Thanks to element14 and Tektronix, I was lucky enough to be a RoadTester of the Tektronix RSA306 USB 3.0 Real-Time Spectrum Analyzer, along with a Lenovo Thinkpad Edge E431 Laptop. This product is very unique, and interesting, as it offers a 40Mhz real-time spectrum display, a frequency range of 9khz-6.2Ghz at 14-bit depth, with signal levels from +20dBm down to -160dBm at a price never seen before.
This particular RoadTest was a marathon effort, with a lot of screen-shots and a video. The conclusion is reproduced here:
In my opinion, Tektronix have delivered a rather unique software-defined instrument, arguably the first in its category. The RSA306 offers a wide frequency range, with a suitably wide power-range, in a form factor which is highly portable, at a price which is compelling and good value-for-money. It is ruggedly built, compact in size, easy to set-up and does not require bulky external power supplies.
The RSA306 leverages the SignalVu-PC software for analysis, which is the same as the tools available on/for use with more expensive MSO/MDO/RSA series devices, which can make future upgrades much more compelling should you purchase options or invest time in developing workflows with the software. The software is stable, frequently-updated, and powerful and features an array of extensive options which can be purchased for your application-specific needs.
Options can be freely evaluated for a 30-day period to determine their suitability for your needs. The base edition of SignalVu-PC provides sufficient useful measurements to get started with basic measurements. The capture ability allows for instrument time to be spent acquiring signals with analysis performed later – or for permanent capture of signals for records.
Because of this, the RSA306 will be attractive for many applications, including 802.11 wireless device development, Bluetooth and Bluetooth Smart/Low-Energy device compliance testing, EMC testing, interference hunting, coverage tests, transmitter tests and radar characterization. Furthermore, to make the unit even more attractive to educators, an education edition of their software is available as well at a very good price.
The unit itself offers bleeding-edge capabilities in terms of real-time USB 3.0 streaming capture and analysis with a 112MS/s 14-bit ADC throwing out 224MiB/s of data and thus requires a beefy computer to ensure maximum performance. Because of the software-defined nature of the instrument, in future, further options may be offered by Tektronix to expand the capabilities of the unit. If not, you are still free to develop your own applications with the provided APIs, or skip that entirely and analyze the raw/formatted/corrected data from SignalVu-PC.
Because of the size, price and design, it is not without some compromises. To expect identical performance to larger, more expensive bench-top units is unfair. That being said, in my experience, the compromises in the linearity, spurious responses and dynamic range to some extent were not really relevant to my usage and with careful, proper use of the instrument, it was more capable than required for most applications and its limitations were not apparent. I have a feeling that, as specifications are easily compared, some users have a habit of comparing them without regard for what they actually require.
Hobby-grade SDRs will continue to rise in popularity, and be available at even more lucrative price-points with more sophisticated specifications, but it must be remembered that the requirements for instruments in terms of their performance is much more stringent. Hobbyist-grade SDRs generally have no/limited guaranteed specifications. Specifically, IF images, spurious response, resolution/dynamic-range and linearity all can be quite problematic as many of these SDRs repurpose application-specific front-ends and ADCs and operate them at frequencies which they were not specifically designed. No calibration is provided in general, and they may not be built robustly. Likewise, measurement and analysis options with those are limited, and can involve time spent in producing flowgraphs or applications to perform the measurements you need. It’s important to remember that the Tektronix RSA306 is more of a refined “package”, ready to go out-of-the-box. In light of this, the RSA306’s price is actually quite attractive.
It is a very likeable unit, even for those who may already own an RSA benchtop analyzer, as it is very convenient for field work. However, those who really need multiple-channel analysis, better linearity and spurious response or wider frequency ranges will probably need to spend significantly more to get what they need.