CN103024306A - Method for transmitting image data of multi-channel high-speed line-frequency-variable linear array CCD (charge coupled device) - Google Patents

Abstract

The invention discloses a method for transmitting image data of a multi-channel high-speed line-frequency-variable linear array CCD (charge coupled device), and relates to the field of transmission of image data of aerospace and aviation CCD cameras. The method includes steps that a digital phase-locked loop clock management unit creates a relation between frequency of a pixel transfer clock and frequency of a TLK2711 transmission clock according to the quantity of transmission channels of the CCD, the pixel transfer clock and the quantity of transmission channels of TLK2711 devices; the TLK2711 devices create a reliable and stable transmission link for transmitting and receiving the image data; and multi-channel image data fusion transmission and line signal and image data fusion transmission units start to fuse the multi-channel data into one channel of data and transmit the channel of data to the TLK2711 devices after the transmission link is stable, and the TLK2711 deserializer transmits the channel of data to a receiving FPGA (field programmable gate array) processor. The method has the advantage that cables of an aerospace and aviation remote-sensing camera data transmission system are greatly reduced.

Description

The variable linear array CCD image data transmission method of multi-channel high-speed line frequency

Technical field

The present invention relates to Aero-Space CCD camera image data transmission field, relate in particular to the method for the variable linear array CCD image transfer of data of a kind of multi-channel high-speed line frequency.

Background technology

In the remote sensing application of high-resolution Aero-Space, along with visual field and the resolution index of linear array CCD camera improves constantly, the CCD output way, splicing sheet number and the single port read-out speed that adopt are also improving constantly, thereby cause the image data amount after the digitlization to be exponent increase, CCD camera operation on orbit line frequency real-time change causes image data transmission very difficult in addition.Existing do not possess at a high speed (number passes parallel clock and surpasses 85MHz) transmittability based on LVDS and Camera Link image data transmission mode, and adopt multichannel LVDS and Camera Link transmission to cause the system transmissions cable to increase, bulky; Adopt the Optical Fiber Transmission mode be suitable at present high-speed applications expensive and easily cause the transmission system module to increase, bulky, increase CCD camera load.

The view data figure place of the analog video signal of now most Aero-Space remote sensing line array CCDs output after the A/D conversion is higher than 8 and be lower than 16, and view data is with the in real time output of behavior unit, and every row comprises valid pixel and blanking pixel.Valid pixel comprises view data and auxiliary data, and the blanking pixel is inactive pixels, need to carry out real-time adjustment in order to carry out friction speed coupling blanking pixel count during the camera operation on orbit, causes each channel C CD line frequency real-time change, and has randomness.Usually adopt the way of batch (-type) transmission namely first the view data of A/D parallel output to be cached among the Cache SDRAM, read the SDRAM data after the buffer memory several rows and transmit by LVDS or Camera Link.Because SDRAM also needs the operations such as pre-punching, activation and periodic refreshing to increase the read-write expense when read-write operation, simultaneously in order to guarantee that the buffer memory real-time need to adopt RAM as auxiliary cache.In the variable line array CCD of line frequency is used, need further process variable capable interrupt event, improve the read-write clock frequency of SDRAM, not only increased system complexity and power consumption, and electromagnetic Compatibility Design has also been proposed harsh requirement; The conversion of carrying out view data buffer memory and figure place in high speed (number passes parallel clock and surpasses 85MHz) situation also is a difficult problem, and easily causes losing of view data.

Summary of the invention

In order to solve problems of the prior art, the invention provides a kind ofly in order to solve problems of the prior art, the invention provides the method for the image data transmission of a kind of multi-channel high-speed (number pass parallel clocks surpass 85MHz) variable linear array CCD camera of line frequency.For Aero-Space remote sensing line array CCD output characteristic, each channel C CD image line signal is regarded as the 1bit data, merge with view data.Then adopting clock multiplier relation strategy is that 1 passage and data are input among the high speed serializer TLK2711 with the multi-channel parallel fusing image data, transmits by coaxial cable after the high speed serializer TLK2711 string.

