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157 Threads found on Carrier Phase
Hi I am looking for IC or circuit which can generate a phase locked sin wave , in phase with the Analog PAL TV sub-carrier. Something like MC44144, and if it can generate in phase and quadrature phase it will be great. the purpose is adding color overlay on Analog TV Picture, using the composite (...)
I have always thought that optical sources had a very flat and high microwave AM or PM noise content. For instance, a DFB laser (locked to one frequency mode), if you looked at its phase noise say 50 to 200 GHz from the carrier, it would be relatively flat. yes/no? maybe you can set up some sort of homodyne receiver with a wideband photodetector
phase noise is usually characterized in the frequency domain. For an ideal oscillator operating at ωo, the spectrum assumes the shape of an impulse, whereas for an actual oscillator, the spectrum exhibits ?skirts? around the center or ?carrier? frequency (Fig). To quantify phase noise, we consider a unit bandwidth at an offset (...)
there are so many ways to calculate phase noise just by giving the waveform its difficult to tell, if you have power analysis it can be calculated by phase_Noise = 10*LOG (Pn / Ps) Pn = Noise Power in 1Hz Bandwidth at particular frequency offset (fn) in Watts Ps = carrier signal power in Watts or for SSB 108293
The transmitter must use a mixer that is switched digitally ( such as diode bridge is a diode XOR gate logic and also a mixer) The binary signal thus selects the normal or inverted carrier signal 0, or +180 deg for binary phase shift key (BPSK) the baseband signals are often duo binary or bipolar baseband voltages or +v, -v . the receiver may hav
If you wish to transmit baseband FM on carrier, it could be messy with image detection and baseband phase noise. I suggest you consider an FM sub-carrier such that deviation of subcarrier, is greater than audio bandwidth. Pre-emphasis is recommended. I assume you have the circuit to modulate the resonant frequency.
You need additionally the power of the carrier signal, and the frequency offset from this carrier, s. e.g. this Wiki explanation.
i am on a project to implement GMSK using Java. I seem to have a little challenge with the delay of the Q-phase input. Please does any one know what i am to do to realize that. What i have in mind is to simply multiply my Q-phase beatsream by a negative sine carrier. is this correct?
One reference says that: "we know that the CFO (carrier frequency offset) causes the phase distortion in the OFDM symbol which can be denoted as 2πβn/N where B describes the CFO effect.."" so, any one can explain how this phase distortion (2πβn/N) is obtained?? Plz explain...
From the posted plot you already have the phase Noise information. The plot shows the SSB phase Noise amplitude (in dBc/Hz) at frequency offset from the 1GHz carrier signal. -125.8dBc/Hz @ 1kHz offset -135.1dBc/Hz @ 10kHz offset -140dBc/Hz @ 100kHz offset -140.9dBc/Hz @ 1MHz offset
Is there a way to re-create the carrier when a SSB signal has the carrier completely suppressed? I'm interested in implementing a RZSSB (Real Zero Single Sideband) reception circuit using the zero crossings and taking advantage of the possibility of using a phase noise cancellation circuit. References:
Read some basics before asking, please. PLL systems are very important in generating accurate and stable frequency, also in synthesizers. A phase or frequency-modulated signal can be well demodulated by a PLL system which recovers a carrier. Locking characteristic is a very important feature in PLL system. A PLL oscillator locked to a reference ha
Syncronized zero span SA can be used to measure locking time any kind of PLL.External Sweep Triggering is coupled to Latch Enable signal-for instance- when sweep is triggered zero spanned ( Time Domain Mode) SA will show you ringing and locking time of the carrier.
No. an SSB modulator has a strong upconverted sideband portion, and very weak carrier leakage and week unwanted sideband output. A single mixer, no matter how many diodes it has, will output both the upper and lower sidebands, hence not "SSB" You need two mixers, some power splitters with specific phase shifts, to select either the upper or lowe
do you have carrier/baud lock? is the QPSK constellation correctly aligned at the receiver and not rotating. Likewise, is the system spectrally inverted? eg, are you swapping cos/sin, or multiplying by the wrong sign for cos/sin on one phase, or etc...
My thesis in year 1979 was a simple demodulator for Double Sideband Suppressed carrier (DSB-SC) signal. At that time, I did it for the IF AM frequency 455 KHz by using CD4046 (PLL IC) and LM339 (quad comparator IC) to recover the phase and frequency of the suppressed carrier. But after I built the project I didn?t find the time to submit (...)
