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Questions tagged [digital]

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

2
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1answer
61 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 ...
1
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3answers
179 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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0answers
33 views

What equipment do you need to make Yaesu WIRES-X work?

I know you need a digital radio like FTM100DR and you need the HRI-200 internet link. Do you also need a WIRES-X repeater?
1
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1answer
119 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 ...
0
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2answers
66 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
78 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 ...
3
votes
1answer
50 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
149 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
votes
1answer
142 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 ...
4
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2answers
53 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 ...
5
votes
1answer
176 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 ...
2
votes
3answers
210 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 ...
1
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1answer
60 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 ...
4
votes
1answer
106 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 ...
1
vote
1answer
487 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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0answers
147 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 ...
1
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2answers
71 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 ...
0
votes
1answer
278 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
votes
2answers
112 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 ...
1
vote
1answer
850 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 ...
5
votes
2answers
325 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 ...
2
votes
0answers
319 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 ...
5
votes
1answer
268 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
191 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
299 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" ...
0
votes
1answer
141 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 ...
3
votes
1answer
442 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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vote
5answers
990 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? ...
8
votes
2answers
926 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 ...
1
vote
3answers
4k 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 ...
0
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2answers
65 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 ...
1
vote
1answer
138 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 ...
5
votes
1answer
136 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 ...
5
votes
1answer
92 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 ...
3
votes
1answer
172 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 ...
8
votes
4answers
282 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 ...
0
votes
1answer
108 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 ...
4
votes
1answer
727 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 ...
4
votes
3answers
623 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 ...
5
votes
2answers
103 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 ...
0
votes
2answers
205 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 ...
1
vote
1answer
66 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 ...
3
votes
1answer
2k 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 ...
2
votes
3answers
122 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 ...
1
vote
1answer
873 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?
1
vote
1answer
133 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) ...
1
vote
2answers
88 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
1k 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 ...
2
votes
5answers
410 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?
4
votes
3answers
387 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 ...