The technical scheme that technical solution problem of the present invention adopts is as follows:

The variable linear array CCD image data transmission method of multi-channel high-speed line frequency, the method comprises the steps:

Step 1: according to port number, pixel transfering clock and the TLK2711 transmission way of CCD transmission, the digital phase-locked loop Clock Managing Unit that sends in the FPGA processor is set up pixel transfering clock and TLK2711 transfer clock frequency relation;

Step 2: TLK2711 serializer and TLK2711 deserializer are set up reliable, stable sending and receiving transmission link;

Step 3: after transmission link is stable, multichannel image data fusion transmission in the transmission FPGA processor and row signal and fusing image data transmitting element begin that multi-channel data is fused to 1 circuit-switched data and are transferred to the TLK2711 serializer, the TLK2711 serializer is with its data encoding, and the serial data after will encoding is transferred in the TLK2711 deserializer by coaxial cable, the TLK2711 deserializer receives data, and become parallel data after the deserializer, then be sent in the reception FPGA processor by the TLK2711 deserializer.

The invention has the beneficial effects as follows:

1, the method for the image data transmission of the variable linear array CCD camera of multipath high-speed line frequency is that the multichannel image data fusion is 1 circuit-switched data, turns to serial data by a pair of 50 Ω coaxial cables transmission by the TLK2711 string.Greatly reduced the cable of astronautics and airborne remote sensing camera number biography system.

2, the method for the image data transmission of the variable linear array CCD camera of multipath high-speed line frequency has solved for the higher Aero-Space remote sensing camera number commonly used of pixel transfering clock frequency and has passed the problem that is difficult to realize, the transmission rate of several biography system has been brought up on the speed of G level bps, and it is very simple to operate.

3, will go signal and fusing image data in the method for the image data transmission of the variable linear array CCD camera of multipath high-speed line frequency and send together, solve in the Aero-Space remote sensing camera because the variable problem that causes the transfer of data complexity of line frequency.

4, before TLK2711 sends image, invented the startup of setting up link transmission and set up the reliability that the stable transfer data link has improved image data transmission.

5, the method for the image data transmission of the variable linear array CCD camera of multipath high-speed line frequency can be determined transmission means according to pixel transfering clock and CCD transmission channel number, and has provided concrete transmission phase relation and frequency reduction formula.

Description of drawings

The variable line array CCD single channel of Fig. 1 high speed line frequency of the present invention image data transmission system reduced graph.

Fig. 2 single channel data transmission relations of the present invention sequential chart.

Fig. 3 CCD transmission channel number was greater than 2 o'clock multichannel ccd data convergence strategies one.

Fig. 4 CCD transmission channel number was greater than 2 o'clock multichannel ccd data convergence strategies two.

Fig. 5 CCD transmission channel number was greater than 2 o'clock multichannel ccd data convergence strategies three.

The variable linear array CCD image data transmission system of Fig. 6 multipath high-speed line frequency structure chart.

Fig. 7 sets up the startup flow chart of link transmission.

Fig. 8 self-correcting data are set up sequential chart.

Fig. 9 sets up stable transfer data link flow chart.

Each bit transfer signal of Figure 10 TLK2711 data/address bus.

Figure 11 multichannel ccd data merges the transmission state transition diagram.

Embodiment

Below in conjunction with drawings and Examples the present invention is described in further details.

As shown in Figure 1,1 channel line array CCD image data are with the output of behavior unit, and every row is comprised of valid pixel and inactive pixels, and the valid pixel number is changeless, and the Line signal that valid pixel is corresponding is " 1 ".The inactive pixels number is because the camera operation on orbit needs to adjust in real time in order to carry out the friction speed coupling, and the Line signal that the inactive pixels number is corresponding is " 0 ".The pixel of valid pixel and inactive pixels moves the frequency f of clock C ₁All the time be identical, cause the frequency F of Line to change when the inactive pixels number changes.If view data is k bit, as pixel data is seen the Line signal of 1 bit in 8＜k≤14, and view data becomes (k+1) bit like this, and (k+1) bit parallel data is input to the low k+1 position of serializer TLK2711 input data bus.View data is directly inputted among the serializer TLK2711 without buffer memory like this, and the variation of line frequency just makes certain " 1 " and " 0 " of the data/address bus of 16bit to change, and not affecting transfer of data does not need the Line signal is carried out special judgement processing etc. yet.

Frequency f for the parallel transmission clock TXCLK of serializer TLK2711 ₂With pixel transfering clock frequency f ₁The pass be f2=n _Channel* f1 (1)

N wherein _ChannelBe the transmission of CCD port number.

