Questions tagged [software-defined-radio]

Radio devices that use digital signal processing in place of analog electronic components to manipulate RF signals.

2
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1answer
79 views

How does one know how a signal has been modulated

I am trying to intercept signals from a drone remote controller and decode them. Before I can do this I need to demodulate the signals. All I have is radio data from the transmitter's operating ...
3
votes
1answer
54 views

Why is GNU Radio “stuttering” with this flow graph?

I have a GNU Radio Companion flow graph, where I have the following connections: 440Hz cosine wave throttle block audio sink All of the above blocks use the same sample rate (48KHz). When I ...
2
votes
1answer
41 views

How narrow-band can a DVB-S2 signal be?

Using software defined radios I can generate and demodulate a DVB-S2 signal live. I'm wondering if I can use this to send single pictures over the air using as narrow BW as possible. Using QPSK and a ...
1
vote
1answer
36 views

Using Satnogs' *.ogg files in GnuRadio flowgraphs

I want to use the *.ogg files available in Satnogs' database to test demodulation software for several satellites (using gnuradio). Can i use the ogg file source (available in gr-satnogs module) and ...
1
vote
1answer
91 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 ...
2
votes
1answer
96 views

Where does this common spurious transmission come from? Is there a quality difference?

I decided to see what my ham transmissions look like on an SDR and was kind of shocked to see how much leaks out. The waterfall display is split between two handhelds during transmit. There are a ...
1
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0answers
49 views

How to limit frame transfer in Gnu Radio Companion?

I have as source a bit frame, then I modulate it, to finally transmit it with my HackRF. I can receive and decode it normally with another HackRF. However I would like to limit to a number of frame ...
1
vote
1answer
70 views

Problem recording morse with sdr#

I have a problem with recording SWS-morse using SDRSharp and RTL-SDR. I want fixed gain, not audio automatic gain control. The problem is that all signal but the weakest will cause the recorded audio ...
3
votes
2answers
69 views

Digital transmission sounds

I'm playing with an RTL-SDR dongle and an LNA, on Linux Mint with GQRX and DSD A lot of frequencies show digital transmissions, which the DSD is not converting. I don't whether it is a format DSD ...
0
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2answers
83 views

RTL-SDR: command or script to obtain power and deviation of an FM radio station

My project is to monitor the power and the deviation of 3 radio FM stations, sending this values into a MySQL database. I can't stream directly the audio of the station, due to limited bandwidth. So ...
0
votes
1answer
110 views

How I can build dvb-t/dvb-t 2 transceiver?

I need dvbt2 transreceiver. I tried gnuradio with https://github.com/BogdanDIA/gr-dvbt. The "apps/dvbt_tx.grc" is working. But, video cannot transfer flexibly. On gnuradio flow, I adjust multiple ...
5
votes
3answers
179 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
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0answers
151 views

How to decode 2FSK signal with SDR?

I'm new to radio and SDR but, as a hobby project, I'm trying to decode a 2FSK radio signal received by an RTL-SDR that I sent using an SI4463 transmitter. The record file contains 3 packets, but I'm ...
3
votes
1answer
122 views

RTL SDR “dark region”

I'm new to RTL SDR, and I noticed there's a "dark region" (around 700-900MHz), and I haven't figured out why this is. My device's tuner is a Fitipower FC0012, where could I find the pinout and ...
3
votes
3answers
124 views

What equipment do I need to receive radio and connect to PC for listening

A great many moons ago, I spent a 24 hour period with a HAM radio connected to a PC, and listening to transmissions from a massive number of sources. Some of the transmissions included Morse, RTTY, ...
5
votes
1answer
140 views

FM spectral amplitudes during silence

General setting I'm playing around with an RTL-SDR and recently captured some FM spectrum in Hannover, Germany. I want to undersand what's going on, so I've read a lot about FM and its spectra, but I ...
2
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0answers
357 views

LimeSDR Mini + Raspberry Pi 3 B+ Transmission problem

I am new at this. I would like to transmit an audio signal cleanly using WBFM but I see two signal peaks occur around my fundamental frequency when I start transmitting. In this case I am using a ...
4
votes
1answer
109 views

SNR measurement for a BPSK/QPSK signal

I have created a software (gnuradio) that performs modulation/demodulation and supports a number of modulation schemes and error correcting codes. I'm in the process of evaluating the BER vs SNR for ...
-4
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1answer
81 views

where to look for (live or recorded) air traffic conversations for a specific area? [closed]

I am wondering if there's any chance to get a short fragment of ATC/pilot radio exchange of any flight to/from small airport of Talkeetna (Alaska). This airport seems to be not present on liveatc.net, ...
0
votes
2answers
1k views

HackRF + Amplifier = HF/VHF QRP Radio?

