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93 views

### what is this type pulses called?

I was wondering what is this type of pulses is call. Is it a sin wave? I know its the result of sinusoidal pulse modulation. is it considerd a quasi-sin wave? I would like to know the name to ...
25 views

### Foster - Seeley FM Demodulator Explanation

Consider this Foster Seeley Demodulator If I have correctly understood, its basic working principle is the fact that at the secondary coils (L2) of the Balun there will be two signals equal and ...
77 views

### Double Balanced Mixer

Consider this double balanced mixer: Its output contains only the frequencies generated by the product of those of LO and RF signals, where LO is supposed to be a large signal (which switches ON and ...
40 views

### Convering bandwidth (frequency) to bit rate without knowledge of the modulation?

How would i convert a bandwidth of say 30kHz to bps if I only know the number of bits per sample (4)? (and I was using a two chanel system). I am assuming it is simply 30KHz * 2 * 4 but this may be ...
60 views

### How phase modulation changes spectrum?

I'm studying amplitude,frequency and phase modulations for an exam. I just studied amplitude and frequency modulations, however i didn't succeed in understanding how the phase modulation changes the ...
335 views

### Why the OFDM symbol length is the total number of original modulated symbol, but not one symbol length?

Recently, I am learning the principle of OFDM, and the reference is http://defenseelectronicsmag.com/site-files/defenseelectronicsmag.com/files/archive/rfdesign.com/images/archive/0101Puegel30.pdf. ...
2k views

### What does “shift keying” mean in the context of digital modulation?

English is not my native language and I do not understand why the words "shift keying" were used to describe some types of digital modulation. What does "keying" mean in the context of signals and ...
1k views

### Why amplitude modulation is not used for sending digital data?

It seems to me that the most simple way of modulating a digital signal is using amplitude modulation. When the signal has the amplitude 0 the bit is 0 and when the signal has some amplitude then the ...
194 views

### What to use as an external 100 Hz modulation source for an RF Signal Generator?

I've got an old-school HP 8656B Signal Generator, for a 433MHz RF project. Typically, I've used the internal 400Hz or 1kHz modulation but for the receiver in question I need a signal source that is ...
244 views

### Delta modulation (DM) signals

Trying to understand this circuit. Will this produce a representation similar to example in second image (if U_inf is the sine wave "original") ? Assuming that, I expect U_DM to look like the "...
65 views

### PAM nonlinear amplitude compression in lower eyes

I needed some help to understand why at Rx, we observe different effective SNRs in individual eyes for higher level PAM signalling. If you need additional info, http://literature.cdn.keysight.com/...
2k views

### Does a carrier wave need to be sinusoidal?

I am trying to AM modulate a song and I have an idea of how I am going to do it, but I need a carrier wave to start with and I've been having trouble creating one with a ceramic resonator because I ...
842 views

### Carrier generation at receiver in DSB-SC modulation?

As shown in fig., In this scheme input signal is square and passed through a narrow(high Q) bandpass filter tuned to $w_c$.Finally the ouput comes to be a sinusoid of frequency $w_c$. But to ...
130 views

### Find Power Spectral Density of given signal

I am given a question with very brief notes to study from. The question is this: Now I was wondering, are the following part of the notes relevant at all: Is this the appropriate method to solve the ...
277 views

### How are the original signal and the AM signal related?

Use the TIMS “Variable DC” module to generate a 1V DC signal. Use the “Adder” module to add this DC signal to the message signal generated in task 1 (this will produce the ...
91 views

### About the combination of two signals with capacitors

Here is a link of an article I've been reading. http://www.analoguehaven.com/moog/thereminblack/hotrod.pdf In page 4 there is a circuit schematic. Notice there is a part called variable pitch ...
129 views

### FM signal example

Sorry if this question is too basic, but I'm a software engineer student who must study communication systems. I try to represent a FM signal in a graphing calculator, but I don't know why the result ...
1k views

### Maximum signal data rate

I have a frequency signal range from 25 Khz to 35 Khz. I know that the the minimum signal sampling to assure reconstruction of the signal from the samples is 70 Khz. Would it be correct to assume ...
141 views

### Which characteristics of a Radio signal are involved to be selected by radio receiver? [duplicate]

the radio antennas receives millions of signals. how our radio selects the appropriate signal as it's input? which characteristics of the signal are involved for this selection.
445 views

### Why it has used BPSK modulation after OFDM?

I am quite new to OFDM modulation. I am reading this from a tutorial. In one of its parts, for showing amplitude variation of the OFDM signals, there is a graph that has used 8 sub-carriers and BPSK ...
169 views

### Finding the Power developed by the Nominal Frequency in FM

Question The sinusoidal signal $f(t) = \cos(2 \pi f_m t)$ is applied to the input of an FM system. The corresponding modulation signal output for $f_m = 1kHz$, is Q(t)=100 \cos(2 \pi ...
2k views

### How to get BPSK data from I/Q signal

I am using AD8347(0.8 GHz to 2.7 GHz Direct Conversion Quadrature Demodulator) to demodulate a BPSK modulated carrier wave. There is no intermediate frequency used. By feeding the signal into this ...
156 views

527 views

### Signal encoding on Realtek TX2 IC

I 'm trying to figure out the way IC TX2 encodes different signals (RIGHT, LEFT, FORWARD, BACKWARD, TURBO). I can understand that presence of voltage means an appropriate signal to be transmitted. "...
147 views

### Confusion with modulation/demodulation

I am following a book: Data communication and networking (Behrouz-Foruzan). It says that modulation means building a bit stream from an analog signal. However as far as I understand it's the ...