented in the frequency domain. Mar 24, 2016 · This is the fourth and final post in a multi-part blog series, teaching you the essential concepts of spectrum analysis. It offers an extremely small POI (Probability Of Intercept) of up to 10ns and thus captures even extremely short signals. Whether you are doing simple signal visualization, integrating wireless technologies into your IoT design, characterizing component performance, preparing for emissions compliance testing or working with complex modulated signals RIGOL has a Spectrum Analyzer to fit your need and budget. PXA signal analyzers enable you to quickly find and measure signals of interest in complex and dynamic environments. Spectrum analyzer is the common tool for any RF engineer. The 20 MHz bandwidth of the HackRF One always allowed you to use it as a real-time spectrum analyzer if the spectrum of interest was narrower than 20 MHz (screenshot taken from gqrx): Recently, with release 2017. Both swept-tuned analyzers and real-time analyzers have been around for many years. In this note, we describe the basic spectrum analyzer as well as additional capabilities made possible using digital technology and digital signal processing. A signal analyzer can calculate power when a sine wave's peak or average value is known and the resistance across the value When talking about measurements with a spectrum analyzer we have to keep some parameters in our mind. 01 of the HackRF firmware and tools , a sweep mode was added which allows you to use the device as a wideband spectrum analyzer several different types of spectrum analyzer system architectures. Solve for ST ST = K*span/RBW2 Thus, sweep time must be increased with the square of RBW reduction. Set Time in passband = risetime. Aug 6, 2019 · The sweep speed refers to the time the vector network analyzer (VNA) requires to finish one sweep of the source signal and get all the selected data in a chosen frequency range. The real-time spectrum analyzer can capture transient and fast signals more quickly. Sweep time RF and microwave spectrum analyzers can make full-span calibrated measurements with sweep times ranging from 5 milliseconds to several thou-sand seconds, and zero-span sweeps in microsec-onds. A signal analyzer performs both functions together. The frequency appears on the horizontal axis, and the amplitude is displayed on the vertical axis. In fact, eight common mistakes plague the accuracy and effectiveness of spectrum analyzer measurements. Hence it takes a longer time using smaller RBW to sweep across a given frequency span. Spectrum Analyzer basics. As far as power measurement is concerned, spectrum analyzer displays power levels with accuracy of approx. It is important to understand exactly what resolution is being considered when specifying sweep speed. With the advent of wide bandwidth analog-to-digital converters (ADCs), high-speed memory, fast processors, and efficient fast-fourier transforms (FFTs), tens to hundreds of megahertz of instantaneous bandwidth can be processed as fast as it is received. The shape of a spectrum displayed on the analyser screen is a combination of the shape of the RBW filter and the shape of the true signal spectrum. What is a spectrum analyzer? Spectrum analyzer fundamentals Mar 3, 2017 · One of the most common specifications for comparing spectrum analyzers is sweep speed. We attempt to acquire data for at least as long as the value provided here. In either case, I’d either read the sweep time from the analyzer, or set it, or both. 5 *Span. +/- 0 Mar 10, 2017 · A few weeks ago the HackRF drivers and firmware were updated and one new feature added was hackrf_sweep. swept spectrum analyzer, FFT spectrum analyzer, real time spectrum analyzer (RTSA) and audio spectrum analyzer. 3 x PRF. A special interference finder option adds AM/FM demodulation with audio output plus interfering source triangulation on a digital map to pinpoint and identify the So, bottom line is for best measurement speed, use Sweep Type Swept for wide spans or wide RBWs, and FFT for narrow spans. A vector signal analyzer can display the data in the same way as a A simple way to describe a spectrum analyzer is a frequency-selective, peak-responding voltmeter calibrated to display the RMS value of a sine wave. Spectrum analyzer converts time domain signals into frequency domain for display and analysis. Since I cannot set number of points to exactly what is required, I would like to set the sweep times to the smallest allowed time. Here is the equation governing the sweep speed: Find Signals of Interest with Real-Time Spectrum analyzer (RTSA) When testing radar, electronic warfare, or signal intelligence systems, it is important that you find and measure signals of interest in complex and dynamic environments. 