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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Getting RSSI values between two B210 USRP to print on a text file [closed]

I have been using Gnuradio for a while and wanted to print the RSSI values to a text file as received from the other USRP. My objective is to print RSSI values from one transmitting USRP to another ...
ZubairAhmed Ansari's user avatar
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data rate for dsss in amateur radio

I have a question about the data rate for a DSSS transmission in amateur radio. I give an example with a bandwidth $B=4$ kHz, a spreading factor $SF=64$, a DQPSK modulation and a convolutive code with ...
bubu's user avatar
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3 votes
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Excessive frequency deviation for DMR handsets?

A Hytera DMR handset that I am working with has a frequency deviation of 2300-2700 Hz. This is higher than the expected 1944.0 Hz frequency deviation specified in the DMR specification (ETSI TS 102 ...
BigBrownBear00's user avatar
2 votes
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Receiving a lot of noise with RTL-SDR and SDR# for GOMX-1

Hi im new to SDR and having issues setting up SDR#. I'm trying to receive from GOMX-1 on 437.25 MHz for a project. My set up is the dongle, a LNA and a self built helical antenna for that frequency's ...
Rob's user avatar
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Building a bat detector using an SDR USB dongle - is it possible?

I'm currently trying to find a way to build a bat detector on a budget (good commercial ones are ridiculously expensive), and came across this video building one using SDR: https://www.youtube.com/...
Giogina's user avatar
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What band/setting is suitable for using SDR in wild area for exchanging beacon messages and alerts? [closed]

The problem we try to fix: We're living in north America. In many wild areas, mostly hilly forest terrain, there's no cellular signal. So far we figured out two solutions: using two-way radio (walkie-...
DingoStiglitz's user avatar
1 vote
1 answer
357 views

How to wire simple homemade long antenna for 100KHz+ on RTL-SDR

I have a rather beginner question, hope that's okay. I use my Quansheng to listen over 50 MHz, and I have heard that one can hack the firmware to go down to 18 MHz, but I really want to listen to the ...
spl's user avatar
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Possible reasons why I only receive FM broadcast via SDR

My setup is the following: terratec SDR dongle directly plugged into my laptop the dongle shows up in gqrx as Realtek RTL2838UHIDH coax cable out to the balcony, not laid in any loops via an adapter, ...
mart's user avatar
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PPM modulation and demodulation

What is the procedure for modulating and demodulating the PPM signal in the samples received by SDR? The samples are in IQ format. I want to play with the ADS-B system in Python (on the desktop of ...
electronsx's user avatar
2 votes
1 answer
307 views

How to use GNU Radio to demonstrate FM demodulation without baseband signals

Using GNU Radio, I'm currently trying to create a flow graph containing a simple demonstration of how FM modulation and demodulation works. Since the target audience is not accustomed with complex ...
Chi's user avatar
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Loss of information and aliasing in superheterodyne receivers

For a radio / SDR that downshifts a signal to an IF / intermediate frequency band, wouldn't information be lost in the case that the original signal is above the IF sampling rate? For example, the ...
Ken - Enough about Monica's user avatar
2 votes
1 answer
160 views

Connect mobile device with coax cable to SDR board

My goal is to connect mobile devices using a coax cable with a SDR board to be independent from using the air interface and antennas. I don't know how to connect my devices with the SDRs since I'm an ...
k_o_'s user avatar
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1 answer
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Transfer digital data over ham radio frequencies using QPSK modulation SSB-QPSK transmitter

If I use QPSK modulator/demodulator is it possible to transfer digital data over ham radio frequencies. SSB-QPSK transmitter
Vinayak's user avatar
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How to trigger transmission using GNU Radio companion on a X310 USRP?

I am trying to transmit an RF signal that is created via GNU Radio Companion (GRC) on an X310 USRP, but I only want the signal to be present on the output when an external trigger is high. There is a ...
XaC's user avatar
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Where to begin with SDR? [closed]

I want to make a ground to ground non-line-of-sight (NLOS) data link. As I understand SDRs are perfect for this because I can specify frequency, bandwidth, channel size, etc., making it suitable for ...
Ri Di's user avatar
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Why does a peak remain at -10db gain and disappear at -50db gain?

