Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [radio]

67 questions
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3 answers

How a diode-detector affects to Frequency Response?

I have a question related to crystal radio. I can't understand how a crystal detector (diode) shifts the spectrum from the carrier frequency to zero. The antenna receives bunch of signals and the LC circuit passes the most of the frequencies to the…
John
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fmcw radar sampling requirements

I have been reading about "all-digital" or "software-defined radars". Lately, I was trying to simulate an FMCW short range radar in Matlab. One thing that struck me during the simulation is that to achieve a range resolution of around a 100 cm or…
user4673
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Time Alignment of 2 Sensors Sampling the Same Signal with Different Hardware Delays

I have two radios sampling simultaneously, and I am trying to time-align their two signals (they will always start sampling at slightly different times with random delays due to hardware differences). I have a circuit that automatically switches…
jstein123
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1 answer

How do I convert a real baseband signal to a complex baseband signal?

I have radio telescope observations that have resulted in two real-valued signals (corresponding to the right- and left-handed circular polarizations). The signals are sampled at rate $2B$, and provide a bandwidth of $B$. I wish to get the full…
XYZT
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Why is the carrier suppressed by AM-DSB-SC modulation?

Lets say I have a message that is a sine wave at 1KHz. As I understand it, I can perform amplitude modulation by multiplying this signal with a carrier, lets say 10KHz, and this process is essentially DSB-SC modulation. Looking at the resulting…
Chris_F
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Phase response of S11/S22 parameter for an RF attenuator?

I am new into the RF measurements. I was measuring the S11/S22 (reflection) parameters of an RF attenuator (with different attenuation levels, e.g., 10 dB) via a vector network analyzer from Rhode & Schwarz. I measured the magnitude of S11/S22 of…
learning
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How can the I and Q components of a quatrature signal be different from each other (apart from the 90º phase shift)

I've spent many hours reading and doing research about this. I don't attend any university classes or any type of classes that may approach such a topic. I am trying to learn this by my own without any help what so ever. So please understand if I…
FFY00
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Measuring signal phase difference between receivers

I am working on a project which aims to locate a transmitter. I consider doing this using several receivers and measuring the phase differnces between them. My problem is that arduino measures once every ca $dt=10^{-6}$ seconds, and therefore, to…
Elisha Modelevsky
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Real world application of signal sparsity?

There are theories based on signal sparsity in frequency domain like Compressive Sensing, Sparse FFT, etc. Throughout searching and studying papers I found out Cognitive Radio is a good example of application of Fourier sparse signals in real…
MimSaad
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2 answers

Quadrature modulation

I have a question: What is the difference between $ I \cos(t) - Q \sin(t) $ and $ I \cos(t) + Q \sin(t) $ except that they are phase shifted 90 degrees ? On the internet I can find both modulators with adding quadrature data and substracting…
Przemek Lewandowski
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The transmission distance of a signal

I am no professional in this area so please forgive me if this question is too immature. And thanks in advance for any help and information. I want to know how to calculate the transmission distance of a signal, say a radio wave or any type of…
user59458
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About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundamentals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time baseband model to the discrete time baseband model. An image of…
Coniferous
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What is the functional difference between DSB and 2SB mixers, and why exactly would 2SB be better for radio astronomy?

The Astronomy SE question 2SB mixer in radio astronomy? asked in 2014 in its entirety: In literature about the instrumentation of radio astronomy, I frequently come across a type of mixer described as "2SB". I'm familiar with single-sideband (SSB)…
uhoh
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Does Radio Communication Have to Account for the Doppler Effect?

I know that radio communications take place in specific frequency bands, and that the doppler effect can cause shifts in frequency when there is relative motion between the source and destination objects. Do moving objects such as planes and rockets…
Matthew Inbox
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SDR spectrum anomalies

Is it normal to see periodic peaks going from 48.75 - 90 MHz? Also i was checking on my SDR dongle once and the whole band was raised above background offset for like a whole 50 MHz bandwidth and then it dropped to background again? Does anybody…
ChemEng
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