Questions tagged [modes]

Questions related directly to the mode of communication (SSB, CW, digital, etc).

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10
votes
1answer
568 views

Why does AM have sidebands?

Why does AM have sidebands? Isn't the whole point of AM to broadcast on ONE frequency and ONLY change the amplitude? In the picture there is only ONE frequency and the amplitude changes, so why ...
6
votes
1answer
826 views

Video transmission between ATV and SSTV

I'd like to experiment with amateur video transmission in a setup halfway between ATV and SSTV. 480 lines of B&W image would be sufficient with 10 FPS, and I'm interested in both digital and ...
1
vote
1answer
402 views

WFM SDR and Audio resolution

How does SDR resolution translate to audio resolution when using an FM demodulation algorithm? For example: using a 8-bit/2.048 Mhz IQ stream, what is the maximum audio sample rate and bit depth that ...
2
votes
0answers
365 views

How did recording ZX Spectrum games from radio work? [closed]

I have recently heard about recording video games' binary codes from radio programmes which was quite popular several decades ago. The computer name was ZX Spectrum. The general idea behind the ...
2
votes
3answers
216 views

Multiple transmitters using same frequency

in our wireless network we have a variable count of devices. Each device contains one transmitter and receiver. Both receiver and transmitter are working on the same frequency, 433 MHz. To keep the ...
1
vote
1answer
50 views

Determining modulation by spectrum

Is it feasible to determine what sort of modulation is used for a given signal by looking at the spectrum / FFT? Does software like this exist?
3
votes
1answer
110 views

Up converted audio transmission

I was thinking about all the different modulation methods and something came to my head. After seeing up converters that convert HF to VHF for SDR (software defined radio) dongles to be able to listen,...
4
votes
1answer
3k views

Why doesn't GNU Radio Companion's wx Constellation Plot doesn't give me the clean QAM constellation I get from its Qt sibling?

Using a RTL2832U USB dongle, I set up GNU Radio to produce a constellation plot of APRS traffic on 144.8 MHz. The result is what I expected: So far, so good. Why not try the same thing using the wx ...
7
votes
1answer
2k views

What should be the modulation when transmitting APRS signal?

Is it SSB or NFM or other type of modulation?
9
votes
1answer
2k views

How does SDR demodulation differ between wideband and narrowband FM?

What is the difference between software demodulation of an IQ signal between wideband FM and narrowband FM? Both seem to look at the 2nd difference in unwrapped phase angles of IQ samples.
3
votes
2answers
430 views

How can I know over what distance or at what speed I can communicate? [closed]

Given some description of some parameters like: transmitter power frequency antenna location time of day how can I know over what distance communication is possible? Can I know the limits to these ...
5
votes
2answers
244 views

Frequency Modulated Light

I've been doing a bit of work on optical open-air transmission, and have been thinking, any hays that varies the intensity of the light or whatever else would affect the amplitude. Would it be ...
2
votes
1answer
189 views

What modes are used for transmitting motion pictures video?

SSTV permits transmission of single images, or if one desires image sequences at a very low framerate. Are there specific Amateur Modes that are meant for real time (motion pictures) video ...
1
vote
1answer
89 views

Can I filter after modulation when using a square wave oscillator? [closed]

Most designs appear to filter most of the harmonics out of the oscillator before modulation, then apply additional filtering as needed for the specific modulation they are using after modulation. ...
5
votes
5answers
2k views

What about the digital mode ROS causes some to consider it spread spectrum?

The FCC disallows amateur spread spectrum communications below 220MHz. At the moment the relatively new digital mode, ROS, is considered, by some, to be spread spectrum. So this mode is getting ...
4
votes
1answer
433 views

What is this short, wide band signal?

I've observed a signal I'm unfamiliar with, and am wondering what it might be: The period of time it lasted is 5 seconds, and it occurs irregularly. You might be able to see it too via WebSDR. How ...
6
votes
2answers
137 views

Is CW necessary to be competitive in most ARRL contests?