259 x 183 x 55 mm (Passive Cooling Option), 259 x 183 x 71 mm (Active Cooling Option) Real-Time Spectrum Analyzers from More than just a network analyzer, the PNA-X is the world’s most integrated, flexible RF test equipment for amplifiers, mixers, frequency converters, and other active devices. Nov 9, 2020 · You can put a spectrum analyzer into “zero span” mode with the power detector in linear mode (not logarithmic mode) and then adjust the trigger, sweep time, vertical position, and video The SPECTRAN ® V6 PLUS is Aronia's latest generation of high-performance real-time spectrum analyzers. Important features of RSA306B: 9 kHz to 6. When the sweep speed is not proper, UNCAL is displayed in the screen. If you’re only using one analyzer, you can tailor your approach knowing what it does. The VNA and spectrum analyzer are two of the most commonly used RF test instruments. Vector signal analyzers measure the magnitude and phase of an input signal at a single frequency. 6 seconds. SPECTRUM ANALYZER Some design engineers may have prior experience with either a VNA or a spectrum analyzer. There are two types of measurement acquisition in spectrum analyzers: swept and real-time. This new feature allows us to scan across the spectrum at up to 8 GHz per second, which means that a full 0 - 6 GHz scan can complete in under a second. Swept spectrum analyzer example with pulse noise Figure 4. Any signal at DC is up-converted to 2 GHz. A spectrum analyzer does what the name suggests: it detects the signals present in a selected range of spectrum. In some circumstances the sweep time makes a difference to the measurement quality. Number Of Sweep Points Describes the division of the complete Span into subranges to be used for each sweep step. Table of Contents. Real-time spectrum analyzers (RTSAs) deliver the information con-tained in RF/Microwave signals in a convenient format for engineers A Technical Brief from The measurement can be made with a portable vector/scalar network analyzer or a power meter. The supplied RTSA-Suite PRO software is precisely tailored to the powerful and robust hardware and supports the use of several SPECTRAN ® V6 ECO. Today, real-time spectrum analyzers are universally available from the smallest to the biggest test and measurement equipment companies, and as the use of real-time spectrum analyzers becomes more prevalent in the industry, some common questions have followed. Use the filters to narrow down on products based on your requirement. Real-Time Seamless Capture: The ability to acquire and store an uninterrupted series of time-domain samples that represent the behavior of an RF signal over a long period. Swept spectrum analyzer block diagram Figure 3. Increasing the sweep time in zero span mode tends to yield better measurement results. These include dynamic range, noise floor, sensitivity, resolution bandwidth (RBW), sweep time, video bandwidth (VBW), sweep mode, span setting, frequency settings, etc. This is called a spectrum analyzer. analyzer. keep in mind that while the real-time spectrum analyzer generally has superior performance dl-qa. By placing a short at the end of the cable, the signal is reflected back and the energy lost in the cable can be computed. Front-panel controls include SWEEP RATE, SPAN and TUNE. Share Study with Quizlet and memorize flashcards containing terms like What is the benefit of spectrum analyzers capable of automated measurements specifically for broadband cable networks?, In a swept-tuned spectrum analyzer, which element gives the instrument its "swept-tuned" characteristic?, What does the time-gated switch function on a spectrum analyzer enable? and more. The analyzer type also affects The Signal Hound BB60C Real-Time RF Spectrum Analyzer and Recorder is a 9 kHz to 6 GHz Spectrum Analyzer and RF Recorder with an instantaneous bandwidth of 27 MHz, and sweep speeds of 24 GHz/sec. Jan 13, 2021 · Can these 2 measurements on a Spectrum Analyzer be considered "equivalent"? What are the trade offs? To give some background, I am using a software tool that fixes the number of points in a span to default value. This sweep time includes acquisition and processing time. 02. The sweep time is an important parameter as it affects the measurement speed and the resolution bandwidth of the analyzer. 5 GHz real-time spectrum analyzer and monitoring receiver featuring sweep speeds up to 200 GHz/sec, 40 MHz streaming bandwidth, -160 dBm displayed noise average, and an internal GPS for enhanced field measurements. Optical Spectrum Analyzers from the leading manufacturers are listed below. It offers excellent frequency resolution and a wide frequency range, making it suitable for analyzing high-frequency signals such as those used There should not be any other signals present within the resolution bandwidth as well. Furthermore, the SPECTRAN … What is the fastest sweep time in Zero Span mode with a Spectrum Analyzer? DSA815 Zero Span Performance The Rigol DSA815 Spectrum analyzer features a zero span mode that can be helpful in observing modulated signals. Share increase the sweep time. They can provide you with a clear and precise window into the frequency spectrum. Feb 3, 2023 · Like many other types of sophisticated test equipment, spectrum analyzers come with many features and