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General Radio Discussion / Russian Comms

« on: March 12, 2022, 1858 UTC »

From the Scan-DC mailing list:
https://rusi.org/explore-our-research/publications/commentary/russian-comms-ukraine-world-hertz

I have seen Reddit postings of supposed sound bites of Russian troops calling home where they talk of looting and murders. If Ukraine is the source of those postings, then they must be actively mining the cellular network. If the Russians are using cellphones for Command and Control like the URL article suggests, then the Ukrainians are reading this too.

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Equipment / Noise around the house

« on: March 04, 2022, 1251 UTC »

Some noise sources you might not suspect:
https://youtu.be/ewcemoXLzcU

I use switches like this to turn off noisy items (like my Keurig) when I am not using them:
https://www.amazon.com/Oviitech-Grounded-Outlet-Adapter-Indicator/dp/B0747N2Z66/ref=sr_1_4_sspa?

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Equipment / Common mode noise

« on: February 19, 2022, 1624 UTC »

N6GN says:

“…….In studying noise sources and in particular the coupling of these sources to the KiwiSDR I’ve come to realize that one of the dominant coupling mechanisms of signals that degrade receiver noise floor is via common-mode signals. These can exist almost everywhere in the system; they exist on the antenna
itself, within ground systems, on the feedline and other connections to the antenna and through the KiwiSDR itself. I’m presently of the opinion that for most amateur stations and even most KiwiSDRs that the dominant source of unnecessary SNR degradation, QRN and QRM, is due to common mode currents. Near-field coupling to a variety of types of local sources, interference which is attenuated as a function of distance faster than the inverse-square field of a radiated plane wave emanating from a distant source dominates a majority of amateur stations.

Although resignation to the existence of “all those noisy digital devices” and the mindset that interference has to be accepted seems to be the prevalent wisdom within the hobby, I’ve found that this is not the case. I have come to believe that the vast majority of amateur receive systems are not limited by either propagated noise, which would be the desired condition, or by radiated noise from local interferers, as is commonly espoused, but by coupling to near-field sources and in particular common mode noise…..”

source:
https://forum.kiwisdr.com/uploads/Uploader/5f/492f44efb5a272d715c5219da67b44.pdf

This pdf has further thoughts on this. (The active antenna he mentions was in the Oct 2018 issue of QST, not Sep 2017 as he states in the pdf.)

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General Radio Discussion / Government auctions…

« on: February 06, 2022, 0608 UTC »

Interesting find. Looks a little rough though.

https://www.reddit.com/r/amateurradio/comments/sbrzh1/interesting_find/?

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HF Mystery Signals / Clicky Carrier

« on: January 29, 2022, 1517 UTC »

http://ka7oei.blogspot.com/2021/12/the-case-of-clicky-carrier.html

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General Radio Discussion / Deep Space Communications

« on: December 28, 2021, 1449 UTC »

All you might ever want to know about Deep Space Communications. The sidebar links take you to even more information.

https://descanso.jpl.nasa.gov/monograph/mono.html

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VHF/UHF Logs, including satellites and radiosondes / Starlink Beacons

« on: December 03, 2021, 1343 UTC »

Here are details on Starlink satellite beacon reception. There is another link early in the Reddit link that takes you to a detailed discussion of the hardware being used.

I first saw mention of this on the RTL-SDR list, but the Reddit post has more details.

For mere detection of the beacons, much less is required. There have been reports of success with nothing more than a Ku LNB pointed straight up, no dish. A generic Ku LNB will mix down to L band, which is in band for almost all the popular SDR receivers. The doppler shift will verify that you are hearing the satellites.

https://www.reddit.com/r/StarlinkEngineering/comments/r7mmsd/a_tale_of_two_satellite_constellations_update_1/

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SDR - Software Defined Radio / KiwiSDR and HFDL

« on: November 16, 2021, 1746 UTC »

The latest software build for the KiwiSDR has added a HFDL decoder.

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SDR - Software Defined Radio / KiwiSDR updates

« on: November 16, 2021, 1719 UTC »

If you own a KiwiSDR, check the firmware version. The latest version is 1.474 (as of today); if you have that then no need to read further.

If your KiwiSDR is showing version 1.462, then the update process is broken and manual intervention is required. Details on what you need to do are here:

http://forum.kiwisdr.com/index.php?p=/discussion/2370/v1-462-manual-intervention-required-to-receive-future-updates/p1

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