Questions tagged [software-defined-radio]
Radio devices that use digital signal processing in place of analog electronic components to manipulate RF signals.
249
questions
9
votes
5answers
752 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 ...
0
votes
1answer
89 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 ...
0
votes
1answer
34 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 ...
5
votes
1answer
215 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 ...
0
votes
2answers
45 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)
...
2
votes
1answer
63 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. ...
0
votes
0answers
52 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. ...
1
vote
1answer
78 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 ...
5
votes
7answers
346 views
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,...
2
votes
3answers
105 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 ...
2
votes
3answers
93 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 ...
5
votes
3answers
630 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 ...
0
votes
0answers
37 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 ...
2
votes
2answers
113 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 ...
1
vote
1answer
72 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
1answer
59 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 ...
1
vote
2answers
179 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 ...
4
votes
3answers
333 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 ...
1
vote
0answers
30 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 ...
4
votes
4answers
114 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 ...
0
votes
0answers
35 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 ...
2
votes
1answer
192 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 ...
1
vote
0answers
81 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 ...
1
vote
2answers
101 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 ...
0
votes
1answer
59 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 ...
1
vote
2answers
102 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 ...
2
votes
1answer
81 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 ...
2
votes
1answer
118 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,...
1
vote
3answers
107 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 ...
0
votes
1answer
269 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 ...
1
vote
0answers
35 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 ...
1
vote
1answer
426 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 &...
1
vote
3answers
302 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 ...
2
votes
2answers
381 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 ...
2
votes
1answer
106 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 (...
6
votes
4answers
434 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):
...
2
votes
0answers
234 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 ...
0
votes
1answer
39 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 ...
4
votes
5answers
194 views
0
votes
1answer
168 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 ...
2
votes
2answers
112 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 ...
0
votes
2answers
110 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 ...
-3
votes
1answer
49 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?
1
vote
3answers
218 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 ...
1
vote
1answer
145 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 ...
1
vote
1answer
105 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 ...
3
votes
2answers
234 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 ...
1
vote
1answer
154 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?
1
vote
1answer
698 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
1answer
104 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 ...
