Questions tagged [digital-modes]

Transmission of digital signals over Amateur Radio, including modes like PSK-31, RTTY, JT-65, JT-9, etc.

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Can someone without privileges on a band operate FT8 on it using the callsign of a ham who does and is present?

I have an Extra license. Is it legal for my dad (who has a Technician license) or my mom (who is not licensed) to operate FT8 on 20 meters using my call sign, if I am physically present at the control ...
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Which is the most efficient FM digital mode (for data and text)?

At University I studied some stuff about modulation (only two lessons, so my knowledge is very limited) and as far I've understood, the FM signal is most reliable in audio than a AM signal, and it is ...
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Automatic identification system (AIS) on aprs.fi - Long Rx -> Tx distances

I've been looking into some of the info available on aprs.fi, which also makes available AIS data, but most of the reports I see have such large Rx->Tx distances that I'm not clear on how things ...
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How do you log (or not) "busted" FT8 QSOs?

When do you decide (when NOT in a contest) to log an "incomplete" FT8 QSO? For example, something like this: ...
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1 vote
0 answers
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Improving Vara HF speeds

I'm using Winlink with a laptop hooked up to an IC-7300. The registered version of Vara theoretically supports speeds up to 8,500 bps, but I'm seeing speeds more like 700 bpm. Is there anything I can ...
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9 votes
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Am I really receiving FT8 signals from 12,000 km away on 144 MHz?

I have been using an Ettus B200 SDR to receive FT8 transmissions in the 2-meter band (144.174 MHz) using the WSJT-X software. Signals are received using a telescopic antenna inside on a window ledge ...
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3 votes
1 answer
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Open source RS41 decoder

I would like to decode the signal from a RS41 radiosonde (from a weather balloon), which are suggested open-source software to do that? I tried RS but after compiling the code and executing ...
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HobbyPCB IQ32 SDR Data modes cable?

has anyone DIY datamodes cable for HobbyPCB IQ32 SDR ? Im thinking of using SPKR/MIC/PTT port and expose it either towards external USB soundcard (or USB soundcard stick), or directly to laptop USB. ...
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2 answers
229 views

FT-450D not transmitting with microphone

I've been using FT8 on my Yaesu FT-450D for quite some time. I decided to try to talk on phone frequencies and discovered neither one of my mics will transmit. My mics are the original hand mic and a ...
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Does anyone have any link to the original papers describing MSK144 and JT4?

I am looking for the original papers describing both MSK144 and JT4 protocols. I can easily find the corresponding papers for some other digital modes such as JT65 or FT8 (mainly at the Princeton ...
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5 votes
2 answers
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How does a digital demodulator know which level it is reading?

I have recently started getting into wireless digital communications and I read about QAM modulation. But I am a little confused as to how the receiving demodulator would know which symbol it is ...
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Is this signal BFSK or BPSK?

I'm trying to analyse a signal from a HVAC remote control (864 MHz) with my HackRF, but I'm facing an interrogation about the used modulation: Is it BFSK (frequency modulation) or BPSK (phase ...
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1 answer
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How do you open ax.25 ports?

I'm trying to follow this tutorial I almost got to the end, about 9:15 was where I got stuck. Right about there, the speaker is about to wrap up- but I get a couple error messages. ...
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2 answers
59 views

What is "allied mode" with regards to PSK31?

Wikipedia says: Colloquial usage of the term 'PSK31' in amateur radio usually implies the use of the most commonly used variant of PSK31: binary phase shift keying (BPSK). BPSK uses no error control, ...
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Transmit data over HF signal 10,000km away [closed]

I would like to transmit trinary data (-1,0,+1) on 20-30m wave to be received 10,000km away. From Europe to US. My first thought was this: https://www.researchgate.net/figure/Burst-modulation-mode-f-...
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-2 votes
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Can I transmit bit data over FM signal on 30m wave 10,000km away? [closed]

I am trying to understand if it's feasible to transmit -1,0,+1 data using FM on 20-30m wavelength to be received 10,000km away. From Europe to US. Ultimately I would like to create a solution which is ...
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1 vote
2 answers
456 views

Why is a separate repeater required for digital modes? Why can't an analog repeater be used for digital modes?

