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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10
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2answers
674 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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3answers
293 views

Viewing the broadcast FM spectrum using a USRP N210

My issue is regards to viewing the FM spectrum using USRP N210 & GNU Radio. I did try to use several blocks of GNU Radio to view an FFT plot of the FM band using the USRP N210 device. My blocks ...
3
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2answers
95 views

GNU Radio - Signal Keeps Getting Smaller?

Really bizarre issue here. Here is an image of a signal taken from SDR Sharp: Freq: 926.365M Bandwidth: 30k Now, using the above measurements, here is this same signal observed in GNU Radio with ...
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1answer
463 views

I want to know the bandwidth of this signal; problems using “QT GUI Frequency sink” to show it

As shown in two pictures,setting a different bandwidth-value in the module, the value of the coordinate axis change accordingly. How did it happen? And I want to know if gnuradio can tell us the ...
6
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1answer
1k views

RX antenna and RTL SDR with upconverter ..How to hear something?

I mounted a small RX antenna (mini whip, bought from eBay) (on 10-th floor) and I want to try to listen to something. I bought a RTL-SDR with Upconverter which supports HF. RX antenna's operating ...
5
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2answers
910 views

How to transmit images and video through a hurricane?

Background You're in the path of a hurricane, and the eye just passed over your head. There is no electricity (apart from your own generator or battery), there is no mobile network and there is ...
2
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1answer
494 views

USRP: Are RX and TX on the same or different channel for single daughterboard?

I've got a USRP X310, currently with just one daughterboard, a WBX-120. I'm writing some C which needs to operate the radio full duplex - I receive on RF A RX2 and transmit on RF A TX/RX. But I'm ...
4
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1answer
1k views

SDR with the Raspberry Pi

I wanted to explore digital modes by connecting a Raspberry Pi via audio cables to a transceiver. However, I realized that thanks to the clock generator, the raspberry pi can produce RF signals ...
1
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1answer
1k views

RTL-SDR with SpyVerter - setup

I need some assistance in setting up a RTL-SDR with a SpyVerter upconverter, using SDRSharp. I have been using the RTL-SDR on its own with success. However, when I connect the SpyVerter (the side ...
7
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2answers
465 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 ...
3
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2answers
2k 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 ...
3
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3answers
1k 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 ...
1
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1answer
723 views

Why is GNU Radio dropping packets when I introduce a Frequency Xlating FIR filter?

I've got a GNU Radio flowgraph intended to take a signal from a USRP X310 at a 25MS/s sample rate and downsample it to 2.4576MS/s for demodulation as 9600 baud GMSK. If I run the USRP straight into a ...
2
votes
1answer
453 views

Serialising a data signal with a Raspberry Pi

I'm working on a project to transmit and receive data by radio. For the transmission, I'm using a Raspberry Pi 3 and the NTX2B transmitter for the transmission. For the receiving end, I am using ...
1
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1answer
979 views

How to change center frequency automatically in GRC?

I'm on reasearch using USRP and GNU radio for solar flare observation. The research is making digital radio receiver in GNU radio companion and using USRP B200. Basically the purpose of system is to ...
6
votes
2answers
481 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 ...
0
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2answers
130 views

Any ideas as to what I might be picking up on SDR?

Any ideas as to what I might be picking up on SDR? They make for some strange patterns. Picked them up at the following coordinates: (31.514596, 74.345092) using GQRX, tuned to 217.25 MHz. As for the ...
1
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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 ...
1
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1answer
359 views

How to make a software defined radio using USRP and GRC

I want to make a software defined radio, based on the hardware device shown in the schematic diagram below. I don't have a strong background in telecommunication engineering (I'm an electrical ...
2
votes
1answer
313 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 ...
2
votes
3answers
367 views

What are the 3 or 5 peaks in an FM broadcast during silence?

Looking at the waterfall spectrum of any ordinary FM public broadcast station (88-108 MHz), during the silence, there are 3 or 5 visible peaks. What are they? It's possible this has a trivial ...
3
votes
1answer
372 views

What is this Morse code-like station?

I’m trying to identify this signal at 928.807 MHz. A sample of the raw I/Q from gqrx is here (9.2 MB, .wav, 48000 Hz) and this is the waterfall: I’ve tried decoding some common digital modes (...
5
votes
3answers
1k views

Cause of harmonic spurs?

Harmonic spurs (harmonics of the transmitter frequency, as seen by a wide-band receiver or SDR) in the RF spectrum might be caused by an imperfectly sinusoidal or badly filtered transmitter carrier ...
2
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2answers
133 views

How to safely connect a digital output to a receiver's antenna input?

