strange 20 meter signals

[K5KTD]

Encountered strong signals, 6 wide, on frequencies 14.150 14.200, 14.250, 14.300, 14.350. No mod, just carrier. Can not identify them. Any ideas?

 

[alcahuete]

Over the horizon RADAR, perhaps?

 

[KC4YIN]

Could be a HAB. High altitude balloon circling the planet. A friend mine launched one 2 weeks ago from here in eastern N.C. It just completed it's first world tour today. It's on 20 meters. NC4ES.

 

[K5KTD]

OTHR? Possiibly, however, there is no signal, just carrier.
An ARS HAB at 14.350 USB is out-of-band.

 

[krokus]

Audio samples, and/or waterfall image of the signals?

 

[K5KTD]

No audio, just carrier.
No panadapter.

 

[jwt873]

I've listened a few times and don't hear anything like that on those frequencies up here in VE4 land. Given that 20 meters is a long haul band, and nobody else on the forum has reported hearing the carriers, I'm going to guess that the signals are noises being generated by a local source.

To see if it is local, start unplugging things., Or turning off breakers.

I've been 'bit' a few times by local noise. I was getting occasional hash, that messed up reception across all the HF bands.. It occurred randomly. Turns out it was coming from a NiCad battery charger that was quite a distance away in another part of the house. It only generated noise when there were batteries being charged.

 

[dlwtrunked]

No audio, just carrier.
No panadapter.

A couple things:
1. If it is a continuous carrier, it cannot be 6 kHz wide.
2. No radar can be a continuous carrier, radars have to pulse so they can "hear" the returns.
3. The signals being 50 kHz apart indicate a probably transmitter problem, some sort of interference, or overload of the receiver.

 

[K6GBW]

I had signals like that on 40 meters. Turned out to be a Motorola power supply under my desk. Even plugging it in caused the signals to appear.

 

[krokus]

2. No radar can be a continuous carrier, radars have to pulse so they can "hear" the returns.

Fire control radars are a CW radar. Granted, they do not operate on HF.

 

[Token]

Fire control radars are a CW radar. Granted, they do not operate on HF.

The term CW can be confusing, especially when crossing from the ham world to other RF centered worlds, such as radar. You would think it would be simple, two little letters, but there are many different interpretations for it. Sure, the meaning is always "Continuous Wave", but the understanding of what that is changes with application. In the radar world, especially the microwave radar world, pulses as short as a few milliseconds, and shorter, can sometimes be called "CW".

But, to CW and fire control (FC) radars, not all FC radars are unmodulated CW radars. Indeed, most FC radars are not unmodulated CW radars. I did not say that some FC radars do not emit a CW signal.

Some FC radars, specifically some missile associated FCs, may include a CW component as well as pulsed or compressed pulse components. Typically the CW component of an FC system is not actually a radar (with the goal of tracking a target for the source or platform of the radar), but instead is a CW illuminator, most often for semi-active missile guidance. Another part of the radar waveform, typically modulated, actually tracks the target, and that target track allows the radar to keep an illumination beam pointed at the target so that a semi-active missile can follow the illuminator reflected energy to the target. The radar tracks the target, the target track points an illuminator beam, the illuminator energy reflects off the target, the missile sees that reflected energy, and follows, rides, the reflected energy all the way to the target. The illumination beam may be emitted from the same antenna as the track beam, or it may come from a different antenna or transmitter. There is, of course, the deeper argument of, is the illuminator a radar or not? It certainly may be, as far as the missile is concerned, but it typically is not, as far as the ship or aircraft launching the missile is concerned. Often the FC radar has no receiver to even detect any information from the illuminator radiation, in many cases the FC radar just transmits the illumination energy, and never looks at it.

There are, of course, unmodulated CW radars that are actual radars, not just illuminators.

Unmodulated CW radars can operate in any frequency range (for example HAARP has done specific HF unmodulated CW radar experiments), however unmodulated CW radars do not give any range information, at best they give angles (CW Angle Tracking) and more typically radial velocity (Doppler shift). Most CW radars give radial velocity only, as applied in police speed measurement radars and other speed / closure rate applications.

With all of that said, many HF radars are indeed CW (the transmitter maintains a constant amplitude and never shuts the carrier off for relatively long periods), but they are modulated CW, typically FMCW (Frequency Modulated Continuous Wave), most commonly LFMCW (Linear FMCW), and can be described as a compressed pulse. The British PLUTO radar, the French Nostradamus, certain specific waveforms of the Australian JORN, an unnamed Chinese radar, etc, all on HF, all use FMCW (specifically LFMCW in all those cases).

To the OPs query, do there appear to be any propagation affects on the signals in question? If I encountered signals as you describe, strong, unmodulated, and every 50 kHz, I would first look for a local RFI source.

T!

 

[dlwtrunked]

...
Unmodulated CW radars can operate in any frequency range (for example HAARP has done specific HF unmodulated CW radar experiments),
...

I cannot find a reference for actual HAARP itself *radar* experiments. The closest I could find is NSF Award Search: Award # 0528111 - SGER: Advanced Modular Incoherent Scatter Radar (AMISR) Studies at High-Frequency Active Auroral Research Program (HAARP) but in the description, HAARP is not acting as a radar. Or this one Observations of HF backscatter decay rates from HAARP generated FAI where HAARP affected an Alaska SuperDARN ionospheric radar.

 

[Token]

I cannot find a reference for actual HAARP itself *radar* experiments. The closest I could find is NSF Award Search: Award # 0528111 - SGER: Advanced Modular Incoherent Scatter Radar (AMISR) Studies at High-Frequency Active Auroral Research Program (HAARP) but in the description, HAARP is not acting as a radar. Or this one Observations of HF backscatter decay rates from HAARP generated FAI where HAARP affected an Alaska SuperDARN ionospheric radar.

Over the years I have talked with a few of the scientist that have worked various experiments at HAARP, and they have mentioned both FMCW (not sure what for) and unmodulated CW mode (looking at Doppler shift) experiments with HAARP. That is in addition to the other, more well known, experiments, such as heating, localized and manufactured sky glow, Luxembourg effect experiments, etc.

T!