Xiegu G1M Longer range coms on a budget

[Lightspeed]

(16 December 2020, 22:33)Skean Dhude Wrote: Don't forget local comms. We can communicate with locals when the phones are dead as well as listen globally and locally.

Indeed yes SD, The receivers on these radios are astounding, permitting good reception of signals not just line of sight but also from Near-Vertical reflection of HF from the Ionosphere which gives continuous receive capability pretty much from your back door out to 500 mils or so.

Again 3.5 Mhz by night and 7Mhz by day for the Near vertical reflections.... You need a horizontal antenna wire to pick these up. Even something strung along the top of a fence will do.

[Mick]

I know zilch about radios, but is there any danger that bad guys could home in on our transmissions or is that just hollywood baloney??

[CharlesHarris]

(31 January 2021, 23:20)Mick Wrote: I know zilch about radios, but is there any danger that bad guys could home in on our transmissions or is that just hollywood baloney??

Not Hollywood baloney. Quickly and easily done. Computerized multiple site direction finding used to locate your mobile phone can do the same thing with a mobile radio. In a major city like Washington, DC, New York or London TPTB can have a fix on you in seconds.

https://www.dhs.gov/sites/default/files/...ly2019.pdf

https://apps.dtic.mil/dtic/tr/fulltext/u2/a128039.pdf

Similarly sound detection equipment called "Shot Spotter" can distinguish the specific characteristics of a firearm discharge from a firecracker and triangulate from multiple cell phone towers at once and automate the dispatch of the nearest armed police unit.

https://www.govtech.com/public-safety/De...-Tech.html

[Mortblanc]

Haven't you heard? The BBC can tap into your brain waves and tell when you are watching TV without a license!

More seriously, triangulation technology is as old as radio. When the Titanic sank they were sending transmissions hoping that someone would triangulate on their position. There were just too few receivers operating at that time.

One of the "secret" projects early in WW2 was recruiting civilian radio operators in England to track German signals and often triangulate the positions of their broadcasters. They actually got a draft exemption for their work.

That was the reason for "radio silence" during operations. They were afraid of giving away their position, not hiding what they were saying. The air force used triangulation to find home runways during inclement weather and the parachute troops had a form of triangulation they used to mark drop zones. Pathfinders went in and set up the transmitters in advance of the drops.

All of this 80 years ago during WW2.

So today you can track your teenager on your cell phone when he does not even have his phone turned on!

[Mick]

As a matter of interest, can radio transmitters of all kinds have adjustable ranges?
For example if you want to transmit to somebody who's say only 10 miles away, can you set the range to 10 miles so that nobody with a receiver beyond that range can eavesdrop on your conversation?

Also, can radio beams be "pointed" in a specific direction? For examp if your receiving pal lives in a specific area could you direct the beam at that area so that anybody outside the beam wouldn't be able to eavesdrop?

[CharlesHarris]

Frequency, transmission mode and transmitter output are selectable, but transmitter range is affected by efficiency of antennas on both transmit and receive sides, the radiation pattern of the antenna, and also by terrain and atmospheric conditions. Even a low power signal, such as a PMR446 hand-held, with inefficient base-loaded helical antenna having negative gain compared to an isotropic source, can be located and monitored from many miles away by satellites or aircraft using advanced equipment.

While yagi and log-periodic antennas are directional, they still radiate in all directions, although the main lobes of the radiation pattern and the highest gain favors where they are pointed.

To avoid eavesdropping avoid RF-based communications unless encrypted, using spread spectrum or being sent in brief digitized burst transmissions.

[Pete Grey]

We can be sure that there’s no such thing as a private conversation, radio, email or phone, but why would TPTB be interested in us?, they have bigger fish to fry. We are all law abiding citizens not criminals or terrorists.

[bigpaul]

we are different Pete, not your usual sheeple citizen, thats what TPTB dont like, we make our own decisions not do what the govt tells us to.

[Lightspeed]

(3 February 2021, 21:56)Mick Wrote: As a matter of interest, can radio transmitters of all kinds have adjustable ranges?
For example if you want to transmit to somebody who's say only 10 miles away, can you set the range to 10 miles so that nobody with a receiver beyond that range can eavesdrop on your conversation?

Also, can radio beams be "pointed" in a specific direction? For examp if your receiving pal lives in a specific area could you direct the beam at that area so that anybody outside the beam wouldn't be able to eavesdrop?

Hard to limit range other than decreasing power Mick. At times even that doesnt work

Yes directional "beams" are viable. Combined with reduced power this can be quite effective.

In your 10 mile scenario ( quite a difficult challenge actually... much easier to reach 70 - 1000 miles) A power adjustable Ultra High Frequency radio into a Yagi beam antenna would work quite well and the antenna would focus energy in the direction you point it, implicitely reducing transmissions in unwanted directions

[Lightspeed]

Update, since Christmas my radio station is exclusively using the little Xiegu radio

So far I've managed two way communications with 32 countries, including most of Europe, Russia, Scandinavia, Iceland, USA and Canada.

Range from 80 miles out to several thousand miles, all achieved at low power and using a very modest homemade wire antenna.

The receiver on this radio is truly amazing, using the same simple antenna I regularly listen broadcast stations worldwide as well as Amateurs discussing Covid situation in their local areas (Australia/NZ, Asia Pacific, India/ Pak, Africa, South America, North America and all of Europe of course)