Back in the 70s when shortwave was still king, we used to pack communications radios, rolls of antenna wire and jump on a train to travel up to northern Scandinavia to listen to faraway exotic stations on the medium and shortwave bands. It was an ideal environment with no electronic noise, mainly due to scarce population, and we were free to roll out 500 meters of longwire in various directions without upsetting anybody. Fun times indeed!

In the 90s I spent a few years working on the Jindalee Over-The-Horizon-Radar. It's in the HF band and located in a quiet spot in the middle of Australia. At that time it wasn't fully operational, so there were substantial periods where the research team had exclusive access. One of the techs was a keen radio amateur and used to patch his HF kit into the beamformed antenna array. Subject to the ionosphere not being complete rubbish he could roam around to his hearts content. A further bonus was real-time access to one of the world's best ionosonde networks. It was HF nirvana.

I occasionally get a long wire between buildings and listen to shortwave and bands. Sometime I’d like to get a HackRF and try out SDR and GNU Radio.

HackRF isn't the only way to go. There are other projects like T41-EP that can give you a really nice software defined platform as well.

Check it out here: https://www.4sqrp.com/T41main.php

(hint: you know it's a group of hams as soon as you see the colored fonts and grey background)

The variation in local noise between different locations is huge. As an apartment dweller and radio amateur, this is something I am fighting every day and in a densely populated environment, the noise floor changes all the time, depending on which neighbor operates which electrical device at the time...

The amateur radio community is very aware of the problems and several initiatives have been launched to quantify the effects. One of them is the DARC's ENAMS, which is described in detail here:

https://web.tapr.org/meetings/DCC_2020/DK5HH/F_ENAMS-DCC-DK5...

I plan to write about my home setup, which is... a little crazy antenna-wise.

The noise here is really bad due to my area and the construction of the building I live in. Much creativity is required to get QSOs from here.

Have you tried a QRM Eliminator? I haven't tried one myself yet, but I hear good things about them. Also, some really simple things can be really noisy. Cheap LED bulbs for example can be super noisy. I had one above my desk that was terrible.

I think that's a phasing device. You attach an auxiliary antenna specially to pick up the noise. The signal from that is phase shifted and mixed into the signal from the main antenna. The phase shift circuitry has knobs to vary the phase and amplitude. You adjust them so that the noise cancels out.

That can be effective but it's really only useful for cancelling out one noise source. I once used a similar device when there was something bad happening on a power pole down the street. It's no use if you have general noise from multiple directions.

This would be an effective method against Iran’s scrambling of satellite TV

Wow! Thats a very cool device. I'll be investigating further for my at-home setup.

A buddy of mine uses one and it is effective. Most of your noise will come from buck converters and other cheap power supplies in the near field. Cell phone chargers, 120ac to 12vdc PSU, computer PSU, and fluorescent lighting ballasts are big culprits. Plasma TVs will generate more noise as they age. Pole-mounted cable repeater PSU go bad and start heating up, generating a shitload of noise. Any arcing on cracked insulators will generate RFI and can be easily located by driving around with a clear AM channel on your car stereo. Report these as they must also be repaired. Cheap solar panel inverters are also noise generators. A process of isolating house circuits helps identify the offending devices if they are in the home. In most cases, it is unlawful for devices to generate spurious emissions. In the case of solar panel inverters, they must fix/replace them if you complain. Another thing to check is cable tv leakage, which is less of a problem today, but can still cause interference. Unterminated cable coax can radiate lots of noise in the 144mhz band, and also on other channels. Great article about RFI hunting and elimination: https://www.arrl.org/files/file/RFI/Thompson%20Noise.pdf

I have a question for amateur radio enthusiasts:

Let's say "radio 1.0" is as it existed since radio was invented: convert raw analog or digital packets into a signal of a given wavelength as assigned by the FCC for the "type" i.e. nautical, hobby, aero, etc. Roughly associated with physical distance.

It's obvious we have the technology at this point where multiple streams of information can be reconstructed from one wire/pipe. My cable internet is mixed with thousands of other users and yet the cable internet system delivers me just my data.

Why is the airwaves not just another physical medium (metal wire, fiber optic, air)?