The ARRL hosts many contests throughout the year, and maintains a leaderboard of sorts to encourage competition. Is it possible to rank on any of the leaderboards without knowing or using morse code?
3
votes
2answers
247 views

HD quality voice?

Are there any existing codecs or modes, or are hams experimenting with modes that provide better than telephone/radio quality sound? It seems like there's a lot of opportunity here to stick to narrow ...
5
votes
4answers
569 views

Is there such a thing as a phase modulation voice signal?

Wikipedia indicates that in the digital domain ASK, FSK, and PSK are common. It seems that only AM and FM are used for analog forms of communication. Why don't we use Phase Modulation techniques, ...
6
votes
2answers
729 views

1200 baud packet radio can't communicate

I'm toying with a simple 1200 baud packet radio I built. I'm attempting for it to be compatible with APRS, which uses the Bell 202 signaling, 1200Hz for mark and 2200Hz for space, which I assume map ...
8
votes
2answers
141 views

How do I notify and publish information on experimental modes?

I'm considering tinkering with a new mode. Of course I'll stick to experimental channels and low power for now, but as people notice my transmissions they won't immediately understand what is being ...
11
votes
2answers
1k views

What does a SSB frequency actually indicate?

An SSB signal is an AM signal with the carrier and other sideband filtered out, if I understand correctly. As such, when specifying an SSB frequency do you specify the carrier frequency, then state ...
6
votes
1answer
311 views

Why do some antennas list modulation type alongside power rating?

Looking at HF antennas I've noticed that occasionally I'll see power ratings similar to "200W (SSB)". Why would the modulation matter for an antenna's power output rating, and in the absence of other ...
7
votes
1answer
442 views

Is FM appropriate for foxhunting?

I'm thinking about an inexpensive way to create a foxhunt kit for youth groups, and am wondering if the cheap dual band HTs could be used. However, it occurs to me that FM doesn't provide any good ...
13
votes
4answers
2k views

Is is possible to operate D-Star from a software-defined radio?

What is preventing a software-defined radio from transmitting the D-Star protocol?
6
votes
2answers
519 views

Is it possible for an amateur to transmit ATSC?

Amateur television has long used the NTSC (analog) television standards to transmit video and audio. Several years ago, the digital broadcast television transition made higher-quality television ...
13
votes
3answers
669 views

What is the role of digital data modes in emergency communications?

Emergency operations are typically reliant on voice traffic today. Are digital data modes used at all in emergency operations, and why/ why not? Couldn't data modes be used to pass information more ...
7
votes
2answers
100 views

Does AM demodulation make use of the redundant information in both sidebands to eliminate noise?

XLR microphone cables, for example, make use of the dual channels out of phase to cancel noise by injecting the inverted and non-inverted signal into one end of the cable. Then any noise injected ...
10
votes
3answers
436 views

Does modulation affect propagation?

Does the modulation scheme, whether OOK, SSB, AM, FM, a digital mode, etc, affect the propagation of a signal?
6
votes
1answer
228 views

Does mixed-mode operation qualify as a QSO? [closed]

Working the bands it's quite possible to work in mixed-mode, albeit I doubt whether it is ever done. Call this a thought experiment: Station A operates CW, Station B operates SSB. I find myself ...
3
votes
1answer
147 views

What are the differences in a QSO over A3F as compared to J3E?

All I've ever used is CW, and a some SSB; even then always replying; haven't seen much difference there in the manner of the QSO. But there are other modes which I have not used, and some that are ...
63
votes
18answers
8k views

Why is Morse code still in use?

Why do people still use Morse code? What are its advantages over newer voice or data communication modes?
8
votes
2answers
3k views

HF Digital Mode Band Plan for the USA

I recently started playing with the digital modes, but have been frustrated with the difficulty in finding where certain modes are commonly used. Is there a digital mode band plan for the HF bands, to ...

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