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8 votes
Accepted

Is it legal to transmit with HackRF one?

You'll need an experimental radio license (Versuchsfunk) from Bundesnetzagentur link for research operation. For demonstration/teaching purposes, a demonstration radio license (Demonstrationsfunk für ...
Marcus Müller's user avatar
7 votes
Accepted

Can we transfer digital files on radio spectrum?

Radio is analog, and modem converts analog signals to digital signals and vice versa. Everything is analog, yet you can do digital things with the physics that is given to us. As you've noticed, ...
Marcus Müller's user avatar
7 votes

Is it legal to transmit with HackRF one?

As for other legal alternatives, one might be transmitting inside a suitably shielded Faraday cage. I’ve seen such facilities at labs where various prototype and pre-production (and competitors?) ...
hotpaw2's user avatar
  • 13.4k
6 votes
Accepted

How do businesses develop and test amateur radio products in the US if you cannot be paid for amateur radio use?

Two parts to this answer: First, most testing would be done against dummy loads, looking at the results on spectrum analyzers. Such tests should not propagate. Secondly, there's a fine line here. As ...
user10489's user avatar
  • 6,415
6 votes

Range of wireless signals

It is an oversimplification to say lower frequencies have longer range. See Is free space path loss dependent on frequency? It's more accurate to say the range of a half-wave dipole decreases as ...
Phil Frost - W8II's user avatar
5 votes
Accepted

Transmit on multiple frequencies with USRP using GRC

To transmit two signals at once, just generate the two signals with the appropriate frequency spacing between them, and add them together. With your mentioned frequencies, you might generate the ...
Kevin Reid AG6YO's user avatar
  • 24.6k
5 votes

Do phones transmit RF when they’re not in a call?

I apologize in advance if this isn’t the right place to post this, but I though some of you might know the answer to my question. Welcome. This question is arguably off-topic because it is about the ...
Kevin Reid AG6YO's user avatar
  • 24.6k
4 votes
Accepted

Is it possible to have multiple people talking on the same radio channel at the same time?

if a number of these devices are transmitting on a specific channel, will a receiver walkie talkie be able to hear all the signals coming from the ground sensors? The exact result depends on the ...
Kevin Reid AG6YO's user avatar
  • 24.6k
4 votes
Accepted

How hard to send files

To get that distance, you're going to need to use an HF frequency, which means you won't have nearly as much bandwidth as Wi-Fi. Transferring a movie could take a very long time. Additionally, you ...
mrog's user avatar
  • 1,023
4 votes
Accepted

Can I contact the International Space Station using my Baofeng UV5R?

In theory, yes. In practice, "probably not". In my experience, the front end on Baofengs is not very good. We have a UV-82, and it just did not work when we tried to use it for amateur satellites (AO-...
hjf's user avatar
  • 1,199
4 votes

Baofeng UV-5R transmitting to Baofeng BF888s - 888s will not receive transmission unless holding "mon"

Most likely the 888s are set up to require a "tone" to break squelch. This is very common for a radio that's been used with repeaters, and almost all repeaters use CTCSS, aka PL tone, to minimize ...
Zeiss Ikon's user avatar
  • 4,097
3 votes
Accepted

How does PTT from one two-way radio prevent input on another?

Well, it's a combination of two features: The squelch setting, and the busy channel lockout setting. Namely, when a sufficiently strong signal has been received, the squelch system will activate the ...
AndrejaKo's user avatar
  • 2,893
3 votes

Can timing information be used to compress data for LoRa transmission?

I think you are taking the wrong approach. Take some time to look at the overhead of a LoRa packet. It contains addressing, checksums, handshaking, etc. It is a large enough overhead that sending one ...
Glenn W9IQ's user avatar
  • 18.6k
3 votes

Can we transfer digital files on radio spectrum?

WiFi has a channel width of 20 or 40 MHz, even up to 160 MHz with 802.11ac. Theoretically WiFi could operate at a lower frequency, though there would be a number of issues. For starters, a single ...
Phil Frost - W8II's user avatar
3 votes

Can we transfer digital files on radio spectrum?

There's a book that's available for free, which is very well-suited to answering your questions. It's called "Wireless Networking in the Developing World", and it's all about setting up wireless data ...
GroundRat's user avatar
  • 131
2 votes

Can we transfer digital files on radio spectrum?

