Questions tagged [fsk]

Frequency Shift Keying - A digital transmission technique in which a "1" is represented by one frequency and a ")" by another. It is the digital equivalent of FM.

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2answers
12k views

What is 2-FSK modulation?

In the documentation for a radio chip, I keep seeing the term 2-FSK, which seems to be a modulation scheme. My understanding is that in FSK, data is encoded by emitting a carrier wave on a number of ...
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2answers
4k views

Best method for sending data over a mono audio channel

I'm looking for a way to send binary data over an audio channel on a video/audio transmitter. This will be an add-on feature to my product because it already has an audio interface. I'm hoping to be ...
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3answers
2k views

Software based Caller ID project- Problem with getting caller ID signal

Nowadays, I am trying to make a Caller ID project without using Caller ID ICs. Firstly, I have done a lot of research in Google to get information of phone lines and their electrical properties. I ...
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3answers
400 views

Why do we need orthogonality for FSK carriers?

I keep on coming across a requirement for FSK carrier separation, \$1/T\$ for non-coherent detection and \$1/2T\$ for coherent detection, where \$T\$ is bit period. I understand where this comes from ...
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6answers
1k views

Identifying 40Hz frequency shift

I have a signal that is at 4 kHz. This signal shifts by 40 Hz depending on some user input. I like to detect this change in software as fast as I can. What should be the ADC frequency I should use? ...
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3answers
2k views

FSK demodulation using DSP

Especifically talking, I need to demodulate a low frequency FSK signal( betwen 120 and 140 kHz ). I already have a circuit of antenna that receive the signal and I already can sample it, but I still ...
2
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1answer
370 views

Receiver understanding FSK bandwidth

I have a small doubt in a one way wireless communication. If I am using a receiver chip to demodulate an FSK signal. How does the receiver understands, which frequency to listen to? For example, I ...
2
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1answer
375 views

Problem in FSK demodulation

I have a FSK modulated signal of binary data. This I am trying to recover using PLL. The mark and space frequencies are in the range of 1.5MHz to 7MHz. I am struggling because, the PLL output is not ...
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2answers
830 views

Simple way to decoding FSK

I'm trying to build simple fsk transmitter and receiver, the transmitter is just an FPGA with a wire, the logic is quite simple, I mix (with a XOR) the transmission ...
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2answers
11k views

Constellation diagram of FSK

I am learning digital modulation basics and I have question about frequency shift keying — how the constellation diagram of M-ary FSK looks like? I can somehow figure how binary FSK diagram looks (it ...
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2answers
558 views

Understanding this circuit for getting sensor data from an arduino to a phone via the headphone jack

I am trying to understand the circuit below which relates to getting sensor data from an arduino to a phone via the headphone jack. The instructions on this page aren't clear on what the function of ...
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4answers
520 views

Has fsk over wired communication channels ever been done?

I have done multiple searches to figure out if fsk encoding of binary data has ever been used in a "wired" communication scheme but have come up with very little. It seems, at least to me, that ...
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1answer
60 views

understanding AFSK and FSK

I’d like to understand 1200Hz/2200Hz AFSK in commonly used APRS/Packet/AX.25 applications. When I look at the datasheets for some of the chips existing projects use (e.g the Si446x transceiver-on-a-...
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1answer
61 views

Why radio exhibits better sensitivity with a wider deviation when Rx bandwidth remains constant

I used an RF generator transmitting FSK packets with a datarate of 50 kbps. The deviation was 12.5 kHz. With this combination of datarate and deviation the modulation index is 0.5. I found that my ...
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1answer
163 views

Stability of crystal and crystal-less oscillator transmitters

I have stumbled upon this very cheap so called "crystal-less" RF transmitter: http://www.mouser.com/ds/2/368/Si4012-35123.pdf It says there on page 5 the Carrier Frequency Accuracy is 250 ppm while ...
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2answers
1k views

FSK constellation and eye diagrams [closed]

why do constellation diagram and eye diagram not show any useful output for FSK? I have tried to find that on Simulink Mathwork, but the progress was negetive.
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0answers
110 views

Help decoding line code

I have collected a burst signal from a radio device using an RTL-SDR and gnuradio and demodulated the FSK, but am having trouble deciphering what the line code is. Signal is at 151.3MHz Here is the ...
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0answers
182 views

How to determine a Signal Generator's Marker (Event) output delay?

