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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28 views

Printing the Signal Power on the terminal from the USRP source block on GNURadio

I'm working on a project that makes use of the Ettus USRP X300 and the GNURadio environment. I have established a connection between the transmitter and the receiver of the USRP and I'm able to read ...
3 votes
1 answer
2k 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 ...
0 votes
1 answer
255 views

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) ...
2 votes
1 answer
289 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 (...
2 votes
1 answer
536 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 ...
1 vote
1 answer
190 views

What is this weird interference/strange radio station?

When I was checking if my antenna is working properly using websdr.org, I came upon this: On 4480 kHz, there are some strange noises. You can also see it in the waterfall here. Is it just some ...
4 votes
1 answer
5k views

Signal Source Block of GNU Radio

GNU Radio has a Signal Source Block which considers a set of variables to produce an output, namely sample rate, frequency and amplitude. In signal processing, we define a basic waveform by its ...
3 votes
0 answers
106 views

Tuning an L-band dish for receiving GOES signals

I've encountered some challenges with my ground station intended for receiving images from GOES satellites, and I'm seeking your expertise to troubleshoot the issue. Here are the system specifications:...
20 votes
6 answers
10k views

SDR: Quadrature demodulation vs direct RF sampling

I see that many SDRs use a quadrature demodulator and sample I and Q signals. But is it possible to downconvert the RF signal instead, sample it with only one ADC, and get the same capabilities of ...
-4 votes
1 answer
128 views

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 ...
0 votes
1 answer
67 views

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 ...
2 votes
0 answers
122 views

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 ...
3 votes
2 answers
154 views

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 ...
4 votes
2 answers
4k 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 ...
0 votes
2 answers
174 views

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/...
3 votes
1 answer
2k 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 ...
-1 votes
1 answer
42 views

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-...
1 vote
1 answer
952 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 ...
2 votes
2 answers
608 views

Why does SDR# sound better than SDR console?

This is kind of odd. I just got my first SDR receiver and I noticed that one application (SDR#) sounds a lot better than another (SDR Console) when listening to stereo FM broadcasts through the same ...
0 votes
1 answer
97 views

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
0 votes
0 answers
115 views

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, ...
0 votes
0 answers
198 views

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 ...
1 vote
1 answer
78 views

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?
8 votes
3 answers
8k 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 ...
7 votes
3 answers
790 views

Long range communication with just 1W of power?

Is it possible, and how can I setup communication between stations 1000km apart from each other by using just 1W of transmission power? By communication, I mean: It can be text based It can be very ...
2 votes
3 answers
194 views

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 ...
2 votes
1 answer
203 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 ...
4 votes
1 answer
504 views

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 ...
-2 votes
1 answer
106 views

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 ...
5 votes
3 answers
4k 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 ...
0 votes
1 answer
769 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 ...
1 vote
0 answers
63 views

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: ...
2 votes
1 answer
432 views

USRP-B210 GPSDO will not lock

Hi I own a B210 and I have a GPSDO that's installed but I do not have the antenna yet. Can I use it as a 10MHz reference and PPS until I obtain the antenna?
0 votes
1 answer
60 views

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 ...
6 votes
1 answer
422 views

What kind of modulation is this?

I was able to demodulate a signal I've received in gnuradio. Here you can see my flowgraph: But now I would like to be able to send data as well. But how should I modulate my data? As you can see I'...
1 vote
2 answers
75 views

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 ...
7 votes
7 answers
10k views

Why is 20m band waterfall showing signals every 50 kHz?

I'm very new to shortwave listening and just got to grips with my RTL SDR HF dongle. Last night while on the 20m band, there were signals exactly every 50kHz, starting exactly at 14.000MHz, then at 14....
0 votes
2 answers
285 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 ...
0 votes
1 answer
177 views

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 ...
2 votes
1 answer
225 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 ...
0 votes
1 answer
175 views

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 ...
2 votes
0 answers
134 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 ...
1 vote
0 answers
59 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 ...
4 votes
4 answers
4k 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 ...
10 votes
3 answers
3k views

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 ...
10 votes
2 answers
307 views

Which qualities/features does an SDR radio device need to be usable for Amateur Radio?

I know what things to note when selecting an analog amateur radio, but SDR devices have completely different specs, e.g. sample rate and resolution. What do I need to know about the device to make ...
0 votes
1 answer
88 views

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 ...
3 votes
0 answers
58 views

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], ...
0 votes
2 answers
286 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 ...
3 votes
1 answer
170 views

RF fading channel model?

What statistical or other descriptions exist regarding modeling of an HF-band RF fading channel? This is allow making (as in code my own software) lots of simulated test input signals for an SDR ...

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