Amodem can be used to transmit at arbitrary baudrates on any transceiver with a TRS port, 3.5mm or 2.5mm, or any other kind. Can take a while, but the data arrives. Includes a checksum (as does zip/...
user400344's user avatar
2 votes

What is the best practice when tuning an antenna on air?

If you are concerned about unintentional interference, then you should use an antenna analyzer. Some of them actually have a mode for that whereby the analyzer sends a tone that beeps; and the closer ...
Poe's user avatar
  • 139
2 votes

Can timing information be used to compress data for LoRa transmission?

The modulation you’re describing seems akin to ultra wide band or pulse position modulation. It won’t be possible with Lora wan devices. They only use Lora, and you’re trying to change up the ...
Matthew Trotter's user avatar
1 vote

How to determine the problem with my FT8 TX in WSJT-X?

At long last, I got the radio to transmit just fine. At this point I'm using RigBlaster, although that's less because it was the solution and more because it's something I was trying along the way ...
Hack-R's user avatar
  • 255
1 vote

Frequency division multiplexing FM Radio stations

Welcome to the site and welcome to radio! A 150kHz channel that is "Centered at 96.5 MHz" means that channel will have 150kHz / 2 = 75kHz below 96.5 AND 75kHz above 96.5 MHz. 50kHz guard ...
webmarc's user avatar
  • 4,210
1 vote

How Duty cycle affects transmission rate in RF module?

Under the heading of "Software features include," the landing page for the RFD868ux says, "Automatic duty cycle throttling based on radio temperature to avoid overheating". This means that transmit ...
Brian K1LI's user avatar
  • 7,858
1 vote

Can a ham radio pickup police signals?

Some ham radios are capable of receiving many signals outside of the ham bands, including in some cases police or emergency services. Some are even capable of transmitting on those frequencies. And ...
MoTLD's user avatar
  • 736
1 vote

Can I contact the International Space Station using my Baofeng UV5R?

I've received the ISS during a school contact as described in the linked article on my UV5R using its supplied helical antenna. Copy was good from a high pass but held up for a long time. A beam ...
Graham G8URP's user avatar
1 vote

Can I contact the International Space Station using my Baofeng UV5R?

You definitely can, but would benefit a lot from a dual band directional antenna. There are plenty of examples of self-built yagi antennas that are perfect for satellite work (such as https://hackaday....
Dieter Vansteenwegen's user avatar
1 vote

Can I contact the International Space Station using my Baofeng UV5R?

Radio waves will travel for billions and billions of miles through space if they're not interfered by matter. Consider the New Horizons Interplanetary Space Probe that did a fly-by of Pluto in 2015. ...
K7PEH's user avatar
  • 2,998
1 vote

Can I contact the International Space Station using my Baofeng UV5R?

You don't need to imagine it, because it's true. Many amateur satellites have around half a watt of output, and they're easily received on the ground with only a modest antenna (a 3-element yagi helps,...
hobbs - KC2G's user avatar
  • 12.4k
1 vote

Can we transfer digital files on radio spectrum?

We, ARES, send files often via VHF packet and via several HF digital modes. My favorite HF digital is based on the many modes of FLDigi, but set up the files (like ICS-213 form) using Winlink Express....
sparks's user avatar
  • 11
1 vote

Can we transfer digital files on radio spectrum?

We certainly did with the PBBS system we used at the Alaska National Guard building with the Alaska Division of Emergency Services. That station used my callsign with a "-1" appended to differentiate ...
SDsolar's user avatar
  • 2,089
1 vote
Accepted

Using Baofeng BF888s with Midland GXT1000

I'm almost 100% certain you have CTCSS (Continuous Tone-Coded Squelch System) enabled on the Baofeng, also known as tone squelch. This means that the squelch circuit (which allows a received signal ...
Rafael KR7MJ's user avatar
1 vote

How do I increase my phone intelligibility?

From this webpage: TL;DR: Get rid of the audio below 300-500 Hz*, and then use audio processing (compression) to raise the average power. *This is accomplished by: Choosing a suitable microphone, ...
Mike Waters's user avatar
  • 7,986

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