Work as n _Channel=1 o'clock, because parallel clock frequency 85MHz≤f of TLK2711 ₂≤ 135 MHz, and f ₁Frequency far below 85MHz, adopt repeatedly sampling policy during transmission, establishing each image pixel sampling number is m, then m satisfies following formula

$\frac{85\mathrm{<figure-callout\; id="1"\; label="MHz\; f"\; filenames="HDA00002627262000071.png,HDA00002627262000081.png"\; state="\{\{state\}\}">MHz</figure-callout>}}{f}\&le;m\&le;\frac{135\mathrm{MHz}}{f1}---\left(2\right)$

1 image pixel of every like this m transfer clock transmission, image data transmission concerns as shown in Figure 2.Every m receive clock received 1 view data when view data received, and recovered enforcement energy signal according to the data that receive, and recovered pixel transfering clock f according to receive clock ₁=f ₂/ m.

Work as n _Channel1 o'clock, need to be with n _ChannelThe ccd image data fusion be 1 the tunnel, at first from the frequency relation analysis of pixel transfering clock and TLK2711 transfer clock, the pixel transfering clock frequency of multichannel CCD is usually all identical, is made as f ₁, 1 road TLK2711 CCD port number n that can transmit then _ChannelScope is

$\frac{85\mathrm{<figure-callout\; id="1"\; label="MHz\; f"\; filenames="HDA00002627262000071.png,HDA00002627262000081.png"\; state="\{\{state\}\}">MHz</figure-callout>}}{f}\&le;n_{\mathrm{channel}}\&le;n_{\mathrm{channel}}{|}_{\max }=\frac{135\mathrm{MHz}}{f1}---\left(3\right)$

Work as n _Channel＞n _Channel| _MaxThen adopt multichannel TLK2711 to transmit.Work as n _Channel＜n _Channel| _MaxThe time, transfer clock f ₂Satisfy

f2=n _channel×f1×k+m×f1≥85MHz （4）

Wherein, k, m are positive integer.By adjusting k, m makes f ₂Satisfy following formula.Size according to k and m adopts different multichannel ccd data convergence strategies.：

Convergence strategy 1: work as m=0, during k=1, Multichannel fusion concerns as shown in Figure 3.The TLK2711 clock frequency is the transmission channel several times of pixel transfering clock frequency, transmits successively the pixel data (row signal, pixel clock, fusing image data data) in each passage in pixel migration period.

Convergence strategy 2: work as m=0, k〉1 o'clock, take k=2 as example, Multichannel fusion concerns as shown in Figure 4.The TLK2711 clock frequency is the integral multiple that pixel transfering clock frequency and transmission channel are counted product, at this moment, in the pixel migration period successively to a pixel transfer of data in each passage k time, until all channel transfer are complete.Among Fig. 4 a pixel in every passage is transmitted 2 times.

Convergence strategy 3: when m ≠ 0, k ≠ 0 o'clock, at this moment, the tranmitting data register frequency f of expression TLK2711 ₂Not k * n * f ₁Integral multiple, at this moment go out the m channel image data pixel migration period is unnecessary, adopt the way that sends fixed data when sending, when receiving, only need receive the view data of front, fixed data discards and does not receive.Take k=1 as example, the multi-channel data syncretic relation as shown in Figure 5.Transmit successively in pixel migration period among the figure after the pixel data (row signal, pixel clock, fusing image data data) in each passage in transmission m passage fixed data.

After multichannel ccd image data fusion, 1 tunnel view data sends by TLK2711, TLK2711 carries out 8/10 bit with 16 bits input data and is encoded to 20bit, wherein 8/10 bit coding is used for guaranteeing minimum transfer density, be conducive to conversion front and back clock synchronous, guarantee in addition " 0 " in the serial transmission, " 1 " number of signals is consistent, to obtain better dc balance, suppress the impact of transmitting-receiving two-end reference voltage difference.Sending parallel clock 20 frequencys multiplication is the serial transmission clock, then carries out serial transmission by 50 Ω coaxial cables with 20 * f2bps speed.For make TLK2711 reliablely and stablely need of work 1 bit link establishment position is being set, here with highest order as setting up a position Start, also need simultaneously initialization to stablize sending strategy, see the variable linear array CCD image data transmission system of the multi-channel high-speed line frequency of the present invention course of work for details.

As shown in Figure 6, the variable linear array CCD image data transmission system of multi-channel high-speed line frequency comprises: send FPGA processor, TLK2711 serializer, 50 Ω coaxial cables, TLK2711 deserializer and receive the FPGA processor; The TLK2711 serializer adopts 50 Ω coaxial cables directly to link to each other with the TLK2711 deserializer.

