DMR Radio

[Hardcalibres]

Hey, you ham experts out there! What about ham radios aboard overland rigs? You know, 4WD vehicles equipped to cross trackless wastes AND outfitted with ham radios? Wouldn't they be harder to locate once the ham radio 'sender' finished his transmission and took off? That OAUSA.NET site was all about ham radios and overland rigs... I believe the guy who set up that site went on to create the American Adventurist Site, which is also pretty cool.

When you drive on most trackless wastes.....you leave tracks.

If they want you bad enough and they have vehicles faster than yours, then they can chase you down.

Vehicle use in a very severe crisis would be purposeful. Radio use should also be purposeful. If you send one word and then receive one word (even just the same word) to acknowledge receipt of message, then it is hard to find your direction.

"Coder Burst" radios were specifically developed to defeat RDF.

 

[Hardcalibres]

Sure, you can set up rigs in vehicles. VHF and UHF are line-of-sight - if you can see the mountain top 12 miles away, you can talk to someone there. If you're in a valley and want to talk to someone on the other side of the mountain, you're out of luck.

HF uses a very different antenna and bounces the signal off the ionosphere. There are HF antennas for vehicles, but how effective they would be for local communications is another matter. HF is designed to reach far, not within 100 miles.

But to address your point, yes, having your radios mobile will be helpful in avoiding being involved in a fox hunt.

Agreed.

Antennas like the ATAS120 can be setup on vehicles.

They also allow super fast retuning of the antenna so you can jump around among frequencies/bands very quickly, which also makes you harder to RDF.

 

[Sourdough]

If you send one word and then receive one word (even just the same word) to acknowledge receipt of message, then it is hard to find your direction.

Question: does the clicking of the "mic" essentially count as one word. When a pilot declares an emergence, if lost in the air, they have you click the mic three times.

 

[Hardcalibres]

Question: does the clicking of the "mic" essentially count as one word. When a pilot declares an emergence, if lost in the air, they have you click the mic three times.

Not sure about that one......ground stations to support air operations would have a range of systems to assess direction (including supporting stations in various locations).

They may also be trying to reduce the pilot's workload........but as you mentioned before, they triangulate a few direction vectors to locate the aircraft.

A single receiver can be used to RDF a stationary "talkative" transmitter, at different times, from different locations to get a fix (again using triangulation).

In a very severe crisis, that is worth avoiding.

The key is to get out of the ham mindset and into a survivalist mindset when the situation changes.

Even in normal times, talking about prepping/survivalism on ham radio is a lot more dangerous than talking about it on a web forum.

Normal ham radio chit-chat is effectively location stamped.

 

[Wingnut]

Quick question: is the 'coder burst' or 'coded burst' like a 'macro' in satcomm systems, only for reasons of security instead of trying to save money?

 

[Hardcalibres]

Quick question: is the 'coder burst' or 'coded burst' like a 'macro' in satcomm systems, only for reasons of security instead of trying to save money?

Coder burst was historically analog.

Satcom macros are more a digital data packet with the encoding aimed as much to ensure accuracy of the eventual decode as it is to achieve security. Macros can also carry various types of data including images and other data (sometimes for control systems on mobile equipment like trains/planes etc).

Satcom TCAS is a good example of how that technology is used commercially:

https://onboard.thalesgroup.com/communication-system-and-tcas-surveillance-solutions-for-korean-air/