I have a Pluto and an RTL-SDR both connected to a computer. On Matlab, I run such a script: ...
Count Zero's user avatar
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How to tell reference from observation channel

I have been following some passive radar tutorials and they all mention a reference channel (for a signal directly from a transmitter) and an observation channel (for a signal reflected off of some ...
pookie's user avatar
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2 answers
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Phase detection accuracy with USRP N210 and CBX-40

I have designed a simple TX/RX system in GRC with a single USRP N210 and CBX-40. I am transmitting sinusoidal signals at various frequencies within the 2-6GHz range and detecting the amplitude and ...
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1 answer
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How do I set the spectrum scope gain on the Icom IC-7300?

I have an IC-7300. When observing weak signals, the spectrum scope has signal peaks that are way too small. Just now I was listening to a clearly audible CW signal that was easily heard but hardly ...
Xunie's user avatar
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Transmitting high-speed PWM over RF

First, let me apologize in advance if this isn't the correct exchange to post this question on. I have a 50 MHz PWM signal (it's actually a 50 MHz 50% DC clock with a 1PPS clock embedded with PWM) ...
aerophage's user avatar
1 vote
1 answer
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Bandwith for streaming multiple channels

what is the preferred bandwith for streaming multiple channels? How does the antenna affects the frequency when your hosting in the computer?
sataniel's user avatar
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Descrambling/dewhitening in GNURadio

I am currently working on project which utilizes RTL-SDR for capturing packets. I know that those packets are whitened with x^9 + x^5 + 1 polynomial. No matter what I do the descrambling each time ...
Artur's user avatar
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110 views

DVB-T gnuradio loopback

I have recently had access to two SDRs a hackrf and a Plutosdr through my university.I am now trying to experiment and learn more about wireless communications and how to implement some examples on an ...
instantrame's user avatar
2 votes
1 answer
191 views

Link budget validation for a UHF satellite ground station

I built a UHF satellite ground station. It has a yagi with G=16.1dBi and an LNA with G=20.1dB. It’s a 430 - 450 LNA with NF=0.68. The RF cable, rg174/u has I think close to a 1dB/m, which would mean ...
Moses Browne Mwakyanjala's user avatar
1 vote
0 answers
56 views

What is the point of using LNA if the SDR can increase the gain itself [duplicate]

Usually there is a LNA next to antenna, while SDR devices also have gain setting so we can increase the gain. As i know LNAs are amplifying all signals with same gain (Am I right?) So i wonder what is ...
Ariyan's user avatar
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3 answers
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Would it be possible for a software-defined FM receiver to demodulate two signals on the same frequency?

When two FM signals are transmitted on the same (or about the same) center frequency, either you hear only one or you hear that noise I'm sure most of you have heard. Would it be possible for a ...
Someone's user avatar
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Sine wave 'frequency' in recorded signals

I'm trying to replicate a signal from a remote using another wireless transmitter (a cc1101 to be exact). I got somewhere, but I am stuck, and have a fundamental question At the top is the signal I'm ...
Koen's user avatar
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3 votes
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What could cause an IQ diagram to shapeshift randomly?

I'm trying to interface a DVB-S2 transmitter to a DVB-S2 demodulator - for now with a direct cable+attenuator link. Both are set up exactly with the same parameters (same carrier frequency [2150MHz], ...
Mister Mystère's user avatar
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244 views

Does the specific frequency of a CW tone make a difference to output from a practical SDR?

I'm using a Nuand BladeRF 2.0 micro, which is based on the AD9361. I'm just trying to get a handle for how it behaves at the moment, so I was testing generation of some CW tones using GNU Radio and ...
nhw76's user avatar
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1 answer
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How to use SDR equipment and Gnuraio record `time domain` data?

From answer, A comment has pointed out that one could think of the saved data as in the time domain under some circumstances because it is literally series of 32-bit values written as fast as ...
kittygirl's user avatar
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3 votes
2 answers
1k views

SDR Transceiver over LAN

The feed line is a limiting factor when designing a home HAM system. The further the antenna is placed from the transceiver, the greater the cost and attenuation. Is there a way to solve this with ...
Christopher J. Grace's user avatar
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1 answer
337 views

How to use RF Input B ports in GNU radio?

I have an Ettus B210, which has 4 ports: RF Input A: RX/TX and RX2, and RF Input B: RX2 and RX/TX. In GNU Radio using the USRP block I can use both ports of RF Input A. But I don't succeed to use the ...
Sjips's user avatar
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2 answers
226 views

Is it possible to use LimeSDR/HackRF with DireWolf?

