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31 Threads found on Carrier Frequency Offset
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 (...)
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 (...)
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
please explian me synchronisation and frequency offset problem in OFDM
You need additionally the power of the carrier signal, and the frequency offset from this carrier, s. e.g. this Wiki explanation.
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 (...)
This picture is from book MIMO-OFDM Wireless Communications with Matlab by Cho Y.S. The MATLAB code is located in book directly below the figure. function y_CFO=add_CFO(y,CFO,Nfft) % add CFO (carrier frequency offset) % y : Received signal % CFO = IFO (integral CFO) + FFO (fractional CFO) % Nfft = FFT size nn=0:length(y)-1; y_CFO = (...)
Hello all, I've a GFSK modem. Packets begin with a preamble of alternating zeros and ones. The first stage is frequency offset estimation(FOE) that counts the no of zero crossings(ZC's) within a certain window (16 bits for example)then estimates the carrier freq offset. I've added a code, within the FOE algorithm, to (...)
The following code is used to estimate and correct the frequency offset errors for a single carrier system %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% freqoffset = 0; phaseoffset = 0; hPFO = comm.Phasefrequencyoffset('frequencyoffset', (...)
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 (...)
Hi all, I'm implementing STBC-MIMO and MIMO-OFDM system using SDRs. Before doing actual coding, I'm working on MATLAB simulation of CFO estimation and recovery and channel estimation. I'm reading some Dr. Giannakis' papers about joint CFO and channel estimation. Besides Dr. G, I know that many people have researched joint CFO and channel es
Send known data, find the amount of rotation, from this find the frequency offset. Then, for subsequent unknown data, multiply this frequency with the with incoming carrier and filter our unwanted frequency. Thus you rotate is back to correct value - b
Hi, I am trying an algorithm for CFO cancellation. I would like to know how well the algorithm performs with respect to the CFO required for commercial systems. Unfortunately, after googling a lot (web+scholar) I could not find any proper table/list/article that defines what is the allowed CFO in relevant applications. I believe there sho
Seems to me that the PLL loop is not locked. If locked you should see a pure sinewave carrier. For measuring phase noise: * Use the phase noise module if the spectrum analyzer has one * Use noise measurement at 10/100 kHz offset with the VCO locked
See figures 4-47 and 4-48 below from Ulrich Rohdes book "Digital PLL frequency Synthesizers, Theory and Design". He claims 168 dBc/Hz at "a few kHz" carrier offset of a 5 MHz crystal oscillator design.
In a comm system, CFO refers to the difference in carrier frequency at transmitter and reciever. The Tx would transmit at the nominal carrier frequency. At the Rx the unmodulated frequency is required for reception; and is usually generated in the Rx with crystals or so. However, it is not physical possible (...)
Did you mean where frequency offset is more than 1/2 of the carrier spacing in the preamble?
I can't understand your code, and maybe I am wrong but it is probably the code is completely wrong. At least there should be a modulation signal such as random bit sequence. And then the bit sequence is modulated with QPSK format on a carrier. Then the frequency offset should be added to the carrier. You can assume the (...)
The origin of the DC subcarrier exception is historical. The analog implementation of TX path in the OFDM had in the past no special methods to suppress the carrier leakage or back referred DC offsets. Together with the situation in the past that there was no baseband controlled frequency offset (...)
Phase noise is measured as dBc/Hz. dBc stands for dB per carrier i.e measured noise power with respect to the carrier power. Phase noise takes a skirt like shape with noise being higher closer to the carrier. The offset frequency is the difference in frequency between the (...)
LO output power, is usually is in the range -10dBm to +10dBm. If you referred to the phase noise power you have to specify the offset from the carrier where you are looking for this power.
In the base band you need to add a dc which will turnout as carrier leakage. Is this what you are looking for. Madhukar
Say there are spurs 1 MHz from the carrier, on either side, that are -30 dBc. Think of them as phase modulation sidebands, with a modulation frequency of 1 MHz. If you divide by 2 the carrier frequency halves, the modulation frequency of 1 MHz does not change, but the phase deviation does (gets smaller), (...)
In my mind Doppler frequency shift is in fact some thing like frequency spread, not just a SHIFT. Typically the doppler frequency spread is U-shape where the frequency at (fc+fd)(fc: carrier frequency, fd: doppler shift) dominates, therefore what AFC detect is not a pure (...)
sorry fot that is at 600kHz offset from the carrier
what is meant by the following terms : 1- channel eqaulization 2- carrier offset frequency thanks chanel equalization means compensating the system response with the intent to get a satisfatory response for interested bands, for example, get linear phase response for different frequency carrier (...)
I find that in some algorithm the received signal(atfer matched filter) is expressed as: r(t)=∑Sk*exp{j*(Δωt+Θ)}*g(t-kT-τ)+n(t) 2 questions: 1, why is Sk a complex array? If so, it will impact the angle of correlation of r(n)(sampled) and the final offset not only contain the carrier frequency (...)
Hi Professional, I remember that Phase noise which often refer to CW carrier for GSM TXVCO can be used to calculate GSM modulated power for certain offset to (desired channel) frequency. It means that if I want to get TXVCO PN requirement by the clue of modulation spectrum of GSM @ 400KHz offset, which is -60dBc, then, (...)
in OFDM sytems carrier frequency offset can occur due to doppler shift and local oscillator mismatch. you have understood the first part. When the baseband signal is converted to RF signal at the Tx, there will be a oscillator used to generate the RF carrier wave. Now, at the Rx end, there will be a similar oscillator (...)
it means that @10 KHz offset we measure the phase noise at carrier frequency plus (+) or minuse (-) 10khz? is it truse?