The carrier frequency of the PWM in a class-D amplifier has only one frequency. PWM changes its duty-cycle not its frequency. Then the signal inversion can be done with a 180 degree phase shift which produces a delay.
Depends on how you generate the "pwm waveform". The phase shift applies to the modulating sine waveform, not the pwm carrier. Assumed you are generating the sine by a lookup table, the 120 and 240 degree phase shift isn't but an offset to the table index.
Hi Sherlock, The transmission of a bit "1" corresponds to a phase increase of pi/2 in the carrier between consecutive bit slices. The transmission of a bit "0" corresponds to a phase lag of pi/2. Look at the sequence of phases shown (alternatively) in figures (b) and (c). The sequence is: 0, π/2, π, (...)
hi, one of my friend is give me a idea that is it possible to use a buck-boost converter(micro-controller based)made a sine wave out put.the idea was for 5 ms we increase,after 5 ms we decrease amplitude & do the same thing at reverse phase.for final output we use a high pass filter to remove the carrier.if it is possible then form only boost par
Chirp function is x(t) = sin set you time vector (eg. t = 0:ts:1) k is the chirp rate, f the carrier frequency and phi the initial phase (can set to 0). in MATLAB should look something like this: x = sin(2*pi(f*t*+k/2*t+phi))
Not really, because of the inductive nature of the motor, most of the high frequency voltages result in none or at least little current flowing at these high frequencies. Most VFDs put a PWM pulse wave form across the motor with a carrier frequency of > 5 KHZ. Frank
In a phase-modulation scheme,rms phase error is very critical,it should be less than 2deg in most cases. This rms phase error directly relates to in-loop phase noise of pll output. while working with PLL frequency synthesizer, we come across two formulae to calculate phase noise: 1) in-loop (...)
Yes, in theory the spectrum can be calculated from the waveform. However, phase noise very close to the carrier requires a waveform for FFT over an extremely long period of time. com discrete carriers(present in ifft) modulate input sequence? Whay call the carriers "discrete". each of them is a continuous signal, they are at discrete frequencies, if you want. Each individual carrier is modulated (eg QPSK) by the input data sequence. 2.which parameter of carrier is changing?(after modlation) (...)
guys I built a stand-alone colpitts oscillator to generate carrier wave Now i want to make a frequency modulator circuit with the help of transistor but no idea to modulate the signal with carrier plz give me circuit diagram to modulate carrier with audio signal using transistor
phase resolution isn't directly related to sampling rate. In a band limited channel, amplitude resolution is converted into phase resolution. In addition, most digital communication channels are bandpass modulators/demodulators. In this case, the sampling frequency determines the bandwidth, not the carrier frequency.
Hellow Guys. Could anyone tell me what is a locked unmodulated carrier signal. What do the word "locked" here mean? THX
Hello, search for quadrature modulator. Such a modulator uses two mixers that have two base band signal (I and Q) as input. The mixers are fed by a cosine and -sine carrier (derived from one oscillator).
I don't know exactly what you mean, but as long as the local oscillator (beat frequency oscillator) has the correct frequency for good demodulation, the phase of the (suppressed) carrier with respect to the beat frequency oscillator doesn't matter. So very slowly changing phase between the original SSB carrier and your (...)
To recover the carrier from a quadrature modulated signal, you need to know the modulation scheme and an unique property that allows to decide about the carrier phase. The effort depends. I don't expect that a comparator serves the purpose in most cases. If it does, the achievable SNR will be considerably worse than with a recovery (...)
How does the receiver distinguish two signals? It depends on the modulation scheme. Clearly, the receiver must be synchronized to the carrier. And there must be a feature that allows to distinguish between both carrier phases respectively extract a reference phase You have to refer to a particular modulation scheme to see (...)
