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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49 views

How a reply system works on a aircraft transponder? [closed]

I'm trying to build a transponder ramp test for mode c and s of aircrafts for my degree. I have a problem, I didn't understand reply system of transponde, how can I doba reply of a signal to test one?
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2answers
103 views

Antenna suggestions for SDRPlay RSP1A

Looking for suggestions for a portable antenna for use with a SDRPlay RSP1A. I notice that most other SDRs come with a few antennas, but not the RSP1A. I have a 2m/70cm HT, so I own a Nagoya NA-771R ...
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2answers
82 views

human voice / music radio signal without RF moduation

This question is about digital voice modes that are used with AM / SSB / FM radios. Dstar , FreeDV , etc. assumptions: pulse width modulation amplifiers can take a digital signal as input. a software ...
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5answers
778 views

What limits a PIN diode or varicap from being used in a “Software Defined [Radio] Filter”?

A PIN diode varies its capacitance based on a DC bias, and a Varicap exhibits this effect even more clearly. What limits the use of "solid state variable capacitors" like these for ...
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1answer
141 views

Modify a CB radio to connect to a wireless network? [closed]

Is it possible to modify a CB radio to connect to a wireless network, and potentially send any data sent from the radio as a buffer to an outside source like an API? If so, what would be the best way ...
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1answer
46 views

How to get the “real” number of samples coming in an sdr

so I am fairly new to this SDR and dsp thing, I am working on a project that calculates the ppm and adjusts the offset, now I kinda got the idea of how to calculate the ppm after going through the ...
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1answer
227 views

Failing to detect Hydrogen line with 105cm dish

I've seen many examples of roughly 1 metre sized dishes being used w H+ sawbird and an SDR to detect and analyze Hydrogen line signal, and have been trying myself but can't seem to get anything beyond ...
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2answers
49 views

Not able to understand some operations in rtlsdr library in python

Here is the part of the program I am having problems with: samples = sdr.read_samples(16*1024) power, _ = mlab.psd(samples, NFFT=1024, Fs=sdr.sample_rate /1e6) ...
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1answer
69 views

Why does QPSK signal in GNU Radio shift away from my center frequency at higher frequencies?

I am transmitting a QPSK signal via GRC and when I look at it on the spectrum analyzer, the signal is shifted away from my center frequency. This shift increases the higher the center frequency (i.e. ...
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0answers
103 views

Writing “Wav” file in GNU Radio 3.9.0

I need to burn an audio file received from a computer sound card. But in the new version of the gnu radio, I found that the "Wav File Sink" and "Wav File Source" blocks were gone. ...
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1answer
225 views

Implementing a BPSK and 4-FSK transmitters in GnuRadio (GRC) with USRP?

Currently trying to transmit a BPSK and a 4-FSK(MFSK) signal via GRC using USRP, I have two attempts at it but don't seem to be going anywhere. Still fairly new to GRC. For the BPSK, how will this ...
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7answers
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How does IQ modulation work (intuitively)?

I'm trying to get my head around IQ modulation. What I understand so far is that each of the I and Q branches of the mixer produce two sidebands with the same frequency components, but in the Q branch,...
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3answers
136 views

How is the Hackrf able to achieve 20MHz of bandwidth with an ADC that only allows 22Msps?

The way I understand it, is that to avoid aliasing on an ADC, you have to be in the first Nyquist zone (so half the sampling speed). What doesn't make sense to me is how the Hackrf is able to bypass ...
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3answers
110 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 ...
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3answers
651 views

Can SDR receivers be detected remotely?

It's my understanding that active superhet receivers can be detected by looking for the emissions from the local oscillator, particularly because the LO's frequency is usually set at some fixed offset ...
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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
122 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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1answer
83 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
66 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
330 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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3answers
354 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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0answers
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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
118 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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0answers
36 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
225 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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0answers
89 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
104 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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1answer
86 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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2answers
119 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
88 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
137 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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3answers
134 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
324 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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0answers
40 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
540 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
398 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
465 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
114 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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4answers
470 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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0answers
336 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
44 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
264 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
243 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
113 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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2answers
114 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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1answer
51 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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3answers
266 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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1answer
164 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
128 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
317 views

Advantages of IQ mixer versus direct 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 0 Hz on up) with a fast ADC or DAC? Are ...

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