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21 Threads found on edaboard.com: Coherent Frequency
Which windowing function are you using? Also can you double check if your coherent sampling is correct.
1st of all, there would be no interference if the two transmitters are not coherent , having the same frequency, so even if spatially they are close to each other it doesn't matter what does matter is the operating frequency. Yes they would if you make a tdm plan that is no module can transmit while the other is, each transmitter have (...)
hi all, kindly, i make sar adc 8-bit and i wanna measure its dynamic performance to calculate ENOB , my max i/p frequency is 574K and fs=2Mhz i choose Nrecord=2048 and Nwindow=585 so fin=573.3K , is this true and what's exactly method to know i.p sinwave needed in fft? thx in advance
If the signals are on different frequencies then they will have a time varying phase relationship with on another, so making any phase adjustments will have no effect. As Darktrax said, phasing is important in a combiner if the signals being combined are coherent, such as the signals received in each element of a beam stearable antenna. Look up an
I do not see any purpose in using two signals at the same frequency. If they are coherent, they will add up to make one wave. What is what you want?
I'm trying to measure the SNDR of a SHA, but I'm having issues with my measurement setup. The sampling clock is 5MHz, and the input frequency is 2.0068359375 MHz, FFT length 1024 for coherent sampling (411 cycles). I am using output strobing to ensure there's no interpolation when the FFT samples. I'm trying to make sure my FFT's are correct, so I
Hello guys, I am designing a 6bit / 1.7Ghz Flash ADC. To get the SFDR / SNR ect, I use the spectrum function with rectangle window. I am using coherent sampling and I strobe the transient data at the clock frequency. I also run a DFT and crosschecked that the function works as it is supposed to. The problem is that I am getting over-optimi
Sorry, but I suggest you to look in some book about digital communications and see the chapter about FSK receivers. If you know the phase you need a coherent FSK receiver, otherwise it will be an incoherent one. Regards Z
Dear All, As I understand the minimum frequency spacing for coherent BFSK is 1/2T which results in minimum shift keying. The maximum bit rate is hence two times the frequency spacing. For non-coherent BFSK the minimum frequency separation is 1/T which limits the maximum data rate to equal the (...)
can any body tell me why coherent receivers are not used in frequency Hopping?
Unless you use an adequate windowing function for sampling then coherent sampling is needed to increase your FFT spectral resolution. Without windowing or coherent sampling you'll have waveform discontinuancies and see spectral leakage / artifacts in your FFT data i.e You see spreading of energy for one frequency across adjacent bins. (...)
Please share your views regarding the reasons why there appears frequency offset in coherent detection of Pilot Signals.
u have to include some information about channel,to can classify the fading like coherent BW and coherent time for channel
also pay attention if spreading spectrum technique is used which requires non-coherent sync
If I understand ur problem correctly .. U r trying to Acquire a PN code having some doppler (frequency offset) from base band. The best approach I can think is FFT acquisition technique if u r using DSP processor for acquisition . U take coherent data and then do non coherent integration for reducing noise, finally perform FFT on it and (...)
How the receiver locks first to the signal? does it do symbol timing lock first, then frequency lock then phase lock? SAy for GSM? How about WCDMA? How about FM? If the receiver can lock to the freq using AFC, so what is the point of TCXO? why not just use a crystal? Thanks in advance.
hello what is the difference between the coherent and non coherent detection of orthogonal FSK signals. i.e.: the minimum required frequency separation in coherent detection is 1/2T, where T is the symbol duration, to achieve the orthoganality. at the same time the minimum required separation in frequency (...)
Also coherent works a few dB better than noncoherent at low SNR while at high SNR they are the same because other impairments dominate the errors. Examples are nonlinear phase across the signal spectrum frequency range and amplitude nonliearities (IMD) between signal spectrum lines.
The reference noise is coherent so the noise voltage adds ie vn + vn = 2vn. ie 6dB noise increase for each doubling of frequency If the noise was not coherent it would add as square root of sum of squares ie sqrt(vn1^2 + vn2^2) for each doubling of frequency. Peter
How non-coherent detection of FSK works? Attached figure is the block diagram of non-coherent quadrature receiver of Binary-FSK. Basically, it will use a correlltor to find out the right frequency of input signal. My question is that how the system knows the right symbol position of do the T-based integration. If the integration is not (...)
You can use a Squaring loop or Costas loop (it is same actualy) to recover your carrier phase. The RF mixer does not have to be coherent. You can still do coherent dectection at IF using Squaring loop to generate coherent LO. BUt RF mixer LO frequency need to be very stable. Most of the system, only TCXO for referent (...)