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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1answer
138 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
342 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
1k 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 available ...
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1answer
273 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
128 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
763 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 ...
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2answers
246 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
3k 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 ...
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2answers
660 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
477 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 ...
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2answers
716 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
272 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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347 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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1answer
1k 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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6answers
4k 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

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
10k 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
74 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
164 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 ...
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1answer
269 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
225 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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1answer
236 views

Build a HamRadio Friendly UMTS Module

I would like to play around with openBTS/yateBTS (experimental, no 24/7 run). What I would like to do is to modify a UMTS/GSM module or mobile phone so it operates in a frequency that can be used with ...
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4answers
430 views

How to operate on HF if an AM transmitter is only 540 feet away?

I'm a General Class Licensee, and due to pulmonary disease I cannot operate voice. I am also about 540 feet from a 24/7 1 kW AM station. The signal is so pronounced that most audio devices in the ...
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1answer
171 views

Using 'amodem' to transfer digitally using a UV5R

I reviewed docs for amodem, and it looks like I can send files and possibly other things with this. I should only need to prep my computer as per the doc and set VOX correctly. Does anyone have ...
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1answer
2k 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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3answers
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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2answers
153 views

Air gapped digital communications mode on VHF?

According to this question MCW (modulated continuous wave) is allowed on large portions of the VHF bands in the U.S. Is using MCW suitable for passing small amounts of digital data between 2 PCs or ...
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2answers
372 views

Why is this signal recognized as PACTOR II but not decoded?

I'm using SDR# and with virtual audio cable sound is piped to Wavecom W-CODE. W-code recognizes a frequency on 4 and 24 MHz as Pactor-II with 100% confidence, but he can't decode in terminal text ...
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1answer
70 views

short bit at beginning of tranmission

I recorded an OOK transmission (of a temperature sensor) and I'm trying to reverse engineer the recording to get the binary out with python. First I searched for the length of a bit. Therefore I ...
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1answer
4k views

DMR / DSTAR / P25 Software Encode / Decode

The large VHF / UHF digital voice communication modes all require the same AMBE vocoder chip from dvsinc. This surface mount chip can be aquired standalone for a relatively high price or all of the ...
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3answers
231 views

Which mode describes this modulation scheme

I have a modulation mode: (to be used for a satellite) (of a series of AX.25 frames) (in the 70 cm band) 9.6 kbps Ideally BPSK or QPSK modulation but could be plain FM Which I need to describe with ...
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2answers
2k views

How to identify type of modulation based on constellation diagram?

The constellation diagrams for a 4-ary modulation using PSK (qpsk),MSK ,QAM and OQPSK look alike. How to differentiate them? What is the modulation for the constellation diagram in the figure?
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1answer
170 views

SDR dongle and HamitUp for QRP Digi-modes

Will SDR, like RTL SDR dongle and Ham it Up converter, performing as well as traditional desktop HF receiver for digi-modes, like JT9, for HF low power (0.1 watt) long distance (500 to 10000km) ...
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2answers
111 views

Transmission speed of modern digi-modes

What are the bit per second ratings and signal-to-noise-ratio ratings of various modern, popular, good performance and well supported digi-modes for HF low power (0.1 watt) long distance (500 to ...
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2answers
3k views

GMRS/FRS data communication

Is it possible to use an ordinary GMRS/FRS UHF handheld set for data communications? I hope to use a Motorola UHF GMRS handheld with a terminal node controller device to for data communication. Are ...
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5answers
592 views

Yaesu FT-950 with G5RV lite antenna auto tune problem on 21Mhz

I am unable to autotune on 21Mhz as the SWR is more than 1:3 which is out side the range of the radio. I would like use it only for digital TX with a max. power of 50 watts. Any solution/s?
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3answers
707 views

Bridging LAN over ~1-2km distance

A friend of mine and I live across a lake from each other, and recently we thought it'd be fun to try and connect our computers together somehow across that distance. Running cable from either side ...
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5answers
7k 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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2answers
994 views

What is Digital Mode on newer HF Transceivers

What does switching to digital mode on Yaesu Xcvr's (or any other HF radio) actually do? The documentation states that "specific digital mode selections, which include custom BFO offsets to optimize ...
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2answers
780 views

GFSK Demodulationsoftware

I need to demodulate and decode a signal.It is transmitted from a satellite using GFSK. The packets are based on AX.25. Could you recommend any out-of-the-box HAM software packages that could do ...
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1answer
1k views

AFSK and GMSK in ICOM IC910 H

I am a newbie in HAM.The transceiver I have in my lab is ICOM IC910 H. My goal is to use it to communicate with our cubesat which uses GMSK. According to the manual, on page 50, there are notes for ...
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1answer
161 views

What is the proper spacing away from a rare RTTY station?

How far away should I transmit from a rare DX station in RTTY? RTTY itself doesn't take that much bandwidth, but I've heard that I should be spaced 2-3 kHz away. Is that true? Thanks!
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0answers
76 views

Is it suitable to use DSSS in a narrow-band channel for a power-starved system

I want to build a system that can transmit data through 2-way radios as far as possible. I use the "line-in" as the input of the baseband signal in the transmitter and use the "audio out" as the ...
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1answer
117 views

List of capturable data services (diy)

Looking for a list of capture-able data services. By browsing some sites I accidentally discovered that it is possible to receive NOAA satellite weather images with DIY receiver (link) or (here), ...
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2answers
187 views

Should a MacBook emit fluctuating EMF when WIFI and Bluetooth are turned off?

I have a couple of MacBooks. Using a Trifield EMF meter with radio/microwave capability, if I hold the meter near the laptop (where I understand the wifi antenna is located), I receive blips ranging ...
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1answer
192 views

What type of digital mode is this?

Currently trying to figure out what type of digital mode I'm listening to. I've purchased a Vaisala Radiosonde RS-92AM. It's a meteorological device usually attached to below a weather balloon. I've ...
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4answers
396 views

Low power long distance wireless data communication

I am looking for a communication solution with the following requirements: wireless unidirectional, point to point low power (li-ion battery powered, should operate at least one hour on the single ...
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2answers
330 views

Software TNC's for Linux? (targeted to BPSK1200)

Are there any software TNC's (like SoundModem) for Linux? This is limited to the ones which deal with BPSK1200 (used by cubesat projects). For some cases Warbler will suffice.
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1answer
227 views

Warbler vs SoundModem

I'm trying to decode a BPSK 1200 (with no success). In this endeavor I tried both SoundModem and Warbler. The scenario here is the following: Ettus receiver + HDSDR with speaker plugged into mic via ...
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1answer
4k 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.