11

Microphone technique has a good bit to do with clarity. Talk across the mic, not directly into it, unless it is a noise canceling type designed to be used that way. Speak no more than 2" away from the mic, even if it is a desk mic or a boom mounted type; many people make the mistake of thinking that just because they have a desk or boom mounted mic that ...


9

Part 97 doesn't have anything to say about frequency error or drift in particular. The question pool, however, does: T1B09 (D) [97.101(a), 97.301(a-e)] Why should you not set your transmit frequency to be exactly at the edge of an amateur band or sub-band? A. To allow for calibration error in the transmitter frequency display B. So that modulation ...


8

You'll need an experimental radio license (Versuchsfunk) from Bundesnetzagentur link for research operation. For demonstration/teaching purposes, a demonstration radio license (Demonstrationsfunk für Bildungseinrichtungen) would be in order. I'm not a lawyer nor have I ever applied for either of these; I'd recommend contacting BNetzA on these aspects. ...


8

Your frequency error is the difference between where your transmitter indicates you are transmitting, and where you actually are transmitting. The FCC does not regulate where you think you are transmitting. They only regulate where you are actually transmitting. Consequently, your frequency error can be whatever you want, as long as you keep it in the bands ...


8

As has been mentioned, many radio amateurs tend to be in the types of fields where various forms of rules are the name of the game. Electricity always behaves the same. So does a computer (assuming it is working correctly, it simply executes one instruction after another; it doesn't deviate or take initiatives of its own). And so on. However, there is ...


8

Assuming that you're operating in the jurisdiction of the FCC, there should be no legal issue with you modifying your radio and using it to transmit on those two bands providing the following: Your modifications comply with good engineering practice, and You do not exceed the privileges (power or frequency) of your license Unlike other radio services in ...


8

It depends on what you mean by propagation. If you mean, does the modulation scheme affect the physical means by which EM energy gets from point A to point B?, then the answer is no. Mostly, EM propagation is linear, so the differences in modulation have little effect on how the wave propagate. However, if you expand propagation to include the ...


7

I am pretty sure this isn't covered explicitly in Part 97 and probably falls under the "don't cause intentional interference" clause. The practice I was taught is this: Tune off the pileup you found several KHz to a 'clear' spot reduce power to the either the lowest the rig will go or the least that will facilitate the tuning process Switch to CW mode ...


7

It's about transmission duty cycles. For example, FM has a very high duty cycle during transmission: the transmitter's output power is constantly at 100% regardless of the amount of modulation. AM varies between 50% (carrier only) and 100% (full modulation). SSB varies with modulation between 0% and 100%. CW is like FM, 100% power output during transmission,...


7

I think there are two parts to this; why are they so "anal" /strict / uptight about the rules? why are they so hostile / aggressive / generally unpleasant? The first part I think is due to something that most people don't appreciate. The Ether (if you'll excuse the name) is a shared resource. The rules are there to try to let us all use it as ...


7

Assuming you are in the US (sorry if I'm wrong, but you didn't specify!), normal WiFi falls under Part 15 regulations which limit the radiated field strength, not the transmit power. This means that, assuming the transmitter is not underpowered, you cannot legally increase the range using directional antennas. Supposing you did so anyway, hooking up ...


7

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?) electronics systems were being tested to measure how far out-of legal compliance they were.


6

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, when transmitting something digital over an analog channel, you typically use a modulator, and to receive the same you'd need a demodulator, and modem is just a ...


6

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 frequency increases. But then so too does the size: a tiny half-wave dipole simply intercept less energy. Solution: antenna arrays, which become increasingly ...


5

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 cell network which is not amateur radio, but it can be answered on general principles of radio communications, so I'll do that. what I don’t understand, is ...


5

Eric Scace, K3NA wrote a two part article for the NCJ a few years back on all the adjustments you can make to your audio chain to improve it's quality. While the article focuses on audio quality for contesting, I think most of the points are relevant "regular" phone contacts. He has 6 main areas that he addresses: Operator training — Things like ...


4

Usually, the answer is no. While modulation may affect the acceptable Signal to Noise ratio, allowing a given signal to be received from further away or in worse conditions than a different modulation, that happens at the receiver, the propagation is the same. The only factors of a radio wave that affect propagation, once it's in the air, are the field ...


4

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 signals at −0.5 MHz and +0.5 MHz, add them together, and transmit with the hardware center frequency set to 915.5 MHz. (You don't have to use the exact ...


4

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 may have legal issues if the file is encrypted. That's not allowed for amateur transmissions in the United States, anyway. I'm not sure about your jurisdiction....


4

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 modulation used, but in no case will it be all that useful. If they use FM (almost certain for any modern off-the-shelf equipment), you will hear mostly the ...


3

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 channel would obliterate most or all of the HF spectrum. That said, there are easily thousands of digital modulations that could be used to send data. I'm not ...


3

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 networks across long distances inexpensively. Look for it at wndw.net.


3

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-91, AO-92, etc). When we replaced it with a Yaesu FT-60R we were finally able to receive the "birds". So while theoretically you should be able to receive LEO ...


2

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 to a 1:1 match, the faster it beeps until it is a solid tone. Just make darn sure you don't transmit into you analyzer, or you will damage it and I can ...


2

I've only been a licensed ham since 1997, but having worked for 30+ years in a technical field with lots of engineers of various disciplines, I've observed a lot of the "passionate responsiveness" you mention. I think this "black and white" thinking is a common trait of individuals that populate the technical/engineering world and it seems to be a similar ...


2

To add to Phil's answer the only time inaccuracies in frequency are of concern to the FCC are when you're at the edge of the band. As Kevin's answer alludes to, as long as you aren't transmitting out of band, the only person who is concerned about what frequency you're transmitting on is you, and possibly someone you planned to meet on the air.


2

So...A couple of things here: According to FCC regulations, a fixed point-to-point link can actually broadcast well above the 30 dbm rule. In fact, you can go up to 52 dbm EIRP. In order to get that high, you will need to regulate the output power of your router. You can do this digitally in the router settings or by putting in-line attenuation at the ...


2

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/rar/7z/etc archives). I've transmitted a few MB on UHF, wasn't a problem. You'll need a computer on either end, a lowly PI would probably suffice. It doesn't use ...


2

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 audio part of the receiver, and allow you to hear transmission. Many radios also have more or less complicated busy channel lockout feature, which prevents the ...


1

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 bit vs two bytes results in almost no time or power difference. So unless you are allowed to alter the complete LoRa stack, your timing scheme will not score ...


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