7 ms·

Taking a Radio Camping

139 points by ewpratten 2y ago

jnord 2y ago
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 2y ago
  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 2y ago
    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 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 2y ago
      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 2y ago
        Not for shortwave. They don’t work below 50Mhz
        brewtide 2y ago
        Rtl-sdr blog v3 has a direct sampling mode that will get you into the single-digit mhz. I assume that the v4 does as well. The earlier versions apparently also have this mode but it requires opening the devices up and a bit of soldering here and there.
        ewpratten 2y ago
        I have an RTL-SDR and an upconverter. Pretty nice setup if you don't need the ability to transmit.
        amatecha 2y ago
        They do indeed, with the RTL-SDR Blog V3 and "direct sampling" mode! I think it's the only one at that price point that you can directly listen to HF/shortwave.
        kQq9oHeAz6wLLS 2y ago
        I have a couple of the super cheap ones I got for like $12 years back. With a simple mod you can get direct sampling and listen to any frequency. Works great.
        lormayna 2y ago
        The best radio for shortwave is without any doubt the Belka. It costs around 200€, but the quality is fantastic. The new versions cover also LW/MW and have an IQ output, so you can use as SDR as well. Otherwise you can find some Chinese clones of SDR play that are really cheap, but I am not suggesting those from a ethical standpoint
    - deleted 2y ago
      [deleted]
- femto 2y ago
  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 2y ago
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-DK5HH.pdf https://web.tapr.org/meetings/DCC_2020/DK5HH/F_ENAMS-DCC-DK5...
- wkjagt 2y ago
  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 2y ago
    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 2y ago
      This would be an effective method against Iran’s scrambling of satellite TV
  - PM_me_your_math 2y ago
    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 https://www.arrl.org/files/file/RFI/Thompson%20Noise.pdf
throw0101d 2y ago
See also perhaps: * https://en.wikipedia.org/wiki/Random_wire_antenna 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.buddipole.com * https://www.youtube.com/results?search_query=Buddipole 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-transceiver https://elecraft.com/products/kx2-ssb-cw-data-80-10-m-transc...
- grendelt 2y ago
  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 2y ago
  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 2y ago
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/ 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 2y ago
  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.
  - swalberg 2y ago
    If you find the park reference you can submit logs to pota.app after the fact. Any qso counts.
    - ewpratten 2y ago
      Thanks for pointing that out. I will do so
  - ted_dunning 2y ago
    Nice article, btw. But I am very curious. Did you use a balun or antenna tuner?
    - ewpratten 2y ago
      Thanks! I used the integrated tuner in my KX2. Worked perfectly.
- brewtide 2y ago
CrimsonCape 2y ago
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 2y ago
  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 2y ago
    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.
amatecha 2y ago
If you like posts like this check out https://qrper.com https://qrper.com , basically focused around low-power "out in a park or mountaintop" sort of operating :)
bigjimmyk3 2y ago
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.
- ewpratten 2y ago
  haha, ya. I was showing my dad what FT8 sounded like with the soundcard unplugged, and I very quickly decided that I didn't want to hear that anymore.
_justinfunk 2y ago
> I had originally intended to spend this trip operating FT8 and CW, but for some reason I found myself really enjoying FT4 (a mode I had never used before), so I spent most of my day camped out on 14080Kc, and then shifted to 10136 and 7074 in the evening. As a non-radio enthusiast, I was following along until this sentence.
- femto 2y ago
  FT8, CW and FT4 are all types of modulations, or ways of imprinting information onto a radio signal. They offer different performance under different channel conditions. 14080Kc ( = 14080 KHz = 14.08 MHz), 10136 (=10.136 MHz) and 7074 (=7.074 MHz) are the frequencies of the radio channels being used. The ionosphere (which is partly powered by the sun) tends to dissipate at night and not reflect higher frequencies as well. Thus one tends to use lower frequencies during the evening/night and higher frequencies during the day. As an aside, an ionosonde is a radar which can measure and display the reflectivity of the ionosphere in real-time as function of things like height/range, radio frequency and direction. Not many people get to play with them, but they are a great tool to learn how the ionosphere works. You can sit in front of the display and watch in real-time as the ionosphere's response changes and it's height increases as night approaches and see how it varies from day to day. Beats reading about it in a text book and it's fascinating to watch. Here's a link to an online ionosonde, displaying ionograms in real-time, updated every 5 minutes: https://www.sws.bom.gov.au/HF_Systems/1/3 https://www.sws.bom.gov.au/HF_Systems/1/3
- ewpratten 2y ago
  Haha, I saw this comment coming as I wrote this sentence. I tried to link to everything you might find relevant in the text. The other comment under yours does a great job explaining things too. As an additional note KC (Kilo Cycles) is the old way of writing Kilohertz. I just happen to prefer writing Kc for some reason even though I know it's no longer "correct"
solardev 2y ago
Can anyone recommend something (as in radio type or particular device) for relatively portable battery based comms between two hiking groups? The use case is a big group hike that often gets separated into two or more smaller groups walking at different speeds, but wanting to still be able to check in with each other every so often. There's no cell reception out there. Basically just want a glorified walkie talkie with a bit more range (a few miles through woods and across hills of possible). I just got my GMRS license and some cheap 5W handhelds to experiment with, but I'm not sure if that is the best option. We might also have the option of setting up a "base station" at the trailhead (our cars or someone relaxing at a picnic table) to act as a higher powered repeater if that would help. How much of it is frequency (radio type), wattage, line of sight, operator skill. etc.?
- ewpratten 2y ago
  I'm not very familiar with GMRS, but your scenario is what that license is designed for. So I'd recommend it. I think in some places you can set up a repeater for GMRS? You'd have to check up with the local regulations. Of course, you could get everyone (or a few designated people) ham licensed. In many areas, operators are allowed to let other people use their radios under their supervision, so you might not need to even get every single person licensed. Frequency plays a very big role, and the rest "depend". There are some frequencies that'd just simply be impossible to use for communication that close (in the grand scheme of things) and others that would struggle to penetrate the trees. Without knowing the area, I'd guess that 2 or 6 meters would be your best bet. (Probably 2m) Your next challenge would be getting good antennas. The antenna matters a lot (even more than power output. (See me hitting Australia with 7w)) I'm always available for questions via email. You'll find it in my website.
  - solardev 2y ago
    Thank for you the response! If this GMRS stuff goes well (getting the radios in a few days, hiking the week after that), a HAM license sounds like a fun thing to look at next. But from the movies, it always seemed like that was more of a way to chat with random strangers around the world (like this "Parks on the Air" thing), rather than coordinating hikes between specific individuals. Is that accurate at all? > Without knowing the area, I'd guess that 2 or 6 meters would be your best bet. (Probably 2m) What is this in reference to? Is that a measure of wavelength (e.g. 2-6m ~= VHF?) or did I misunderstand? I thought for longer-range comms, you would want to utilize not just repeaters but things like ionosphere reflections and HF. Are you saying that's actually not the best thing to use for wooded areas a few miles apart? I appreciate the info :) If I really get into this as a hobby, I'd love to hit you up via email. Please give me a few weeks to test the waters first.
hjfjh 2y ago
[dead]

