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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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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1answer
674 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 ...
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1answer
430 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 ...
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1answer
920 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 ...
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2answers
454 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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2answers
129 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 ...
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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 ...
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1answer
344 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 ...
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1answer
296 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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3answers
333 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 ...
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1answer
351 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 (...
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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 ...
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2answers
130 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 ...
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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 ...
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2answers
438 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 ...
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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 ...
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208 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
256 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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2answers
67 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 ...
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1answer
611 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
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1answer
693 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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2answers
154 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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1answer
922 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 ...
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1answer
384 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
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1answer
61 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 ...
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2answers
164 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
159 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 + ...
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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 ...
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0answers
766 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 ...
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1answer
202 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
534 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 ...
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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 ...
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2answers
414 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
704 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 ...
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0answers
86 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 ...
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1answer
436 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 ...
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1answer
196 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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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 ...
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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 ...
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1answer
339 views

Oscillators inside SDR hardware

Are the oscillators in SDR hardware (that are used to mix the input to sinusoidal waves) purely digital? In other words, is the sinusoidal analog signal is created digitally? For example getting the ...
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2answers
547 views

SDR hardware architecture schematic

Is this a good representation of the sound card SDR systems in which a receiver has a simple hardware detector producing two quadrature audio channels that can be fed to a computer's sound card? ...
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3answers
1k 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 ...
4
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1answer
4k views

How to choose the right sampling rate and bandwidth for RTL-SDR dongle?

Receiving the frequency of 97.9 MHz I have a Terratec SDR dongle and I am trying to capture a radio frequency. The FFT window shows the frequency range from -500 to 500 KHz. Is there a way to ...
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2answers
649 views

Can I use old TV FM card as SDR?

I tried searching a lot before, but couldn't find anything about it; I have an old TV/FM card from an old computer, I wish to know if it can be used as an Software Defined Radio, and if yes, how? The ...
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2answers
3k views

Decimation to listen to FM radio with gnu radio

I am trying to listen to FM station using an SDR and GNU radio. I have followed this procedure Is there a reason that the decimation is done gradually? For example would it make a difference if I ...
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2answers
584 views

Software defined radio demodulation

I am trying to increase my knowledge on software defined radio and according to what I have read its hardware consists of three parts: Amplifier Tuner ADC I just wanted to make sure that my ...
4
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1answer
344 views

ADS-B for Trains?

Is there any kind of technology similar to ADS-B for trains? I'm aware of HOT/EOT/DPU messages, but as far as I can see these don't allow you to see its location. I'm specifically wondering about the ...
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2answers
2k views

How to recieve 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
145 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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1answer
917 views

33cm 5W(effective output power) tx amplifier for ATV (HamTV)

I am searching for a 5W effective output power TX amplifier that I can use with my BladeRF to send DVB-T Signals for ATV (33cm band). Can someone tell me on what things I have to look for when buying ...