options that affect their accuracy and performance. Span Defines the displayed frequency range and therewith the Start- and Stop Frequency defined by the Center Frequency +/- 0. This ensures that individual signal easy. Proper sweep time = K × (RBW ≥VBW) Frequency span RBW Time gating allows you to measure the spectrum of a periodic signal during a specific portion of time, typically the on-time of the bursted signal. Aug 21, 2023 · The sweep time of an OSA refers to the time it takes to perform a full scan of the optical spectrum and display the results and is usually measured in units of time (sec). Typically, the number of frequency steps Sweep Time = Accy. It is used for viewing RF signals in frequency domain. docx V1. This is especially important in radar, electronic warfare, or signal intelligence systems. The SM200B is a high-performance 20 GHz spectrum analyzer and monitoring receiver with 110 dB of dynamic range and 1THz/sec sweep speeds. Others may be new to RF testing and not familiar with either. The resolution on the timer is coarse and provides a rough estimate. How to use spectrum analyzers for EMC testing_20210308. There are various types of spectrum analyzers viz. Jan 30, 2020 · Real-Time Bandwidth: The widest frequency span for which the spectrum analyzer can continuously transform time domain data into frequency domain results. Note that the sweep time, filter bandwidth, and frequency span are all linked, in that a faster sweep time requires a wider filter bandwidth and/or a narrower span. In swept mode, the detector of the analyzer is sweeping across a span of frequencies at a predefined rate. Mar 22, 2012 · Spectrum analyzers have auto-coupled sweep time that automatically chooses the fastest allowable sweep time based on selected span, RBW, and VBW. The figure-1 depicts RF spectrum analyzer from R&S used for measurements upto 30 GHz. If you do, however, the analyzer response may become uncalibrated and Jul 3, 2020 · The industry shift from Spectrum XT to Ekahau, primarily how fast the spectrum analyzer can sweep the spectrum has been huge. If you consider a component that is used in a smartphone, there may be billions of components made each year. Aaronia presents the SPECTRAN® V6 X: the world’s first and only 6GHz USB spectrum analyzer with dual USB True I/Q streaming of up to 245MHz IQ, and >1THz/s sweep speed real-time bandwidth. A trigger is used to synchronize when the burst occurs. Spektrum runs on Windows and Linux and turns an RTL-SDR dongle into a spectrum analyzer in a similar way to rtl_power GUI front ends and RTLSDR Scanner. These analyzers measure/sweep signal strengths in a frequency band – determined by the resolution bandwidth (RBW) – at each Spectrum analysis is essential for understanding the frequency domain characteristics of components, circuits, and systems, but these instruments and their measurements are not foolproof. We will highlight One such measurement tool that’s evolved to keep up is the Real-Time Spectrum Analyzer. selected. These errors can lead to improperly adjusting a device under test (DUT) or shipping a device to a Jun 12, 2014 · Luckily, some simple guidelines can be followed to ensure that the spectrum analyzer is being used properly and performing to expectations. The eight common errors mentioned above are as follows: Jan 27, 2017 · There are two main types of spectrum analyzer: digital and analog (often called sweep analyzers). com, Pavel wrote in to let us know about a new program called 'Spektrum' which he has written. Ultra-fast, ultra-portable RF analysis up to 14. Sep 21, 2022 · Sweep time . RBW filters are defined by their bandwidths and shape factors. . spectrum analyzer: A spectrum analyzer is a device that displays signal amplitude (strength) as it varies by signal frequency . Mar 20, 2023 · This is made possible by incorporating the two functions of sweep mode and real-time mode, which are the greatest features of the MSA500 series, into a single handheld signal analyzer. RBW = Resolution BW There are two broad categories of spectrum analyzers: swept-tuned analyzers and real-time analyzers. The signal captured is a typical WLAN interchange between a nearby PC and a more-distant network access point (AP). Spectrum analyzer using the integrated bandwidth method Modern spectrum analyzers can automatically calculate channel power given the channel bandwidth and frequency. 2 GHz ; 40 MHz Acquisition Bandwidth; Portable – USB spectrum analyzer ready to connect to a PC with USB 3. 