139 points by ewpratten 2y ago

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 2y ago
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 2y ago
  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 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 2y ago
    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 2y ago
      Not for shortwave. They don’t work below 50Mhz
      - brewtide 2y ago
        Rtl-sdr blog v3 has a direct sampling mode that will get you into the single-digit mhz. I assume that the v4 does as well. The earlier versions apparently also have this mode but it requires opening the devices up and a bit of soldering here and there.
      - ewpratten 2y ago
        I have an RTL-SDR and an upconverter. Pretty nice setup if you don't need the ability to transmit.
      - amatecha 2y ago
        They do indeed, with the RTL-SDR Blog V3 and "direct sampling" mode! I think it's the only one at that price point that you can directly listen to HF/shortwave.
      - kQq9oHeAz6wLLS 2y ago
        I have a couple of the super cheap ones I got for like $12 years back. With a simple mod you can get direct sampling and listen to any frequency. Works great.
      - lormayna 2y ago
        The best radio for shortwave is without any doubt the Belka. It costs around 200€, but the quality is fantastic. The new versions cover also LW/MW and have an IQ output, so you can use as SDR as well. Otherwise you can find some Chinese clones of SDR play that are really cheap, but I am not suggesting those from a ethical standpoint
  - deleted 2y ago
    [deleted]
femto 2y ago
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 2y ago

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

wkjagt 2y ago
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 2y ago
  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 2y ago
    This would be an effective method against Iran’s scrambling of satellite TV
- PM_me_your_math 2y ago
  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 https://www.arrl.org/files/file/RFI/Thompson%20Noise.pdf

throw0101d 2y ago

See also perhaps: * https://en.wikipedia.org/wiki/Random_wire_antenna 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.buddipole.com * https://www.youtube.com/results?search_query=Buddipole 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-transceiver https://elecraft.com/products/kx2-ssb-cw-data-80-10-m-transc...

grendelt 2y ago
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 2y ago
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 2y ago

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/ 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 2y ago
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.
- swalberg 2y ago
  If you find the park reference you can submit logs to pota.app after the fact. Any qso counts.
  - ewpratten 2y ago
    Thanks for pointing that out. I will do so
- ted_dunning 2y ago
  Nice article, btw. But I am very curious. Did you use a balun or antenna tuner?
  - ewpratten 2y ago
    Thanks! I used the integrated tuner in my KX2. Worked perfectly.
brewtide 2y ago

CrimsonCape 2y ago

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 2y ago
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 2y ago
  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.

amatecha 2y ago

If you like posts like this check out https://qrper.com https://qrper.com , basically focused around low-power "out in a park or mountaintop" sort of operating :)

bigjimmyk3 2y ago

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.

ewpratten 2y ago
haha, ya. I was showing my dad what FT8 sounded like with the soundcard unplugged, and I very quickly decided that I didn't want to hear that anymore.

