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It is worth pointing out that you do not need an amateur radio license to receive signals, and indeed transmitting is not necessary for this experiment. Any sh
by LeoPanthera 5y ago
It is worth pointing out that you do not need an amateur radio license to receive signals, and indeed transmitting is not necessary for this experiment.
Any shortwave or "HF" radio will do. A simple receiving antenna for the HF band is simply a length of wire, as long as possible, and as high as possible.
WWV and WWVH transmit on 2.5, 5, 10, 15, and 20 MHz. (Though 2.5MHz is outside the HF band and difficult to receive with most radios.)
If you live on the US west coast it is often possible to receive both, especially at night, which is why their signals are offset in time.
- drmpeg 5y agoWWV also transmits on 25 MHz. This is an experimental transmitter that's not mentioned in the broadcast at minute 0. WWVH does not transmit on 20 MHz.
- mhh__ 5y agoIf I'm not mistaken in the UK you actually need a licence to listen to some frequencies. I may be misremembering but it always struck me as rather Sisyphean the moment I bought a cheap SDR.
- LadyCailin 5y agoOk. Good luck enforcing that.
- junon 5y agoI don't know how this could even remotely be enforced.
- Majromax 5y agoSuperheterodyne receivers (https://en.wikipedia.org/wiki/Superheterodyne_receiver https://en.wikipedia.org/wiki/Superheterodyne_receiver) use a local oscillator to downmix the received radio or television signal for processing at a much more sane, lower frequency. That local oscillator emits its own RF radiation, so it is potentially detectable.
- BenjiWiebe 5y agoCorrect. However, if using an rtl-sdr by itself to listen to HF, you are utilizing direct conversion which doesn't use an intermediate frequency. I believe the IF is still being generated (?), but it's no longer indicative of what you are listening to.
- formerly_proven 5y agoDirect conversion has no IF but still uses a mixer and a LO, and the LO still leaks out of the input port of the mixer. Because you're directly converting the RF to baseband, LO frequency is the tuned frequency. Unlike e.g. a dual or triple conversion receiver (used in e.g. spectrum analyzers), where the first IF is way above the highest tunable frequency.
- mhh__ 5y agoThere is almost definitely something to detect if you brought a van full of RF gear, but it's not like the good old days where it was obvious.
- jasonzemos 5y agoGreat link as it mentions Radar Detector Detectors. This is actively enforced in the US state of Virginia.
- tata71 5y agoWhich is one of very few places radar detectors are against the law in the US.
- jaywalk 5y agoI would love to see it challenged all the way up to the Supreme Court if necessary. These laws seem blatantly unconstitutional, and it's kind of amazing that they've held up for so long.
- dguest 5y ago
- User23 5y agoIn the UK you need a license to receive the BBC[1]. And they drive around in vans[2] looking for evidence of unlicensed receivers. [1] https://en.wikipedia.org/wiki/Television_licensing_in_the_United_Kingdom https://en.wikipedia.org/wiki/Television_licensing_in_the_Un... [2] https://en.wikipedia.org/wiki/TV_detector_van https://en.wikipedia.org/wiki/TV_detector_van
- brigandish 5y agoI'd be willing to wager that the detection techniques said to be used in the vans are a product of mendacious fantasy (some might say that is par for the course with the BBC), and the actual method used is to simply correlate homes that do not have licences with those that previously had them, and to simply look towards the roof and see if an aerial is present. Ockham's razor and all that.
- bloak 5y agoAnalogue CRT television sets emitted some distinctive signals, I think, like the horizontal scan rate of about 15 kHz: https://en.wikipedia.org/wiki/Horizontal_scan_rate https://en.wikipedia.org/wiki/Horizontal_scan_rate That's hardly relevant today, of course.
- ivanhoe 5y agoTrue, but it's low power signal and it's not an easy job to triangulate on that in say a 12-storey building, 8 apartments per floor, and where everyone has TVs emitting on the same frequency. It makes very questionable the legality of entering someone home based just on that.
- UncleSlacky 5y agoThey're not legally allowed to enter your home without your consent, anyway.
- 5y ago
- jonp888 5y agoIt's the reason that there are no live streams of ATC transmissions online for UK airports. Doing that would trigger some "enforcement".
- mike_d 5y ago"No live streams" is a little broad. LiveATC specifically was targeted by Ofcom. GlobalTuners and dozens of other sites have UK ATC broadcasts, they just can't advertise them publicly.
- deleted 5y ago[deleted]
- BuildTheRobots 5y ago> Under Section 5(1)(b) of the WT Act 1949 it is an offence if a person "otherwise than under the authority of a designated person, either:(i) uses any wireless telegraphy apparatus with intent to obtain information as to the contents, sender or addressee of any message whether sent by means of wireless telegraphy or not, of which neither the person using the apparatus nor a person on whose behalf he is acting is an intended recipient; So yes, use of radio receivers to listen to anything in the UK, other than general broadcast or frequencies you're specifically licenced to listen to is an offence without express permission. I believe it's the main reason you can't stream Air Traffic Control frequencies in the UK, where as their available for other countries. More information available here: http://www.monitoringtimes.com/html/mtlaws_may04.html http://www.monitoringtimes.com/html/mtlaws_may04.html
- Mindless2112 5y agoYou don't necessarily need a radio at all to tune into WWV/WWVH -- you can listen on a telephone. (Nevermind that most telephones today use radio waves.) (303) 499-7111 for WWV (Colorado) (808) 335-4363 for WWVH (Hawaii) https://www.nist.gov/time-distribution/radio-station-wwv/telephone-time-day-service https://www.nist.gov/time-distribution/radio-station-wwv/tel...
- LeoPanthera 5y agoThis would, however, void the entire purpose of this experiment.
- User23 5y agoAlso it greatly reduces the value of the time signal. Over the PSTN it's usually a couple hundred milliseconds off.
- anyfoo 5y ago> It is worth pointing out that you do not need an amateur radio license to receive signals, and indeed transmitting is not necessary for this experiment. I don't think that's true everywhere. There is a reason that at least in the 80s/90s, scanners were exclusively sold as "export equipment" in Germany, meaning you were not allowed to buy them for use within Germany. (Don't know if that's still the case.) They still were advertised next to all the other non-export equipment in consumer electronic store catalogues, just with a warning. I would be shocked, shocked, if there ever were any customers who bought such a scanner without the explicit intent to export it to another country.[1] [1] I didn't, like actually didn't. Not only was I too young to have that kind of money, at that age I actually thought using one might get me into serious trouble (I have no idea how).
- Aloha 5y agoA scanner and a shortwave receiver are not the same thing.
- anyfoo 5y agoI don't know if listening to this particular signal is legal or not in Germany or anywhere else, I'm just pointing out that for the general case (as I read OP's sentence) it may well depend on the jurisdiction.
- Aloha 5y agoThe only countries as far as I know that banned shortwave reception were the former eastern block countries and other similar regimes.
- LeoPanthera 5y agoReception of the entire HF band is legal globally, as defined by the ITU. You don't need a scanner to receive shortwave radio, and in fact most scanners can't receive shortwave radio.
- 5y ago
- 8bitsrule 5y ago>as long as possible, and as high as possible. Caveat about 'long as possible' (for general shortwave listening): Once the antenna is over a half wavelength long at the operating frequency (10MHz, one wavelength is ~~ 100 feet, 30 meters), it becomes increasingly more directional along its axis. (Longer still, even more directional.) This may dampen the signal amplitude for signals coming in 'off the side' (compared to a dipole at least).
- deleted 5y ago[deleted]