Keep in mind that without working repeaters, the baofeng will only have a range of a few miles on level ground with nothing in the way. If the power goes out, most of the repeaters will go down too. Some have battery backups that may last a few hours to a few days. Depending on where you are, a few may be solar powered, but heavy use will drain the batteries. Some repeaters are also reliant on the internet for linking to increase the coverage area.
What you really want in that case is a portable HF radio and a wire antenna you can string up over a tree branch or a support with a fishing pole. In the daytime, you can use the upper HF bands for long distance communication. That has a range of thousands of miles, but nearby stations won’t be able to hear you if they are beyond line of sight. Since the portable radio doesn’t have much power, you may need to use digital modes to get through. For more local contacts you can use NVIS propagation on the lower HF bands. That has a range of several hundred miles and can even be used to talk to someone on the other side of a mountain. Even 5 watts and an antenna strung 3 feet off the ground can work for voice contacts out to over a hundred miles.
Since the portable radio doesn’t have much power, you may need to use digital modes to get through.
I don’t know much about radio stuff, but ever since I learned about LoRA I’ve wondered what kind of range a station could get if the longwave or AM bands were repurposed for use with a spread spectrum digital protocol. And what kind of bandwidth something like that would have.
I think being able to do datacasting over really long ranges would be useful, so, for example, you could send emergency alerts to people even if the local cell infrastructure was down. But with the way things are headed I guess that role will be taken up by satellites.
For LF and MF, you typically want narrow signals, not spread spectrum. It’s hard to make wide band antennas for such low frequencies and propagation can change a lot in just a few tens of kHz.
In your opinion is there anything useful we can do with that part of the radio spectrum as those stations switch off, or are those frequencies going to be silent in the future? Will they be turned over to hobbyists maybe? (or would the power requirements be too high at those frequencies?)
The AM broadcast stations aren’t going anywhere, at least in the US. Above the broadcast band is mostly aircraft, marine and the 160 meter ham band. None of that is likely to change.
Below the AM broadcast band are non directional beacons. Those are slowly being decommissioned. Eventually they will all be gone and that spectrum may get repurposed. I don’t know what the spectrum may get used for, but it would be nice if the 630 meter ham band was expanded.
LF and MF can be used at low power. The 2200 meter ham band has a power limit of 1 watt EIRP and the 630 meter band has a limit of 1 or 5 watts EIRP depending on the country. Actually radiating that much power is difficult because it’s not practical to build an efficient antenna. Luckily there is no limit on how much power the amplifier can put out, so we can put hundreds of watts into a very inefficient antenna. Narrow band digital modes work great on those bands.
In the US, we have LowFER, which allows hobbyists to use 160-190 kHz for experimental use without a license. The power limit is 1 watt input and the transmitting antenna is limited to 15 meters. People still manage to make long distance contacts with those significant limitations.
Oh nice. I see it for ~$80 on their site, but still, that’s cool. Never heard of it. I ended up getting a Xiegu G90 for HF. I’m curious how well the RT-880 works for HF. Gonna see if there are any reviews of it. I would’ve loved to know about it last year lol.
Keep in mind that without working repeaters, the baofeng will only have a range of a few miles on level ground with nothing in the way. If the power goes out, most of the repeaters will go down too. Some have battery backups that may last a few hours to a few days. Depending on where you are, a few may be solar powered, but heavy use will drain the batteries. Some repeaters are also reliant on the internet for linking to increase the coverage area.
What you really want in that case is a portable HF radio and a wire antenna you can string up over a tree branch or a support with a fishing pole. In the daytime, you can use the upper HF bands for long distance communication. That has a range of thousands of miles, but nearby stations won’t be able to hear you if they are beyond line of sight. Since the portable radio doesn’t have much power, you may need to use digital modes to get through. For more local contacts you can use NVIS propagation on the lower HF bands. That has a range of several hundred miles and can even be used to talk to someone on the other side of a mountain. Even 5 watts and an antenna strung 3 feet off the ground can work for voice contacts out to over a hundred miles.
I don’t know much about radio stuff, but ever since I learned about LoRA I’ve wondered what kind of range a station could get if the longwave or AM bands were repurposed for use with a spread spectrum digital protocol. And what kind of bandwidth something like that would have.
I think being able to do datacasting over really long ranges would be useful, so, for example, you could send emergency alerts to people even if the local cell infrastructure was down. But with the way things are headed I guess that role will be taken up by satellites.
For LF and MF, you typically want narrow signals, not spread spectrum. It’s hard to make wide band antennas for such low frequencies and propagation can change a lot in just a few tens of kHz.
I see
In your opinion is there anything useful we can do with that part of the radio spectrum as those stations switch off, or are those frequencies going to be silent in the future? Will they be turned over to hobbyists maybe? (or would the power requirements be too high at those frequencies?)
The AM broadcast stations aren’t going anywhere, at least in the US. Above the broadcast band is mostly aircraft, marine and the 160 meter ham band. None of that is likely to change.
Below the AM broadcast band are non directional beacons. Those are slowly being decommissioned. Eventually they will all be gone and that spectrum may get repurposed. I don’t know what the spectrum may get used for, but it would be nice if the 630 meter ham band was expanded.
LF and MF can be used at low power. The 2200 meter ham band has a power limit of 1 watt EIRP and the 630 meter band has a limit of 1 or 5 watts EIRP depending on the country. Actually radiating that much power is difficult because it’s not practical to build an efficient antenna. Luckily there is no limit on how much power the amplifier can put out, so we can put hundreds of watts into a very inefficient antenna. Narrow band digital modes work great on those bands.
In the US, we have LowFER, which allows hobbyists to use 160-190 kHz for experimental use without a license. The power limit is 1 watt input and the transmitting antenna is limited to 15 meters. People still manage to make long distance contacts with those significant limitations.
Yeah… if I am trying to reach people tens of miles away during The Apocalypse, I am already dead.
Anyone who is within range to be helpful (or… not) would generally be within signal range of a handheld.
HF handhelds do exist. Do they have the range of a dedicated HF rig? No. Better than a Baofeng? Yes, and they’re about $10 more.
Like what? Can you name one?
Radtel RT-880 comes to mind. Baofeng-level handheld capable of HF comms. I got one for ~$50.
Oh nice. I see it for ~$80 on their site, but still, that’s cool. Never heard of it. I ended up getting a Xiegu G90 for HF. I’m curious how well the RT-880 works for HF. Gonna see if there are any reviews of it. I would’ve loved to know about it last year lol.
The G90 is a much, much better radio.
For an extra 0 on the price I hope so lol. I’ve been happy with it!
What about after surviving the initial disaster? During the rebuilding? Or the ongoing survival?
Long-distance radios are useful as hell in stuff like The Last of Us.
That’s not an emergency scenario, that’s an apocalyptic scenario.