SPECTRUM ANALYSIS
Spectrum analysis is still the backbone of most wireless tests. You get that feature in a vector signal analyzer (VSA), but a straight spectrum analyzer often offers features that can do more for your particular application. A particularly intriguing new device is Tektronix’s enhanced RSA6000 real-time spectrum analyzer (Fig. 7).
The 14-GHz RSA6000 was first introduced in 2006. Besides a bandwidth of 110 MHz, it featured Tektronix’s Digital Phosphor (DPX) technology. This display technique color-codes the display with intensity grading, selectable color schemes, and statistical traces to communicate more information in less time.
With DPX technology, you can see multiple signals sharing the same frequency at different times, not just the largest, smallest, or average levels as you would see on a conventional spectrum analyzer. You also can see signal details that are completely missed by conventional spectrum analyzers and VSAs. This leads to faster and more thorough troubleshooting and debugging.
Tektronix essentially reinvented the RSA6000 by improving its specifications and adding features. The new model captures 292,969 spectrums per second—up from the original model’s 48,000 spectrums per second—so you can capture very short duration transients missed by other conventional spectrum analyzers. Such a feature is especially helpful when testing software-defined radios and radar.
You can also perform a sweep across the full input range from 9 kHz to 14 GHz. The RSA6000 collects hundreds of thousands of spectrums per second in 110-MHz chunks, which greatly enhances the reliability in capturing time-interleaved and transient signals.
The RSA6000’s DPX Density trigger enables triggering on signals within other signals. With it, low-level random events are isolated faster and easier. Other enhancements include the new time-domain triggering, which adds a runt trigger and the ability to time-qualify any trigger. These trigger features are ideal for radar, EW, and spectrum-management testing.
Wireless design, research, development, and production test engineers in military communications, satellite test, radar, portable mobile radio (PMR) test, and other applications can take advantage of Aeroflex’s 3250 series. The family comprises four models, each measuring a range beginning at 1 kHz, with the 3251 ranging up to 3 GHz, the 3252 to 8 GHz, the 3253 to 13.2 GHz, and the 3254 to 26.5 GHz.
Each model includes a Windows XP operating system, remote-control capabilities via a LAN, general-purpose interface bus (GPIB), and RS-232C, in addition to a 7-in. touchpanel screen, which makes them easy to operate with exceptional connectivity, according to Aeroflex. The display provides an ample viewing area so data can be seen easily, even in split-screen mode or with multiple windows open. Three traces can be displayed per window, and as many as nine markers can be selected with a marker table viewable in an alternate window.
Al so, the ser ies includes digi tal demodulation capabilities for the analysis of 802.11a, b, and g wireless networks, enabling engineers to analyze the transmitter characteristics of wireless devices. Optional measurement personalities include GSM/EDGE, WCDMA, WiMAX, and WLAN, as well as electromagnetic compatibility (EMC) pre-compliance test.
Built-in functions simplify the evaluation of many common measurements, including channel and multi-channel power, pulsed measurement, gated sweep, occupied bandwidth, spectrum emission mask, third-order intercept (TOI) measurement, total harmonic distortion, AM/FM and digital demodulation analysis, X-dB down, and phase-noise measurement.
The 3250 devices offer local-oscillator (LO) of –115 dBc/Hz and a display average noise level (DANL) of –145 dBm/Hz. They also incorporate 30-MHz I/Q demodulation bandwidth and a removable hard disk as standard. The software provides a GUI within the spectrum analyzer menus to display the required suite of user-selectable parameters. These high-performance, portable spectrum analyzers range from 24 to 20 lb.
ATE TESTING
One of the most critical components in automated test systems for wireless is the switch needed to select inputs, outputs, and miscellaneous connections for various tests. They must be fast, transparent, and able to work at the highest frequencies. Peregrine Semiconductors’ PE42552 SPDT 50- RF switch fits that set of requirements (Fig. 8).
The device is designed with the company’s HaRP-enhanced UltraCMOS siliconon- sapphire process technology. It covers from 9 kHz to 7.5 GHz without gate lag and phase drift, and it has a fast switch settling time. This CMOS switch also features an isolation of 47 dB at 3 GHz and about 30 dB at 7.5 GHz.
Another frequently sought ATE component is the attenuator. Peregrine’s PE43703 is a 7-bit digital step attenuator (DSA) with a three-wire interface bus. The attenuation range is 31.75 GHz in steps of 0.25, 0.5, and 1.0 dB. The DSAs operate from dc to 6 GHz and have an attenuation accuracy of ±0.2 = 2% at 3 GHz with an insertion loss of 1.6 dB. Its third-order intercept point (IP3) is +57 dBm. The DSA is a good companion for the PE42552 switch.
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