Fascist/authoritarian scum the world over are TERRIFIED of the concept of regular human beings having the ability to communicate with each other without being censored, coerced, and surveilled. This is a nightmare scenario for them: people speaking freely
It’s also worth mentioning that the bandwidth requirements of actual, honest, information and news, are appallingly low. The level of slop and waste in our current social media landscape is in no way representative of what it takes to communicate effectively.
100 years ago we used to get the word out to broadcasters at 100 baud over teletype.
So, imagine a network that uses less than 1% of the bandwidth we currently use. It’s a pocket-sized situation that almost disappears into the noise of everything else, yet is free, accessible, and effective. Radio and mesh networks are absolutely up to the task, even if they have to be covert and/or mobile.
Right, this doesn’t get enough attention. Either weirdly or completely understandable. Especially since the Egyptian uprising I think scared a lot of governments.
you’re also a shining beacon every second you transmit and even states with moderate capabilities record their radio spectrum 24/7 even during peacetime
I’ve seen tests where a reasonably equipped military vehicle could not detect a drone in the air near them, because the drone was roving through a band of several gigahertz at a thousand hops per second.
yes i know how spread spectrum schemes work, but this is not really practical or relevant here
for spread spectrum things to work you need some wide bandwidth, this works great for microwaves where you can spread your 90GHz band signal so that it covers 5GHz, you can’t have a signal centered on 5MHz that is 5GHz wide; HF is relevant because while microwaves work with this microwaves are line of sight only and most people’s line of sight still terminates in their own country. if you live on a lone hill next to border good for you, but the rest would need to use HF to get out, and there’s simply not that much bandwidth available in the first place, which would make any scheme like this extremely slow if at all viable. and you can still jam it
i don’t assume that satellite repeaters would be a viable option because satellite, or any other receiving party for that matter, would need to be aware of modulation scheme to receive it in the first place, so it only works if your international contacts are pre-arranged, and even then you need radio that has much larger bandwidth that is usually available. yapping on LSB or narrow digimodes will get you heard within continental range, but also it will get you noticed, but if you hide from your adversary you also hide from everyone else not in the know. and even then, you can still get noticed, because it’s under noise level only at some distance from you
also some of these schemes require precise time to be known, and if you have gps jammed you’ll get extra problems from that
A compact antenna for long bandwidth: wind a spiral. For 40 meters, you could could make a spiral of 1.6 m outer diameter (“a bit less than average human height”), 10 cm inner diameter and 15 turns of wire (if I used the calculator correctly). Not a terribly efficient antenna, but a very compact one for given wavelength.
I have heard (myself I don’t use HF) that HF radios work tolerably with an antenna horizontally on a car roof (could be a truck bed). But it’s true that there is little bandwidth on such frequencies. As for throughput: a channel that is 9 KHz wide is supposed to transfer 9.6 kbit / s of with military data radios (with ionosphere reflection, despite all the multipathing that it causes - I have not checked, but recall a scientific paper telling so). A reasonable detection avoidance technique might be broadcasting from a depressed location or an urban canyon with tall ground clutter. You’d want the direction finder to chase reflections.
Even more fun scenarios exist: launch your guerilla transmitter on a free flight balloon, and will have plentiful line of sight. Essentially a pseudosatellite.
this is just a really extravagant heater, physics forbids antenna this small to have good radiation resistance. for your contrived below noise communications scheme, you need more bandwidth that is physically possible on hf, yet you choose antenna design that is even less wideband than regular dipole. 40m of wire is for 80m band, which is usable more often in this configuration, ignoring everything else
As for throughput: a channel that is 9 KHz wide is supposed to transfer 9.6 kbit / s
5500kbps in extremely favourable conditions is your peak attainable speed, bandwiths in normal radios are narrower
A reasonable detection avoidance technique might be broadcasting from a depressed location or an urban canyon with tall ground clutter
if you don’t want anyone to hear you
launch your guerilla transmitter on a free flight balloon, and will have plentiful line of sight.
