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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13 views

RS41 weather balloon unable to decode data

Some times ago I tried to decode the signal from a weather radiosonde (RS41) passing in my area using a cheap RTL SDR (using both standard antenna and a home-made one, with similar result). The ...
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2answers
96 views

Is it at all possible to make a ham alert radio?

Would it be possible to make an alert radio... for shortwave? Out of something like Arduino, or RPi. Sort of like the NOAA Weather Radios. I got to thinking one day. Say you wanted to send a message ...
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36 views

How can I know (check or detect or analyze) which modulation using of my remote control switch?

Please forgive me, my native language is not English. I'm new to radio, but I have several years of programming experience. I have a raspberry pi 4 model B (...
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1answer
51 views

Transmit filter for Amplitude-shift keying

I want to transmit an ASK signal with GNU Radio and HackRF, the parameters are: Frequency: 27.12 MHz (ISM) Sample rate: 2MSPS Symbol rate: 2000 bps Samples per symbol: 1000 The flowgraph currently ...
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2answers
107 views

Signal in the center frequency of my SDR spectrum always

I'm pretty new to SDR, but I understand a little bit about RF. On all 3 of my SDR device (two RTL one HackRF) The center frequency is always full of interference from something unknown.....it doesn't ...
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305 views

SDR: How are I and Q determined from the incoming signal in quadrature sampling on the receiver side?

I'm new to digital radios and signal processing, so I apologize if this question is trivial but I haven't been able to find an answer here or by googling. Also, some terminology might be off, please ...
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27 views

Sending custom EWS over DAB+ with a HackRF One

Disclaimer: I'm aware of legal issues regarding EWS! Rest assured that there is no need for concern as this is a small-scale, proof of concept done in a controlled enviroment! Greetings! I'm trying to ...
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4answers
94 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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28 views

Ofdm carrier allocator block in gnu radio

I have some very basic question of the ofdm carrier allocation in gnu radio that am not understanding.please help me to understand. I want to pass a LTE based ofdm modulated signal simply like the ...
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1answer
144 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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69 views

Capture Uplink GSM packets using 820T2 and SDR

I am an extreme beginner with SDR. I am trying to use the 820T2 & SDR device to capture uplink gsm packets sent by my phone to the nearest Base Station. I have an Rx Monitor App installed on my ...
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2answers
96 views

Increasing communication range by boosting output and input power

ORIGINAL QUESTION I am trying to increase the range of communication between two SDRs to simulate near space communication. The output power of TX is 10dBm but I would need 37dBm for near space ...
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35 views

Upconvert Signal with USRP N210 in GNU Radio Companion

I'm using a USRP N210 with this GRC diagram where I'm trying to upconvert a 1kHz sinewave. I tried just upconverting the signal from the signal source to 2.5GHz. However, I keep getting the output ...
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89 views

What does antenna frequency range mean in practice?

I'm trying to wrap my head around software defined radios and antennas and noticed that lots of antennas are described in terms of a frequency range. For example, this one is described as operating ...
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1answer
73 views

Could not observe the Meteor M2 even though I scanned the sky at the time it passes with a high elevation degree (77). What might have happened?

I am currently trying to observe and obtain data from the meteorological satellites. I have constructed a V-dipole specifically for the 137 MHz and was able to observe the NOAA 15, NOAA 18, and NOAA ...
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1answer
108 views

Receiving an Coded Odd Signal at 137.25MHz but don't know what it might be. It can affect my detection on NOAA 19. Need help

I am a newbie trying to detect NOAA 15, 18, and 19 satellites, which have downlink frequencies between 137 MHz and 138 MHz. I am using an SDR dongle and attached a photo of it to this post. Of course,...
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82 views

Lab599 Discovery TX-500 connectors?

The Lab599 Discovery TX-500 is coming out soon. A lot has been said about that radio's use of weather-resistant proprietary connectors, but what are the actual connector types? The antenna is female ...
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1answer
169 views

Implementing FM receiver using GNU Radio C++ API

This is my first ever experience with GNU Radio. I am trying to implement a simple FM receiver shown below with its C++ API. I seem to have pedantically deconstructed this receiver into its smallest ...
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31 views

2GFSK digital filter bandwidth calculation

I'm working on a S2LP from ST and I am configuring the RX digital filter. I need to calculate the bandwidth of the signal which has 2GFSK modulation. Do you think the code below is correct for ...
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1answer
298 views

How does an Airspy HF+ Discovery compare to a “real” radio?

I was looking for a secondary radio for RX only and I thought a SDR may be a better option. I read about upconverters but then I saw Airspy has a SDR with the upconverter onboard, and claims to have &...
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3answers
186 views

Practicality of SDR-based TX/RX

When it's not possible to be at the same location as a TX/RX appliance, some form of remote control is needed. There's basically two ways to TX/RX: classical radio appliance, with or without digital ...
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2answers
282 views

What is the current state of the art in CW filters?

In the 1970s I made a CW “filter” based on a phase locked loop that detected a specific audio frequency, and this drove an NE555 oscillator: the result seemed at first like a “zero bandwidth” CW ...
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1answer
94 views

Can these in-band spurs from rpitx be eliminated somehow?

I'm putting together a 2m NBFM transmitter/receiver combo using rpitx and rtl-sdr. During testing my low-pass filter I discovered that rpitx is generating spurious signals within and around the band (...
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403 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): ...
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149 views

Receiving and decoding RDS in GnuRadio

I'm new in radio, so I started with seemingly easy task - receive and decode RDS data. I use GnuRadio to understand the concept of working with RF signals. So according to standard RDS receiver looks ...
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1answer
37 views

Does DCS intefere with SDR reception?

