There was a time when experimenting with software defined radio (SDR) was exotic. But thanks to cheap USB-based hardware, this technology is now accessible to anyone. While it is fun to play with the little $20 USB sticks, you’ll eventually want to move up to something better and there are a lot of great options. One of these is SDRPlay, and they recently released a new piece of hardware — RSPduo — that incorporates dual tuners.
We’ve talked about using the SDRPlay before as an upgrade from the cheap dongles. The new device can tune either a single 10 MHz band over the range of 1 kHz to 2 GHz, or you can select two 2 MHz bands. This opens up a lot of applications where you need to pick up signals in different areas of the spectrum (e.g., monitoring both sides of a cross-band repeater).
You may wonder how you can take advantage of the two tuners with software. There’s an online review that covers how the software works with the dual tuners. You can also see a video from [SevenFortyOne] that shows the radio in use.
In addition to dual band receive, a unit like this could be useful in building systems for cognitive radio, diversity reception, reducing noise, and radio location. You can find a spec sheet for the device which shows it has a 14-bit converter and several antenna, filter, and reference clock options.
You might think that for almost $300 you could buy more than one USB dongle and get the same result. There are a number of advantages to using the RSPduo, though. First, the performance of the RSPduo with its expanded converters and built-in filters will be better. It also has a wider frequency range than a cheap dongle. However, for any application where you want to understand the relationship between the two signals, using multiple USB devices will be tricky if not impossible. With the RSPduo, the data is on a single USB interface, so the data are correlated with no additional effort.
Not that it isn’t possible to use multiple USB devices, just harder. The RSPduo is very similar to the company’s earlier offereings, with the addition of an extra tuner. If you want to see how to use the RSPduo’s cousin, we did a GNURadio tutorial on the SDRPlay.