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170 Threads found on edaboard.com: Carrier Phase
phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing (modulating) the phase of a reference signal (the carrier wave). The modulation is impressed by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication. Best Essay W
How to draw the Phasor diagrams of A.M and F.M. what are the reasons for the following two cases (1). In A.M the resultant of the two side band vectors is always in-phase with carrier component ,Why? (2). In F.M the resultant side band vector is always in phase-quadrature with carrier component,Why?
Hi Guys, I am facing an unusual problem while testing a analog phase modulated carrier generation system. The system has following PCBs: 1.TCXO PCB(reference source,20MHz) 2.PLL PCB(2GHz carrier generation,loop bandwidth 20KHz) 3.Buffer amplifier(to provide isolation between VCO o/p and diode phase modulator) (...)
@600kHz offset from the carrier frequency why interest only in offset of 600kHz? -100 dBc/Hz @500kHz versus -121 dBc/Hz @ 600kHz?
- Vapor phase should be obsolete with harmful gases to environment - MCPCB is an ideal carrier as heat mass is far greater than components so smooth substrate temperatures can be achieved. -but convection Reflow ovens using Quartz halogen heaters may cause black epoxy chips to over heat from higher absorption, thus if compromised
phase noise of the VCO almost ALWAYS gets better, within say +/- 50 KHz of the carrier, when you phase lock it. That is because the phase noise of the crystal oscillator clock, even when multiplied theoretically by 20 LOG N, is much better than the free running phase noise of the VCO. If you look at a (...)
you need to understand the units dbc/hz. DB means "decibels". C means "with respect to the carrier" there is also an important thing you left off, the "offset frequency" where that phase noise is measured at. For instance, you might say you have a signal, that is 0 dBm power, and has -80 dBc/hz phase noise at 10 KHz offset. If you (...)
I am working on phase codes (examples - Frank, P1, P2, Zadoff Chu) to generate minimum side-lobes on matched filtering. I considered a sinosoidal carrier wave at 45 mHz45 mHz, and phase modulated with 37 bit Chu code. The image shows the resultant wave 130943130943 I want to generate a similar s
I have been designing PLL circuits using VCOs to generate carrier frequencies close to 4GHz. The VCOs come with wide tuning range,but quite bad close-in phase noise. My application demands,best possible phase noise,atleast an improvement of 10 folds over VCO based PLL. I looked for options, and found that DRO based (...)
You have to add ~8bit on top of high frequency range to avoid phase jitter, which brings 24 bits you have calculated to 32 bits. Sounds like a misunderstanding of DDS principle. You can get pretty low jitter after the DDS output filter with a carrier fulfilling the Nyquist criterion, achieving low jitter is much more a problem of s
I want to change the frequency of the carrier by changing the phaseshift. To change the carrier frequency by 25Hz a. How often the phase shifter values to be changed ? b. What are the phase shifter values c. at what point of time the phase change of the carier will cause the (...)
Ring modulator :- You can use it to switch the carrier phase 180 degrees, not 90. If you had two and fed the carrier into the second in quadrature, if the two outputs were summed, you would have all 4 phases available. Frank
You can imagine a water sea that has a ideal sea level and this is constant (no perturbation) .When the rain starts,this level will not be constant any more and its sea level will show some small differences compare to before. phase Noise looks like that.Noise vector is added to the main vector ( carrier ) and it creates phase fluctuations and a
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
I was reading a paper abt baseband digital transmitter. It was put that the preamble is composed of BPSK symbols ie (1,-1). Suppose we give a digital input to a BPSK block, this binary data is multiplied with a sinusoidal carrier wave and phase is shifted. I get this part but wat will the BPSK output be... Because later the BPSK output wave is dif
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
This is just a thought - ignoring the technical issues. Listening to 'raw' SSB through an AM demodulator it is clear that there is a correlation between the original voice and the resulting RF output, even though it isn't intelligible. Tuning through an SSB signal changes the recovered amplitude as the IF filter bandwidth is imposed on the baseband
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 th
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
The PLL has a loop bandwidth. If you are inside of +/- the loop bandwidth from the VCO carrier, then the phase noise of the output is no better than 20 Log N + Reference phase noise. i.e. the reference phase noise as degraded by the PLL. If you are outside of the loop bandwidth, the phase noise can be (...)
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.
1.how 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 (...)
Usually, "indirect method" for generating FM refers to Armstrong method described by Chukey. The AM with no carrier or DSB-SC (double side-band with suppressed carrier) is generated with a balanced mixer. When the 90° carrier is added, we have a PM (phase modulation) signal with low phase deviation. If the (...)
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 (...)