Multi-detector image data transmission method

Abstract

The present application provides a kind of multi-probe image data transmission method, communication instruction sent by imaging control unit to multiple probe units contains time parameter, and also increase a synchronization pulse for reducing the error accumulation caused by communication instruction receiving interval, utilize synchronization pulse so that each probe unit obtains the same time parameter at synchronization pulse moment, keep time by crystal oscillator, and agree to pack transmission with unit of line in image data transmission process.The present application corrects the data transmission time of different detectors, effectively reduces the time interval of different detector transmission data, facilitates image splicing, in addition, the present application also carries out image data transmission with unit of line, reduces the requirement of imaging control unit to image cache ability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data transmission, and particularly provides a multi-detector image data transmission method of a large field of view space camera. BACKGROUND

[0002] With the development of space technology, a large field of view high-resolution space camera has become a research hotspot. In order to achieve the requirement of a large field of view and high resolution, an optical splicing or detector splicing method is commonly used at present. The former is more flexible in space, but has a higher requirement on optical design. The latter is relatively easy to implement compared with the former, but loses some pixels. Regardless of which splicing method is used, the front unit needs to have several detectors for photoelectric conversion. In order to facilitate image processing, the rear image processing unit often requires the front unit to output a spliced whole image. However, when multiple high-resolution detectors perform field splicing imaging according to the received instruction time, the starting time of imaging is often different due to the unsynchronized reception of the instruction time, which increases the difficulty of the rear image processing.

[0003] At present, a common method for realizing the synchronization of multiple detectors is to make multiple detector modules send a synchronization instruction or signal containing a plurality of parameter information, and to judge whether the synchronization is achieved according to the feedback or response information of each detector module to the instruction or signal. This method has a large synchronization difficulty and needs to judge the feedback or response information.

[0004] The working instruction of each detector unit is controlled by the imaging control unit through an RS-422 communication instruction. The number of bytes of the communication instruction is often long, and the time of each detector cannot be completely synchronized, and there is a certain time interval δ, wherein the maximum time interval is δ start-max . The reasons for generating the time interval are mainly as follows:

[0005] First, although the instruction interface chip used by each detector unit is of the same type, due to individual differences, the delay of signal processing cannot be completely consistent. In addition, each instruction cycle is composed of a plurality of high and low pulses, so that the cumulative error increases, and therefore the starting time of the communication instruction recognized by the actual detector unit has a certain time interval δ start .

[0006] Secondly, due to the error of the active crystal oscillator used by each detector unit, the actual frequency is not consistent, and therefore each clock cycle accumulates a certain time interval. When the detector is in long-time exposure, the maximum time interval δ max between the detector units will become larger after the clock error accumulates.

[0007] Therefore, for a large field of view high-resolution space camera, a multi-detector image data transmission method capable of effectively solving the time synchronization problem is urgently needed. SUMMARY

[0008] The present application provides a multi-detector image data transmission method, which mainly adds a synchronization pulse signal to reduce the error accumulation caused by the communication instruction receiving interval, and includes a time parameter in the communication instruction sent by the imaging control unit. The synchronization pulse can make each detector unit obtain the same time parameter at the synchronization pulse moment, and then each detector unit performs time keeping and agrees to pack and transmit the image data in units of lines.

[0009] The multi-detector image data transmission method provided by the present application comprises:

[0010] The imaging control unit sends a communication instruction to the plurality of detector units, and the same time parameter is included in the communication instruction. The detector units cache the same time parameter. The imaging control unit sends a synchronization pulse to the detector units. The detector units obtain the same time parameter when receiving the synchronization pulse. The crystal oscillator in the detector units performs self-time keeping according to the same time parameter. Meanwhile, the detector units send image data to the imaging control unit in units of lines, and cache the image data in the imaging control unit.

[0011] When the imaging control unit receives the first row of image data sent by any one of the detector units, the imaging control unit counts Δt after receiving the first row of image data, where Δt is greater than or equal to the maximum transmission delay δ caused by the clock error of all the detector units max The imaging control unit sends the received first row of image data to a subsequent image processing unit. After all the first rows of image data are sent, the imaging control unit clears all the cached first rows of image data, and then transmits the next row of image data in the same way until all the rows of image data are transmitted.

[0012] Preferably, the image data transmission is used for a large field of view space camera.

[0013] Preferably, each detector unit comprises two pieces of Gsense6060 detector, the pixel resolution of the detector is 6144(V)×6144(H), and each pixel has a 14-bit output.

[0014] Preferably, the imaging control unit uses FIFO when caching image data.

[0015] Compared with the prior art, the present application can achieve the following beneficial effects:

[0016] The application corrects the data transmission time of different detectors, effectively reduces the time interval of data transmission of different detectors, facilitates subsequent image processing such as image splicing, and in addition, the application transmits image data in units of behaviors, reducing the requirement of the imaging control unit on the image cache capability. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the time interval of the communication instruction received by the multi-detector unit in the background art;

[0018] Figure 2 is a flowchart of the multi-detector image data transmission method provided by the embodiment of the application;

[0019] Figure 3 is a schematic diagram of the multi-detector image data transmission using the method of the application. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the application will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0021] In order to make the objectives, technical solutions and advantages of the application clearer, further detailed descriptions of the application will be given below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, and do not constitute a limitation on the application.

[0022] Figure 1 shows the time interval of the communication instruction recognized by the multi-detector unit in the background art.