with what power source? better study for and get your license, start using radio and stop embarrassing yourself
NIVIS is intended to be used between actual mountains. You know, these kilometer tall things of rock. There’s a hundred-kilometer reflector dish above you, courtesy of the home planet. An urban canyon will only protect you from direction finding, it won’t prevent you from being heard 200 km away. At a distance of 10 km or 20 km, you don’t even want to be heard, and NVIS makes it conveniently hard to hear you at close range.
this is just a really extravagant heater
Which of them? The Swedish guy’s copper tape antenna? Maybe, but it seems to receive nicely.
for your contrived below noise communications scheme, you need more bandwidth that is physically possible on hf,
I know that communicating at the noise floor is not suitable for HF. I did not intend to give that impression. Same for balloons. When you have a line of sight, you choose higher frequencies, isn’t that logical without telling?
with what power source?
High altitude pseudosatellites (I advise to look up the term, they’re fun) almost unexceptionally use battery and solar. I don’t propose carrying a steam engine. :) A LiPo cell will output 100 amps and more. You wait and charge, then work, then wait again. No need to run at 100% duty cycle.
better study for and get your license
For what? To make drones find their way home better? I’m not a radio amateur and I don’t need or intend to be. I build stuff that flies, uses gigahertz frequencies and navigates using radio when fiber runs out and snaps. I admit I know little of HF, but I know the basics acceptably. No need to assume a holier than thou attitude.
5500kbps in extremely favourable conditions is your peak attainable speed
Well, some people write: “In [112] we find measurements on a MIL-STD-188-110C [113] link over distances of up to 160 km, providing the users with bit rates up to 9.6 kbps in 6–9 kHz RF bandwidth.”
Maybe they’re wrong, maybe I read them lazily. Regardless, you can send SMS, teletype or something comparable just as nicely with 5 kilobits per second as you can with 9 kilobits. But as I said, I haven’t tested and don’t intend to test. I approximately know what HF does and how it propagates, but don’t use that band in practise.
By the way, the same people write:
In [5] a car-mounted vertical half loop antenna is described, using capacitance loading to achieve an NVIS antenna gain between −12 and −10 dBi from 3 to 8 MHz.
So yes, a car roof antenna definitely is a heater. Probably much more of a heater than the ones I linked to. You need much power to make it radiate. Now let’s grab a presumably representative example of such a heater, and its real world performance:
Seller self-promotion (grain of salt advised): “As the 2018 predominantly radiates RF energy towards the ionosphere as a vehicle mounted NVIS (Near Vertical Incidence Sky wave) antenna, it is effective in overcoming the skip zone common in whip based antenna systems providing superior operation in the range of 30 to 150 kms. For the same reason the 2018 antenna is highly effective for communication in mountainous areas.”
Maybe you should refresh your information about ionosphere-using comms. I have refreshed mine recently. Not for a practical reason but curiosity. You absolutely don’t need an crazy big antenna. One person can carry all that’s required. Bur of course, not in a pocket, but a backpack.
A PDF I can recommend is here. It also proposes “tent antennas” (inverted V antennas) that are portable, but need putting a pole in ground.
and stop embarrassing yourself
I’m not embarrassed. I am not qualified to teach radio to a radio amateur, even if it seems that I should. I just pass on some tips. I also remind: holier than thou will get you two word answers from most people. I don’t need your goodwill. I don’t need to give a **** or be patient. I reply because I think you are missing out on some methods of communication that some people actually like. From what I’ve heard, ionosphere bounces are fun and practical. If you don’t care, don’t care.
End of communications. I do not intend to continue this conversation as it offers nothing to me.
It is a thousand times more easy to send a secure electronic message then to broadcast an untraceable radio transmission to someone if any physical distance.
Any government they is locking down electronic communication that effectively would fine your radio based solution trivial to intercept and trace.
…broadcast it upwards with a reasonably directional antenna, reflecting off the ionosphere.
…broadcast it from a solar powered relay station which you access via optical link.
