Wednesday, July 19, 2017

ColibriNANO SDR: Test of the RF Noise Blanker

Intermittent broadband noise, possibly from high voltage lines, periodically pests the MW band here. In fact it covers most part of the SW band up to 8 MHz as well. Unwelcome as the noise is, it still gave me the opportunity to test the noise blankers issued with ExpertSDR2. They are also available in the dll for HDSDR.

Short version: The RF noise blanker works, and works well! In HDSDR it is possible to adjust the effect of the noise blanker, which is not possible in ExpertSDR2. This turned out to be quite important in order to find the best balance between noise level and audio quality.

The two jpgs below show the MW band with (above) and without the NB algorithm activated.
Admittedly there is a range of a 100 kHz or so with no noise, where the NB is not very efficient, but the overall impression is very good. An audio example from 999 kHz is quite convincing.


Sunday, July 09, 2017

Airspy R2/Spyconverter R2: After a Few Days of Testing

Interesting days with my second mini-sized SDR! I am preparing a comprehensive evaluation, from a MW DX-ers perspective, of the Airspy. Hard-core MW DX-ers have had a preference for Perseus and RFSpace SDRs (and also the Elad FDM-S2), so there are a couple of interesting questions here: We're unfamiliar with these kind of devices, and the manufacturers and prorammers may be a bit unfamiliar with how MW DX-ers use our radios.


Some observations:

  • Its 0.5 PPM TCXO gives excellent stability when using SDR#, but SDR Console V3 (preview version) and HDSDR have some strange intermittent offsets, up to 500 Hz. Simon Brown, the owner of SDR Console is aware of the problem and I'm sure it will be addressed.
  • SDR# has limited IQ recording functionality. I hope this can be resolved, by native software or by plugin. SDR Console V3 does this very well, except a bug which is being addressed.
  • For best gain vs. protection from overloading, it's necessary to pay attention to the gain controls. I remember this being an issue also with the 12-bit Afedri SDR-net.
  • Audio quality in SDR# is very good.
  • Sensitivity isn't measured, but compared to the KiwiSDR in an A-B test on threshold signal levels. The Airspy is apparently marginally less sensitive on a MW test I did. I couldn't hear any difference when I did the same test on SW. Mind you there are many factors that determine sensitivity, not least how the AGC is used and gain settings. True DX situations late summer/early autumn will give me more answers.
  • The Airspy has a fixed 10 MHz sampling rate. Smaller bandwidths are made by decimation of the sampling rate. The more decimation (smaller bandwidth), the better performance. I'm using 2500 kHz (of which 2000 or more kHz are alias-free) for my MW tests.
  • Apparently very good sensitivity on FM. Both SDR# and SDR Console V3 have RDS decoding.
I'm looking forward to doing more work with the R2 in the weeks to come, and I hope that I can make some contributions to software and plugin programmers. There's a bit of work to be done before I would recommend the R2 for hard-core MW DX-ers. The hardware part is good though.

Saturday, July 08, 2017

QSL: HLQH KBS-2 Daegu, 558

This KBS station is heard practically every day when conditions allow, but I hadn't sent a report until now. I received a KBS World QSL card, and a short note from the technical  department at KBS Pohang.

KBS-2 is the drama and entertainment channel of KBS.

Saturday, July 01, 2017

Airspy R2 + Spyverter R2

This interesting wide-band SDR arrived with personal delivery from the USA yesterday. Actually a friend took it with him so I could save VAT.

Just had time to see it play with SDR# and SDR Console V3.
SDR Console V3

SDR# without Spyverter, FM & RDS

SDR#