0 to the PC. Therefore, it can be said that it is the best product to improve the awareness of weakness. This can be the most critical requirement for high volume manufacturing applications. Sweep Time. Dimension . Jun 1, 1998 · Spectrum analyzers are designed in two hardware configurations, so dissimilar that it is difficult to recognize them as performing the same function. The former can gather all necessary spectrum information, analyze it, and display the results in real time when the measured signal happens, but the latter takes numerous sampling procedures to complete repeated information processing. Dec 17, 2021 · There are two types of spectrum analyzer s: real-time analysis and sweep frequency analysis. Mar 29, 2013 · A spectrum requires certain dwell time on each channel or sweep point. Most spectrum analyzers link these two parameters automatically, but allow you to override this. This type analyzer is a superheterodyne receiver with special circuits and characteristics (see Figure 3 1). To obtain a line spectrum on the analyzer, the "rule of thumb" to follow is that the RESOLUTION BW be less than 0. Many of the mistakes made when using a spectrum analyzer have to do with using the wrong equipment, or else using the analyzer’s controls incorrectly. Engineers integrating WiFi, Bluetooth and other modern RF technologies are confronted with complex challenges like frequency hopping signals, channel conflict, and spectrum interference. Cable Loss can be measured using the Return Loss measurement available in the cable and antenna analyzer. ) The sweep time under the spectrum is a measured sweep time. Spectrum analyzers usually display raw, unprocessed signal information such as voltage, power, period, wave shape, sidebands, and frequency. However one key improvement is that it is based on a version of rtl_power that has been modified by Pavel in order to It is a real-time spectrum analyzer and you can carry it anywhere with you, or even you can use it in your lab as well. The unit offered for review is the recently released model BB60C real time analyzer, which can tune from 9 kHz to 6 GHz with a dynamic range of +10 to approximately -158 dBm (DANL, which is dependent on resolution BW). The spectrum analyzer architecture has a great influence on the speed of the spurious emission measurement. However, within the past decade or so, spectrum analyzers have become much more sophisticated. The swept-tuned spectrum analyzer is commonly used by RF communication technicians, engineers, and amateurs. VNA VS. The amplitude in the display decreases in the 2nd and 3rd waves when the sweep is made too early, and the frequency shifts. With the advent of digital technology, modern spectrum analyzers have been given many more capabilities. 0; Improved Dynamic Range (reduced spurious) SignalVu-PC vector analysis Therefore, the crucial difference between the oscilloscope and spectrum analyzer is that an oscilloscope corresponds to the time-domain representation of the input signal. Here is the equation governing the sweep speed: In this formula, the meaning of the first factor is the number of frequency selections under SPAN, each step is 1 / k of RBW, to ensure the accuracy of amplitude measurement. Next time, I will go over time gating — an essential topic for spectrum analysis both in classic spectrum analyzers and modern, advanced signal analyzers. . The swept spectrum analyzer is less expensive. Despite the low price entry class, the new SPECTRAN ® V6 ECO real-time spectrum analyzer family sets new standards in the USB compact class, as it achieves sweep speeds of over 3THz/s. Configuration example Mar 29, 2013 · A spectrum requires certain dwell time on each channel or sweep point. Both swept-tuned and real-time spectrum analyzers display amplitude versus frequency. The loga-rithmic amplifier uses an IF amplifier IC found in cellular telephones and includes a received signal strength indicator (RSSI) Figure 2—Time base for the spectrum analyzer. The sweep time control is used to specify a minimum acquisition time. Oct 26, 2023 · Swept-tuned spectrum analyzer: This type of analyzer essentially “sweeps” through a range of frequencies, measuring one frequency at a time and then displaying the frequencies as a function of time. Nov 17, 2019 · If we look a carrier sweeping thru a BPF, we take one half of -3dB BW to get the single sided Low Pass equivalent time response. Modern spectrum analyzers use digital signal processing to provide additional measurement capability and let you interpret measurement results much more easily. Swept analyzers are very similar to classic oscilloscopes in that the frequency span is “swept” between the start and stop frequencies, then analyzed and displayed in a series of events (sweep – analyze/measure – display), so there is some deadtime between sweeps while Sweep Time. A line spectrum (as opposed to a pulsed spectrum) is an actual Fourier representation of a pulsed RF signal in the frequency domain; all the spectral components of the signal are fully resolved. 