Does digital coded squelch (DCS) interfere with the analog-to-digital conversion in software-defined radios (SDRs)? I noticed that I can receive normal transmissions with my SDR just fine, but I have ...
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5answers
174 views

What is IQ in the context of SDRs?

What is IQ, in the context of software-defined radios (SDRs)?
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1answer
132 views

GNURADIO: What does the complex output of an osmosdr source translate to?

Warning: Noob question. I'm new to Software Defined Radio. My aim is to write a program that tells me the signal strength of a radio emitting source (I'll use three such sources and then try to ...
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2answers
109 views

Whats wrong with this radio signal?

I have a code that sends a beacon every 1 minute with a data-rate of 1200bps (BPSK-G3RUH). I do receive the signal using a custom software defined ground station that also decodes the beacon. After a ...
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105 views

Imaging with radio Frequency

Is it possible to image bones and tissues with radio waves (2.7GHz-5GHz) with a tiny radio frequency source and on one side and a receiver on other side which can image the data through a PC mediated ...
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48 views

Can the power output of a software defined radio be adjusted? [closed]

Some SDR transmitters have a very low power output. Can their output be adjusted?
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163 views

SDR transmit on more than one frequency

I'm new to SDR. Is it possible to transmit on more than one frequency, and if so what do I need? more on computer type network side one for each 800, 2.4, 5, 60 How can I get more than one SDR to ...
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120 views

Receiving different gain values on two RX channels on Ettus USRP B210

I am transmitting a continuous wave and using one USRP B210 with the kitchen_sink tool in order to save the received samples from two RX channels (v.3.15.0) When I look into the received signal on ...
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1answer
85 views

Can I get non demodulate IQ signals from WebSDR

I want to take a non demodulate audio signal from webSDR portals (http://www.websdr.org/). In order to try to feed these in DREAM DRM Radio software or GNURADIO. Could be cool almost try it for ...
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2answers
138 views

Advantages of IQ mixer versus baseband sampling SDR architectures?

What might be the advantages, if any, of HF SDR architectures that use a mixer between the ADC/DAC and RF, versus those that sample or generate RF directly at baseband with a fast ADC or DAC? Are the ...
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1answer
133 views

How is gqrx producing audio?

How exactly is GQRX converting signal in any frequency to produce audio output? Is it actually done by gqrx or some other element of the stack?
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1answer
545 views

How to send DMR SMS using MMDVM modem or hackrf?

I have a baofeng DMR radio with SMS feature, and since there is not much DMR radio owners in my area I want to do something myself. The easiest thing I can do I thought is to send myself some SMS as ...
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1answer
98 views

Most accurate way to measure signal power with (cheap) Spectrum Analyzer

I am using an USRP X310 which is unfortunately not calibrated and the specs given are only very vague. Hence I would want characterize the device with first-order measurements. Unfortunately I only ...
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2answers
272 views

Can I use a “bunny ears” TV antenna for RTL-SDR?

I'm trying to get into SDR and was planning on buying an RTL-SDR. For an antenna, I was thinking of using an old set of bunny ears I have lying around. However, I first want to make sure that they'll ...
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525 views

DIY SA612 + RTL-SDR HF receiver: good on laptop, but huge wideband noise on Raspberry Pi

I recently built a SA612 mixer for HF reception. I used an USB-frequency oscilator to shift the incoming frequency up by 28.8 MHz. I used a random wire antenna outside my balcony and connected it to ...
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1answer
50 views

Shifting frequency outside of the band

In theory when i need to shift some frequency i just multiply that signal by some sin or cos wave with the right frequency and than apply LPF or HPF. But when there is a wideband complex signal with ...
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87 views

Is there any 2.4 GHz tuner ICs for SDR receivers?

I have a hackrf one sdr, which i use to transmit test signals. I am using ISM bands, so I can omit transmitting my callsign, checking correct sub band (FM, digital) etc. And one of most interesting ...
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81 views

what is the center frequency

in GRC for this source block ?
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1answer
86 views

Turning raw APT data into an image

I apologize if this question is a little out of scope for the amateur radio stack exchange but I feel like it fit better here than over in any other forum. I have successfully parsed raw PCM data out ...
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1answer
102 views

Gnuradio AM broadcast receiver distorted audio

I have been trying to build a gnuradio AM broadcast receiver, but without success. I have tried a lot of combinations, but all of them produce a very distorted audio. I have an NBFM receiver using the ...
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1answer
113 views

audio problem with SDR on MacOS

I'm experimenting with SDR on MacOS High Sierra. Trying both CubeSDR and GQRX and experiencing similar issues with both. The applications seem to work, but the audio is choppy and chipmunk-like. ...
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3answers
357 views

What is the typical latency of a SDR setup running on a desktop computer?

It's well-known that the signal processing of an SDR adds a significantly amount of latency, the SDR software on the computer adds more latency due to data buffering, FFT, decoding, demolutaion, audio ...
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3answers
243 views

ARRL handbook as a reference for all your radio learning needs?

Looking to take up learning understanding everything from basic electronics to how today's wideband radios work, so that I can build my own radio systems (not just ham radios), and talk radio concepts ...
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65 views

Demodulating ISO14443 (part of NFC) using SDR?

I'm looking for info on demodulating both sides of an ISO14443 communication using a cheap SDR, preferably an RTL-SDR (R820T2+RTL2832U). The application is passively monitoring an NFC exchange for ...
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1answer
95 views

Using dvb-t device as rtl-sdr

I am wondering if I can use that dvb-t device to listen 48-836 mhz? if it's no, why? thanks..

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