Regardless of the mode: digital or analog, the radios always transmit sinusoidal EM waves. So wouldn't a regular analog repeater be able to rebroadcast that EM signal regardless of its encoding?
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What is the format of Yaesu FT3D's QSOPCTDIR.dat and QSOPCTFAT.dat files?

The Yaesu FT3D can send photos, but only if taken with the optional external mic that has a camera. I want to be able to send photos that come from elsewhere, by putting them on the SD card. But it ...
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I configured FlDIGI to dislay letters before my PSK31 signal and then I forgot how I did it

Several months ago, before I had a Transceiver that worked, I configured FLDIGI to graphically display the letters QC 13P in the waterfall as a preamble to my PSK31 transmission. I remember I was ...
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1 vote
1 answer
1k views

How to send DMR SMS using MMDVM modem or hackrf?

I have a baofeng DMR radio with SMS feature, and since there is not much DMR radio owners in my area I want to do something myself. The easiest thing I can do I thought is to send myself some SMS as ...
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Which digital modes are formally specified sufficiently to be implemented?

Which currently popular digital/SDR modes do not require a pre-compiled library or pre-written source code? (e.g. has actually been used for QSOs as implemented from specification or sufficiently ...
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2 votes
1 answer
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Is there a way to get FreeDV output level to follow the input audio amplitude?

I'm using a commonly available imbedded firmware implementation of FreeDV with an SSB HF transceiver. It seems that FreeDV encodes the input audio signal in both the frequency and time domains, ...
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3 votes
1 answer
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How to fix SignaLink non-linearity problem?

I decided to check the linearity of my Yaesu FT-891 signal using an RF sampler and an oscilloscope. To generate two-tone (1550 Hz, 2150 Hz) signal I used Audacity. To connect the transceiver to the PC ...
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2 votes
2 answers
93 views

What contemporary digital modes do not require a GUI? [closed]

Assume a computer (Raspberry Pi, Mac, etc.) is used to connect to a radio (HF transceiver, etc.) via audio cable(s), USB port, or GPIO, etc. What contemporary computer DSP/digital modes, of those ...
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1 vote
1 answer
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How to connect MX614 to an ATmega 328p and a DRA818V to make an APRS transceiver

I am in a process of making a nanosatellite on which I am considering putting an APRS digipeater. I know about micro-modem based on ATmega 328P but it is pretty power hungry. MX614 has really good ...
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4 votes
0 answers
80 views

What value goes in the AX.25 PID field if the Layer 3 protocol is not defined in the standard?

I am working on space-ground networking for a Cube Satellite, and one of our candidate Layer 2 protocols is AX.25. We haven't settled on a physical layer, but it's likely to be some form of quadrature-...
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4 votes
1 answer
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Relative computational requirement for various digital modes?

What might be the relative computational performance requirements for the various popular digital modes? (FT, JT, WS, PSK31, etc.) I seem to recall FSK modulation/demodulation being done with 1 or so ...
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1 vote
0 answers
185 views

FLDigi Crashes When Trying to Load RigCAT Description File

I am trying to setup FLDigi with my ICOM-7300 via the USB connection so I can start using digital modes. Everytime I try to follow the instructions here, it doesn't work. Specifically, everytime I try ...
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4 votes
2 answers
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JS8: does a QSO over a relay counts as a valid QSO?

I'm playing with the new JS8 mode. One feature I find particularly interesting is an ability to relay messages using rigs of other OP's. Though I'm not sure whether such QSOs should count as valid ...
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3 votes
1 answer
62 views

Digital networks -- operator at control point, or automatic relay?

I've recently (part of studying for Extra license exam) learned about "mesh networks", where it's common to use repurposed wifi routers to connect at 2.4 or 4.8 GHz and form a network over a much ...
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1 vote
1 answer
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Sending a downloaded file on digital: third party communication?

This came up in comments on this question. Since before the Internet was widely available, it's been common to pass along files received from other users or downloaded from a server somewhere. For ...
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5 votes
3 answers
495 views

Is compression "encryption" under FCC regs?

I read this question about digital signatures and FCC prohibitions on "obscuring" messages in amateur transmissions, and it cause me to think of something: the difference between encryption and ...
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5 votes
3 answers
997 views

Unidentified signals on FT8 frequencies

When I work in FT8 mode I often see signals like these: I couldn't identify these signals using SigiWiki nor managed I to decode them using WSJT-X. Though these signals seem to use 15 second frames. ...
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8 votes
2 answers
2k views

How does signal strength relate to bandwidth?

