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test&measurementZONE Products for the week of September 1, 2008
Tektronix Says…
Real-Time Spectrum Analyzers Show Live RF
Complete DPX Enabled Field to Bench Portfolio Includes New SA2600 and H600 Handhelds
Tektronix, Inc., a leading worldwide provider of test, measurement and monitoring instrumentation, announced the new SA2600 handheld Real-Time Spectrum Analyzer that includes DPX waveform image processor technology that provides a live RF view of the spectrum. DPX is now also available on the H600 "RF Hawk" handheld unit originally introduced in February. With these additions, Tektronix offers a full portfolio of Real-Time Spectrum Analyzers with DPX for use in the field and the design bench.
The rapid expansion of digital RF applications has driven the measurement needs of many applications including mobile communications and spectrum management beyond the capabilities of swept spectrum and vector signal analysis. Digital RF signals carry complex modulation and change from one instant to the next, hopping frequencies, spiking briefly and then disappearing. These transient and time varying transmission techniques help RF devices avoid interference, maximize peak power and, oftentimes, evade detection. Finding and physically locating RF emitters that are misusing the radio spectrum can be a challenging process, especially when risk mitigation and time to response are critical.
"The new Tektronix Real-Time Spectrum Analyzers are designed to offer benchtop performance on a portable handheld platform, specifically to solve problems created by digital RF technologies from WiFi to WiMAX to UWB and UMTS," said Bob Hiebert, general manager, Wireless Field Test Product Line, Tektronix. "The new SA2600 and H600 handheld spectrum analyzers extend the application of DPX to serve a broad range of fielded wireless technologies. These units uniquely assist customers with the discovery of interference and the mapping of wireless technologies in a variety of environments, both indoors and outside."
The explosion of digital RF has created a highly complex technology environment that is moving from the design bench to the field, requiring the need for next generation test and measurement instruments. DPX waveform image processing provides a unique live RF view of the spectrum, enabling an unprecedented RF signal discovery capability for a broad range of applications including radio communications and spectrum management. DPX transforms volumes of real-time data and produces a live RF spectrum display that reveals previously unseen RF signals and signal anomalies.
Portable Real-Time Spectrum Analysis with New SA2600
The SA2600 with 10kHz-6.2GHz frequency coverage, 20 MHz real time bandwidth and -153 dBm Displayed Average Noise Level (DANL) is designed to deliver benchtop spectrum analyzer performance in a battery-operated, handheld field unit. With a spectrum processing rate more than 100 times faster than any swept spectrum analyzer from other vendors, the SA2600 and H600 provide 100% probability of intercept for transients with minimum event durations of 500 microseconds on the SA2600 and 125 microseconds on the H600.
The SA2600 and H600 are designed for field measurements. The new models combine a high performance spectrum analyzer with an intuitive set of user controls, allowing for the quick and simple classification and location of both analog and digital RF transmissions. The user interface is designed specifically for enhanced productivity in the field including a touch screen for easy navigation. While other solutions may require offline GPS and mapping software, the SA2600/H600 includes integrated GPS and mapping tools to allow more efficient interference location capability.
DPX Makes All the Difference
DPX waveform image processor technology in the SA2600/H600 displays the live spectrum by processing >2,500 or >10,000 spectrum measurements per second respectively. This is orders of magnitude more information than is shown by any other conventional spectrum analyzer without DPX, minimizing the analysis gaps inherent in swept spectrum and vector signal analyzers. To achieve thousands of spectrum measurements per second, DPX makes use of dedicated, real-time hardware to process the incoming signal.
In addition to live RF, the waveform image processor also provides an intensity-graded persistence display that holds anomalies until the eye can see them to show the history of occurrence for dynamic signals and immediate feedback on signal variations over time. This provides engineers the ability to rapidly see on screen both transients and signals that ordinarily could not be seen, either because they are masked by other signals or could only be deduced after time consuming offline analysis. DPX waveform imaging will enhance productivity by quickly capturing elusive anomalies and transient events, improving accuracy and insight, and accelerating design debug.