I was wondering if one could use DireWolf with the LimeSDR/LimeSDR Mini/HackRF. The bandwidth would be much more acceptable than even the highest rate sound cards, which rarely reach even 192 khz. Can ...
Steve Mucci's user avatar
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1 answer
162 views

Identifying the signal picked up at 363mhz with sdr++. It is from Burmese military's communication. I want to know what it is and how to decode it

As shown in the picture, I want to identify the signal and how can I decode it, please. Here is the link to audio.wav file: https://u.pcloud.link/publink/show?code=XZRoY5VZggSdx8NPqKp3hAOaphcsKVVCqrik
Maung Maung Gyi's user avatar
0 votes
1 answer
219 views

Why does my transmitter spam the SDR waterfall with this strange pattern?

I was recently playing with a combination of SDR and a Baofeng using two separate antennas and I noticed something strange when I transmit using the Baofeng: I heard that it's normal to observe ...
d33tah's user avatar
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4 votes
1 answer
453 views

Why would a VNA not make a good Spectrum Analyzer? Or an SDR a good VNA?

Happy to be corrected where I'm wrong in any of this but in broad strokes my understanding is: Spectrum Analyzer measures input signal strength while sweeping across frequencies, measuring RF ...
natevw - AF7TB's user avatar
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1 answer
555 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 ...
kittygirl's user avatar
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0 votes
1 answer
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detecting transmissions around the house

A few years ago I bought an SDR and installed it on my home security system. While I was playing around with it I discovered a program or something that allowed me to see the transmissions from three ...
PeteC's user avatar
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-2 votes
1 answer
76 views

How to know whether aliasing occurs when observe unknown signal?

Per my good but downvote question,I am hard to set sample rate even to a standard cosine wave. When I observe unkwon signal,how to judge whether aliasing occurs?
kittygirl's user avatar
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-3 votes
1 answer
164 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 ...
kittygirl's user avatar
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0 votes
1 answer
65 views

Help synchronize on unknown frequency sequence

I am having trouble to synchronize on a frequency hopping pattern between an emitter Tx and a receiver Rx. More precisely, the ...
aheuchamps's user avatar
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2 answers
40 views

Is number of items in`file sink` integer multiple of `sample rate`?

I use flow graph for file sink as below: When I stop running this flow graph, there are 110000 float numbers in file ...
kittygirl's user avatar
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-1 votes
1 answer
247 views

What's the usage of `Multiply Const 1` and `Multiply Const 0`?

Based on Gnuradio, Multiplies the input stream by a scalar or vector constant (element-wise if vector). output = input * constant In above web page, I found ...
kittygirl's user avatar
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0 votes
1 answer
74 views

what's the usage and benefit of segments in Gnuraio `file meta sink`?

In Gnuradio website, Max Seg. size is Length of a single segment before the header is repeated (in items) At first,I think ...
kittygirl's user avatar
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2 votes
1 answer
254 views

Are there major advantages to using DVB-S2 vs CCSDS (or vice-versa)?

In Cubesats, DVB-S2 and CCSDS are both equally present as communications standards. Are there really any pros and cons, that is - a "best choice for a given application", or are they just ...
Mister Mystère's user avatar
0 votes
1 answer
192 views

How to set external clock of `--device-settings` in soapy_power?

External pps equipment connected with USRP. In soapy_power,I set --device-settings 'clock_source=external' but failed. ...
kittygirl's user avatar
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0 votes
1 answer
567 views

Why can't I get the radio/waterfall to show in SDRAngel - GQRX works fine

I was wondering why the digital decoder in SDRAngel wasn't working, but now I see that even broadcast FM isn't showing a bump in the spectrum: I can play broadcast fm radio stations (the ones playing ...
NoBugs's user avatar
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2 votes
0 answers
177 views

Why the Receiver Sensitivity theoretical value doesn't match its experimental value when using USRP B200mini in GNU Radio?

I'm using a USRP B200mini SDR card for my GNU Radio energy detector project. I wanted to measure its Receiver Sensitivity ($RS$) experimentally and compare the experimental value to the theoretical ...
HadK's user avatar
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1 vote
3 answers
406 views

What can be used to protect an SDR receiver against bursts?

I am using a USRP B205 to detect electromagnetic pulses. Sometimes the signal power bursts to 100 dB, average power is around 10 dB. What can be used to protect the SDR receiver against bursts?
kittygirl's user avatar
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-1 votes
1 answer
71 views

What's the negative float of rtl_power output means?

I got below float numbers after soapy_power -f 80M:100M -B 1000 --output a --format rtl_power: ...
kittygirl's user avatar
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