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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51 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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3answers
773 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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574 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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1answer
27 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 ...
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1answer
90 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 ...
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2answers
75 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 ...
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66 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 ...
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1answer
423 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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1answer
68 views

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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2answers
123 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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48 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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4answers
478 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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2answers
103 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 ...
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1answer
149 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-...
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1answer
2k views

Digital-mode signal reports

When operating analog voice, we give a qualitative (or possibly just arbitrary) signal report, 'scoring' the signal either out of a maximum 'five by five', or a maximum '599'. How do you report the ...
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6answers
3k 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? ...
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1k 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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1answer
169 views

FSK real world application BER

I have designed a receiver for FSK reception in 434 MHz ISM band. For this I used USRP1 and GNU Radio. Now, I would like to measure performances of my receiver. For this purposes I did following: I ...
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1answer
54 views

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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2answers
581 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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3answers
2k views

How to receive a signal from multiple sources simultaneously (helical antenna)

I'm working on a system (theoretical at the moment) whereby I wish to receive data from multiple sources all transmitting at the same time. I've read that a helical antenna is capable of this. I'm ...
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1answer
1k 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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2answers
122 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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0answers
82 views

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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1answer
55 views

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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1answer
172 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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1answer
90 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 ...
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2answers
658 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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2answers
84 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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1answer
71 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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1answer
1k views

Confusion about radio-computer interfaces: TNC, CAT, TRRS, Wolphi Link, …?

This is probably a very simple and stupid question, but I'm getting more confused over time. Perhaps it is a matter of terminology, but a unified resource differentiating and explaining the different ...
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1k views

Open Source Library for Digital Mode

I want to play a bit more with programming side of digital modes. However, a quick Google search turned up lots of software and some general explanations but no open-source library implementing such a ...
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0answers
49 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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4answers
786 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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2answers
2k views

What makes JT65 preferable for VHF, and JT9 for HF

Are the bands really that different in characteristics where JT65 works better for VHF, and JT9 for HF? The claim comes from the WSJT website: JT65 was designed for EME (“moonbounce”) on the VHF/...
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1answer
492 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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1answer
66 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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1answer
3k views

Why there is no AFSK in FLDIGI

I was expecting to see an AFSK option in the Fldigi "Op Mode" menu (as there is one option for CW, i.e.), why isn't it there? Basically, I want to get the data send according to this.
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1answer
183 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 ...
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2answers
2k views

What rig should I start with when trying to get hands-on experience with Fldigi?

I would like to get hands-on experience with Fldigi. What setup is recommendable?
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1answer
375 views

What is the difference between MFSK64 and MFSK64L?

I noticed this after updating fldigi to decode a Voice of America Radiogram. The only thing I could find in the fldigi changelog was this: ...
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2answers
407 views

BPSK raw data aquisition with HDSDR and FLDIGI

I was playing with HDSDR+ExtIO and Ettus USRP1 to track a BPSK signal. In the end I successfully heard the signal. But I would like to see the data, I mean the raw data (HEX values). For that I tried ...
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107 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
241 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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5answers
5k views

Are there any commonly used digital modes that work with an FM transceiver?

Like many new hams, I have just one radio: an inexpensive 2m/70cm FM transceiver. It doesn't do SSB and it doesn't have a digital input. If I wire up a connection between the radio and my computer's ...
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1answer
789 views

How can I generate a list of APRS IGates on 30m?

I am investigating using a Tiny Trak 4 with my portable HF radio to self-spot on SOTA activations via APRS on 30m. I usually self-spot via a text message. When I don't have any cell coverage, I can ...
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3answers
377 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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1answer
145 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 ...
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2answers
289 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 ...
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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 ...