In commercial diving, it involves a variety of underwater video equipment, mainly in the form of underwater video recorder, underwater surveillance system, underwater camera and so on. Underwater Video Recorder (VCR) refers to a complete set of equipment in which divers carry underwater cameras, transmit video to land by wired way, and watch and record video through the main machine of VCR. Underwater surveillance system refers to an integrated system in which one or more cameras are fixed under the water to monitor and record underwater video through a hard disk recorder on the shore. Other types of underwater video equipment include underwater cameras, underwater camcorders, and other types that have screens and allow divers to photograph themselves while underwater. This paper mainly introduces the application, development and present situation of underwater video recorder in commercial diving. Underwater monitoring system is mostly used for monitoring the working environment and video recording in the fields of aquaculture and scientific research. Underwater cameras and video cameras are mostly used for recreational diving, and ROV is used as the carrier of video equipment. This paper will not introduce too much.

 

Application of underwater video recorder in commercial diving

 

1. Underwater detection

 

Bridges, docks, ship, dam, offshore wind, offshore platform and submarine pipeline, culverts and so on all need to detect and record video on a regular basis, in order to understand the workings of these facilities, equipment, and archive in the form of video, to ensure that these facilities, able to timely maintenance equipment, safe operation, and history archives. In this application, the ground technician usually watches the picture on the main camera and directs the diver through the diver's walkie-talkie. The diver holds a front-end underwater camera and a headlight to take pictures of a specific underwater target.

 

2, construction work site record

 

Compared with the construction on land, commercial diving operation has the characteristics of high risk and high cost. Therefore, it is very important to make a detailed video recording of the underwater operation. This kind of application form is usually for the diver to wear underwater camera and light on the diving helmet or mask, the land technician and safety personnel watch the picture through the main video recorder, and direct the diver to carry on the construction operation through the underwater intercom.

 

3. Underwater video search

 

Underwater video search involves the field of emergency rescue, including underwater search for drowning people, drowning vehicles, etc., and this kind of application is mostly towed and vertical. When large area is searched, underwater camera, lighting and sonar probe can be carried on the fish tow, and side scan and video search can be carried out under the water by the boat towing the fish tow. For example, the location of the salvage object has been determined by sonar. The underwater camera and light can be lowered from the water surface to the specific location for video confirmation.

 

4. Other fields

 

Underwater video is widely used in the field of evidence collection in criminal investigation, underwater archaeology, underwater surveying and mapping, Marine pasture, underwater robot and intelligent identification of underwater objects, and plays an important role in all of them.

 

Second, the necessity of underwater video recorder application in commercial diving

 

1. Provide video basis for detection data

 

In underwater detection, divers need to measure and record a large amount of data. However, due to the limitation of divers' working environment, and the different understandings of divers on the data measurement process and measurement methods, the data provided by divers alone may be biased. Using underwater video recorders, a technician can guide and supervise the divers' measurements while on land, and video recordings can provide visual evidence of the measurements.

 

2. Provide reliable basis for operation plan customization and safety assessment.

 

Through the video uploaded by the underwater camera carried by the divers, on-site technicians and safety management personnel can monitor the underwater operation situation in real time, effectively master the working environment and conditions, and make reasonable operation plan according to the actual situation. If the working environment and conditions change and are not suitable for continuing the operation, the diver's operation can be terminated in time.

 

3. Accumulation of construction experience and case filing

 

The cost of commercial diving operations is high, the risk is high, and there are many kinds of operations. The operation process and operation plan can be recorded by video, which can effectively accumulate and share the operation experience. Archiving the implemented projects as cases contributes to the sustainable development of enterprises.

 

4. Traceability

 

During the implementation of the project, after the occurrence of technical problems, safety accidents or accidents, the event can be traced back through the video recording at the scene, so as to provide help for the investigation of accidents or accidents, and summarize the experience in time to avoid the recurrence of similar situations.

 

The development of underwater video recorders

 

1. The first generation of underwater video recorder uses video tape as the storage medium, and the host is composed of a VHS, a kinescope monitor and a group of control units. The underwater camera uses a 480TV line analog camera. The underwater floodlight uses a halogen bulb, and the brightness is controlled by a voltage regulator in the control unit. The voltage adjustment range is 0 to 130V. This underwater video recorder file retrieval is cumbersome and is not suitable for long-term storage. Lighting using a voltage of 130 V beyond the safe range, with the development of The Times will soon be eliminated.

2. The second generation of underwater video recorder uses optical disc as the storage medium, and the host is composed of a home optical disc burner, a liquid crystal display and a group of control units. The underwater camera uses a 600 or 700TV line analog camera. Underwater lights still use halogen bulbs, with a voltage regulator controlling brightness. This form of CD burning is not convenient for long-term preservation, and the burning process is prone to errors, resulting in file loss.

3、第三代水下录像机发展为数字格式，录像主机由硬盘录像机或计算机代替，将水下摄像机上传的700TV线模拟视频进行数字压缩，存储在硬盘上。水下照明灯过渡为LED灯，使用低压供电。这一代产品多采用机械硬盘存储，设备工作要依托硬盘录像机的嵌入式操作系统或者计算机windows操作系统。采用计算机作为录像的设备，由于计算机有内存卡、显卡、视频编码卡等多块板卡插接在主板上，在户外工作时，可靠性差，性能不稳定。机械硬盘高速运转，磁头与盘片因震动经常造成硬盘损坏，从而丢失重要数据。但是因为这是第一代数字化产品，有相当多的优点，比如文件便于检索、复制、存储，所以保有量很大，目前仍然在大量使用。

IV. Development status of underwater video recorders

 

After several generations of technology replacement, at present, the fourth generation of high-definition video recorder has the following features and functions:

 

1. Adopts high-definition camera, the resolution is 1920*1080, and the lowest illumination is 0.001Lux. It has high sensitivity chip, which can effectively reduce noise in low illumination. The video has no lag and no lag.

 

2. Underwater lighting adopts high-power LED chip, low-voltage power supply, safe and energy saving. It can achieve 0~50W stepless dimming.

 

3, the screen adopts 15.6 inch industrial screen, high clear and high bright fog surface screen, LCD resolution reaches 1920*1080, brightness reaches 1000CDM ², is 4 times the brightness of ordinary LCD screen, in direct sunlight without blocking, no reflection.

 

4. The recording medium is solid state hard disk, SD card or U disk, which is easy to copy, read and archive files. Enhanced reliability and versatility.

 

5, support two video, two dimming, a video recorder can be equipped with two sets of cables, video recording, taking photos at the same time.

 

6, with the depth and temperature superposition display function, land personnel at any time to grasp the depth and water temperature of the location of the diver.

 

7. Integrated design, one button to record, one button to stop, one button to take photos, the whole machine is more beautiful and light. Certain models have video pause.

 

8. Underwater audio and video can be transmitted wirelessly through WiFi hotspots, 2.4G or Internet. Company management and field project managers can watch the underwater video and listen to the diving supervisor and the diver talking at the same time without leaving their homes.

 

9, Built-in diver communicator, audio can be synchronized recording, the function is more humanized, with the development of national independent brands, some brands have their own patent technology, the products have been in the international leading level.

With the development of The Times and the progress of technology, it is believed that more and more advanced technologies will be integrated into our commercial diving equipment field, and national independent brands will also flourish and contribute to the construction of the motherland.