The FPGA processor comprises that digital phase-locked loop Clock Managing Unit, multichannel image data fusion send and the row signal is set up the unit with control signal generation and the initialization link of fusing image data transmitting element, TLK2711.The digital phase-locked loop Clock Managing Unit produces pixel transfering clock and TLK2711 tranmitting data register, and produce the frequency multiplication relation according to top analysis, as establish space camera and adopt 9 panchromatic CCD to be spliced, every CCD adopts the output of 4 passages, every passage pixel number is 3000, and the pixel transfering clock is 22MHz, tries to achieve CCD port number 4≤n that 1 road TLK2711 can transmit≤6 by formula (3), get n=6, only need 6 road TLK2711 just can transmit for 9 36 channel C CD.The transfer clock that can be tried to achieve TLK2711 by formula (1) is 6 * 22=132MHz, and 22MHz and 132MHz can be produced by the digital phase-locked loop Clock Managing Unit.The multichannel image data fusion sends and row signal and fusing image data send state machine and merge the relation of transmission according to the multi-channel data of Fig. 3-Fig. 5 view data and the signal of going are input among the TLK2711.The control signal generation of TLK2711 and initialization link are set up the unit and are guaranteed TLK2711 stable transfer data, have invented initialization consistent link Establishment strategy in this unit, and then guarantee the reliability and stability of ccd image transfer of data.The TLK2711 serializer is encoded the parallel data that receives, and then transmits by 50 Ω coaxial cables.

The method of the variable linear array CCD image transfer of data of multipath high-speed line frequency comprises following three steps:

Step 1, the port number according to the CCD transmission, pixel transfering clock and TLK2711 transmission way, the digital phase-locked loop Clock Managing Unit that sends in the FPGA processor is set up pixel transfering clock and TLK2711 transfer clock frequency relation;

As shown in Figure 2, m sheet CCD adopts the output of n channel data, and every passage pixel transfering clock frequency is f1, and video processor adopts the A/D converter of k bit.The ccd image port number that 1 road TLK2711 can transmit is

, n _Tlk2711Desirable

~

Any value, the value of getting guarantee that the TLK2711 transmission way l that whole transmission system needs is integer, then TLK2711 transfer clock frequency f 2 is f2=f1 * n _Tlk2711

Step 2, TLK2711 set up first reliable, the stable transmission link of sending and receiving before sending view data.

In order to make TLK2711 enter the normal operation transmission state, invented TLK2711 initialization link Establishment strategy more fast and stable.At first, set up the startup of link transmission, definition of T LK2711 data/address bus highest order Txd[15] be masked as Start for starting, select control signal TKLSB and TKMSB according to k code and the d code of data/address bus transmission, start transmission link.Start flow process as shown in Figure 7.

System powers on, behind voltage stabilization, TKLSB and the TKMSB of transmitting terminal TLK2711 set to 0, transmitting terminal TLK2711 data wire is inputted 16 bit fixed datas, wherein Start is set to 1, send this fixed data time is 3000 * 1/f2 second always, then TKLSB and TKMSB are set to 0, Start still is set to 1,16 identical bit fixed datas of its data wire input, and send this fixed data time is 3000 * 1/f2 second always, above-mentioned two processes, to guarantee that the data wire data portion changes, the control signal TKLSB in the stabilizing circuit system and TKMSB, wherein transmitting time be control signal by unstable to the stable excessive time.Then turn back to for the first time transmission state, namely TKLSB and TKMSB set to 0, and its data wire is inputted 16 bit fixed datas, and wherein Start is set to 1, and delays time 3000 * 1/f2 after second.Guarantee that closely stable control signal TKLSB and TKMSB are constant, change data-signal, carry out equally 2 times, behind the pending data signal stabilization, transfer to and set up the stable transfer data link stage.

Secondly, set up the stable transfer data link.Set up the stable transfer data link by transmission self-correcting data, at first set up the self-correcting data according to the capable signal of ccd data and pixel transfering clock, opening relationships as shown in Figure 8, row signal and pixel shifted clock signal adopt the CCD image-generating unit to send, the self-correcting data sampling is from the mode that adds, be that the 1st pixel value of every row is 0x01, each pixel adds 1 successively, and pixel value is 0x00 when effective to row.Then the final self-checking number certificate that produces is fused to parallel 16 Bit datas with selfing data, row signal and pixel shifted clock signal, is input among the TLK2711 and transmits.The single channel transmission relation of transmission self-correcting the data Fig. 2, transfer process as shown in Figure 9.Among the figure, transmission link starts and to be step 2 process, when transmission link start finish after, transfer to the transmission data mode, i.e. TKLSB, TKMSB sets to 0, Start puts 1. and then sends selfing data, the row signal that Fig. 8 produces.Selfing data Check_data with Fig. 8, row signal LEN and Start signal fused are that 16 Bit datas are assigned to TLK2711 data wire TXD_DATA[15:0], then send, and delay time 9000000 * 1/f2 after second, and carry out the selfing data that 7 above-mentioned methods are sent, during this period of time in the system transmissions data link can be by unstable transition to stable state.