(no a ham radio operator, but an anarchist)
I feel sad for the Belarusian ham radio operators, however. In case of crisis, they would be the people who could help develop something interesting to help others. I guess KGB (they still have it) has decided that nothing interesting is needed in their land. :(
you super stealthy nvis signal might not be noticed by anyone, including intended recipient, but your antenna farm made form 40m long wires certainly will
Yes, let’s nitpick words. Broadcast implies that something is available to others. An ionosphere reflection definitely is. An agile frequency hopping signal conditionally is - if they know a key. Which would arguably make it unicast.
and you should probably stop pretending to understand how radio transmission works
Oh higness, thou areth much holier than me. I am humbled.
New ideas and methods are going to be what people need to combat these crackdowns. Posing new thoughts is what people have to start attempting, even at the risk of ridicule. Not every innovative idea is a winner, but eventually a new method will solve the problem. Everyone should keep thinking about how to acheive untracible HAM radio.
Yes, and immediately become subject for closer surveillance by doing so.
My take, as mentioned in another reply: Retain plausible deniability by communicating in plain sight and use good old codebooks or similar techniques for the secret parts of your messages.
Yeah sorry I meant like from different places in a city, not just not at home.
It’s for sure rude and not something I’d try/recommend but we’re talking about espionage here.
Am I wrong in thinking that if I wanted to propagate revolutionary thought and went to a different neighbourhood with an HT and transmitted to the local repeater, it would be hard for the state to find me if my transmission was less than 5 minutes?
I’m saying an intermittent signal from varying locations would not be easy to trace. ARDF is a nearly continuous signal from immobile stations and it is not trivial, it is competitive.
Fascist/authoritarian scum the world over are TERRIFIED of the concept of regular human beings having the ability to communicate with each other without being censored, coerced, and surveilled. This is a nightmare scenario for them: people speaking freely
It’s also worth mentioning that the bandwidth requirements of actual, honest, information and news, are appallingly low. The level of slop and waste in our current social media landscape is in no way representative of what it takes to communicate effectively.
100 years ago we used to get the word out to broadcasters at 100 baud over teletype.
So, imagine a network that uses less than 1% of the bandwidth we currently use. It’s a pocket-sized situation that almost disappears into the noise of everything else, yet is free, accessible, and effective. Radio and mesh networks are absolutely up to the task, even if they have to be covert and/or mobile.
Right, this doesn’t get enough attention. Either weirdly or completely understandable. Especially since the Egyptian uprising I think scared a lot of governments.
Make no mistake. The Arab Spring also taught governments around the world that “shut off the internet” is a crucial element in crushing mass dissent.
agree on uncensorable but keep in mind ham radio is antiprivate by design - every time you say your callsign you sign off
If you do that…
you’re also a shining beacon every second you transmit and even states with moderate capabilities record their radio spectrum 24/7 even during peacetime
I’ve seen tests where a reasonably equipped military vehicle could not detect a drone in the air near them, because the drone was roving through a band of several gigahertz at a thousand hops per second.
yes i know how spread spectrum schemes work, but this is not really practical or relevant here
for spread spectrum things to work you need some wide bandwidth, this works great for microwaves where you can spread your 90GHz band signal so that it covers 5GHz, you can’t have a signal centered on 5MHz that is 5GHz wide; HF is relevant because while microwaves work with this microwaves are line of sight only and most people’s line of sight still terminates in their own country. if you live on a lone hill next to border good for you, but the rest would need to use HF to get out, and there’s simply not that much bandwidth available in the first place, which would make any scheme like this extremely slow if at all viable. and you can still jam it
i don’t assume that satellite repeaters would be a viable option because satellite, or any other receiving party for that matter, would need to be aware of modulation scheme to receive it in the first place, so it only works if your international contacts are pre-arranged, and even then you need radio that has much larger bandwidth that is usually available. yapping on LSB or narrow digimodes will get you heard within continental range, but also it will get you noticed, but if you hide from your adversary you also hide from everyone else not in the know. and even then, you can still get noticed, because it’s under noise level only at some distance from you
also some of these schemes require precise time to be known, and if you have gps jammed you’ll get extra problems from that
Thanks for contructive criticism. :)
A compact antenna for long bandwidth: wind a spiral. For 40 meters, you could could make a spiral of 1.6 m outer diameter (“a bit less than average human height”), 10 cm inner diameter and 15 turns of wire (if I used the calculator correctly). Not a terribly efficient antenna, but a very compact one for given wavelength.
