scholarly journals Ultrashort baseline synchronous-clock emergency resynchronizing method in the Jiaolong deep-sea manned submersible

2019 ◽  
Vol 16 (1) ◽  
pp. 172988141982779 ◽  
Author(s):  
Tongwei Zhang ◽  
Baohua Liu ◽  
Yeyao Liu ◽  
Jialing Tang ◽  
Shengjie Qin ◽  
...  
Keyword(s):  
Time Delay ◽  
Acoustic Communication ◽  
Communication System ◽  
Deep Sea ◽  
Waveform Generator ◽  
Correct Position ◽  
Trigger Signal ◽  
Manned Submersible ◽  
Delay Difference

During the dive operation of the Jiaolong deep-sea manned submersible, the synchronization clock in the manned cabin may be falsely triggered and cause asynchrony between it and the synchronization clock installed in the mothership, rendering it impossible for the ultrashort baseline to provide the correct position of the Jiaolong deep-sea manned submersible. To solve this problem, this article proposes an emergency resynchronizing method for the two synchronous clocks, used by the ultrashort baseline, in the Jiaolong deep-sea manned submersible. Initially, based on the depth and horizontal range measured by the ultrashort baseline and the manned submersible depth transmitted by the acoustic communication system, the time-delay difference between the two synchronous clocks is estimated. The time-delay difference is then compensated by delaying the synchronous clock trigger signal by an external waveform generator in the mothership. Finally, by comparing the depth measured by the ultrashort baseline and the manned submersible depth transmitted by the acoustic communication system, the time-delay difference is finely adjusted. Using this method, the ultrashort baseline problem, which occurred suddenly while the Jiaolong deep-sea manned submersible was diving, is successfully solved.

Joint Estimation with Time Delay and Doppler Frequency Shift in the Multi-Carrier Acoustic Communication

2012 ◽  
Vol 263-266 ◽  
pp. 994-999
Author(s):  
Jia Chun Zheng ◽  
Wen Xu ◽  
Jianwei Guo ◽  
Wei Dong Xie
Keyword(s):  
Time Delay ◽  
Frequency Shift ◽  
Acoustic Communication ◽  
Lower Order ◽  
Communication System ◽  
Doppler Frequency ◽  
Estimation Algorithm ◽  
Doppler Frequency Shift ◽  
Joint Estimation ◽  
Cycle Frequency

Timing synchronization is very important in the multi-carrier acoustic communication system. With regard to the transmitted signal of the baseband OFDM in the acoustic communication system, which is in the complex environment over the acoustic channel gauss noisy and SαS impulse noisy interference,this paper proposes a joint time delay and Doppler frequency shift estimation algorithm based on the fractional lower order cyclic cross ambiguity function with multi-cycle frequency(FCCAF). This method combines the fractional lower order moment with the feature of cycle stationary, and can detect the signal characteristic of cyclo-stationarity under the SaS impulse noisy. The algorithm takes full advantage of the cycle frequency information of the signal, and can be equipped with the capacity of suppression interference. The simulation results show that the algorithm proposed in this paper can work very well in the presence of the impulse noise and interference, the superior to that algorithm based on the second order cycle fuzzy function, and is a robust joint estimation algorithm with time delay and Doppler shift.

scholarly journals Experimental Research on the Process Parameters of a Novel Low-Load Drill Bit Used for 7000 m Bedrock Sampling Base on Manned Submersible

2021 ◽  
Vol 9 (6) ◽  
pp. 682
Author(s):  
Yu-Gang Ren ◽  
Lei Yang ◽  
Yan-Jun Liu ◽  
Bao-Hua Liu ◽  
Kai-Ben Yu ◽  
...  
Keyword(s):  
Deep Sea ◽  
Field Tests ◽  
Polycrystalline Diamond ◽  
Design Criterion ◽  
Penetration Length ◽  
Technical Data ◽  
Low Load ◽  
Manned Submersible ◽  
Rotary Speed ◽  
Cutting Model

Due to the need for accurate exploration of deep-sea scientific research, drilling techniques by combining the operational advantages of the Jiaolong manned submersible is considered one of the most feasible methods for deep-sea bedrock drilling. Based on deep sea bedrock cutting model and discrete element simulation, as well as efficient drilling as the design criterion, the development of a deep sea 7000 m electromechanical coring apparatus was carried out. The outstanding feature of this technology is that the bit load produced by the drill pressure is usually within the range 100–400 N while the recommended load for diamond drilling is 1–3 KN or even more. Therefore, searching for the drilling bits that can drill in extremely hard formations with minimal load and acceptable rates of penetration and rotary speed is the necessary step to prove the feasibility of electromechanical deep-sea drilling technology. A test has been designed and constructed to examine three types of drill bits. The results of experiments show that the new low-load polycrystalline diamond compact (PDC) bit has the highest penetration length of 138 mm/15 min under a 300 N load and 250 rpm rotary speed. Finally, field tests with the Jiaolong submersible were used to conduct deep sea experiments and verify the load model, which provides theoretical and technical data on the use of a low-load core sampling drill developed specifically for a deep sea submersible.

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