[HN Gopher] Taking a Radio Camping
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Taking a Radio Camping
Author : ewpratten
Score : 96 points
Date : 2024-07-27 02:26 UTC (20 hours ago)
(HTM) web link (ewpratten.com)
(TXT) w3m dump (ewpratten.com)
| jnord wrote:
| 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!
| lloydatkinson wrote:
| 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.
| ted_dunning wrote:
| 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)
| amatecha wrote:
| yeah you can also get an RTL-SDR for like $30 USD (or
| something) and listen to a pretty wide range of frequencies
| - definitely good enough to get started with a very small
| cost.
| fortran77 wrote:
| Not for shortwave. They don't work below 50Mhz
| femto wrote:
| 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.
| curiousfab wrote:
| 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...
| wkjagt wrote:
| 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.
| ztetranz wrote:
| 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.
| aaomidi wrote:
| This would be an effective method against Iran's scrambling
| of satellite TV
| PM_me_your_math wrote:
| 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
| ewpratten wrote:
| Wow! Thats a very cool device. I'll be investigating further
| for my at-home setup.
| ewpratten wrote:
| 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.
| throw0101d wrote:
| 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...
| grendelt wrote:
| 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.
| ewpratten wrote:
| 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.
| hvs wrote:
| 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.
| ewpratten wrote:
| 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.
| ted_dunning wrote:
| Nice article, btw.
|
| But I am very curious. Did you use a balun or antenna tuner?
| ewpratten wrote:
| Thanks! I used the integrated tuner in my KX2. Worked
| perfectly.
| swalberg wrote:
| If you find the park reference you can submit logs to
| pota.app after the fact. Any qso counts.
| ewpratten wrote:
| Thanks for pointing that out. I will do so
| CrimsonCape wrote:
| 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?
| YZF wrote:
| 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.
| CrimsonCape wrote:
| The purpose of the post is trying to understand 1. can a
| viable mesh-network exist 2. does the mesh network not
| currently exist because it's artificially suppressed by
| centralized networking (i.e. cellphone service providers'
| influence over the FCC), or 3. Does a mesh network not exist
| because physics
|
| On point 3, we have made huge strides in miniaturization of
| electrical components since the dawn of radio; we have also
| made huge strides in battery technology.
|
| That would suggest it's physically possible to build better
| devices, so maybe the limiting factor is more #2 nowadays,
| the ability to innovate is capped not by physics but by
| regulation.
|
| Sure, things like LoRa exist, but are not widely useful.
|
| If iPhones were a little more brick-like, maybe we wouldn't
| need to dump money into ISPs pockets; we could just have a
| standard communication language to bounce packets around.
| Then we don't need to pay cell phone bills, just buy new
| batteries.
| dingnuts wrote:
| 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.
| BenjiWiebe wrote:
| 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.
| amatecha wrote:
| If you like posts like this check out https://qrper.com ,
| basically focused around low-power "out in a park or mountaintop"
| sort of operating :)
| bigjimmyk3 wrote:
| I did something similar last month; I took my FT-817 with me to
| scout camp. I wanted to work some FT8 but didn't bring the
| required doodads with me to hook the radio's audio interface to
| my Surface Pro X. No problem, I'll just use the mic and speaker
| on the laptop. To my surprise (and much to the annoyance of my
| fellow leaders) it worked! wsjt-x is an amazing piece of
| software.
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