Suppose I have a 3.3 or 5V GPIO digital signal (from an Arduino or Raspberry Pi, etc.), periodically toggling at some HF or VHF frequency. Since it has such a "dirty" spectrum, I don't want to hook ...
5
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2answers
2k views

How to determine the PPM value of a NESDR SMArt?

a) Given that I don't have a frequency standard or other known transmitter available, what is the easiest way to calibrate the NooElec NESDR SMArt which is using a TCXO rated at 0.5 PPM.? I.e. to ...
4
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2answers
466 views

Linux based SDR spectrum capture via CLI

I need to setup a Linux box to run unattended capture of about 10 MHz - contiguous worth of spectrum (Hardware must support between 500 kHz and 200 MHz) targeting voice (mix of AM and FM voice ...
3
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2answers
1k views

Where can I download NESDR Smart (NooElec) drivers for Mac OS Sierra?

Just bought this NESDR Smart USB dongle from Amazon in Canada. Wrote the company asking for drivers, but they sent links which didn't help. Anybody have a better place to download drivers for Mac OS ...
4
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2answers
218 views

Very odd and wide 30m signal. What is it?

A local ham friend copied this strange, wide signal on 30 meters on his Flex 5000. Anybody know what it might be?
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2answers
282 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 ...
2
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2answers
71 views

What function do high-pass filters in a direct conversion receiver perform?

Use case: I'm considering hacking into my SoftRock RXTX to bypass the filters, then add external filters. I'm wondering if I can use just the low-pass filters I've already built, or if there's a ...
4
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1answer
653 views

FM squelch SDR algorithm?

What signal characteristics in an SDR receiver signal path should be evaluated or computed to determine whether the audio output should be squelched or not? What sort of computed result should be ...
2
votes
1answer
778 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 ...
6
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2answers
166 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 ...
3
votes
1answer
1k views

What is a panadapter?

To what does the term "panadapter" refer? (Physical hardware or software?) How did the term "panadapter" originate as related to radios or electronics? How is the term "panadapter" different from ...
1
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1answer
405 views

SDR demodulation of SSB

Is there any difference between demodulating LSB versus USB in software from IQ samples other setting the complex mixer frequency (LO) below or above the SSB signal frequency? (and excluding any ...
2
votes
1answer
62 views

crt TV emissions

I have my Hack RF plugged in my TV antenna to have a cheap setup and I have observed on the spectrum analyser a signal (Bandwidth: ~400Khz) that is emitted by my old analog TV from 80ies. These are my ...
2
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2answers
165 views

RF scanner w/ graphic output

I debated putting this question on the electrical engineering forum vs. here. I settled on here since I figured many of you amateur radio experts have probably wondered about this too. I am ...
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1answer
171 views

transmitted FSK, sniffed something PSK-looking

I am transmitting a FSK signal on 433,941 ± 32 kHz at 19200 baud rate. From what I read I should be able to recover my signal with a a modem centered on my carrier and having a bandwidth of 32 × 2 + ...
6
votes
2answers
1k views

What protocol or API does WebSDR use to stream audio?

What documented protocol or API does WebSDR use to stream audio over the internet? I'm interested in capturing a WebSDR audio stream using a small embedded device which has lots of audio DSP ...
3
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0answers
818 views

OFDM spectrum, HACKRF, and GNUradio companion

I am trying to analyze the spectrum of wifi spectrum. I getting a good OFDM spectrum with my HackRF at 2.412 GHz (from my first QTGUI Sink). But I get nothing out of OFDM Receiver. I was wondering ...
3
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1answer
211 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 ...
2
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1answer
552 views

Gnu Radio with Funcube Dongle SDR

I am Trying to use Funcube Dongle Pro+ on Windows with Gnu radio companion with no success. My PC is detecting The Funcube Dongle Pro+, and it works on SDR#, But It doesn't work on Gnu Radio. I have ...
3
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1answer
5k views

HackRF One — Expected 'hackrf_transfer -t' file format and its creation?

What file format does the HackRF One expect on the command line, using the -t option with hackrf_transfer? Also, how would I create or convert that format from a ...
2
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2answers
440 views

HACKRF_ERROR_NOT_FOUND

I have connected my HackRF to my computer that runs Ubuntu and it was working fine until now. It gives me an error: ...
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2answers
732 views

HackRF Hardware

How does the demodulation done with HackRF? Is the mixed with IF and then the frequency spectrum is shifted to baseband frequency by sampling OR the frequency of the mixer in the hardware can be ...
2
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0answers
94 views

Capturing the key fob signal with SDR [duplicate]

Is it correct to assume that not all the key fob signals have preamble section? I am playing around with bunch of key fobs and I am trying my best to capture their OOK transmitted signals with RTL-SDR ...
2
votes
1answer
439 views

How to process signals captured using a SDR?

I saw that Oona Räisänen uses C and Perl to process digital signals: https://github.com/windytan So I was wondering if there is any book (or ebook) about how to use programming to process digital ...
2
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1answer
203 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 ...
0
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2answers
2k views

DIY 433MHz antennas from copper wire

I need to build two minimalistic antennas for RX/TX at ~433MHz. I have insulated solid core copper wire, but I need to make it perfectly straight. I was thinking of using the type of sticks you set ...
1
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1answer
67 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 ...