Gsm Frequency Error
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kHz) measurement of the modulation quality and frequency accuracy of the mobile station's transmitter. The test set measures frequency error, rms phase error and
What Is Frequency Error
peak phase error over the useful part of the burst. The PFER what is phase error measurement demodulates the data and compares the measured wave form with the "ideal" waveform that was expected
Frequency Error Ppm
for the data received. The frequency error is the difference in frequency, after adjustment for the effect of the modulation and phase error, between the RF transmission from frequency error definition the mobile station and the test set. The phase error is the difference in phase, after adjustment for the effect of the frequency error, between the mobile station and the theoretical "ideal" transmission. This measurement conforms to ETSI GSM 05.05; and ETSI GSM 11.10, section 13.1. The PFER measurement demodulates the guard bits according to the Tail Bit phase error definition Demodulation parameter setting. This parameter determines how the PFER measurement performs demodulation on the guard bits, which in turn impacts the demodulation of the tail bits. For details on the settings available for this parameter, see SETup:PFERror:TBDemod . You can measure one of the six adjacent uplink bursts of the multislot configuration at any one time. You can specify the burst to measure using CALL:(PDTCH|PDTChannel):MSLot:MEASurement:BURSt . The relative power level is within 30dB according the data sheet. For GPRS mobiles, this measurement conforms to ETSI GSM 05.05 (Ver 8.2.0, 7.2.0, 6.6.0), section 4.6.1. It also conforms with 3GPP 51.010 (formerly ETSI GSM 11.10) if used as part of a type approval system. For EGPRS mobiles, the Phase and Frequency Error measurement conforms to 3GPP 51.010 (formerly ETSI GSM 11.10), section 13.16.1. You can control the modulation and coding scheme (either 8PSK or GMSK modulation) used by the data connection to be measured using CALL:(PDTCH|PDTChannel):MCSCheme . Additionally, you can manually control what modulation should be expected for individual bursts using CALL:MODulation[:FORM
GSM_FRQ performs the frequency error measurement described in [1, 2]. The frequency error measurement is used to verify
Frequency Of Error In Test
GMSK modulation accuracy. The GSM_PHS measurement can be used to how to calculate frequency error perform the phase error measurement that is also part of the GMSK modulation accuracy measurements. Parameters
Deped Frequency Of Error Form
Name Type Range Block Diagram System Diagram N/A GSM Vector Signal Analyzer GSM VSA Meter N/A X-Axis display List of options N/A Y-Axis display List of http://rfmw.em.keysight.com/rfcomms/refdocs/gsm/meas_pfer_desc.html options N/A Display overall maximum Check box N/A Display cumulative average Check box N/A Display reference limit Check box N/A Result This measurement returns real values. If more than one display option is checked, multiple traces are displayed, with the first trace corresponding to the top-most checked display option. The X-axis display parameter determines https://awrcorp.com/download/faq/english/docs/VSS_Measurements/gsm_frq.htm what is displayed for the x-axis. For the power options, the x-axis values are in the log power units (dBm or dB) specified in the project options. The Y-axis units are determined by the Y-Axis display parameter. If Y-Axis display is set to "ppm" and the measured signal has a carrier frequency of 0, the results are displayed in Hz. Graph Type This measurement can be displayed on a rectangular graph or tabular grid. Computational Details This measurement must be connected to a GSM_VSA meter. The measurement compares the measured signal to the generated test signal from the VSA meter in several steps: 1. The phase trajectory (phase versus time) over the useful part of each burst is calculated for both the reference and the measured signal. The useful part of the burst starts halfway through the first symbol and continues for 147 symbols. The phase trajectory is calculated using the following: φ[i] = φ[i-1]+Δθ[i]+adj[i] φ[0]=θ[0] Δθ[i]=θ[i]-θ[i-1] adj[i]=-2π if Δθ[i]>
ComparedOEMs traditionally used DSP-based hardware, plugged into a PC, for motion control. But new software-based solutions have challenged this approach, claiming equal or better performance at https://www.dsprelated.com/showthread/comp.dsp/32000-1.php lower cost.View Forums comp.dsp freq error estimation of GMSK (GSM) signals Started by Bhaskar Thiagarajan ●March 26, 2005 ChronologicalNewest First Hi all I'm looking at some code that is supposed to be estimating (coarsely) the frequency error of a GSM signal (that is basically a bursted GMSK modulated signal). The algorithm that I gleaned frequency error out of the code is as follows (in pseudo code with some matlab notations). input is baseband (I,Q) data. I_temp = I.^2 - Q.^2 Q_temp = I.*Q fft_out = fft(I_temp + j*Q_temp); CenterPoint = mod(floor(270833/2/fft_resolution), Nfft) %270833 is the GSM symbol rate Search for peak power +/- 1000 points around CenterPoint of fft_out and record PeakPowerPoint frequency of error CoarseFreqError = (PeakPowerPoint - CenterPoint)*fft_resolution/2; I'm hoping someone can shed some light on this algorithm and how and why it works. Here is my interpretation of it, The first step seems to be squaring of the complex baseband signal (I+jQ)^2 The constellation of a GMSK signal has 4 points with pi/4 offsets (well, a GSM signal ends up with more points on the constellation due to ISI I guess). By squaring the signal, the constellation folds into 2 points (on a line). Taking an FFT of this results in 2 peaks that correspond to the input signal frequency and since we know where an ideal signal would be located we can then get the delta_frequency from ideal?? I'm not sure I'm making much sense and I can't find any references that come close. BTW, you can consider me to be a beginner when it comes to digital (de)modulation and digital communications in general. I suspect this is a "Oh yeah - here is how it works..." kinda
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