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# Carrier Frequency Offset

76 Threads found on edaboard.com: Carrier Frequency Offset

## what's CFO(carrier frequency offset)

What's CFO(carrier frequency offset)? What mean? Why use it?

## OFDM - Carrier Freq. offset

Hello I am new to this forum and new to OFDM Can some body explain the mechansims that cause carrier Freq. offset... i keep reading unmatched local osc. at TX and RX. but what OSC? the carriers are generated by IFFT/FFT there is no physical OSC. THere are RF and IF osc. which also can cause but not the main concern... Doppler can (...)

## a question about frequency offset estimation!

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 (...)

## A paper about coarse frequency offset in ofdm

Did you mean where frequency offset is more than 1/2 of the carrier spacing in the preamble?

## What is the frequency offset in phase noise ?

it means that @10 KHz offset we measure the phase noise at carrier frequency plus (+) or minuse (-) 10khz? is it truse?

## How to simulate frequency offset in Matlab between transmitter and receiver?

ok fine but what about carrier recovery?

## Matlab code for Baseband frequency offset and correction

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 (...)

## Carrier frequency offset (CFO) spec.

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

## Practical meaning of 'Joint Carrier Frequency Offset and Channel Estimation'

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

## Frequency offset and rotating constellation plot

Hi greeting.. At digital receiver, carrier frequency offsets cause rotating constellation plot. Can someone explain me how this is visualized in mathematical equation. :) PN

## OFDM Carrier Frequency Recovery

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', (...)

## GSM frequency offset tracking

Hi Esourour! FCCH appears only once in a while - GSM specs will tell you how often. Please, consider if that is often enough to do estimation. If FCCH occurs not often enough then you should do what your collegue offered - go for midamble in every burst. While FCCH is purely sinusoidal, midambles are not due to GMSK modulation. Midambles a

## Doppler frequency shift and frequency offset ?

analog AFC circuits are designed for a single carrier modulation. It changes the tuning of the receiver so that the mean/median peak of the power spectrum is in the center of the IF stages. There may be more sophisticated DSP methods of doing this.

## mixer output DC offset

if the upconversion mixer have a feed through then the output of the mixer will have the carrier frequency un modulated , then in reciver this component will appear as DC offset but this may not ahppen coz the TX freq is different fromRX and that's why there is duplexer at the anteena khouly

## Why the spurs of a signal after a divider have the same offset as before the divider?

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), (...)

## How to do carrier recovery ?

Hi, Are you able to acquire the signal with the modulation? What is happening to the carrier during acquisition. BR M

## PLL and offset frequecy

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 (...)

## need master thesis very important and ureget

I need this thesis very very urgent I search alot to find link for downloading I coldn't find but,I have all it's detail name: carrier frequency offset ESTIMATION IN MIMO OFDM SYSTEMS A DISSERTATION Submitted in partial fulfillment of the requirements for the award of the degree of MASTER OF TECHNOLOGY in ELECTRONICS AND (...)

## Effect of sampling frequency change in OFDM

Hi guys, I have this question, I know in OFDM system, when you upconvert the signal with certain carrier frequency with certain sampling frequency and when you downconvert it, if the carrier frequency is same, but the sampling is not, then you will have a sampling frequency (...)

In Zero-IF receivers after mixing the LO with the incoming signal the carrier would appear as a DC offset. If the LOs are slightly offset, due to crystal tolerances, there appears to be a large signal near zero, at a couple of kHz. Is this signal just filtered out with a high-pass filter? Is this phenomena still considered to be a DC (...)

## Why phase noise is generally seen at 100 Hz offset in RADAR applications ?

I need to know why the phase noise of oscillators are generally seen at 100 Hz offset from the carrier ? is there any reason for the measurement at this frequency offset in RADAR application?:?:

## FOE with and witout carrier detection

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 (...)

## question about ifft size in ofdm!!!!

I am not sure about the practical chips of FFT/IFFT, but as far as the MATLAB is concerned you can use FFT/IFFT of any size, but it is most efficient in terms of computation when the number of subcarriers is in the form of 2^x. If you have an FFT/IFFT of size 128 and you only need to transmit 72 subcarriers, then you will need to nul

## What is SSB meaning in phase of SSB phase noise?

to point to the drip rf is a circle like a plop but ssb is a plop plipp { the plipp being the next circle out like mushrooms grow but at the frq in circles at your antenna {dipole} radiation pattern is ssb the plipp of the plop without the plop{the plop is filtered out s

## Algorithm for Residual frequency removal?

Paper with some algorithms carrier synchronization of offset QPSK, J. B. Berner,; P. W. Kinman, 2002 IEEE Aerospace Conference , March 9, 2002 :)

## How to select a transistor for S-band local oscillator ?

Hi,Willem How is your vco's phase noise perfomances at the offset frequency of 100kHz and 1MHz from the carrier frequency? thanks.