SA2600 and H600 Are Part of Digital RF Test Portfolio
Tektronix offers digital RF test tools from signal generation to acquisition. In addition to Real-Time Spectrum Analyzers, Arbitrary Waveform Generators generate ideal, distorted or "real-world" signals. Logic Analyzers enable the capture and analysis of the digital I/Q information to more quickly debug elusive problems within the digital baseband segment of a Digital RF design. Digital oscilloscopes allow measurements of strict timing relationships including signal integrity analysis. With these instruments and supporting software, Tektronix provides what customers need to test demanding digital RF applications.
EN-Genius Says…
A number of portable RF spectrum analyzers have made the scene of late, in lockstep with the proliferation of wireless equipment. Our recent observations and reviews of the Boonton Wireless Telecom Group 9103 7.5-GHz handheld spectrum analyzer and the low cost B&K Precision Model 2652 3.3-GHz analyzer prove the point. Nomadic analyzers are now available from Bantam Instruments, Berkeley Varitronics Systems, Rohde & Schwarz, and Anritsu Co., to name a few.
From an engineering point of view, the reason we're seeing this proliferation is largely due to the advent of so-called digital RF. Folks need to characterize the RF environment where transmissions occur in short bursts and sometimes at random. In most CSMA (collision sensing multiple access) packet data systems, transmissions turn on only for the time it takes to transmit a packet. The spectrum is then released for other CSMA emitters.
Cognitive Radios
In addition to bursty emissions, there are other reasons for owning a portable spectrum analyzer. System modulation formats, frequency levels, and RF power often change in response to more-or-less random protocol events. So-called cognitive radios adjust frequency, modulation and power in response to the spectrum environment at a particular point in time and location. A spectrum analyzer that can measure modulation and power is handy, indeed.
Nowadays, multiple RF devices can also be housed within a single product package (such as a notebook with wireless LAN capability, Bluetooth, cellular, and RFID). Gosh, in some cases RF emitters now actually share the same module or even the same silicon as a product's microprocessor or embedded controller.
Typical systems that share spectrum include short-range UWB (ultra-wide-band) wireless and CDMA (code division multiple access) cellphones. For designers and implementers of RF components for these types of systems, it pays to know as much as you can about non-linear component behavior, and how that behavior changes over short time periods. That's where Tek's DPX Digital Phosphor technology comes in. The company likens it to turning on a light in a dark room.
Patented Processing
DPX uses intensive processing to emulate the venerable long-persistence of yesterday's CRT storage scopes. Unlike that timeworn technology, DPX combines Tektronix patented display processing with dedicated DSP hardware.
The two DPX-equipped instruments can now do frequency transforms orders of magnitude faster than most conventional spectrum analyzers. The combination of processing horsepower and color display technology gives Tek portables the ability to convey meaningful displays of vast amounts of information. A key point is that DPX generates displays at full-motion rates, with statistical persistence processing supporting motion viewing of signals over time.
DPX also makes weak signals interspersed with strong signals immediately visible, and it can highlight short-duration events. If you were looking for a terrorist pushing a transmitter button once to detonate a device remotely, Tek's portables could likely find the source.
These portables are also equipped with nifty persistence adjustments. They let you optimize a DPX system display for varying signal conditions. That can range from live RF views of dynamic signals to the discovery of single and infrequent RF bursts.
The Known And Unknown
The new SA2600 spectrum analyzer, and Tektronix predecessor H600 RFHawk, both leverage DPX to the hilt. The battery-powered H600, rolled out earlier this year, and the new SA2600, can classify known signals, and locate unknown signals. The latter is just the ticket for spotting illegitimate analog and digital RF sources.
In its Scan mode, the RFHawk covers 10 kHz to 6.2 GHz, a range over which it can detect signals as low as -153 dBm DANL (displayed average noise level). The RFHawk matches signals to known standards, too, in part using frequency and bandwidth criteria. An on-board expert help database, replete with on-screen profile masks, lets you make frequency offset estimations.
