Review: Tektronix RSA306 spectrum analyser (part 2)

December 19, 2014 // By Kenneth Wyatt
In part 1 of this review, we discussed some of the basic operations and specifications of the new Tektronix RSA306 USB spectrum analyser. This time, we’ll cover some of the more advanced features and measurements.

Briefly, the RSA306 is a well-built rubber-covered unit (30 x 190 x 127 mm) that will slip into a large coat pocket. It is a rugged product designed to meet MIL-STD-28800 Class 2 environmental, shock and vibration for use in harsh environments. The RSA306 is powered solely through the USB 3.0 port. The frequency range is 9 kHz to 6.2 GHz and can measure from +20 to -160 dBm (at minimum resolution bandwidth of 100 Hz). The unit can capture fast transient pulses with its 40 MHz real-time IF bandwidth. There are also external 10 MHz reference and trigger/sync SMA inputs, so you can sync to line frequencies, for example. The measurement input is an N connector with protective rubber cap. With all this, Tektronix has been able to keep the cost down to $3,490 for the basic unit. Included in this price are a safety/installation manual, USB 3.0 cable and USB flash drive containing the documentation files, user manual, drivers and SignalVu-PC software.

Figure 1 - The Tektronix RSA306 is a small rugged package that can easily fit into a briefcase, along with your laptop.

One reason for the low cost is that much of the functionality lies in the SignalVu-PC RF analysis software. The software includes 17 standard spectrum and signal analysis measurements, with several optional application-specific options available (€757, each). These options include mapping, modulation analysis, standards support (such as APCO P25 and WLAN), pulse measurements and frequency settling. The real time (DPX mode) can detect transient or intermittent signals as short as 100 µsec, which would aid in interference hunting. The software can also capture streaming and audio demodulation for long-term surveillance monitoring. Because the personality of the instrument lies within the software, upgrades and adding optional measurement capabilities are easy. We'll demonstrate some of these more advanced measurement features.

Because of the 40 MHz real-time bandwidth and horsepower required to process the “digital phosphor” mode (DPX) and other advanced modes, the PC requirements are pretty demanding. Tektronix recommends a PC with at least the following specs: USB 3.0 port and 64-bit Windows 7 or 8 OS and 8 GB of RAM. For full support of the real time features, an Intel i7 4th-generation processor is needed. Storage of streaming data requires the PC be equipped with a drive capable of streaming storage rates of 300 MB/sec, such as most solid state drives. I tried using the RSA306 on my Macbook Pro with 8 GB of RAM and 500 GB SSD running Windows 8.1 via Parallels 10 and everything seemed to run fine, but adding the DPX (real-time) mode did make the software choke. Running the unit with a high-end PC works fine, though. I suspect running a virtual operating system slows the processing down too much. See my “wish list” at the end of this review.

OFDM power measurement

Assuming the signal is “noise-like”, it’s possible to measure integrated power and power density measurements of a modulating signal using power markers. When measuring signal density, the measurements are corrected to a 1-Hz bandwidth. When power measurement markers are selected, it automatically switches the detector to average RMS for accurate results. This is an easy way to measure the power of a modulated signal without using a dedicated channel power measurement.

Figure 2 - OFDM measurement in the 2.4 GHz band, showing the readouts of power and power density.

Next page – DPX mode, transient capture