_justinfunk 2y ago

> I had originally intended to spend this trip operating FT8 and CW, but for some reason I found myself really enjoying FT4 (a mode I had never used before), so I spent most of my day camped out on 14080Kc, and then shifted to 10136 and 7074 in the evening. As a non-radio enthusiast, I was following along until this sentence.

femto 2y ago
FT8, CW and FT4 are all types of modulations, or ways of imprinting information onto a radio signal. They offer different performance under different channel conditions. 14080Kc ( = 14080 KHz = 14.08 MHz), 10136 (=10.136 MHz) and 7074 (=7.074 MHz) are the frequencies of the radio channels being used. The ionosphere (which is partly powered by the sun) tends to dissipate at night and not reflect higher frequencies as well. Thus one tends to use lower frequencies during the evening/night and higher frequencies during the day. As an aside, an ionosonde is a radar which can measure and display the reflectivity of the ionosphere in real-time as function of things like height/range, radio frequency and direction. Not many people get to play with them, but they are a great tool to learn how the ionosphere works. You can sit in front of the display and watch in real-time as the ionosphere's response changes and it's height increases as night approaches and see how it varies from day to day. Beats reading about it in a text book and it's fascinating to watch. Here's a link to an online ionosonde, displaying ionograms in real-time, updated every 5 minutes: https://www.sws.bom.gov.au/HF_Systems/1/3 https://www.sws.bom.gov.au/HF_Systems/1/3
ewpratten 2y ago
Haha, I saw this comment coming as I wrote this sentence. I tried to link to everything you might find relevant in the text. The other comment under yours does a great job explaining things too. As an additional note KC (Kilo Cycles) is the old way of writing Kilohertz. I just happen to prefer writing Kc for some reason even though I know it's no longer "correct"

solardev 2y ago

Can anyone recommend something (as in radio type or particular device) for relatively portable battery based comms between two hiking groups? The use case is a big group hike that often gets separated into two or more smaller groups walking at different speeds, but wanting to still be able to check in with each other every so often. There's no cell reception out there. Basically just want a glorified walkie talkie with a bit more range (a few miles through woods and across hills of possible). I just got my GMRS license and some cheap 5W handhelds to experiment with, but I'm not sure if that is the best option. We might also have the option of setting up a "base station" at the trailhead (our cars or someone relaxing at a picnic table) to act as a higher powered repeater if that would help. How much of it is frequency (radio type), wattage, line of sight, operator skill. etc.?

ewpratten 2y ago
I'm not very familiar with GMRS, but your scenario is what that license is designed for. So I'd recommend it. I think in some places you can set up a repeater for GMRS? You'd have to check up with the local regulations. Of course, you could get everyone (or a few designated people) ham licensed. In many areas, operators are allowed to let other people use their radios under their supervision, so you might not need to even get every single person licensed. Frequency plays a very big role, and the rest "depend". There are some frequencies that'd just simply be impossible to use for communication that close (in the grand scheme of things) and others that would struggle to penetrate the trees. Without knowing the area, I'd guess that 2 or 6 meters would be your best bet. (Probably 2m) Your next challenge would be getting good antennas. The antenna matters a lot (even more than power output. (See me hitting Australia with 7w)) I'm always available for questions via email. You'll find it in my website.
- solardev 2y ago
  Thank for you the response! If this GMRS stuff goes well (getting the radios in a few days, hiking the week after that), a HAM license sounds like a fun thing to look at next. But from the movies, it always seemed like that was more of a way to chat with random strangers around the world (like this "Parks on the Air" thing), rather than coordinating hikes between specific individuals. Is that accurate at all? > Without knowing the area, I'd guess that 2 or 6 meters would be your best bet. (Probably 2m) What is this in reference to? Is that a measure of wavelength (e.g. 2-6m ~= VHF?) or did I misunderstand? I thought for longer-range comms, you would want to utilize not just repeaters but things like ionosphere reflections and HF. Are you saying that's actually not the best thing to use for wooded areas a few miles apart? I appreciate the info :) If I really get into this as a hobby, I'd love to hit you up via email. Please give me a few weeks to test the waters first.

hjfjh 2y ago

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