Synchronous Acquisition System for Large Space Channels with High Time Accuracy

Abstract

The invention discloses a high-time-accuracy large-spatial-channel synchronous acquisition system. The high-time-accuracy large-spatial-channel synchronous acquisition system comprises a signal acquisition unit and a plurality of communication nodes, wherein the signal acquisition unit is respectively connected with the communication nodes; the signal acquisition unit comprises a first FPGA module, a signal acquisition module and a signal processing unit, and the first FPGA module is respectively connected with the signal acquisition module and the signal processing unit; the first FPGA module comprises a data packing unit and a clock receiving and processing unit; the communication node comprises a second FPGA module, the second FPGA module comprises a UTC restoring unit, a PPS restoring unit, a DDMTD reference signal restoring unit and a precise time delay adjusting unit; and the UTC restoring unit is connected with the data packing unit, and the PPS restoring unit, the DDMTD reference signal restoring unit and the precise time delay adjusting unit are connected with the clock receiving and processing unit. By adopting the high-time-accuracy large-spatial-channel synchronous acquisition system, the channel measurement accuracy can be improved, and the time synchronous accuracy of the channel measurement is increased from 100ns to a sub-ns scale.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to a time synchronization system, in particular to a high time precision large space channel synchronous acquisition system. Background technique [0002] In order to improve communication quality, technicians have never stopped studying the spatial transmission model of the channel. In research, space and time are two sensitive parameters. When researching a fixed site or a static or slow-moving target, the spatial information is definite, and the temporal information is insensitive. In this case, the time information usually depends on GPS timing, and the synchronous reference clock and trigger signal are transmitted through coaxial cable or optical fiber. [0003] However, for fast-moving transmitters, it is very important to resolve signals in time and space. Taking in-vehicle communication as an example, two vehicles traveling in opposite directions at a speed of 120Km / h...

AI Technical Summary

Problems solved by technology

[0004] The existing communication methods have the following disadvantages: (1) The time accuracy of test stations that rely on GPS and other satellite timing can reach 100ns level accuracy, and the codewords can already be distinguished for channels at the Mbps (megabit / second) level. However, for higher-speed communication protocols and faster-moving communication terminals, better resolution cannot be provided.

(2) The accuracy of the trigger signal between the slave stations depends on the length of the transmission medium. Whether it is a coaxial cable or an optical fiber device, it restricts field deployment and function expansion

The medium is easily affected by external conditions such as temperature, and cannot be adjusted and fed back. The results can only be compensated through the parameters calibrated in the previous stage, which affects the accuracy of the test system

However, the transmission in the form of coaxial cable is susceptible to external interference.

(4) There is a beat difference in the synchronization of the time stamp signal and data recording

[0006] (1) Satellite timing technology such as GPS solves the problem of large-scale timing, but the signal is easily affected by weather and tunnels and other sheltered environments

Under ideal working conditions, the timing accuracy is only on the order of hundreds of ns

[0007] (2) Limited by technological development, triggering in the prior art relies on the detection of signal rising or falling edges, which is heavily dependent on the length of the medium

Therefore, the deployment topology, temperature and other factors will damage the signal quality, and the transmission protocol is relatively simple, the anti-interference ability is not strong, and it is easy to be interfered by space noise

[0008] (3) The reference clock depends on the technology of optical fiber transmission, the transmission protocol is simple, and it is not convenient to realize adjustment and compensation

[0009] (4) The timing signal is often transmitted to the acquisition device through RS232, RS485, GPIB and other means, and the trigger and reference clock are input through the dedicated trigger port and reference clock port. These signals cannot accurately control the time delay when communicating with the instrument

And affected by registers and CPU scheduling, asynchronous errors will occur when time stamps and data signals are merged

If the acquisition device does not provide interface support, there is no way to achieve signal integration

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