After step 3, the transmission of data link are stablized, begin that multi-channel data is fused to 1 circuit-switched data and be transferred among the TLK2711.

Every channel C CD data comprise 3 signals: view data, enforcement energy and pixel transfering clock, pixel transfering clock and TLK2711 transfer clock have the fixed frequency relation, therefore do not need individual transmission pixel transfering clock.The information that needs transmission is view data and row signal, for fear of the variable problem that causes the transfer of data complexity of line frequency, the 14th transmission row of definition of T LK2711 data/address bus signal, transmit the capable signal of each channel C CD data, as shown in figure 10, the data structure of the 16 Bit data lines of TLK2711, wherein the 13rd ~ 0 bit sends view data, the 14th bit sends the row signal, and the 15th bit is the opening flag signal.This data structure has realized the capable signal of CCD and fusing image data are transmitted simultaneously to 16 Bit datas, and then has solved the variable trouble that causes transfer of data of line frequency.Like this view data and row signal fused are transmitted together, when the 14th of TLK2711 data/address bus is " 1 ", represented that the 0th ~ 13 is valid pixel.The multichannel ccd data is fused to the transmission of 1 circuit-switched data, and 1 road TLK2711 transmits n _Tlk2711Channel C CD view data merges the transmission state machine as shown in figure 11.Among the figure, initial condition is idle Idle state, then make when execution in step one and step 2 data transmission link stable, enter data after stable and send state Data_send, the Data_send state is with beginning flag Start signal, the view data of the capable signal of the 1st channel C CD, first pixel is dealt in the 16 Bit data lines of TLK2711, after the 1st channel C CD data are sent completely, send view data and the row signal of first pixel of second channel, successively, until after all passages sent first pixel data, sending strategy sent according to 3 kinds of convergence strategies.Then adopt in a like fashion, send second pixel data of each passage, the like, finished multichannel ccd image data transfer after, with transfer of data to receiving in the FPGA processor.

Claims (4)

1. the variable linear array CCD image data transmission method of multi-channel high-speed line frequency is characterized in that, the method comprises the steps:

Step 1: according to port number, pixel transfering clock and the TLK2711 transmission way of CCD transmission, the digital phase-locked loop Clock Managing Unit that sends in the FPGA processor is set up pixel transfering clock and TLK2711 transfer clock frequency relation;

Step 2: TLK2711 serializer and TLK2711 deserializer are set up the sending and receiving transmission link;

Step 3: after transmission link is stable, multichannel image data fusion transmission in the transmission FPGA processor and row signal and fusing image data transmitting element begin that multi-channel data is fused to 1 circuit-switched data and are transferred to the TLK2711 serializer, the TLK2711 serializer is with its data encoding, and the serial data after will encoding is transferred in the TLK2711 deserializer by coaxial cable, the TLK2711 deserializer receives data, and become parallel data after the deserializer, then be sent in the reception FPGA processor by the TLK2711 deserializer.

2. the variable linear array CCD image data transmission method of multi-channel high-speed line frequency as claimed in claim 1, it is characterized in that, described step 2 comprises the steps: at first, set up the startup of link transmission, definition of T LK2711 data/address bus highest order is Start, k code and d code according to the data/address bus transmission are selected control signal, start transmission link; Secondly, set up the stable transfer data link, set up the stable transfer data link by transmission self-correcting data, set up the self-correcting data according to the capable signal of ccd data and pixel transfering clock, transmission self-correcting the data single channel transmission relation.

3. the variable linear array CCD image data transmission method of multi-channel high-speed line frequency as claimed in claim 1, it is characterized in that, described step 3 comprises the steps: at first, calculate TLK2711 frequency and pixel transfering clock frequency relation, determine convergence strategy, then send the multichannel ccd data according to convergence strategy.

4. the variable linear array CCD image data transmission method of multi-channel high-speed line frequency as claimed in claim 1 is characterized in that, described coaxial cable is 50 ohm.

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