I have worked in Telecomms for 40+ years and am struggling with the term "indirect". The problem with FM, is not the modulation but to keep the mean carrier frequency correct. The smart thing is to generate your FM at IF (~39 MHz), then to mix it up to the output frequency. This way you can supply a transmitter to a different output channel with
Hi everyone. I am trying to implement an Amplitude shift Keying ASK modulation and (synchronous)demodulation in Matlab,I have to use a PLL at the receiver end for demodulation.The task is to read a hexadecimal file (attached) and convert it to a binary stream. the binary stream is the modulated with a carrier frequency of 30,000 Hz. The channel
Hi, I don't think that the proposal of Biff44 works. The carrier as well as the sidebands of the signal in one linear polarization are at 90? out of phase (lead or lag) with respect to the components in the other orthogonal polarization. Them, the envelopes are the same (let's think in the phasors). As an alternative to the use of CP antennas
This is exactly the system that is used for the transmission of a PAL or NTSC colour sub-carrier for TV transmission. One important factor is that the receiver needs a phase reference signal to decode the QAM. In the TV system, during the period when the picture is inactive (line blanking) a reference colour burst is transmitted that phase (...)
To know the lower integration frequency, you would want to know something about the way the communications system works. Lets say it is a 64 QAM system that has a carrier tracking loop in the receiver. Such a system has a carrier tracking loop. Lets say you are sending 10 Mbps of data, and the carrier tracking control loop bandwidth was (...)
Hello everyone!!! I have a problem. I would like to perform phase demodulation using PLL. I have some matlab code that do that in the case of FM. Here is the code: %This m-file demonstrates a PLL which tracks and demodulates an FM carrier. clear all; close all; f=1000;%carrier frequency fs=100000;%Sample frequency N=5000;%Number of (...)
one of two ways. An IF frequency carrier is modulated (phase, Amplitude, or both) in some sort of I/Q modulator, and it is upconverted. The other way is that a single or dual DAC generates a modulated carrier, which is also upconverted.
phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal (the carrier wave). Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of (...)
I have recently created a FSK transceiver in hardware using a 555 timer circuit as the modulator and a XR2211 as the demodulator and I am now looking to implement the system using a dsPIC or similar low cost chip. I however do not have much DSP experience. My problem is that I am currently working with low frequency carriers(space - 140k, high
by seeing an impulse at frequency Fc in the frequency spectrum of DSB SC ,we can say that whether there is carrier or not but how can we recognize from the amplitude vs time graph in time domain that there is no carrier in DSB SC . with out using any equations just from plot how can we recognize it?
The description isn't clear, I think. Do you see the low frequency signal after demodulation? How about the 10 kHz modulated sensor signal? Any interferences visible here? If some what kind? In carrier magnitude or phase? 1 Hz base band?
Hi, I am working on a project with a PLL synthesizer for an FM receiver. There occurred following problem: For the receiver, the phase noise at a distance of 20 kHz to the carrier is the most important parameter to comply with certain guidelines. This area is dominated (with correct dimensions of the loop filter) only by the VCO (channel spac
Hello, I am designing a optical comb to be used in DWDM systems, can anyone please help me in giving some conceptual inputs regarding how the laser can be gain switched to achieve the comb. I have a code that solves the rate equations to give photon density, carrier density and phase of the light emmitted. So can you please throw some light on t
As you are suggesting (although not exactly stating, in my opinion) the basic problem of SSB or DSB demodulation is to recover the carrier (frequency and phase). Unfortunately, the analog modulated DSB signal doesn't contains an unequivocal carrier phase information. Without additional means, e.g. a pilot tone, there's no (...)
Your question does not make too much sense. If you have one ideal carrier, modulated by another ideal modulating tone, the phase NOISE is zero. There is no random noise on the signal. Try to imagine your modulated signal in the frequency domain. You are very much modulating the carrier with a large angle modulation. Your spectrum will (...)
If the problem is related to 13.56 MHz RFID, all processing (for receive and send) has to be done synchronous to the carrier frequency. So for 100% ASK (e.g. ISO 14443 type A), a PLL locking to the carrier would be a solution.
In a CW carrier, the time jitter is figured out by integrating the phase noise, thereby converting it to pk-pk or rms time jitter. If one is deliberately FM modulating a carrier, then that FM modulation will easily dominate over the phase noise effect. So all you have to do is analyze the fm modualtion and you will have (...)
how to design a digital loop filter to be used in a alldigital fm receiver or phase locked loop? spec: Here, the system clock frequency and the sampling frequency are 16MHz = 16,000,000Hz. FM modulation is +- 10KHz at center of 1MHz=1,000,000Hz. The modulation is just +-10% of the 1MHz carrier frequency.. could you please tell how to desig