Microwave, radio frequency (rf) technology has been widely used in military and civilian fields, such as radar, final guidance, rapid reconnaissance, electronic countermeasures, and communication and navigation, etc., with the development of the military electronic technology, the demand for radio frequency band of the instrument and test equipment is more urgent, rf spectrum analyzer as a kind of universal test instrument, is developed, and an essential tool for many military electronic products testing and maintenance;
Namisoft will introduce in the spectrum analysis of the development to the overall design based on LabWindows/CVI software, compared to other software tools, LabWindows/CVI powerful, easy to learn, can make a lot of complex function more easy to implement,
2 LabWindows/CVI overview
Development platform, LabWindows/CVI is interactive C language can run under multiple operating systems, it is at the core of ANSIC interactive platform for instruments and measurement and control process, it has a simple graphical user interface (GUI), control of powerful, strong real-time performance, easy in programming, mainly suitable for all kinds of test, control, fault analysis and information processing software development, especially large, complex test software, using LabWindows/CVI development can obtain good test performance,
Namisoft realized in the actual development, compared with those of other virtual instrument development tool LabWindows/CVI has the following characteristics:
(1) based on the standard C language and programming technology is mainly driven by time way and the way of the callback function, easy to learn and master,
(2) is visual, interactive development tool, has the human-computer interaction interface editor. Using visual interactive technology to realize the "wysiwyg", simple realization of human-computer interface intuitive,
(3) has the ability of program automatic generation, and can reduce the code in the process of software development effort,
(4) has a fully functional software kit, instrument control, I/O control, communication, data processing, etc.) and powerful function library, including GPIB, RS232, VXI, VISA, etc.,
(5) there is a lot of connection mechanism with external code or software, such as a DLL (dynamic link library), DDE (Shared libraries), ActiveX,
(6) has a variety of flexible means of function calls,
3 Namisoft spectrometer SPC software overall scheme design
The overall design scheme of
Overall demand, from spectrometer software Namisoft spectrometer SPC software mainly consists of three parts: the main interface and display, data analysis and processing and the communication and the underlying hardware, one of the main interface mainly complete the configuration parameters setting, user commands sending, the graphics and the results of the analysis: data analysis and processing this part is responsible for the parameters according to user's command, will obtain the original data analysis processing, can be used to display results; And the underlying communication part is responsible for the user to control commands and instrument configuration data, and access to hardware upload the raw data used for data analysis, and obtain the state of the equipment data feedback users,
Main interface: mainly refers to the man-machine interface parts, the user through the man-machine interface to complete the instrument's operation, and intuitively get the need analysis, measurement results, this part mainly for the user, so more on interface style design is to meet the user's habits. Because the software is in PC operation, display window should be designed as a whole, in order to suit the user different sizes of display, in addition to design for users to use the mouse to click the soft keyboard and menu. Menu should also be considered and compatibility of the keyboard and enhance the adaptability of software, on the interface display, should guarantee the continuity of graphic display, avoid even the appearance of graphical pause,
The menu interface should include as follows:
(1) the center frequency, the initial frequency. Termination of frequency, frequency step: (2) the reference level, unit conversion, attenuation; (3) the frequency span (span). The SP shaft, zero span; (4) FFT/digital detection mode selection, real-time analysis bandwidth Settings, video filter bandwidth setting, digital detection mode set, scan time. (5) open/close the cursor, single cursor, double the cursor, the cursor to the center frequency (6) trace (maximum trace, the minimum trace, the current trace) : (8) : (7) calibration software reset,
Data analysis and processing: this part is the core of the whole software, it related to the accuracy of software operation, reliability and performance, in the software, data are divided into the following categories: (1) control and configuration data, the user through the man-machine interface of measuring parameters are set, called the sent to the hardware part of the parameter control data; Call for data analysis of parameter configuration data, (2) the receiving data, receive data from the V Ⅺ bus information or state information, (3) shows the result data, used to display graphics and the measured results, (4) read the data. From a peripheral read into the factory calibration data, the data flow diagram is shown in figure 1,
Figure 1 flow chart of data
And the underlying communication: the spectrometer and the underlying communication using VXI bus communication mechanism, VXI communication system hardware and software of the essential interface effect, communication software and hardware is mainly completed by this part, the hardware interface section based on VXI bus, the software should first ensure can communicate and VXI bus, secondly to ensure that the user can set the parameters accurately, real-time, accurate to read out the current state of the information and data, therefore, the need for information on the interface communication to develop a synchro mechanism, so as to guarantee the data transmission will not appear in the process of data, data loss situation,
According to the above three aspects of function, therefore, got Namisoft spectrometer SPC software hierarchy diagram, as shown in figure 2, the software since the item down into three levels: the top is a graphical user interface, it includes graphic display and human-computer interaction platform to provide customers with: centring is data processing analysis layer, it includes the data processing, configuration of control commands, such as: the bottom is associated with the VXI bus information processing. Such as software, hardware interface, interrupt instruction, control commands issued, data read as well as the software and hardware synchronization and so on,
Figure 2 software hierarchy diagram
Namisoft spectrometer SPC software in the process of using two threads: data processing threads and thread processing interface, interface thread involving the parameter configuration. Distributed parameter, graphics, etc., which need to release part variables, space redistribution and initialization. These variables and the data processing threads will have access to, and in between the two threads need to undertake the corresponding protection, adopted in this software is delay and sign the way of combining in the UI thread, need to release variables, take some time delay, this time a data thread running time, and will sign at the entrance of thread of data bits for setting, in this way,
In the interface thread on variable to initialize the data before the thread will not perform specific functions, just interrupt response and
Preliminary scheme of 4
Because of LabWindows/CVI provides VISA function library, very convenient and VXI bus, also provides a powerful signal processing such as FFT transform function. And plenty of map function library interface display and waveform, so Namisoft spectrometer SPC software is easy to realize the function of the above, and displayed on the control interface, all have the corresponding control callback function, which are very convenient,
5 conclusion
This article Namisoft spectrometer upper software design are given, and preliminary realized the change in LabWindows/CVI, has certain engineering value, but should in the research and development of the spectrometer and use still need further research,