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
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 transfering video, because the data link was roving through a band of several gigahertz at a thousand hops per second.
If you stay close to the noise floor, especially if you use parts of spectrum that others are using (very impolite, but people who don’t want to be caught are unexceptionally impolite)… good luck to the catchers. Especially if the signal occurs at a pre-agreed time and remains short (read: don’t try sending video, send something SMS sized).
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 especially like the last one, third generation is made of copper tape and sized like a laptop computer, and the guy in Sweden is getting reception from as far as the Far East.)
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 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.
Good luck sending an e-mail that can’t be filtered and blocked or traffic analyzed, even if the content is encrypted.
As a minimum before trying, I would advise a peer to peer mix network (TOR, I2P). But repressive governments block those as well as they can, and may pay users a visit if they suspect something.
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 from distance.
(Not a ham radio operator, but an anarchist, but I can draw a Doppler radar in GnuRadio and have implemented a monopulse tracker… with lots of help from other people who know better. My assessement: it’s easy to track powerful signals on an expected frequency, but very hard to track weak signals which do agile frequency hopping with a random key, or hide among other traffic.)
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. They were practising their hobby openly and became targets because of that. People who do clandestine business don’t exchange contact information openly.
I guess KGB (they still have it) decided that nothing interesting is ever 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
You don’t seen to understand what the word “broadcast” means and you should probably stop pretending to understand how radio transmission works.
Your recommendation is essentially to not transmit in a way that anyone can receive and therefore you can’t be caught. I can give you a simpler plan to achieve that: turn off your radio.
Yes, let’s nitpick words. Broadcast implies that something is available to others. An ionosphere reflection definitely is. An unmanned pirate station also is. An agile frequency hopping signal conditionally is - if others know a key. Which would arguably make it unicast, a term I should have used in that part of my sentence.
and you should probably stop pretending to understand how radio transmission works
Oh highness, thou areth much holier than me indeed, I am humbled by this mere sentence.
Your recommendation is essentially to not transmit in a way that anyone can receive
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
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 transfering video, because the data link was roving through a band of several gigahertz at a thousand hops per second.
If you stay close to the noise floor, especially if you use parts of spectrum that others are using (very impolite, but people who don’t want to be caught are unexceptionally impolite)… good luck to the catchers. Especially if the signal occurs at a pre-agreed time and remains short (read: don’t try sending video, send something SMS sized).
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.
Examples:
https://sergeev.io/projects/spiral-dipole/
https://www.avalonarc.org.uk/2019/10-27-an-80m-spiral-loop.html
https://sa0pej.wordpress.com/build-page-nvis-spiral-loop-antenna/
(I especially like the last one, third generation is made of copper tape and sized like a laptop computer, and the guy in Sweden is getting reception from as far as the Far East.)
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 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.
Or you could send an email.
Good luck sending an e-mail that can’t be filtered and blocked or traffic analyzed, even if the content is encrypted.
As a minimum before trying, I would advise a peer to peer mix network (TOR, I2P). But repressive governments block those as well as they can, and may pay users a visit if they suspect something.
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 from distance.
(Not a ham radio operator, but an anarchist, but I can draw a Doppler radar in GnuRadio and have implemented a monopulse tracker… with lots of help from other people who know better. My assessement: it’s easy to track powerful signals on an expected frequency, but very hard to track weak signals which do agile frequency hopping with a random key, or hide among other traffic.)
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. They were practising their hobby openly and became targets because of that. People who do clandestine business don’t exchange contact information openly.
I guess KGB (they still have it) decided that nothing interesting is ever 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.
Your recommendation is essentially to not transmit in a way that anyone can receive and therefore you can’t be caught. I can give you a simpler plan to achieve that: turn off your radio.
Yes, let’s nitpick words. Broadcast implies that something is available to others. An ionosphere reflection definitely is. An unmanned pirate station also is. An agile frequency hopping signal conditionally is - if others know a key. Which would arguably make it unicast, a term I should have used in that part of my sentence.
Oh highness, thou areth much holier than me indeed, I am humbled by this mere sentence.
I made several recommendations.
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
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. But correct me if I’m wrong.
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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?
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.
It’s not significantly more difficult than transmitting from a mobile station.
We are taking about hiding from a government. They could pinpoint you in seconds.
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.