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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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What would the Signal to noise ratio be for SSB under normally (just) readable conditions?

I want to estimate an upper limit for the data that can be sent over single side band. The upper limit can be determined using Shannon-Hartley theory. The Shannon-Hartley theorem is given by: $$C = B \...
Mr Purple's user avatar
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rsid seems hard coded to be disabled when in PSK31 or RTTY mode. Only works for other modes

So I asked ARRL about the RSID being sent before they make a bulletin transmission, which they said was on but it was not being sent that I could see before the transmission. The RTTY mode just starts ...
elle threethrity's user avatar
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1 answer
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Is there a malware problem with latest JT Alert?

I just went to update JTAlert 2.62.1 and when it finished downloading the built-in Windows scanner flagged it as malware, said there was a "severe" vulnerability in one of the DLLs in it, ...
QuantumMechanic's user avatar
5 votes
1 answer
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Checking if the frequency is in use for digital modes

On CW and phone, we are taught to ask if the frequency is in use before calling CQ. Is it correct to say that with digital modes, that is impractical, and you should just listen (over the bandwidth ...
gschro's user avatar
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Can I use a generic FM 2m radio for meteor scatter or other digi modes?

Firstly, I know it’s possible, but is there any actual activity for 2m MS. I want to get into Meteor scatter but i am wondering if i can use my 2m FM transmitter with a TNC and a yagi for meteor ...
I_like_python's user avatar
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APRS-IS filter by message sender

I'm using KD0NKS' JS-based APRS-IS demo to query APRS-IS servers directly. I'm trying to only receive messages sent from my callsign using server-side filters. I've tried using a budlist filter (b/), ...
user19095's user avatar
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Is APRS the tracking protocol for the BTech GMRS PRO or the Vero 75 Ham version

Looking for confirmation if the Btech GMRS Pro and the Vero 75 are using APRS as the tracking protocol for their radio's. We're working on an EmComm/ EOC integration project and were looking to see ...
Jon.Blincoe's user avatar
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2 answers
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FSK: Selecting center frequencies and Carson's Rule

I'm implementing 2FSK and 4FSK modulation schemes for an experimental system. I'm using GNURadio, although that shouldn't affect the question. I'm trying to figure out how the center frequency should ...
Jordan's user avatar
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Why does Tone Spacing decrease with increasing T/R Periods in WSJT-X modes?

In various weak signal modes of WSJT-X, the Tone Spacing decreases with increasing T/R Periods. For instance for FST4 / FST4W (as decribed on page 1 of the Quick-Start Guide) we see: T/R period (s) ...
JayPulsar's user avatar
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Transfer digital data over ham radio frequencies using QPSK modulation SSB-QPSK transmitter

If I use QPSK modulator/demodulator is it possible to transfer digital data over ham radio frequencies. SSB-QPSK transmitter
Vinayak's user avatar
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What exactly are Gold sequences and how are they used?

I recently became familiar with the FX.25 protocol extension for AX.25. Within the protocol is what they call a "correlation tag", which is a Gold sequence or Gold code. I've heard that Gold ...
Steve Mucci's user avatar
7 votes
3 answers
446 views

Has any computer been hacked over amateur radio digital modes?

We don't normally worry about security in ham radio, because we can't encrypt our transmissions anyway in the vast majority of cases. Some niche protocols support authentication of messages, but that'...
Someone's user avatar
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Are there any modes that use pseudo-random noise codes to "amplify" signals?

GPS for example uses them to allow receivers to decode extremely weak signals far below the noise floor. From https://blank005.tripod.com/gps/psedo_random.html : If we tuned our receivers to the GPS ...
2080's user avatar
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Is there a list of public datacasts?

I know several datacasts which are free to almost free to receive. Like there is the outer(other-)net, which can be received using a lora module - it contains a subset of APRS messages and weather ...
NajiqAlef's user avatar
4 votes
1 answer
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Digital Protocols, Public Documentation, and Encoded Messages

When is a new digital protocol considered "documented publicly" enough to be used for amateur radio transmissions? Part 97 states the following about prohibited communications: (a) No ...
James KE5JOO's user avatar
3 votes
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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 ...
Someone's user avatar
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Getting a PTT Signal for Digital Radio Kit; Right Channel PTT in JS8Call

I want to buy this 5 W transceiver kit from QRP Guys, link. My plan is to use it with JS8Call on an ARM64 Chromebook I have or even my smart phone with AndFlmsg (FSK modes). It's clear that the radio ...
wbg's user avatar
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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 ...
Gigi's user avatar
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2 votes
1 answer
233 views

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 ...
Jared's user avatar
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2 answers
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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: ...
QuantumMechanic's user avatar
1 vote
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254 views

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 ...
Brad Mace's user avatar
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10 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 ...
David's user avatar
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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 ...
Paa's user avatar
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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. ...
Vladimir Ivkovic's user avatar
2 votes
3 answers
713 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 ...
Lyndon's user avatar
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1 vote
1 answer
48 views

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 ...
user3141592's user avatar
6 votes
2 answers
112 views

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 ...
YellowBadger's user avatar
2 votes
0 answers
178 views

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 ...
Rascafr's user avatar
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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. ...
BJsgoodlife's user avatar
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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, ...
Xunie's user avatar
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831 views

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-...
Boppity Bop's user avatar
-2 votes
2 answers
124 views

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 ...
Boppity Bop's user avatar
2 votes
2 answers
1k 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?
rsn's user avatar
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3 votes
1 answer
365 views

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 ...
Thomas's user avatar
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4 votes
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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 ...
user141802's user avatar
3 votes
1 answer
2k 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 ...
Hose Dias's user avatar
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2 votes
0 answers
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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 ...
hotpaw2's user avatar
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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, ...
Andrew's user avatar
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3 votes
1 answer
170 views

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 ...
Aleksander Alekseev - R2AUK's user avatar
2 votes
2 answers
112 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 ...
hotpaw2's user avatar
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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 ...
Rohit Bokade's user avatar
4 votes
1 answer
181 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-...
VE9PEG's user avatar
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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 ...
hotpaw2's user avatar
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1 vote
1 answer
306 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 ...
SandPiper's user avatar
  • 777
4 votes
2 answers
311 views

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 ...
Aleksander Alekseev - R2AUK's user avatar
3 votes
1 answer
84 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 ...
Zeiss Ikon's user avatar
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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 ...
Zeiss Ikon's user avatar
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5 votes
3 answers
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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 ...
Zeiss Ikon's user avatar
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5 votes
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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. ...
Aleksander Alekseev - R2AUK's user avatar
8 votes
2 answers
3k 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 ...
Aleksander Alekseev - R2AUK's user avatar