Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [software-defined-radio]

32 questions
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4 answers

Can somebody explain what IQ (quadrature) means in terms of SDR?

This is a bit of a basic question, but I am having trouble understanding why a signal needs to be broken up into I and Q components to be useful for software-defined radio (SDR). I understand that the I and Q components are the same signal, just 90…
Malvineous
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How does an AM radio filter out only the desired frequency?

I understand that electromagnetic waves in the air induce an alternating current in the antenna. I also understand how, once you filter the signal to obtain the desired frequency, you can get the envelope of the signal and drive a speaker. What I…
Rag
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Can I/Q signals from two perpendicular antennas be simplified to any less than 4 signals?

Say I have two magnetic loop antennas oriented perpendicularly, such that one antenna has a null facing east/west, while the other has the null facing north/south. Each of these antennas is connected to a receiver with an I/Q mixer, and then I feed…
Phil Frost
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Why no 24 Bit Software Defined Radios?

I have researched and I understand why there are no 32 bit Analog to Digital converters; it is because basically when you go beyond 24 bit, you begin to pick up on the noise generated from the vibrations of the atoms. With that in mind, I predict…
user3045
3
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1 answer

Implementation ideas for software defined radios

I find Software defined radios interesting, and was searching for ways to learn about it. One way is getting your feet wet with devices like USRP products. However, USRPs are rather expensive. What are alternatives/less expensive suggestions for…
vvavepacket
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Expected peak-to-peak output voltage of satellite LNB

Anyone know what the output voltage of a typical DirecTV LNB might be? I've converted an old dish to be a backyard radio telescope and I'm hoping to record output levels with a USB oscilloscope, as I find the results of using an SDR dongle to be…
SciStrike
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Can I amplify high frequency signal?

I have found this awesome Raspberry PI FM transmitter project. It uses RPi GPIO pin to simulate FM signal. After some filtering to smoothen it, this could act like a real transmitter. But at this moment, I've problems with signal quality. I'm in a…
Tomáš Zato
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Two signals alternately on the left and right of a frequency

I was listening to the WebSDR of Twente University, just outside the amateur band, and saw these signals. The x axis is frequency in kilohertz, the y axis is time, where the whole axis shown is about 15s. It occurred to me that the two signals are…
user17592
2
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1 answer

RF Harmonics and Spectrum Analysers

Please forgive the long question. I have split it into 2 parts. I am very confused about how harmonic suppression is measured in RF system (in my case, ham radios). I have picked up a couple of the Baofeng radios: The UV-5R+ and the GT-3, and I am…
Jonny
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Down-Conversion of RF signal

I have a basic question about down-conversion of RF-signals. The ideal scenario is described as follows. Given a RF-signal (coming from an antenna), i.e., a real-valued function x(t), and given a frequency f (say f=100Mhz), one wants to…
OldFella
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Listening to Atmospheric noise

I want to pick up atmospheric noise at 7 MHz and multiply that up to 400 some odd MHz. The reason to do this is I have a USB receiver for digital television that I would like to open in windows and grab some random numbers using the noise. What…
Brady
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How can I record RF?

For audio I can use just sound card, plus OS api to record any signal from 20 hz (below that's blocked via capacitor) to 96khz(that's half of max samplerate). But what if I just want to go higher? As high as it possible! How far could I go and what…
xakepp35
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Interpreting IQ Data (as hex) from an RTL-SDR/Hack-RF

I am wondering if someone can shed some light on how to meaningfully interpret I/Q data that is produced from an RTl-SDR dongle (RTL2832U) using the Osmocom RTL-SDR library. I have used I/Q data before to calculate power levels of signals, but after…
Mayo123
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Maintaining phase continuity of LO when switching from Tx to Rx mode

I am building a two-way communication setup based on software defined radios. Setup: The Tx needs to send a sinusoid to the Rx, and the Rx - after some processing - sends its own sinusoid in return. It is basically a ranging problem. Problem: What…
QMC
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Television Radio Module or Circuit

I want to listen TV channels without display (terrestrial) just like FM Radio channels. There are lots of FM receiver circuits on the web but I couldn't find for TV channels. Is such a thing possbile for beginners or it is just an advanved topic?
Ricardo Cristian Ramirez
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