Questions tagged [modes]

Questions related directly to the mode of communication (SSB, CW, digital, etc).

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176 views

What would be a good modulation scheme for communicating a single bit of information with no more than 4ms of latency?

This question has been suggested in the comments to a closed question a couple of days ago. I have nothing to do with the original question, but this aspect of the problem made me quite curious, so it ...
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2answers
242 views

(HF) How to maximize probability of successful transmit given constrained packet duration? [closed]

I need a HF link that will be (mostly hah) operational 24/365. Edit: at least at local daytime. The link is supposed to transmit a controlling signal (just one bit) in one direction for quite a ...
2
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1answer
88 views

Can I filter after modulation when using a square wave oscillator? [closed]

Most designs appear to filter most of the harmonics out of the oscillator before modulation, then apply additional filtering as needed for the specific modulation they are using after modulation. ...
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3answers
203 views

Which mode describes this modulation scheme

I have a modulation mode: (to be used for a satellite) (of a series of AX.25 frames) (in the 70 cm band) 9.6 kbps Ideally BPSK or QPSK modulation but could be plain FM Which I need to describe with ...
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1answer
93 views

overly large bandwith for a FSK signal?

I am trying to recover my 2FSK signal using an SDR. I have centered the SDR modem on the median frequency (the virtual carrier) and captured my signal via some 90 kHz bw modem. THis is the recording ...
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1answer
208 views

transmitted FSK, sniffed something PSK-looking

I am transmitting a FSK signal on 433,941 ± 32 kHz at 19200 baud rate. From what I read I should be able to recover my signal with a a modem centered on my carrier and having a bandwidth of 32 × 2 + ...
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2answers
91 views

different digital modulations interference. Does it happen?

Bottom line is I have got a very strange (but regular) reading on a < $1 type of ASK 433 MHz receiver. Have a look at it - those 3 spikes are sometimes caught by my receiver, don't know their ...
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1answer
346 views

Can HDSDR perform the work of Direwolf?

I have a setup in which Direwolf is used in conjunction with a Baofeng radio to basically send data (AFSK). My app connects to the TCP server provided by Direwolf, send him some data which then is ...
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2answers
414 views

BPSK raw data aquisition with HDSDR and FLDIGI

I was playing with HDSDR+ExtIO and Ettus USRP1 to track a BPSK signal. In the end I successfully heard the signal. But I would like to see the data, I mean the raw data (HEX values). For that I tried ...
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1answer
49 views

Determining modulation by spectrum

Is it feasible to determine what sort of modulation is used for a given signal by looking at the spectrum / FFT? Does software like this exist?
2
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1answer
187 views

What modes are used for transmitting motion pictures video?

SSTV permits transmission of single images, or if one desires image sequences at a very low framerate. Are there specific Amateur Modes that are meant for real time (motion pictures) video ...
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0answers
75 views

Is this signal BFSK or BPSK?

I'm trying to analyse a signal from a HVAC remote control (864 MHz) with my HackRF, but I'm facing an interrogation about the used modulation: Is it BFSK (frequency modulation) or BPSK (phase ...
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3answers
265 views

Why can I hear Morse when not in CW mode?

I don't "get" CW. I can't understand the chatter on an FM radio broadcast when my radio is set to AM. This makes sense, the signal is modulated using frequency modulation and I am trying to ...
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3answers
92 views

Why do PSK modes have “bandwidth”?

My understanding of a naive PSK scheme is that you have some frequency(s), f(n), at baseband, and you modulate information by shifting the phase (what "point in time") the signal is at. Isn'...
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2answers
1k views

How to identify type of modulation based on constellation diagram?

The constellation diagrams for a 4-ary modulation using PSK (qpsk),MSK ,QAM and OQPSK look alike. How to differentiate them? What is the modulation for the constellation diagram in the figure?
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1answer
502 views

How does a transceiver work?

I recently joined my university's Cube-Sat Program and was delegated the task of looking for software that modulates and demodulates signals (~437MHz, GMSK, AX.25). The problem now is that I don't ...
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3answers
570 views

Is it possible to have multiple people talking on the same radio channel at the same time?

I understand that my question is not desireable for ham radio communication at all, but bear with me. I want to use long range walkie talkies whose microphone is attached to an underground acoustic ...
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1answer
285 views

What are all the three letter codes for the different emission designators?

For example, A1A is "morse telegraphy by on-off keying". What are the others?
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1answer
1k views

What is the FM-N mode?

I'm reading the Icom IC-51E PLUS2 manual and it says it supports the following modes: AM FM FM-N DV What is FM-N? I'm new to amateur radio and never heard of it before. It's not listed on Wikipedia ...
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1answer
188 views

SSB Modulation and Differential Signaling

I'm trying to learn about how SSB modulation works. My current understanding from reading and looking at spectrum plots from SDR software is that the sound is modulated with the carrier, but only ...
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1answer
124 views

Parts for a 915 MHz low power transmitter

I'm interested in doing some experimentation with custom modulation in the 915 ISM band. Off-the-shelf radio modules use specific known modulations (FSK, QAM, etc.) so those won't work for my ...
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1answer
63 views

What determines the bandwidth of an FM signal?

With an FM signal, it takes up more room in the radio spectrum presumedly because the carrier frequency is changed. On average what's the width of the FM sidebands? Does the deviation from the center ...
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1answer
67 views

Why AM modulation side bands have higher frequencies than the carrier?

I cannot understand while the AM modulations have sidebands which are of a frequency higher than the carrier. If for example we are modulating a 4kHz signal to a carrier of 1MHz how we end up with a ...
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2answers
296 views

Software TNC's for Linux? (targeted to BPSK1200)

Are there any software TNC's (like SoundModem) for Linux? This is limited to the ones which deal with BPSK1200 (used by cubesat projects). For some cases Warbler will suffice.
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31 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 ...
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1answer
390 views

WFM SDR and Audio resolution

How does SDR resolution translate to audio resolution when using an FM demodulation algorithm? For example: using a 8-bit/2.048 Mhz IQ stream, what is the maximum audio sample rate and bit depth that ...
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2answers
202 views

Peak envelope power should be 2:1 or 4:1 on meter?

I've always been reading my AM modulated signal on a Bird wattmeter and trying to set the carrier to 1/4 of the peak envelope power (PEP). Recently, I was told by a CBer that you only can see it that ...
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2answers
87 views

How to decode a message with unknown bit rate in interstellar signal

I have a question about FSK modulation I'm going to frame in terms of a hypothetical: Imagine that you are transmitting a message to an ET in another solar system. The message is encoded in binary ...
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1answer
46 views

Both OOK and FSK used in the same transmission

My gas burning heating unit takes its temperature readings from a 433 MHz thermostat, which is emitting precisely the same data packets in a packet train at some ~100 ms interval like this: 2 x OOK ...
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960 views

What is Digital Mode on newer HF Transceivers

What does switching to digital mode on Yaesu Xcvr's (or any other HF radio) actually do? The documentation states that "specific digital mode selections, which include custom BFO offsets to optimize ...
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1answer
1k views

LoRa Radio RFM96/98 SX1276/8 configuration settings for Longest Range

I have a pair of HopeRF LoRa RFM98 Radio Modems(based on Semtech SX1278) and I want to configure them for the longest range possible, without taking care about any second factor like transmission time ...
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19 views

16-FSK recovering bits

I'm looking for help with one exercise. Firstly I was supposed to download modulated signal. (It's Olivia 16-FSK) [y,fs] = audioread('Olivia16-500.wav'); And then ...

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