Exaples:
https://sergeev.io/projects/spiral-dipole/
https://www.avalonarc.org.uk/2019/10-27-an-80m-spiral-loop.html
I have heard (myself I don’t use HF) that HF radios work tolerably with an antenna horizontally on a car roof (could be a truck bed). But it’s true that there is little bandwidth on such frequencies. As for throughput: a channel that is 9 KHz wide is supposed to transfer 9.6 kbit / s of with military data radios (with ionosphere reflection, despite all the multipathing that it causes - I have not checked, but recall a scientific paper telling so). A reasonable detection avoidance technique might be broadcasting from a depressed location or an urban canyon with tall ground clutter. You’d want the direction finder to chase reflections.
Even more fun scenarios exist: launch your guerilla transmitter on a free flight balloon, and will have plentiful line of sight. Essentially a pseudosatellite.
this is just a really extravagant heater, physics forbids antenna this small to have good radiation resistance. for your contrived below noise communications scheme, you need more bandwidth that is physically possible on hf, yet you choose antenna design that is even less wideband than regular dipole. 40m of wire is for 80m band, which is usable more often in this configuration, ignoring everything else
5500kbps in extremely favourable conditions is your peak attainable speed, bandwiths in normal radios are narrower
if you don’t want anyone to hear you
with what power source? better study for and get your license, start using radio and stop embarrassing yourself
NIVIS is intended to be used between actual mountains. You know, these kilometer tall things of rock. There’s a hundred-kilometer reflector dish above you, courtesy of the home planet. An urban canyon will only protect you from direction finding, it won’t prevent you from being heard 200 km away. At a distance of 10 km or 20 km, you don’t even want to be heard, and NVIS makes it conveniently hard to hear you at close range.
Which of them? The Swedish guy’s copper tape antenna? Maybe, but it seems to receive nicely.
I know that communicating at the noise floor is not suitable for HF. I did not intend to give that impression. Same for balloons. When you have a line of sight, you choose higher frequencies, isn’t that logical without telling?
High altitude pseudosatellites (I advise to look up the term, they’re fun) almost unexceptionally use battery and solar. I don’t propose carrying a steam engine. :) A LiPo cell will output 100 amps and more. You wait and charge, then work, then wait again. No need to run at 100% duty cycle.
For what? To make drones find their way home better? I’m not a radio amateur and I don’t need or intend to be. I build stuff that flies, uses gigahertz frequencies and navigates using radio when fiber runs out and snaps. I admit I know little of HF, but I know the basics acceptably. No need to assume a holier than thou attitude.
Well, some people write: “In [112] we find measurements on a MIL-STD-188-110C [113] link over distances of up to 160 km, providing the users with bit rates up to 9.6 kbps in 6–9 kHz RF bandwidth.”
Maybe they’re wrong, maybe I read them lazily. Regardless, you can send SMS, teletype or something comparable just as nicely with 5 kilobits per second as you can with 9 kilobits. But as I said, I haven’t tested and don’t intend to test. I approximately know what HF does and how it propagates, but don’t use that band in practise.
By the way, the same people write:
So yes, a car roof antenna definitely is a heater. Probably much more of a heater than the ones I linked to. You need much power to make it radiate. Now let’s grab a presumably representative example of such a heater, and its real world performance:
https://airadio.com/hf-ssb-commercial/barrett-communications/2018-mobile-magnetic-loop-hf-antenna
Seller self-promotion (grain of salt advised): “As the 2018 predominantly radiates RF energy towards the ionosphere as a vehicle mounted NVIS (Near Vertical Incidence Sky wave) antenna, it is effective in overcoming the skip zone common in whip based antenna systems providing superior operation in the range of 30 to 150 kms. For the same reason the 2018 antenna is highly effective for communication in mountainous areas.”
