Digilink Nano - WSPR results.

I've had a chance now to run a fairly limited test with the Digilink Nano, despite the temptations of a very busy upper HF and VHF period, where making 'real' QSOs competes strongly for attention!

The WSPR Challenge result for the day was number 15, which is of course a 'total station' assessment, and does not necessarily reflect the performance of the interface.  Tomorrow, I could be number 8, or 5, or something else; it depends critically on many factors.

 

I had believed at the time of writing this post, that the Nano did not have a soundcard of its own.  The maker of the Nano - it has to be said a very long time after having been first been made aware of this blogpost - today (14/7/21) corrected this belief as follows: 

'DigiLink Nano is an autonomous external USB soundcard and is completely independent from the onboard soundcard. In fact uses the very same chip to do this as the ZLP devices, the TI PCM2912. As such, I'd expect similar noise levels. For full disclosure, I’m HB9ZHK, the creator of DigiLink Nano.'

Now, ZLP has consistently advertised his interfaces as having low noise, and I certainly have no complaints about how reliable and apparently low noise they are. He asserts that his interface has a noise value "better than -93dB", contrasting this with the Tigertronics Signalink noise figure of "-71dB" (ZLP site accessed 07:28UT, 25/05/2021).  I can't say whether this is an accurate statement, but a search online does seem to reveal the Signalink did, and may still have, noise issues that led some to make modifications, which were apparently successful.

The 'D' layer forms early, now it's summer, so a quick and useful test was to look at a few short-haul spots and then switch back to the ZLP interface for a comparison.  I know that, under prolonged testing, I am typically in the top 10 or better; sometimes I get to number 1.  So the ZLP is certainly a quiet circuit.

I looked at a number of stations, and present the results for UR5KHL, where spots before 06:34UT were the Nano, and for the ZLP thereafter.  This had to be a very short test, because propagation might change quickly, especially in the morning:

As you can see, there is no difference between the interfaces.

Another typical result, showing again no significant difference, is as follows:

And then again, for F6KOP, no significant difference:

With this particular set of equipment, there seems to be no significant difference between the ZLP and Digilink Nano interfaces. Note that both sets of computer-to-interface cables had a TDK, HF-rated split ferrite fitted (two turns).

What you do certainly need to look out for with any interface using a USB connection to a computer, whether it is using its own soundcard or the computer's, is RFI conducted along the cables.  Even if you can't hear/see RFI on one band, the chances are it will be there, degrading RX performance.  Use good quality, appropriate-for-frequency ferrites everywhere!

With both interfaces competing at the same price point, and both now having no on-board physical level controls, the question of which interface to choose is perhaps just a matter of personal preference, and maybe the fact that the Nano is considerably smaller and lighter than even the latest ZLP unit.