The RFHawk actually examines a cyclo-stationary make-up of a given signal to look for specific cyclical components. By color-coding events based on the rate of occurrence, the RFHawk DPX display can reveal the results of 10,000 spectrum updates every second.
With that, transients as brief as 125 µs can be frozen in the frequency domain. With built-in classification for CDMA, W-CDMA, and GSM cellular signals, as well as ATSC digital TV signals, the expert help system with on-screen profile masks will let you make frequency offset estimations.
As mentioned in the press release, these instruments can also hunt down outdoor signals by plotting measurements directly into GPS geo-referenced maps. For in-building signals, you can also enter location on your maps with a so-called tap-and-walk-and-tap human interface.
For its part, the touchscreen-controlled Windows CE-based SA2600, just like the RFHawk, also uses DPX color-coding to give you an intuitive understanding of the RF environment it's sniffing. The colors on-screen are based on the frequency of a signal's occurrence. An SA2600 can display 2500 spectrums every second, and spot 500-µs transients with a 100% probability of intercept. Like the RFHawk, the SA2600 covers a range from 10 kHz out to 6.2 GHz.
Thanks to DPX, Tek claims the RFHawk and SA2600 spectrogram displays exhibit clarity exceeding that of most laboratory spectrum analyzers. Using DFT (discrete Fourier transform) processing, the sample rate and capture frame overlap of the SA2600 reveal a very sharp spectrogram, which is what's needed to find very brief or elusive signals.
The SA2600 RBW (resolution bandwidth) can also be set to narrow, placing the noise-floor below signal levels. Alternatively, you can set the noise-floor at the same level as the receiver threshold. The SA2600 streamlines this process by means of continuously variable DFT-based RBW.
Using a statistical process to reveal more information than the typical peak signal level-detection process used in most spectrum analyzers, DPX accumulates the rate of occurrence that energy is found at each pixel in a unit's display. This capability leverages the DSP and digitizers to give true real-time capability, rather than short recordings of a signal environment.
With spectrum analyzers that use recording techniques, signal capture time is limited by available memory, with possible gaps in time between data records. As such, these kinds of analyzers can't observe a spectrum for hours, days or weeks to snag rare pulses.
Staring Forever
In contrast, an SA2600 or RFHawk will essentially stare at a spectrum forever, to detect interference events with very short durations. That's just what's needed to validate claims of intermittent interference events. Such brief events are downright difficult, if not impossible, to capture on a conventional swept analyzer, or even a DFT-based analyzer that doesn't have real-time capability.
 Scanning an RF spectrum of interest should let you spot each and every RF emitter in an area under test and analysis. The conventional spectrum display is suited for continuous signal emitters, but the waterfall-style spectrogram on the additional time axis is well suited to studying intermittent signals. You can display either or both at the same time.
Significantly, these portables can spot weak signals, even if they're close to strong signals. Signals can also be stored as references, and deviations can then be identified using trace-math features. An SA2600, for example, can log signals that are weak, bursty, hopping, time-MUXed, or random. Beyond that, FFT analysis then lets you see the shape of the signals, even when they're bursty.
Another convenient feature is mask creation. Masks can be automatically created from traces captured earlier, and you can then compare a mask to a current trace. What's more, if a mask violation occurs, that trace can be logged, and you can then scroll through the spectrogram's time-axis and view all the results.
Mask Triggering
Once discovered, frequency mask triggers can be set up to trigger on each and every occurrence of a particular spectrum, capturing any signals that match the criteria, and storing them in memory. Once captured, you can then analyze a signal's time-domain, frequency-domain, and modulation-domain characteristics, and even look at and analyze events preceding the trigger, as well as those following it.
It's no overstatement to say that the RFHawk and the SA2600 comprise serious field instruments that in many cases surpass the capabilities of benchtop analyzers. Taken afield, you can realize five hours or more of continuous RF spy-vs-spy operations.
The SA2600, with all models and options available for order is priced at $22,900 and the H600 at $38,900. Existing H600 owners can obtain a free DPX upgrade.
Product Page SA2600
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