Jamming on PSK

I was on 15m PSK31 and in the process of calling PY3ED when a vicious jamming signal started up.

Jamming on 21MHz

As you can see, it did a good job of obliterating all signals. It seemed to be centered around 21.070MHz and extended for 50kHz or so in either direction.

I don't know how long it stayed on for because it was lunch time so I went to have something to eat. When I came back the interfering signal had gone.

Was it something local to me or has anyone else seen it?

5V noise generator

An increasing number of electronic devices can be powered or charged from a USB socket. To charge them independently of the computer they usually come with a small switched mode wall-wart. Finding enough wall sockets for these broadband noise generators - in addition to all the wall-warts that already exist in the ham shack - can be a challenge. It would be nice if ham radio power supplies had a few 5V DC outputs.

When I started using my HTC Touch Pro smartphone as an APRS iGate I wanted to avoid using the HTC charger as I knew it created a few warblies on some of the HF bands. I wondered if I could power the phone from the shack supply instead. In the junk box I found a car charger for an old satnav that had the same mini-USB plug and fitted the cigar lighter type socket on my Diamond GSV3000 power supply. That seemed to do the job very well and didn't appear to generate any RF noise (though the noise level here is now so high that the incremental difference made by one more switched mode device is hard to detect.) The only annoying thing about it was that it sticks rather a long way out of the front panel of the GSV3000, which is a bit of a nuisance on my narrow operating desk.

My next thought was that it would be nice to have more than one 5V outlet, perhaps in USB format, to occasionally charge other devices without requiring the computer to be on or plugging in another wall wart. Browsing eBay I saw a Griffin Dual Power USB Car Charger. This would give me two 5V USB outlets. And it was also designed to be flush with the top of the cigar lighter socket so it would look like an integral part of the GSV3000 once installed.

When it arrived I was quickly disappointed. As soon as I plugged a USB cable into one of the outlets, even with no load attached, broadband HF noise jumped up about 3 S-points. The device also got surprisingly hot even though nothing was drawing any current from it. I guess I should have anticipated that  a device that size would use some kind of switching regulator and that this might result in noise.  For the typical user wanting to power or charge two USB devices from their car, the noise is unlikely to be a problem. So I guess this particular solution to eliminating wall-warts is a non-starter.

PLT debated in parliament

The issue of interference to short wave from power line networking devices was debated in Parliament yesterday. You can view the televised debate here. It's quite long, but worth watching if you can spare the time.

If you don't, here's a summary: The only complaints are from a few hobby radio amateurs and the number of complaints has been too few to justify banning a technology that brings potential benefits to millions of homes.

Other points: "Hobby radio amateurs are not legally entitled to a completely clean radio spectrum", and "no specific limits on interference levels have been set so that radio users can adapt as the use of PLT technology evolves." It is also projected that the number of installed PLT devices will quadruple by the year 2020. So this spectrum-destroying interference will be coming soon to an antenna near you!

I'm afraid that the writing is on the wall for amateur radio. In today's world, the only things that count are money and big business vested interests. There are too few radio hobbyists to count at the ballot box and they don't contribute anything to the country that can be measured in financial terms. So we are just going to have to "adapt" to increasing interference levels by giving up hope of receiving weak signals, confining our activities to quiet portable locations, or using modes like D-Star which are interference-free once the signal level rises above the noise threshold.

I think we just saw a death sentence passed on our hobby!

PLT a threat to British intelligence gathering?

A report produced for the British intelligence gathering organization GCHQ claims that noise from power line networking devices is causing a detectable increase in interference at its monitoring stations and could adversely affect its operations. The report, which can be found on the website Ban PLT, was originally released by GCHQ's Director of Engineering and Technology but has since been disowned by GCHQ which now claims it contained "inaccuracies." The government organization also forced the online tech news journal The Register, which published an article containing details of the report, to remove the author's identity from the article using measures designed, ironically, to suppress information that could be considered a threat to national security. So much for freedom of speech.

Ofcom meanwhile continues to deny that PLT devices cause a problem, stating that there have been "only" 272 complaints of interference (all from radio amateurs) and that of 233 cases referred to BT all but one have been resolved so there is nothing to worry about. Has pressure been brought from on high to force GCHQ to disown the report which is embarrassing to BT which has a couple of million of the Comtrend PLT devices installed nationwide? It is blatantly obvious that Ofcom couldn't give a damn about the possible effects on a few hobbyists who don't even pay a license for the spectrum they use. But a threat to the country's ability to monitor the short waves to gather intelligence about potential security threats is something they would have had to take seriously.

Interference on 14.077MHz

Anyone else seeing this diabolical interference on 20m?

Interference on 30m

I was in the shack making a few adjustments to the Echolink software configuration. The K3 was on 30m APRS with the speaker volume turned down to almost inaudible. Suddenly, at about 1410 UTC, I heard a buzzing type of interference. I looked at the TrueTTY waterfall and saw there were interference bars every 50Hz right across the screen, strong enough to prevent anything from being decoded.

50Hz is the mains frequency here in the UK. With a sinking feeling my immediate thought was that one of the neighbours had discovered a new way to make the HF bands unusable. Then I remembered that Lynn, KJ4ERJ had posted a screenshot of similar interference only the day before in an APRS forum. I checked back, and sure enough the interference Lynn had seen in Florida was exactly the same.

I don't know what it is, but I don't think even my neighbours are capable of generating interference that could be heard across the Atlantic. It's still going strong 30 minutes later. I haven't seen an HF band wiped out like this since the Woodpecker fell silent back in the '80s. Well, at least I've got Echolink!