Questions tagged [software-defined-radio]

Radio devices that use digital signal processing in place of analog electronic components to manipulate RF signals.

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No module named 'gnuradio'

I encountered with the "No module named 'gnuradio'" error while I was trying to run GnuRadio python code in my python web server. And this is my gnuRadio generated code: ...
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19 votes
3 answers
6k views

SDR sampling bandwidth - do the bits per sample matter?

I'm looking at data converter chips for a homebrew SDR design, and I see that I can choose not just the sampling frequency, but also the bits per sample. Obviously the sampling frequency has to be ...
11 votes
1 answer
2k views

Why is dynamic range relevant for an SDR?

Sometimes I see dynamic range mentioned as a figure of merit for an SDR. For example, I know that the bits per sample used by the analog to digital converter can affect the dynamic range. Why do I ...
11 votes
2 answers
801 views

Can an amateur use cellular technologies with SDR?

Software Defined Radio is opening up many new possibilities for amateur digital modes. One family of technologies that interests me is cellular. 2G GSM voice/sms and 2.5G GPRS data has been proven to ...
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7 votes
4 answers
663 views

How can quadrature mixing adjust the phase of all frequencies by the same amount? Can it be done in the digital domain?

This came up in some feedback I got when I tried to answer What is IQ in the context of SDRs? and revealed some of my own misunderstanding. Initially, I gave an answer something like (paraphrasing): ...
4 votes
4 answers
236 views

Understanding how quadrature heterodyning captures information from negative frequencies

The way I understand how SDR works, there is a receiver input, generally connected to an antenna pulling in signals from the ether. That input is connected to two mixers (linear multipliers), being ...
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3 votes
3 answers
3k views

Broadband antenna for SDR radio

I recently bought a very wideband SDR receiver (DX-Patrol MK4, declared covered frequencies are 100kHz-2GHz). I'm experimenting with antenna designs because unfortunately I live in an apartment ...
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2 votes
1 answer
247 views

Preamble of a garage door opener

After detecting the transmitted signal of a garage door opener with SDR, is it correct to assume the first repeating pattern of the signal is preamble? I only see two one and zeros with equal ...
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13 votes
4 answers
2k views

Is is possible to operate D-Star from a software-defined radio?

What is preventing a software-defined radio from transmitting the D-Star protocol?
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10 votes
2 answers
2k views

Multiple simultaneous tunings with SDR

I just found out about WebSDR, and I was wondering how is it possible that many listeners listen and tune to different stations simultaneously. Which components/technologies allow this, and how does ...
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10 votes
3 answers
2k views

AIS and RTL-SDR Dongles

I am looking for an Windows-based AIS Decoder for RTL Dongles. Currently, there is a solution available using GNU Radio and SDR# but it is complicated to set up and keep running. ADSB has a dedicated ...
9 votes
2 answers
812 views

IQ imbalance after quadrature mixing

What is IQ imbalance in the output of complex or quadrature downconverter/demodulator/mixer? What are the causes and effects of IQ imbalance? (A spike in the spectrum display of RF noise?) Are there ...
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8 votes
2 answers
662 views

How to calculate if low-pass filtering is sufficient?

An answer on this question Suggested method for boosting 0.05 watt transmitter up to 10+ watts? suggests putting a filterless 19dB amplifier between the HackRF (or similar general-purpose SDR) and a ...
6 votes
1 answer
2k views

Suggested method for boosting 0.05 watt transmitter up to 10+ watts?

Long time ham operator here, new to this particular challenge - I have a software defined radio transceiver that I'd like to try and use to make contacts on HF, in particular 20-meters. Tuning ...
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6 votes
2 answers
771 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 ...
6 votes
2 answers
1k views

How does rpitx generate arbitrary SSB data with a clock peripheral?

While it wasn't the first to do so, the rpitx software seems to be the most active and mature implementation of what its own comments call "a code fragment by PE1NNZ". The trick is explained in Guido'...
6 votes
2 answers
498 views

Advantages of IQ generation at Mixer Stage or within FPGA for SDRs

I draw two possible architectures for Software Defined Radios below. In the first architecture, I,Q signals are generated at the mixer stage and two ADCs are required. The FPGA down-samples the ...
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6 votes
2 answers
286 views

SSB offset determination?

Is there any algorithmic way to determine if the mixed frequency offset in an SSB SDR demodulator is wrong (too high or low), other than listening for funny sounding voices? (perhaps by checking to ...
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5 votes
5 answers
1k views

What is IQ in the context of SDRs?

What is IQ, in the context of software-defined radios (SDRs)?
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4 votes
2 answers
4k views

Choosing a wideband antenna design

On a previous question I asked about proper antenna design for wideband SDR receiver and ways to improve signal/noise ratio. Ideally the reciever has a range of 100kHz-2GHz. Keeping in mind is ...
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4 votes
2 answers
580 views

Sampling a 50 MHz Max Frequency 50 MHz BW Signal with a 50 MSps ADC

I paste below a superhetorodyne based Software Defined Radio Architecture for an Rx channel below. Suppose the IF signal has a max frequency of 50 MHz and 50 MHz IF BW. In that case, is it possible ...
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3 votes
4 answers
590 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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2 votes
3 answers
245 views

Constructing a ground level antenna array to monitor radio frequencies using SDR

New to this community and also a newish Ham. Hello everyone. This question could easily have been posted under 'Astronomy', but I thought I would start here since Hams tend to be quite knowledgeable ...
2 votes
1 answer
403 views

Can HDSDR perform the work of Direwolf?

I have a setup in which Direwolf is used in conjunction with a Baofeng radio to basically send data (AFSK). My app connects to the TCP server provided by Direwolf, send him some data which then is ...
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2 votes
1 answer
217 views

How does one know how a signal has been modulated

I am trying to intercept signals from a drone remote controller and decode them. Before I can do this I need to demodulate the signals. All I have is radio data from the transmitter's operating ...
2 votes
1 answer
362 views

Heterodyning complex values in gnuradio

I have been working at educating myself on how SDR and GNU Radio works. In order to demonstrate heterodyning, I set up a flow-graph consisting of 2 signal generators, a Multiply block, and QT GUI ...
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1 vote
2 answers
3k views

How to best connect an FM transmitting GPIO pin to an antenna?

I'm trying to use a RaspberryPi3 as a FM transmitter, using pifm and/or PiFmRds to send audio in 88-108 MHz band. The RPi can then use the GPIO-4 pin to transmit between ...
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0 votes
1 answer
280 views

Is Gnuradio `file sink` data time domain data or frequency domain data?

When I enable file sink,I could save and read data of Gnuradio as below: Questions as below: 1.Is the file sink data time ...
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0 votes
0 answers
57 views

A gnuradio program that can output some arbitrary waveform read from a file containing I/Q values

I am trying to figure out how to create a gnuradio program that can output some arbitrary waveform read from a file containing I/Q values. I would highly appreciate any guidance in this topic. Simple ...
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-3 votes
1 answer
103 views

GNU Radio does not work expectedly when the frequency is 2x the sample rate

Simple flow in GNU Radio 3.8.2.0 (Python 3.9.2). If samp rate is 32k, when Frequency moves to 64k the recovered ...
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