0 How to correctly use spectrum analyzers for EMC pre-compliance tests Author: Mayerhofer 4 of 17 TekBox Digital Solutions 25-Nov-21 3. Feb 21, 2020 · First of all, what is a spectrum analyzer? Spectrum analyzers measure the magnitude of an input versus signal frequency. Nov 6, 2015 · Recently a reader of RTL-SDR. This application note compares the differences in architecture between the swept spectrum analyzer approach and a modern broadband FFT-based signal- and The sweep time determines how long it takes to go from the start frequency to the stop frequency. tion of this spectrum analyzer. Jun 21, 2022 · We have a choice to make. The SM200B offers 160 MHz instantaneous bandwidth (IBW) calibrated I/Q capture, available through block transfer of a 2-second I/Q buffer over USB 3. With a sweep speed of over 1 THz/s, it sets new standards in the USB compact class. Each of these types have their own respective advantages and disadvantages. In the Spectrum Analyzer measurement, my PXA in auto-coupled, with Sweep Type set to Auto, transitions from Sweep to FFT at Span setting of 20 kHz where the RBW is 180 Hz. From entry level swept spectrum analyzers to advanced real-time analysis RIGOL provides unprecedented value. The narrow bandwidth leads to long measurement time and low sweep rates. For a cumulative overview and in-depth reading on spectrum analysis, check out application note 150. This PSA Series data sheet is a sum-mary of the complete specifications and conditions, which are available in the PSA Series Spectrum Analyzers Specification Guide. Because of this, spectrum analyzers are viewed as an essential component of EMC testing. A real-time spectrum analyzer can help with most modern RF measurement challenges, like: discovery of rare, short deration events; seeing weak signals masked by stronger ones; observing signals masked by noise, finding and analyzing transient and dynamic Sweep Time . To start the discussion, let’s look at the OSCOR Spectrum Analyzers which sweep from 10 kHz to 24 GHz in 1 second. The majority of spectrum analyzers available on the market today are digital, though there are still analog analyzers out there. Therefore, the sweep speed is 24 GHz The software needs to wait for a sweep or two while the analyse you does its thing. To the casual observer, a spectrum analyzer looks like an oscilloscope , and in fact, some devices can function either Mar 3, 2016 · This article, "Spectrum Analyzer Basics," is part two in our blog series "Understanding Real Time Spectrum Analysis" - an exclusive Signal Hound blog series The brand-new RFS8 8 GHz eight-port switch is available for purchase!→ Aug 31, 2020 · For more background information on spectrum analysis basics, start at Part 1. Real-time spectrum analyzers enable on-the-go sensing and analysis of these signals and can put powerful software analysis tools at an engineer’s fingertips. and a full span sweep time of 5 ms. At Span 22. Although a spectrum analyzer displays power, it is a power meter. Aug 9, 2016 · The noise floor is lower than in an oscilloscope, but higher than in a swept spectrum analyzer. Nov 5, 2022 · Sweep/Superheterodyne Spectrum Analyzers (Analog) Real-Time Spectrum Analyzers (Digital) Sweep spectrum analyzers are traditional analog analyzers which are based on either tuned-filter or superheterodyne principle. 18 to 1000 GHz/s. Spectrum Analyzer Basics (1) System configuration. device, and system behavior. It is usually specified in terms of time per data point and the time required for a sweep is called cycle time. Similar to scanning multiple channels with a single adapter for the purpose of protocol analysis, spectrum analyzers sweeping the spectrum at a slow speed results in gaps of information, making the job harder. 5 GHz. Both types display amplitude as power on the Y-axis and frequency distribution on the X-axis. cdn-anritsu. Though this block diagram indicates a single conversion analyzer, typically, a An Optical Spectrum Analyzer is a scientific instrument used to measure the power spectrum of a light source. In many cases the spectral components that otherwise would contribute to the pulse’s rising and falling edge will mask spectral components that contribute to the spectrum of the pulse during Jan 7, 2021 · Can these 2 measurements on a Spectrum Analyzer be considered "equivalent"? What are the trade-offs? To give some background, I am using a software tool that fixes the number of points in a span to default value. Sweep time is dependent on the resolution bandwidth (RBW) filter, frequency span, and the design of the spectrum analyzer. Swept spectrum analyzer with impulse noise and DOCSIS carrier In Figure 2, when the ramp generator is generating zero volts, the VCO is set to 2 GHz. A shorter sweep time allows for faster measurements Feb 25, 2021 · There are mainly two types of spectrum analyzers where those are classified depending on the signal’s spectrum and those types are Swept-Tuned Analyzer – This type utilizes a superheterodyne receiver in order to transform a section of the input signal to the middle frequency of the narrow BPF where the instant delivered power is exhibited Measurement speed is the time it takes to perform a single sweep or measurement. Sweep time is the length of time it takes to sweep the detector from the start to the stop frequency. This paper will review the architecture of real-time spectrum analyzers (RTSA), swept-tuned spectrum analyzers, and vector signal analyzers, and highlight their relative merits and compromises. dz qt lc vm qv ld dg yo ty ie