Do you think it would work to combine a HackRF One and an amp like the following to create a QRP SDR? Link to eBay Output of HackRF is approximately 10dBm, which fit's this amp nicely... What is ...
6
votes
2answers
200 views

Advantages of IQ generation at Mixer Stage or within FPGA for SDRs

I draw two possible architectures for Software Defined Radios below. In the first architecture, I,Q signals are generated at the mixer stage and two ADCs are required. The FPGA down-samples the ...
4
votes
1answer
328 views

GNU Radio sinusoid multiplication does not produce perfect results

I created a simple sketch in GNU Radio that multiples two signals. One is a sine and the other is cosine. I paste a screenshot of it and its results below. I have heard that in DSP, we can do almost ...
2
votes
2answers
415 views

Fast TCP/IP radio modem on UHF band

I'm interested if it is possible to have a data radio modem that works on the UHF band 400MHz for TCP/IP communication. What I have in mind is something similar to a router, but using UHF band for ...
3
votes
1answer
125 views

How high an SWR can the USRP 2901 (B210) handle?

I connected a USRP 2901 (B210) to an amplifier I designed. The USRP seems to shutdown every time I try to transmit. I guess I messed up with the input impedance matching on the amplifier. Is it the ...
5
votes
2answers
60 views

Weak signal digital modes and clock synchronization

Why to some weak signal digital modes (jt9, jt65, etc.) require knowing a clock time? Does knowing this clock time provide any gain in signal detection ability? (lower required S/N?) What clock ...
4
votes
2answers
91 views

Can a Digital Down Converter, at the same time, generate I,Q streams & Downconvert?

A Digital Down Converter (DDC) is usually used to convert Real Digital Signals at a high frequency to baseband (centered around 0Hz). DDC does this so by producing negative and positive frequencies. ...
4
votes
2answers
255 views

Sampling a 50 MHz Max Frequency 50 MHz BW Signal with a 50 MSps ADC

I paste below a superhetorodyne based Software Defined Radio Architecture for an Rx channel below. Suppose the IF signal has a max frequency of 50 MHz and 50 MHz IF BW. In that case, is it possible ...
7
votes
2answers
681 views

IQ imbalance after quadrature mixing

What is IQ imbalance in the output of complex or quadrature downconverter/demodulator/mixer? What are the causes and effects of IQ imbalance? (A spike in the spectrum display of RF noise?) Are there ...
4
votes
2answers
158 views

SSB filtering in the frequency domain?

I'm not sure whether it's more appropriate to ask this question here, or in the dsp.stackexchange. But I'll try here first. There seems to be a lot of information available on the filtering and ...
5
votes
1answer
266 views

What is “Billion Code” for garage door openers from around 1996?

I've been trying to "hack" my garage door using an SDR (LimeSDR) for a high school physics project, and I have run into a snag. When I look at the signal and demodulate it using ASK in Ultimate Radio ...
5
votes
2answers
181 views

Doppler shift compensation without using predictive modelling

Doppler shift mitigation has been studied extensively in the literature. In my implementations of satellite receivers (using GNU Radio), I use predicted Doppler shift from a software (GPredict) to ...
1
vote
2answers
133 views

What wireless communication technologies can travel long distances with a high bandwidth?

I couldn’t find a better place to ask this question, so I have asked it here. I am looking to transmit and receive internet connectivity wirelessly over a distance of 6 miles (9.7 km) with a minimum ...
3
votes
1answer
281 views

What are the maximum possible speeds of download over Amateur Radio frequencies?

