The Sound card

One of the nice things of this setup is that it uses a soundcard embedded in the unit itself. First of all, it is a good idea to use an external soundcard. The soundcards usually found in laptops are not very good. I did some comparison between the laptop’s internal card and this one, and it made a hell of a difference.

The Behringer UCA222 I use, is quite reasonably priced; I paid €25,00 for one. It has a decent AD/DA chip from Burr-Brown. The only drawback is that the maximum sampling frequency is 48kHz, so the view window is not that big. There are external cards that can view up to 192kHz, but these are far more expensive.

As I said, I did compare internal soundcards with the external one, and found the Behringer outperform all of them. I tried two laptops; a HP and a Packard-Bell, as well as a Lenovo Desktop. Here are some screen copies from the test with my HP NX9105 laptop. This one runs Linux, so I used the SDR software Quisk to do the test. This is how it looks when no SDR is connected to the internal sound card:

Compared to the external sound card with no connection: A real life reception of 20m with the internal sound card: And finally with the Behringer:

Another nice feature is that it doesn’t need special drivers. There are drivers available, but I found out that using the default drivers that come with Windows, the unit performs best. So it is plug and play! The product is primarilly meant for musicians and audio hobyists, so the Behringer drivers are adding stuff for that use to it, but we don’t need that for the SDR.

The UCA222 is used only to process the signals to and from the Lima SDR. The internal sound card of the PC is used to interface you, i.e. speaker/headphone and microphone. In my opinion this is much more reliable than using one sound card and switching over the signals. Besides that, HDSDR can only work with separate sound cards. Power SDR however seems only capable of working with one soundcard, so in that case you have to use the change-over functions in the Lima SDR.

FInally I like the fact that the unit has RCA connectors instead of the usual 3,5mm stereo jacks.