l introduction
Along with information science’s swift development, the data acquisition and the storage technology already were in the digital signal processing the very important link, it widely applies in domains and so on radar, correspondence, telemetering remote sensing, biological medical service, environment examination. It already became the people to gain is not easy to obtain the signal important means that realizes half simulation and the algorithmic analysis in kind, playbacks the scene gathering the real signal, conducts the research to the system performance, has saved the massive outfield run time and the research spending.
But when A/D resolution and sampling rate enhancement, data transfer rate corresponding also becomes higher, will maintain the high speed data memory process the reliability, timeliness will become a quite thorny question. The Spring and Autumn Period video researched and developed real-time high speed high resolution signal gathering to save with pays a return visit the system, realized the data which high speed (80 MB/s) continued to gather the memory and playbacking continuously finally. The system main performance index is as follows:
* sampling rate: Single channel 40MS/s, double channel 20MS/s, four channel 10MS/s;
* resolution: 12 bit A/D,12 bit D/A;
* has the simulation, the digit and the software and so on many kinds of burst modes;
* outside clock, in clock input;
●D/A playbacking simulated signal.
2 system structure designs
The overall system by the computer, the gathering card, the real-time recording system and gathers the memory playbacking software four major part to be composed (as shown in Figure continuously 1). The real-time recording system two major part is composed of the UltraSCSI-320 real-time recording controller and UltraSCSI-320 plate, may act according to the user different storage time decision storage capacity the size. When signal playbacking, according to the user different request might the arbitrary selection playbacking data reference and the end position.
Generally IDE hard disk’s data transfer rate is quite low, to realize the real-time high speed data storage, selects hopes the Czechoslovakia rotational speed is 10 Krpm SCSI hard disks; The corresponding SCSI hard disk controller selects Adapetec Corporation’s Ultra320-SCSI hard disk controller, sets up the RAIDO floppy disk array architecture with the above hardware to realize 80 MB/s to gather the storing velocity continuously.
In the request high speed, real-time, gathers and in continuously the memory situation, on the one hand request system uninterrupted clear signal gathering, meanwhile must carry on the data the real-time memory, otherwise the obliterated data, will cause the data not to be incomplete. We in the system structure design the event notice call-back pattern which provides through the gathering card actuation, completes the data acquisition and the data storage work. Uses the double buffer pattern, when gathers the data reads when the first buffer starts, in the event call-back function the second buffer’s data stores the SCSI hard disk; When the data reads in the second buffer, stores in the event call-back function the first buffer’s data the SCSI hard disk, so circulates. The RAIDO floppy disk array which moreover tests the Ultra320-SCSI hard disk controller through the actual experiment to coordinate to hope Czechoslovakia Corporation to produce ST3146707LC which the SCSI hard disk composes, continues to read in the speed to be able to achieve 200MB/s. Is bigger than 80 MB/s far the gathering speeds. Therefore when the data acquisition thread writes all over before a buffer, data storage thread already another buffer in data storage into SC-SI hard disk. Therefore this method can guarantee the data timeliness, the integrity and the continuity.
Discovered in the test: The data stabilization transmission’s speed and the buffer establishment size and the SCSI floppy disk’s integer has the close relation. Simultaneously the memory application way uses the hypothesized assignment, causes the memory page to aline, raises the transmission speed.
3 software architecture design
3.1 software function module design
The system by the gathering card control module, the display module, gathers the control module as well as the playbacking control module continuously is composed, as shown in Figure 2.
CAcqCard kind: Realizes to gathers the card the control. Including the gathering card parameter disposition, single gathering, gather, save, playback and so on functions continuously continuously continuously.
CCurveShow kind: Realizes the signal time domain demonstration, the scope axis reproduce by pantograph, the time axis reproduce by pantograph, the signal size demarcation, the signal color choice and so on.
CStreamDisk kind: Realizes parameter hypothesis which gathers continuously saves.
CShowStream kind: Realizes parameter hypothesis which playbacks continuously.
3.2 control interfaces
Has the good man-machine contact surface based on the VC platform development’s high speed high resolution signal gathering memory playback system, the easy user operation, as shown in Figure 3.
3.3 software nucleus module principle of design
We according to the double buffer’s principle, have developed and use in high speed signal gathering specially based on the PCI main line’s actuation software package the API function, realizes to the data real-time, high speed, the continual gathering memory and playbacking.
The double buffer pattern is called “the pingpong” in the project the buffer pattern. The principle of work is: Opens two capacity equal buffers in the memory to take the continuous data input the buffer. Starts when gathers, the signal gathering card the first data reads in the first buffer, when the signal gathering card starts the data to read in the second buffer at the same time, the user program may take out in the first buffer according to own need the data to make specific processing. After the second buffer is written all over, the signal gathering card returns to the first buffer the section start, covers the legacy data the way, reads in the first buffer the recent data; Meanwhile uses with the program fetch second buffer data. The entire data acquisition treating processes may the so unceasing circulation work.
The double buffer pattern’s merit is, it may use the low-power memory, the uninterrupted cushion nearly infinitude’s data (input and out-port must joint operation). Software nucleus module flow as shown in Figure 4.
3.4 software nucleus module code
(1) gathers the control section continuously
4 performance appraisals and the future will forecast
In order to confirm this system’s performance, we to gathering which and the memory speed and the data accuracy its could achieve have carried on the test and the analysis. Uses the CG4300 high speed signal which in the test Canadian Famous GAGE Corporation produces to produce the card design special supply oscillator (as shown in Figure 5). Simultaneously has designed the examination signal complete procedure.
Discovered after the test: When the memory buffer establishment is appropriate, may stabilize gathers the memory continuously continually by 80 MB/s speeds; When the buffer establishment is too small, gathers continuously saves can have the interrupt.
Because the data acquisition and the memory process bidirectional take the PCI main line band width, in 32 /33 MHz on the PCI main line, has realized 48 MB/s continual gathering memory playbacking speeds; 64 /66 MHz the PCI main line band width model’s output data volume of goods handled is 528 MB/s,80 MB/s (100% accuracies) gathering and the storing velocity are equal in take 160MB the main line band width, simultaneously the floppy disk array writing speed stabilizes in 200 MB/s, is higher than the data acquisition far the speed, therefore also has in the data acquisition aspect very in a big way enhances the space, at present we are studying develop 200 MB/s the high speed high resolution signals to gather the memory and the playback system continuously.
