Messages

1

Huh? / Re: Anyone ever check-out this magazine, The Spectrum Monitor?

« on: April 10, 2022, 1030 UTC »

I’ve been a subscriber from issue #1.  It’s an excellent magazine with relevant and timely content — a worthy successor to Monitoring Times.  I especially appreciate that the issues come out as pdf files vice something tied to a proprietary platform with DRM like Zinio.

While we are talking about magazines, I would like to put in a plug for the RSGB magazine Radcom.  They put QST to shame, having far better technical content.  It reminds me of the old QST, decades ago.

2

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. 

3

General Radio Discussion / Re: Shortwaves for Freedom Project (Ukraine / Radio Free Europe rebroadcast project)

« on: March 09, 2022, 1510 UTC »

It is looking likely that Russia will isolate their Internet from the outside world.
https://fortune.com/2022/03/07/russia-runet-disconnect-ukraine-dns-chernenko-letter/


The USAGM thinks the internet is the way to go.
https://thehill.com/policy/technology/597411-grassroots-effort-uses-shortwave-radio-to-broadcast-voa-in-ukraine-russia

Even if USAGM can’t restore some of the government transmitter sites quickly to bring VOA back to SW, there are something like 15 licensed SWBC stations, commercial and religious, in the US and it’s territories.  I’d bet that some of them would be tickled pink to sell airtime to USAGM.

4

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?

5

General Radio Discussion / Re: BBC launches new shortwave radio service in Ukraine

« on: March 03, 2022, 2034 UTC »

BBC goes old school.

https://www.huffingtonpost.co.uk/entry/bbc-ukraine-shortwave-radio-frequencies_uk_621fa132e4b0a7784bb2808f

6

General Radio Discussion / Re: BBC launches new shortwave radio service in Ukraine

« on: March 03, 2022, 2023 UTC »

Listeners in the area will be able to tune into the broadcasts at 15735 kHz from 16:00-18:00 GMT and 5875 kHz from 22:00-00:00 GMT.

Is it possible that those times are actually 1400-1600Z and 2000-2200Z?  That seems more consistent with what other people are reporting.

7

Longwave Loggings / Re: 100kHz time signal? 1320UTC 2/27/2022

« on: February 28, 2022, 1448 UTC »

The KiwiSDR radios have an integrated Loran-C decoder built in.  It could be used to help decode what Loran you might be hearing.  But as Sigint noted, there aren’t voice announcements.  My guess is you are hearing an image.

BTW, a few years ago I was hearing eLoren out of Wildwood on 100 kHz.  I haven’t heard them since.

8

Longwave Loggings / Re: Receiving LWBC in North America

« on: February 28, 2022, 1439 UTC »

I should probably invest in a few more ferrite toroids and the like. There's still so much noise coming out of my house! And I do have an AM BCB filter around here somewhere, so I'll experiment with putting that in line.

Be sure to use ferrites with the right mix!  Mix type 75 or 77 is what you should be using.  You can get them at DXEngineering.

I also have all of the connections to my KiwiSDR going through Type 77 ferrite cores - antenna, GPS, ethernet, and power.  Each has two cores glued together, and then wrapped in fiberglass cloth tape (the tape helps protect the ferrites from chipping).

The purpose of the LPF is to ensure that strong out of band signals on the BCB or SW don’t drive the receiver into compression.

The KiwiSDR is a very capable LW receiver.

9

Longwave Loggings / Re: Receiving LWBC in North America

« on: February 27, 2022, 1501 UTC »

I have received them in Virginia on a KiwiSDR and a Wellbrook loop before, but not every day.  Conditions need to be good.  Winter is better because thunderstorm QRN is much reduced.  Many believe the best months for LW propagation are Sep-Oct, but there will still be audible thunderstorm QRN.  A large Loop-On-the-Ground (LOG) antenna worked well too, better I think than the Wellbrook.

If you hear electrical noise when you tune through the LW band, you probably need to work to reduce that first.

You need to put effort into reducing any local noise sources and eliminating common mode noise.  Common mode filters on your feedline, at both the antenna and at the receiver, that use the correct ferrite mix for LF (e.g. Type 75 or 77) are important. I also use a LPF that cuts out the AM BCB.

10

HF Mystery Signals / Re: "RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022

« on: February 23, 2022, 1403 UTC »

In the past, Lojack was on VHF high band.  The police cars with Lojack trackers all had 1/4 wave VHF whips in a group of four…probably a doppler df unit.  I imagine they are still on VHF.

11

Equipment / Re: Question about ordering aluminum tubing

« on: February 22, 2022, 1218 UTC »

If you really want to go with aluminum tubing, DX Engineering has a selection of tubing:

https://www.dxengineering.com/search/part-type/aluminum-tubing


Another alternative is the Hygain AV18-VS antenna.  It sells for about $200 and is really nothing more than a vertical aluminum antenna, with a loading coil at the base.
 
The S9v31 approach seems to work well for many.  DX Engineering also sells fiberglass tubing if you elect to follow this path.

12

Equipment / Re: Common mode noise

« on: February 22, 2022, 1159 UTC »

Your comment about OCF dipoles and end fed wires is interesting.  I had never considered them as being worse for common mode noise pickup before, but your logic makes sense.

A decade ago I had a 80 meter dipole with a balun, fed with coax.  The coax went straight down and then entered an underground pvc pipe that led to the house.  At the house it connected to a grounded metal plate for entry into a basement hamshack.  I remember that antenna as being very quiet for RF noise, even though I was surrounded by neighbor homes in close proximity in all directions.  I see now that it was well situated to minimize common mode noise pickup, though that wasn’t done knowingly.
 

13

Part 15 AM and FM Station Operation / Re: Questions about part 15 shortwave

« on: February 20, 2022, 1429 UTC »

This ISM band runs from 13.553 to 13.567 MHz - a 14 kHz wide bandwidth.  It won’t support more than one or two AM transmitters.

This doesn’t seem like a good idea.

* If you want to stay legal, your output power will only be a few milliwatts at best.

* You are going to be competing will all sorts of industrial noise emittters.

* You are going to be interfering with a number of established hobbiest beacons.

14

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.)

15

Propagation / Re: Three Cheers...

« on: February 10, 2022, 1313 UTC »

There is better detail in the story here:
https://www.space.com/spacex-starlink-satellites-lost-geomagnetic-storm

There is more to the story I imagine.  It isn't clear why they couldn't leave "safe mode".  Was this a design issue?  Were the spacecraft at a point that their propulsion system couldn't recover them?

There will be more details in the weeks to follow.  Starlink has to provide information to keep financial investors interested.

The spacecrafts use Hall thrusters to maneuver.
https://spaceflightnow.com/2019/05/15/spacex-releases-new-details-on-starlink-satellite-design/