## How to create an ASK source in hspice?

Amplitude Modulation Source Function The general syntax for including a single-frequency, frequency-modulated source in an independent voltage or current source is: Syntax Vxxx n+ n- AM < (> sa oc fm fc <)> or Ixxx n+ n- AM < (> sa oc fm fc <)> The arguments are: Vxxx, Ixxx Independent voltage source, which exhibits the amplitudem

## Zero if need two ADC ??

Hi If you use low IF, you will need only one ADC. If you use zero IF, and your modulation scheme is like an FSK which signal spectrum is not symmetric around carrier, you should use two ADCs and I/Q downconversion. Regards

## Does the VCO noise is reduced due to dividing ?

Hi all, Is it correct to say that by divided the VCO frequency by a N divider, the VCO phase noise a frequency offset N*f from the carrier will become the Phase noise of the signal after division at a frequency offset f (N*f/N) from the carrier? Thanks for your explanations.

## what is meant by the following terms

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 (...)

## What does rad?/Hz unit for VCO phase noise mean?

For a VCO I measured in lab -30dBrad?/Hz of phase noise. Most of the examples I've seen express the phase noise in units of dBc/Hz, which I understand is the ratio of noise with respect of the carrier at a frequency offset. What does rad?/Hz mean ?? regards !

## how to simulate DC offset of the ZIF receiver?

In the base band you need to add a dc which will turnout as carrier leakage. Is this what you are looking for. Madhukar

## DC subcarrier doubt in WiMax??

Hello Frnds!!! i have a deep doubt related to DC subcarrier. i.e. As per Wimax802.16d PDF: "DC subcarrier is the subcarrier whose frequency is equal to the RF centre frequency of the transmitting station." what is the significance of "RF centre frequency of the transmitting station." (...)

## (Discussion)The position of the matched filter.

The carrier recovery is achieved together with timing recovery in DSSS. The reason is the SNR in DSSS is quite low, which makes the carrier recovery loop difficult to get a correct results

## measuring phase noise of my vco

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

## How does spur change after frequency divider?

Well, imagine a carrier with some sort of small frequency modulation going on. If there is a single tone at frequency Fm modulating the carrier, the spectrum can be approximated by: sideband power in dbc = 20 Log (Δf/(2* Fm)) where Δf is the frequency deviation, and Fm is the modulating (...)

## Any body know about Low Phase Noise Amplifier???

When you design an amplifier for low noise figure, you are designing it so that the TOTAL added noise power of the amplfier is low. You integrate over a wide frequency range, say 1 Hz to 20 MHz offset from the carrier, and the total integrated noise power yields your amplifier noise figure. When you design a low phase noise amplifier, (...)

## Help me with constellation diagram plotting of received signal

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

## a question about phase noise calculation

Hello, Phase noise is often expressed as the noise density, PSD , referenced to the carrier power at a certain frequency offset from the carrier. Phase noise, Side band noise = (PSD (at offset) ) / (carrier power) When you convert this to decibels, you get dBc/Hz. The "c" (...)

## Early Late Gate Clock synchronization

Hi KericWard I had the 2nd edition in mind. I just checked the 2nd and 3rd edition and they are quite different in several aspects. Gardner says in the preface of 3rd ed.: Several parts of the second edition have been omitted: the chapters on optimization and synchronization, and the mathematical appendix. ... Synchronization (recovery of carr

## a quastion about CDMA and doppler shift

hi, i'm doing a comprfassion between ofdm and cdma. doppler spread destroy the orthogonality between the sub carriers in OFDM and cause ICI. but i cant figure if and how doppler spread effects CDMA (not MC CDMA but DS CDMA) i mean, every user spread its information with PN code on all the BW can somone explein how and why is it effects\dosen

## How to decide offset frequency in phase noise

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 (...)

## Why do we usually use IF(Intermediate frequency) ?

DCRs use a method of phase locking the local oscillator to the received carrier in order to properly process AM and FM. It is necessary to eliminate frequency drift. The output of the mixer is then the demodulated signal. It might need a lot of audio amplification if the signal level is low (due to lack of AGC and the need to tolerate strong signal

## 4046 FSK demodulation / loop filter design

Hi I would really appreciate it if someone could help me. (Sort out some confusion :-)) I am intending to use the 74hc4046 to demodulate a FSK signal. The carrier centre frequency is around 165Khz and the deviation is around +/-2.5%. So I am using a frequency offset. (I am not using any frequency (...)

## Low phase noise oscillator & narrow band passive BPF

I guess Fant has probably presentetd the best way of acheiving lowest phase noise! You said that you had HP10811 on hand and this is a sc-cut ovencontrolled oscillator which used to be THE standard which everyone else did compare to. I am not sure what the phase noise is at 10 Hz offset but I would guess -130 to -135 dBc/Hz. Ulrich Rohde shows

In general you are using a double side band modulator to get your low frequency (or DC) input signal higher in frequency so it can be amplified as an AC signal. This way you are out of the 1/f noise region of the amplifier and the DC offset and drift of the amplifier does not come into play. At the output of the amplifier you synchronously (...)

## testing phase noise of VCO

If your VCO is frequency modulated, how you will be able to measure PN ?? It's impossible !! PN is essentially frequency/phase modulation with noise and how you will extract this deviation from main modulation?? I mean, when you make a frequency/phase modulation, how will you define this noise modulated signal?? The way of measurement of (...)

## FM are the same PM at certain conditions?

This is my intuitive approach: An instantaneous change in Phase produces a change in frequency and viceversa. If the modulating signal is varying the PM or FM signals are the same. The only diferences are probably with DC or DC level. In FM a DC level will shift the carrier to another frequency. In PM a DC level will not change the freq. (...)

## Power conversion from CW to GSM, GPS modulated ??

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, (...)