Let's say I have a 25 W transmitter. First I transmit some SSB signal with 2500 Hz bandwidth (no audio compressor is used, etc...). Then I transmit a BPSK31 signal with at most 100 Hz bandwidth using ...
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2 votes
1 answer
499 views

What devices are able to decode the EAS SAME headers, attention signal, and encoded marker?

When I was watching television, especially when I was younger, I sometimes heard a loud noise, followed by either a test message, or a genuine emergency broadcasts, like an Amber alert. The first ...
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3 votes
2 answers
3k views

WSJT-X V2: How to identify stations already logged?

In V1.9 of WSJT-X, there was a feature that allowed one to change the color of stations already logged. This was necessary in knowing whether or not to respond to a given CQ. In version 2, I am ...
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1 vote
1 answer
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Digital Modes Transmission Traffic Comparisons

I am looking for data that compares the number of transmissions per month or year among the various digital modes such as DMR, D-star and Fusion. I want to see how popular these technologies have ...
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3 votes
3 answers
2k views

What equipment do I need to receive radio and connect to PC for listening

A great many moons ago, I spent a 24 hour period with a HAM radio connected to a PC, and listening to transmissions from a massive number of sources. Some of the transmissions included Morse, RTTY, ...
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15 votes
11 answers
7k views

Is Morse code a digital, binary mode?

At first glance Morse code looks like a digital mode - there are dits and dahs, two values which contain the information of the transmission. Alternatively, at any point in time there either is a ...
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4 votes
2 answers
1k views

What is the minimum equipment necessary to get on the air with FT8?

To the extent that FT8 is a way to bring people into the hobby or re-ignite passion among those who haven't been on the air in a while, what's the easiest way to get someone on the air with this new ...
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3 votes
1 answer
109 views

How to scan while avoiding digital/noise frequencies?

Is there an established way of scanning frequencies, while avoiding listening to digital signals or static? For example, is there a scanner on the market which will allow you to blacklist a specific ...
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2 votes
4 answers
1k views

Amateur Radio Long Distance Data Communication

My friends and I are going off to college ~180 miles/290 kilometres apart. As a project, we are looking into creating a data communication connection between our two schools. Our requirements would be:...
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2 votes
2 answers
819 views

Receiving audio output from IC-9100 through USB port

Can someone please give me a clue here? I'm having problems receiving data from the IC 9100 radio. I want to receive ax25 packets using FSK G3RUH modulation with an IC-9100 radio. It is configured ...
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0 votes
2 answers
111 views

How to decode a message with unknown bit rate in interstellar signal

I have a question about FSK modulation I'm going to frame in terms of a hypothetical: Imagine that you are transmitting a message to an ET in another solar system. The message is encoded in binary ...
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10 votes
2 answers
3k views

Do FCC regulations limit digital data rate?

Are there FCC regulations that specifically limit digital data rate on the amateur bands? Are there any recent or proposed changes? If so, what are they specifically?
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2 votes
2 answers
247 views

Can an SSB transmitter be used to transmit PSK?

Can a generic/typical analog SSB transmitter be used to send PSK modulated digital signals? If so, how does that work? How is a computer or DSP interfaced with an SSB transmitter? Line level ...
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3 votes
1 answer
368 views

How/where can I learn about ft8? [closed]

Where can I find information about the digital modes and how to get started on them? I would like a concise yet easy to understand tutorial.
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2 votes
2 answers
1k views

Fast TCP/IP radio modem on UHF band

I'm interested if it is possible to have a data radio modem that works on the UHF band 400MHz for TCP/IP communication. What I have in mind is something similar to a router, but using UHF band for ...
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6 votes
1 answer
1k views

Is there a legal limit to the bandwidth of a signal used in the amateur bands?

While a normal voice channel is ~10kHz-15kHz in bandwidth, some digital modes can be significantly wider. Are there any legal restrictions on how much bandwidth I could use for amateur radio ...
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5 votes
2 answers
107 views

Weak signal digital modes and clock synchronization

Why to some weak signal digital modes (jt9, jt65, etc.) require knowing a clock time? Does knowing this clock time provide any gain in signal detection ability? (lower required S/N?) What clock ...
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