Clock Synchronization Errors in Circuits: Models, Stability and Fault Detection

Typical radio frequency (RF) digital beamformers can be highly complex. In addition to a suitable antenna array, they require numerous receiver chains, demodulators, data converter arrays, and digital signal processors. To recover and reconstruct the received signal, synchronization is required since the analog-to-digital converters (ADCs), digital-to-analog converters (DACs), field programmable gate arrays (FPGAs), and local oscillators are all clocked at different frequencies. In this article, we present a clock synchronization topology for a multichannel on-site coding receiver (OSCR) using the FPGA as a master clock to drive all RF blocks. This approach reduces synchronization errors by a factor of 8, when compared to conventional digital beamformer.

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Influence of synchronization errors оn the noise immunity of coherent reception of M-PSK signals

Российский технологический журнал ◽

10.32362/2500-316x-2019-7-5-47-61 ◽

2019 ◽

Vol 7 (5) ◽

pp. 47-61 ◽

Cited By ~ 1

Author(s):

G. V. Kulikov ◽

Nguyen Van Dung

Keyword(s):

Information Transfer ◽

Noise Immunity ◽

Clock Synchronization ◽

Signal To Noise Ratio ◽

Dynamic Error ◽

Radio Waves ◽

Satellite Television ◽

Synchronization Errors ◽

Dynamic Errors ◽

Ieee 802.11 Wireless Networks

Signals with multiple phase-shift keying (M-PSK) have long been successfully used for highspeed information transfer in many applications – a number of adopted protocols of IEEE 802.11 wireless networks, digital satellite television DVB-S, DVB-S2/S2X systems, cellular networks CDMA and others. The most important characteristic of such systems is their noise immunity, which depends not only on the propagation conditions of radio waves in the communication channel, but also on the quality of operation of the component nodes of the information transmission systems themselves. The paper investigates the influence of the inaccuracy of estimating the frequency and phase of the carrier and the inaccuracy of the clock synchronization system on the noise immunity of coherent reception of M-PSK signals. Analytical expressions were obtained by statistical radio engineering methods. The expressions allow calculating the dependence of the probability of a bit error on the signal-to-noise ratio for various errors of the receiver auxiliary systems. In this case, the magnitudes of the errors were assumed to be either constant (static error) or dynamically changing (dynamic error). The dynamic errors were modeled using the Monte Carlo method, and the dynamic errors themselves were assumed to be Gaussian random variables. It is shown that the inaccuracy of estimating these parameters strongly influences the noise immunity of the coherent reception of the M-PSK signal, and this effect increases with increasing signal positionality. Estimates of the maximum permissible errors of the analyzed systems are given. When M-PSK signals are received, a tolerable value of the frequency of the reference oscillations can be considered as a ∆ωTs value of about 0.05. The allowable inaccuracy of the carrier phase estimation depends on the positioning of the signal and varies from π/36–π/72 for 2PSK to π/180 for 32PSK. The allowable time offset of the clock moments can be considered the value of 3–5% of the clock interval duration.

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Sensitivity of orthogonal frequency-division multiplexed systems to carrier and clock synchronization errors

Signal Processing ◽

10.1016/s0165-1684(00)00031-1 ◽

2000 ◽

Vol 80 (7) ◽

pp. 1217-1229 ◽

Cited By ~ 43

Author(s):

Heidi Steendam ◽

Marc Moeneclaey

Keyword(s):

Clock Synchronization ◽

Frequency Division ◽

Synchronization Errors

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Influence of phase and clock synchronization errors on the noise immunity of coherent reception of signals with quadrature amplitude modulation

Российский технологический журнал ◽

10.32362/2500-316x-2021-9-2-35-43 ◽

2021 ◽

Vol 9 (2) ◽

pp. 35-43

Author(s):

G. V. Kulikov ◽

A. A. Lelyukh ◽

E. V. Batalov

Keyword(s):

Amplitude Modulation ◽

High Speed ◽

Noise Immunity ◽

Clock Synchronization ◽

Signal To Noise Ratio ◽

Phase Error ◽

Relative Displacement ◽

Quadrature Amplitude Modulation ◽

Digital Television ◽

Synchronization Errors

Signals with quadrature amplitude modulation (QAM) is widely used for high-speed transmission of information in many radio systems and, in particular, in digital television systems. In the receiver, which is part of the transceiver equipment of such systems, there is a block for the formation of reference oscillations and a clock synchronization block. Due to hardware instabilities and propagation conditions, phase and clock errors may occur, which cause additional errors during demodulation of the received signal, and which can significantly impair the noise immunity of the reception. The paper investigates the effect of phase and clock synchronization errors on the noise immunity of coherent reception of QAM signals. Using the methods of statistical radio engineering, the parameters of the distributions of processes in the receiver are obtained and the probability of bit error is estimated. The dependences of the probability of bit error on the magnitude of the phase error in the formation of the reference oscillations and on the relative displacement of the clock moments, as well as on the signal-to-noise ratio, are obtained. It is shown that these errors can greatly reduce the noise immunity of the reception, and with an increase in the positioning of the signals, this effect increases. If we assume that the admissible reception energy loss is 0.5 dB due to each of these errors, then the allowable phase error is from ~3° at M = 4 to ~1° at M = 64, and the allowable clock synchronization error, respectively, is from ~5% at M = 4 to ~2% at M = 64. To provide more stringent requirements for the magnitude of losses, the requirements for the indicated errors increase significantly.

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