Maybe you should refresh your information about ionosphere-using comms. I have refreshed mine recently. Not for a practical reason but curiosity. You absolutely don’t need an crazy big antenna. One person can carry all that’s required. Bur of course, not in a pocket, but a backpack.
A PDF I can recommend is here. It also proposes “tent antennas” (inverted V antennas) that are portable, but need putting a pole in ground.
I’m not embarrassed. I am not qualified to teach radio to a radio amateur, even if it seems that I should. I just pass on some tips. I also remind: holier than thou will get you two word answers from most people. I don’t need your goodwill. I don’t need to give a **** or be patient. I reply because I think you are missing out on some methods of communication that some people actually like. From what I’ve heard, ionosphere bounces are fun and practical. If you don’t care, don’t care.
End of communications. I do not intend to continue this conversation as it offers nothing to me.
Or you could send an email.
Good luck sending an e-mail that can’t be intercepted.
It is a thousand times more easy to send a secure electronic message then to broadcast an untraceable radio transmission to someone if any physical distance.
Any government they is locking down electronic communication that effectively would fine your radio based solution trivial to intercept and trace.
Pretty stupid when you are literally broadcasting a radio direction finder beacon directly from your home out to the entire world.
…broadcast it upwards with a reasonably directional antenna, reflecting off the ionosphere. …broadcast it from a solar powered relay station which you access via optical link.
(no a ham radio operator, but an anarchist)
I feel sad for the Belarusian ham radio operators, however. In case of crisis, they would be the people who could help develop something interesting to help others. I guess KGB (they still have it) has decided that nothing interesting is needed in their land. :(
you super stealthy nvis signal might not be noticed by anyone, including intended recipient, but your antenna farm made form 40m long wires certainly will
No kidding.
You don’t seen to understand what the word “broadcast” means and you should probably stop pretending to understand how radio transmission works.
Yes, let’s nitpick words. Broadcast implies that something is available to others. An ionosphere reflection definitely is. An agile frequency hopping signal conditionally is - if they know a key. Which would arguably make it unicast.
Oh higness, thou areth much holier than me. I am humbled.
New ideas and methods are going to be what people need to combat these crackdowns. Posing new thoughts is what people have to start attempting, even at the risk of ridicule. Not every innovative idea is a winner, but eventually a new method will solve the problem. Everyone should keep thinking about how to acheive untracible HAM radio.
Imaginary bullshit isn’t actually useful to anyone.
Dude you can just encrypt a radio broadcast if you want to do private comms over radio
Yes, and immediately become subject for closer surveillance by doing so.
My take, as mentioned in another reply: Retain plausible deniability by communicating in plain sight and use good old codebooks or similar techniques for the secret parts of your messages.
It’s laughably easy for them to track you down if you don’t.
ranked competitive version is called foxhunting and even kid can do it
Not with a handheld that you don’t use at home.
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Yeah sorry I meant like from different places in a city, not just not at home.
It’s for sure rude and not something I’d try/recommend but we’re talking about espionage here.
Am I wrong in thinking that if I wanted to propagate revolutionary thought and went to a different neighbourhood with an HT and transmitted to the local repeater, it would be hard for the state to find me if my transmission was less than 5 minutes?
Yes. You would get tracked by your phone
It just takes 3 or more synchronized receive stations to pinpoint your location. The state has an unlimited budget compared to you.
3 synchronized receive stations to fix my location, and then what would they do?
You can still be tracked while broadcasting.
It’s not laughably easy.
It is, though. Finding the source of a radio signal is a trivial task for a government. They currently do it all the time.
Heck, it’s so easy that it’s a legitimate competitive sport that some grade schools use in their PE program.
I’m saying an intermittent signal from varying locations would not be easy to trace. ARDF is a nearly continuous signal from immobile stations and it is not trivial, it is competitive.
Most hams do, its part of the culture, experience and fun.
I think HAMs are required to?
It’s the law, every 10 minutes in conversation and at the end of every contact, at least in the US.