Questions tagged [dsp]

Questions about digital signal processing, whether of RF, audio, or digital signals. For RF, consider [software-defined-radio].

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2answers
181 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 ...
6
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4answers
374 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): ...
1
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1answer
244 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 ...
2
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0answers
81 views

Which digital modes are formally specified sufficiently to be implemented?

Which currently popular digital/SDR modes do not require a pre-compiled library or pre-written source code? (e.g. has actually been used for QSOs as implemented from specification or sufficiently ...
6
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1answer
165 views

Calculating the signal-to-noise ratio for CW (Morse Code) signals?

How is the signal-to-noise ratio for received CW and QRSS CW (and/or other ultra narrow-band DSP digital modes) typically computed? e.g. What noise bandwidth should be used to measure the spectrum ...
0
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1answer
48 views

Shifting frequency outside of the band

In theory when i need to shift some frequency i just multiply that signal by some sin or cos wave with the right frequency and than apply LPF or HPF. But when there is a wideband complex signal with ...
3
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1answer
83 views

Turning raw APT data into an image

I apologize if this question is a little out of scope for the amateur radio stack exchange but I feel like it fit better here than over in any other forum. I have successfully parsed raw PCM data out ...
6
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2answers
74 views

Can an ultra-wideband system transfer data at high speed without precise clock synchronization?

Recently, ultra-wideband technology has been in the news again. From the Wikipedia article: UWB transmissions transmit information by generating radio energy at specific time intervals and ...
3
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1answer
439 views

What is Spectral Subtraction for noise reduction?

I previously asked a general question about noise reduction, but none of the answers mentioned this specific method or algorithm. (the noise reduction button on some radios and DSP software seems to ...
5
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1answer
83 views

What does a receiver's noise reduction function do?

Some receivers contain a noise reduction button or function. What does this noise reduction do? Is there more than one type of noise reduction? How does the circuit or software know what part of ...
4
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1answer
66 views

Relative computational requirement for various digital modes?

What might be the relative computational performance requirements for the various popular digital modes? (FT, JT, WS, PSK31, etc.) I seem to recall FSK modulation/demodulation being done with 1 or so ...
2
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1answer
93 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 ...
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2answers
161 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 ...
0
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2answers
67 views

Is the Nyquist rate independent of the power of the analog signal being digitized?

In analog-to-digital conversion, how independent is the Nyquist rate from the power of the signal?
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1answer
46 views

Will the quantization noise be increased if the step level is increased?

Will the quantization noise be increased if the step level is increased? I was wondering about the relationship between the step size of the quantizer and quantization noise,
1
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1answer
214 views

AX25 + Reed Solomon : Bit stuffing errors

I'm currently working with a satellite that has AX.25 + Reed Solomon code (truncated RS(255,223)) in GNU Radio. Since there is no frame synchronization pattern, the 0x7e flags are used for frame ...
5
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3answers
261 views

Detecting signals using statistics

I have sampled a section of spectrum every few Hz. I have mean, standard deviation, and range data for every frequency sampled (and I can gather more statistics if necessary). I've sampled for ...