In this scenario, I would have a base station connected to a modem that essentially allows me to access the internet/local network via radio, irately I am not fully aware of what information I need to ...
2
votes
1answer
220 views

Is MFJ-1708SDR safe with RF switching

I just got an SDRPlay and an MFJ-1708SDR transmit switch. I use the the PTT on my Flex to key the amp, so I am wondering if the RF sense is fast enough to protect my SDR radio?
3
votes
3answers
310 views

Is there an FT8 or other weak-signal digital mode specification available?

Is there a complete and programming language independent specification available for the FT8 digital mode? Detailed enough to implement both transmit and receive SDR software from scratch in two ...
0
votes
1answer
125 views

Playback entire FM Band

Is SDR technology a way for me to listen to a large group of stations or even the entire FM band at once?
0
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2answers
49 views

SDR (RTL-SDR v3) USB audio much less than LSB

Why does USB have so much less audio output than LSB? I've checked all settings and they are correctly set or not used, like AGC etc. Using same band pass on both modes.
2
votes
2answers
92 views

FFT showing evenly spaced signals when tuned to ~56 MHz down to 25.680

I'm running GQRX on Mac OS X 10.11.6 hooked up to an RTL-SDR dongle. I noticed when I'm tuned anywhere between ~56 MHz on down to 25.680 MHz I see evenly spaced signals on the FFT. But when I tune ...
2
votes
2answers
120 views

Measuring dBs with software defined radio

If the "floor" of the graph in my SDR is at -110dB, and when I key up, it goes to -70dB, and the wattage is 5W....is there a direct correlation between dBs and wattage?
3
votes
2answers
394 views

Understanding WFM modulation

I am using "HDSDR" software to demodulate a WFM broadcast ("Classic FM" in the UK, on 100.1 MHz, 192 KHz bandwidth). I'm using an "SDRPlay RSP1" software defined radio and a cheap indoor discone ...
1
vote
1answer
423 views

SDR - discone antenna setup

Here's a picture of my SDR receiver setup... This entire setup lives indoors as I'm not able to put anything up on the roof right now. My understanding of a discone antenna is that the downward ...
0
votes
1answer
90 views

Tx-Rx synchronisation to frequency changes

So I am part of an SDR project using GNU Radio and USRPs, where we are trying to set up a link between USRPs. The ideal is similar to the DARPA spectrum challenge (https://...
4
votes
3answers
410 views

SDR set up that will TX & RX on CB, UHF and VHF

I would like to use SDR to receive and transmit on CB, UHF and VHF. Is this possible and if so what type of equipment will I need (antennae, dongle etc)? I currently have both UHF/VHF and CB but atm ...
2
votes
1answer
112 views

How to find transmitting (voice and CW) Amateur stations in UK?

Background info: I own an SDR (model "SDRPlay RSP1") and I have a fully working HDSDR software system installed on my PC. I can successfully use this to tune-in to my local airport's radio traffic ...
0
votes
1answer
54 views

Buffering Delay/ Jitter between voice calls

I have designed a TDMA protocol to reduce the voice spurts between voice calls in SDRs. The protocol runs in this manner: control cycles proceeded with data cycles and again control cycles. Control ...
3
votes
1answer
185 views

How can I determine if out of band interference is affecting my AIS reception?

AIS I am receiving ship AIS messages. These are low power, digital messages periodically sent on two marine channels close to 162mhz. This frequency is surrounded by FM broadcast, weather radio, and ...
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0answers
172 views

Is there any open-source solution to scanning / decoding GSM/UMTS traffic? [closed]

I want to build a passive (rx-only) scanner to listen to GSM and UMTS traffic. I am not interested in breaking encryption or anything like that - but more interested in collecting statistics and such. ...
9
votes
2answers
479 views

Multiple simultaneous tunings with SDR

I just found out about WebSDR, and I was wondering how is it possible that many listeners listen and tune to different stations simultaneously. Which components/technologies allow this, and how does ...
0
votes
2answers
358 views

Hopping from one frequency band to another in SDR (ex: USRP)

This question is not about Frequency Hopping Spread Spectrum! In SDRs, say USRP, if we are transmitting in a particular frequency band, can we dynamically hop from that band and transmit from ...
1
vote
3answers
256 views

Viewing the broadcast FM spectrum using a USRP N210

My issue is regards to viewing the FM spectrum using USRP N210 & GNU Radio. I did try to use several blocks of GNU Radio to view an FFT plot of the FM band using the USRP N210 device. My blocks ...