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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2answers
68 views

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

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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1answer
42 views

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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0answers
34 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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1answer
61 views

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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0answers
34 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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1answer
67 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 ...
3
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1answer
48 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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1answer
37 views

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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3answers
305 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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2answers
583 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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2answers
975 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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1answer
116 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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1answer
323 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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1answer
129 views

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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3answers
156 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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11answers
5k 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 ...
3
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1answer
196 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 ...
2
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1answer
92 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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4answers
512 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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1answer
393 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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2answers
79 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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2answers
145 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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1answer
256 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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2answers
547 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 ...
5
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1answer
264 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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2answers
63 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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1answer
343 views

What is “Billion Code” for garage door openers from around 1996?

I've been trying to "hack" my garage door using an SDR (LimeSDR) for a high school physics project, and I have run into a snag. When I look at the signal and demodulate it using ASK in Ultimate Radio ...
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3answers
350 views

Is there an FT8 or other weak-signal digital mode specification available?

Is there a complete and programming language independent specification available for the FT8 digital mode? Detailed enough to implement both transmit and receive SDR software from scratch in two ...
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1answer
84 views

DMR Repeated Audio Packets

I have been performing several weak signal tests using the DMR mode. One of three things seems to happen when a signal gets weak. Audio is completely dropped for duration of weak signal. Audio ...
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1answer
220 views

Why does P25 occasionally break through tone squelch on my analog HTs?

When listening to our local repeater, which is now a combined P25/analog machine, every once in a while my squelch opens to a blast of digital noise. I've noticed this problem with at least two ...
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1answer
772 views

How do I install the DV4mini software on Ubuntu?

The documentation says the following: The program requires the complete installation of Mono. You install for example with apt-get the packet mono-complete. Until an installation packet is ...
8
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1answer
218 views

How can I do direct digital synthesis of a 630m WSPR signal?

I want to do direct digital synthesis of a 630m band WSPR signal. Specifically I'd like to use an Atmega 328 chip running at 20 MHz to produce such a signal. I will use standard phase accumulator ...
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2answers
90 views

Multiple CDMA transmitters with same frequency and code

Theoretical assumption: I have multiple CDMA transmitters operating at same frequency and code placed 5 metres apart. My questions: Does the chances of my receiver receiving the data improve? That ...
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1answer
497 views

GNU Radio BPSK reception from ICOM SSB audio

I have BPSK flowgraphs that work fine in simulation as well as between two USRP boards at 1200 bps and sample rate of 48000 baud. In the transmitter flowgraph, the transmitter reads HDLC bits from a ...
4
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2answers
158 views

Is using a DDS chip directly a viable way to transmit 2FSK and PSK on HF?

I'm thinking of building an HF transmitter for data (AX.25 or PSK31). Rather than using an IF stage, I'm thinking of generating the RF frequencies (or phases) directly with a Direct Digital Synthesis ...
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1answer
2k views

How to make GRC flowgraph run and stop automatically during some period

I have beacon receiver program the flowgraph is shown here I have to make the flowgraph run and stop automatically during a preset period, because I have to make the flowgraph only work when the ...
6
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2answers
466 views

Filtering for PSK31 demodulation

What's the ideal filter for PSK31 demodulation? That is, something that minimizes ISI, while having a narrow bandwidth to reject adjacent channels, while being reasonably matched? Most PSK modes use ...
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0answers
439 views

Direction Finder using directional antenna, digital signals amid clutter [closed]

There are several methods for implementing direction finder. 1. One of the method is by using directional antenna pointing to target device, and reading the received signal strength from the target ...
4
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1answer
436 views

Troposcatter: really all that bad?

The previous question, Packet Radio at 100 miles and specifically, Phil's answer raised an interesting question: In a 50–100 km distance situation where Line-Of-Sight beams aren't an option for ...
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2answers
235 views

How does DAB radio garbled noise come about?

I'm a sound designer and I'm interested in using/simulating that effect of DAB radio when you have a low signal/interference, where voices become garbled, bubbling, burbling, broken up, etc. I ...
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0answers
651 views

Blocking a specfic DMR ID

Is it possible to block a specific DMR ID Rx, sort of "ignore"? If so, is it repeater-based, or it has to be set locally, on radio? Speaking of popular md380/390 radios, there is a "Call Alert" ...
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2answers
234 views

Cannot establish AX.25 connection to RMS gateway

I'm trying to establish an AX.25 connection to a nearby RMS gateway (should be within a mile) using a Baofeng BF-F8+ on 2 meters. I'm trying to establish a connection with either RMS Express and UZ7HO ...
2
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1answer
715 views

How do I go about identifying an unknown digital signal?

I'm playing around with an SDRPlay. I'm using the CubicSDR app, and I'm tuning around the HF bands. I get to 5.650 MHz and I see this: This looks like a bunch of discrete RTTY signals. How would I ...
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5answers
2k views

Can we transfer digital files on radio spectrum?

Radio is analog, and a modem converts analog signals to digital signals and vice versa. So is P2P sharing of digital files (like .exe, .7z, .pdf or any other file) possible using radio spectrum? ...
7
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2answers
994 views

Moon->Earth 433MHz link achievable digital bandwidth

Let's assume we have the following situation: Transmitter on moon orbit (distance from earth ~400'000km), around 433Mhz. Transmitter power 1W, antenna gain 10dB, circular polarization. Steered to ...
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3answers
6k views

Tytera MD-380 software (DMR radio software) not working on Windows 10

I installed the latest MD-380 software (from Radioddity) , but I cannot get the MD-380 software to work on Windows 10. When I plug the MD-380 USB programming cable in my Surface Book (obviously ...
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2answers
68 views

Extracting received power info from teletype like audio

Is it possible to digitally extract received power info (like VU meter perhaps) from and PSK31 audio (or alike), actually the mode for text encoding over audio hasn't been chosen yet and the ...
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1answer
145 views

Radio Modem suggestion [closed]

I need to transmit digital data, from an Arduino, Raspberry or alike, but using VHF band (aprox 150 MHz), would anyone care to suggest a cost effective device to use as transceiver? 10W would be ...
4
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1answer
172 views

Expected practices for one ham operating under another's privileges?

I understand that in the United States, amateur operators and even non-licensed persons may participate in domestic (and approved international) communications on bands they wouldn't normally be ...
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1answer
132 views

Pre-transmission burst sent by fldigi

Every time I click on a PSK macro, before transmitting the message, fldigi outputs a burst of something for about a second. This is visible but not readable on my waterfall display. It wastes time ...