# Tag Info

Accepted

### Why can so little digital information be stored on a cassette tape?

I had heard that tape is still the best medium for storing large amounts of data. well, "best" is always a reduction to a single set of optimization parameters (e.g. cost per bit, ...
Accepted

### FSK and IQ modulation

There are many ways of demodulating the FSK signal Indeed! What is the advantage of performing the FSK using IQ modulation? Depends. Generally, IQ is the only shape you have your signal in, so ...
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### How to convert sampled real audio signal to it's IQ components for IQ modulation?

I’ll answer the question I think you’re asking here: If you have a real valued signal that came right out of an A/D and you’d like to recover signal phase, you can use the Hilbert transform to ...
• 863
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### How to estimate the frequency characteristics of a nonlinear chirp?

How about just using $\dfrac{d\phi}{dt}$ to compute the instantaneous frequency? GNU Octave code (I just made up a sample rate of 2 Msps): ...
• 2,710
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### Positive slope of BER with a greater frequency deviation?

This could happen as discriminator gain is increased with a filter discriminator approach since in many of those approaches the gain would be maximum and linear for small signals only and then the ...
• 53.8k

### Why can so little digital information be stored on a cassette tape?

Typical cheap cassette tape recorders and players in the 1970's used audio circuitry that did not have a completely flat frequency response and added a lot of phase distortion (mostly inaudible to ...
• 35.6k
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### Frequency modulation of $m(t)$ in MATLAB

Integration was incorrect. I was integrating it with $dx= 1$. Doing m(j)*1/Fsoperation in the for loop, I have made $dx= 1/Fs$ now. As can be seen, frequency ...
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### How does the RaspberryPi radio hack convert digital GPIO signals to an FM signal?

I just skimmed https://github.com/SaucySoliton/PiFmRds/blob/master/src/pi_fm_rds.c#L454 and from what that code looks like, it initializes a clock generator to run at an adjustable clock. Then, it ...

### Impact of modulation index in FM

Assuming an FM modulation of a sine wave of frequency $f_m$. Theoretically, the modulated signal is an infinite sum of cosines at the frequencies $f_c + nf_m$ ($n\in \mathbb{Z}$) which the amplitudes ...
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### difference between GMSK (Gaussian Minimum shift keying) and GFSK (Gaussain frequency shift keying)

With GMSK, the frequency modulation index is 0.5. With GFSK, the frequency modulation index is larger than 0.5 (the signaling tones are farther apart). The receiving techniques used for GMSK as an FSK ...
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Taken from this excellent RDS tutorial, and original source: De-emphasis filter, $H(s) = \frac {1} {RC.s + 1}$, implemented as IIR filter via a bilinear transform: ...
• 473