If I want to build an amateur transmitter to airstream my Twitch to my friend in Brazil, the FCC would say no, because

1. Can't clutter up the airwaves (the FCC manages the wavelengths) 2. For "safety" (government wants to monitor the stream)

In "radio 2.0" I can build my hobby hardware to whatever transmit power I want and use whatever wavelength I want because air is just another medium for the same signal. My question is roughly, why cant the organizing principles of my router, isp cable internet system, etc apply to over the air transmission?

Is it a physics limitation? Or a "we always did it this way therefore you can't have it" (FCC, etc)

Let's say I hypothetically have a high power handheld transmitter in my pocket powered by modern batteries, the FCC doesn't exist, and the power is the best that the modern batteries can provide, with the only tradeoffs being weight of the transmitter and duration of batteries, i.e. physics based tradeoffs.

Don't we have the technology to mix thousands of such handheld transmitters so that everyone can carry one, broadcast their own stream, and intermix the streams, and deconstruct the stream back to my own data?

The same principles are used and airwaves are just another physical medium. The problems are this is shared media with everyone else and also it's somewhat inefficient media (EDIT: and noisy).

Your hypothetical high powered handheld transmitter (e.g. you cellphone?) is limited by the amount of power from your batteries and other factors.

EDIT: The bandwidth of radio waves is also limited and there's noise which limits the total amount of data you can broadcast.

Well the whole HF band is a tiny fraction of cable bandwidth, plus a LOT more natural and manmade noise, plus some of it only works during the day, some at night, some mostly at the right time of the solar cycle... And THEN remember that it's "one cable" you are sharing with up to the whole world.

You might be just describing packet radio, which does exist, but it's extremely slow due to the physical size of the radio waves involved, as I understand it. The frequency of the waves, due to their extremely long wavelength, is very low.

The trade-off for the long wavelengths is better permeability of the signal, which is why the author of the article is able to transmit so far on seven watts, but your Wi-Fi (high frequency and very short wavelength) has trouble getting through walls.

A big part of Ham radio today is what are known as POTA (Parks on the Air) activations where hams go to different parks to make contacts with other hams. These are often low-power transmissions (Known as QRP, or 10W or less). I think a big driver of this is the fact that our cities have become so noisy.

https://parksontheair.com/

Side note: if you read Hacker News, enjoy tinkering with electronics, and want to meet/talk to more people like you, I recommend becoming a Ham. The Technician and General exams from the FCC are relatively easy if you have any technical background and it's a great outlet for experimenting.

I actually intended to make these proper POTA activations, but I couldn't figure out the park identifier due to lack of cell service, and I also didn't bring anything for VHF to try doing so over APRS.

Next time I guess.

If you find the park reference you can submit logs to pota.app after the fact. Any qso counts.

Thanks for pointing that out. I will do so

Nice article, btw.

But I am very curious. Did you use a balun or antenna tuner?

Thanks! I used the integrated tuner in my KX2. Worked perfectly.

See also perhaps:

* https://en.wikipedia.org/wiki/Random_wire_antenna

There are also commercially available products that are fairly portable and probably give you a better SWR; e.g.:

* https://www.buddipole.com

* https://www.youtube.com/results?search_query=Buddipole

From one of the photos, seems like the author is using an Elecraft KX-2, which is really a clever bit of kit that packs a big bunch in small package:

* https://elecraft.com/products/kx2-ssb-cw-data-80-10-m-transc...

A buddipole has been on my list for a while, but as you said the KX2 is really good, and happily tunes even the worst of my antenna experiments. I've made contacts with the output of this radio tied directly into a grounding rod and nothing else before.

On this particular trip, I had my antenna at a perfect 1:1 the whole time.

Yeah, the KX2 is an amazing little radio. I take mine with me on work trips for doing POTA in new places. The tuner in the KX2 is said to be able to tune a wet noodle.

The receiver is very sensitive and the filter can be adjusted to clamp down on one signal. I do CW most of the time so I can setup and make contacts in a lot of noisy, challenging places, from Grants Tomb in NYC to a little POTA site just north of KC airport with power distribution lines high overhead, I've been able to work coast to coast with either an end-fed halfwave or a Chelegance MC750 vertical. (Far easier and less bulky than my Buddipole or Buddistick). I also have an end-fed random wire for use with my KX2. I took it to Old Town San Diego and was able to band-hop while a friend was on 20m at the same picnic table. With the random wire I was still able to pull in Italy on 5W!

I'm headed for Madison, WI tomorrow and will be playing radio in the evenings weather (and solar storm) dependent.