I am using an Agilent N5182B Signal Generator for modulating a 2-FSK waveform on a 160MHz RF carrier. For that, I am using a baseband waveform (I/Q mode), generated by a Matlab FSK modulator script. ...
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1answer
99 views

Generating two signals with small difference in frequency using one oscillator

I am building a data transmitter for which I chose FSK modulation. The frequencies should be around 27 MHz. I have single crystal with 27 MHz frequency and I need to get two separate frequencies that ...
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2answers
56 views

In CPFSK, suppose we transmit a continuous bit stream of 1, then for how long will the frequency go on increasing?

I read something about phase memory but didn't get proper information. My specific doubt is, let's say phase memory is L, then after L '1s', will we have a phase discontinuity and will the frequency ...
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1answer
488 views

How to build a FSK modulator and demodulator?

I want to build a FSK modulator and demodulator, the center frequency is 4.234MHz +-175kHz, FL is 3.951MHz, FH is 4.516MHz, mean data rate will be 564.48kbit/s. After searching the web, I found that ...
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2answers
1k views

How to generate 2-FSK signal from the bit stream(symbols)?

I’m trying to generate a 2-FSK Signal, Let’s just consider the following, Symbol Rate : 1 MS/s Sample Rate : 10 MHz, Frequency Deviation: 150 KHz & -150 KHz And assume I’ve 100 symbols : {1,0,0,...
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1answer
56 views

Distinguishing simple FSK and Manchester coding?

I'm examining the signal sent by my car's fob. Using an RTL-STR and GNU Radio Companion, I've been able to capture and demodulate the signal. Now I'm working on decoding the signal. What I'm not ...
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1answer
70 views

Multi-fixed-station AM receiver

I'm in the pencil-and-paper stage of building a radio receiver that has the following characteristics: AM shortwave/HF three fixed frequencies - 3.33, 7.85 and 14.67 MHz single upper sideband with ...
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1answer
604 views

How to perform FSK modulation in VHDL

FSK Modulation in VHDL Hello, I have a VHDL block that performs FSK modulation. It looks like this The operation of the VHDL block goes like this. Fsk_data selects ...
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1answer
657 views

Transmitting data over inductive charging coils (or boosting RFID/NFC power supply)

I know that data can be sent over power lines through various different types of modulation - that is as far as my knowledge ends. I have a small D.I.Y. project (a board game) that requires some form ...
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2answers
78 views

Protocol design in a steel conductor

I was wondering what energy efficient protocol should I use for a FSK modulation in a steel conductor. My limitation is on the number of continuous bits I can transmit due to the charging and ...
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1answer
260 views

BFSK Modulation Output

I'm having trouble understanding outputs of a BFSK modulator. $$S_1(t) = cos(πt/T)$$ $$S_2(t) = cos(2πt/T)$$ If the input 0 or 1, how can I calculate the output? Edit: There is a formula to ...
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1answer
175 views

Build an FSK modulator using the HB100's transmitting signal

I want to use the HB100 to make an FSK modulation on a microwave signal. The reason why I use HB100 is that in this way the RF circuit is ready. I thought about doing an FSK modulator like the scheme ...
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0answers
148 views

Coherent FSK Modulation correlation coefficient derivation

FSK has a large bandwidth requirement and its minimum bandwidth is around \$4 B_T\$, where \$ B_T \$ is the bit rate. In a coherent FSK system the signals \$s_1(t)\$ and \$s_2(t)\$ representing bit ...
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0answers
225 views

FSK Bandpass Filters for 900 MHz

I'm attempting to design a basic FSK transceiver (architecture shown below) using only discrete components (transistors, diodes, resistors, etc). My idea was to separate the two binary frequency ...
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0answers
427 views

Filtering and Delay Compensation in Matlab and Simulink

I have built a FSK modulator and demodulator in Simulink. Everything is working fine except the received signal after the channel has short spikes, which are introducing a short pulses in the ...