[0023] As Figure 1 shown, the image data transmission imaging process of the large field of view spatial camera mainly includes:

[0024] Imaging control unit: has the functions of sending a communication instruction to a detector unit, receiving and caching image data output by each detector unit by rows, and packaging image data of the same row of multiple detector units and sending them to a subsequent image processing unit. In addition to the interface for transmitting the communication instruction between each detector unit and the imaging control unit, there is also a synchronization pulse interface.

[0025] n detector units: numbered as detector unit 1, detector unit 2, …, detector unit n, the number of the detector units corresponds to the number of the image data transmission channels of the imaging control unit, wherein each detector unit has the same function, such as driving the detector, receiving and buffering the detector data, receiving the communication instruction from the imaging control unit, outputting the image data row by row, adding the time parameter of the current transmitted image data in the header of the detector data packet, etc. Each detector unit uses two Gsense6060 detectors produced by Changguanchen Co., Ltd., the pixel resolution of the detector is 6144(V)×6144(H), and each pixel has a 14-bit output. Each detector unit is provided with a crystal oscillator for outputting the system clock, and the system generates the timing and logic of each functional module according to the clock.

[0026] A post-stage image processing unit: used for receiving the image data transmitted by the imaging control unit and performing image stitching imaging according to the image data.

[0027] As described in the background, due to the inevitable hardware reasons, the starting time of the communication instruction received by each detector unit from the imaging control unit has an interval, and the interval of the starting time of the communication instruction received by any two detector units is denoted as δ start , wherein the maximum time interval is denoted as δ start-max Due to the time interval, the image data transmitted by each subsequent detector unit to the imaging control unit also has a time interval, which brings great trouble to the post-stage image processing unit for image stitching imaging. When the detector is in long-time exposure, the clock error is accumulated, and the maximum time interval between the detector units is denoted as δ max , that is, the maximum transmission delay of all detector units caused by the clock error.

[0028] Figure 2 A multi-detector image data transmission method according to an embodiment of the present application is shown.

[0029] Figure 3 A multi-detector image data transmission method according to an embodiment of the present application is shown.

[0030] As shown in Figure 2 , Figure 3 , in order to solve the time interval problem of each detector unit, an embodiment of the present application provides a multi-detector image data transmission method, and the main process is as follows:

[0031] The detector in the plurality of detector units detects image data of an imaging target, and the imaging control unit sends a communication instruction to the plurality of detector units, which is used to drive the detector units to transmit information in the prior art. In the method of the present application, a synchronization pulse is added to drive each detector unit to start sending image data to the imaging control unit, and the communication instruction contains the same time parameter. Each detector unit will cache the same time parameter after receiving the communication instruction and wait for the synchronization pulse.

[0032] After all the detector units completely receive the communication instruction, the imaging control unit sends a synchronization pulse to the detector units again. According to the cached same time parameter, each detector unit receives the synchronization pulse at the same time and obtains the same time parameter. Each detector unit uses the same time parameter as a reference to perform self-keeping time using a system clock, and at the same time, each detector unit starts sending image data to the imaging control unit in units of rows. At this time, due to the synchronization pulse and the same time parameter, the time front of the image data sent by each detector unit is the same, and the image data in units of rows is cached in the imaging control unit.

[0033] The image data transmission process in units of rows is as follows:

[0034] First, the image data is cached by using FIFO in the data channel between the imaging control unit and each detector. When the imaging control unit receives the first row of image data sent by any detector unit, it starts the operation of the timer. When the timing time reaches the set time threshold Δt, where Δt is greater than or equal to the maximum transmission delay δ max of all the detector units caused by clock errors, the received first row of image data is packaged and sent to the subsequent image processing unit according to the number of the detector unit or the number of the image data transmission channel of the imaging control unit. The header of the image data packet has a time parameter as a label. When the first row of image data of all the detector units is sent, the imaging control unit empties the FIFO, i.e. empties all the cached first row of image data. At this time, the transmission of the first row of pixel image data of a frame of image has been completed. The transmission of the next row of image data of the frame of image is performed in the same way. The above process is repeated until the transmission of all the rows of image data of the frame of image is completed, so that the splicing imaging of the frame of image is realized.

[0035] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

[0036] The above detailed description does not limit the scope of the application. Any other corresponding changes and modifications of the application according to the technical concept of the application are to be included within the scope of the claims of the application.

Claims

1. A multi-detector image data transmission method, characterized by, The imaging control unit sends a communication instruction to the plurality of detector units, the communication instruction containing the same time parameter, and the detector units cache the same time parameter; the imaging control unit further sends a synchronization pulse to the detector units, the detector units obtain the same time parameter upon receiving the synchronization pulse, the detector units perform self-keeping time by crystal oscillator according to the same time parameter, and the detector units send image data to the imaging control unit in units of lines and cache the image data in the imaging control unit; When the imaging control unit receives first line image data sent by any one of the detector units, the imaging control unit sends the received first line image data to a subsequent image processing unit after timing Δt, where Δt is greater than or equal to the maximum transmission delay of all the detector units due to clock error, the imaging control unit clears all the cached first line image data after all the first line image data is sent, and the transmission of next line image data is performed in the same manner until all the line image data is transmitted. Each of the detector units includes two pieces of Gsense6060 detector, the pixel resolution of the detector is 6144x6144, and each pixel outputs 14 bits. The imaging control unit caches image data by using FIFO.

2. The multi-detector image data transfer method of claim 1, wherein, Image data transmission for large field of view space camera.

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