The rapid development of today's technology has made engineers constantly face new and increasing challenges. The audio and video industry is an area of ​​rapid technological change. There are currently two major trends in this area that merit attention.
First, more and more digital standards are emerging and replacing traditional analog standards. Taking the rapidly developing television standard as an example, traditional analog standards such as NTSC, PAL and SECAM are now being replaced by digital standards such as ATSC in the United States, DVB-T in Europe and ISDB-T in Japan. From March 1, 2007, the United States and Japan will no longer broadcast analog television signals. Although digital television provides viewers with higher quality and better fidelity, it brings more complexity to engineers responsible for design and testing. One of the factors is the variety of audio, video encoding and digital modulation methods. For example: MPEG-2, MPEG-4, H.264/AVC, VC-1, MPEG-2 AAC, AAC-Plus, PCM, AC3 , COFDM, QPSK and QAM. This technical complexity is leading, or requiring engineers to choose an optimal solution to deal with.
Second, with the rapid development of wireless communication technology, audio and video products often integrate wireless functions. People not only need to hear and see, but also need to communicate information wirelessly. Popular commercial products such as mobile phones, PDAs, wireless headphones, and even PS games are representative of the close integration of audio, video, and wireless communications. Of the many different wireless standards that exist in the market at the same time, it is still unclear who is the ultimate winner. Therefore, many devices are designed to be compatible with many different standards. An example of this is the Blackberry developed by Motion. As shown in Figure 1, it supports both GPS, GPRS, Bluetooth and HSCDS.
As a result of the rapid development of technology and the continuous drive of the market, today's test engineers need to apply new technologies to complete new product testing tasks in the shortest possible time. In general, test engineers face the following challenges:
1. The product design is more complex to meet the versatility of the product.
2. The development cycle is shorter and shorter in order to remain competitive and meet the needs of consumers.
3. The test budget is less.
Modular Instruments Traditional benchtop instruments are often more restrictive in terms of flexibility. For example, software processing and user interfaces are defined by the instrument supplier and can only be upgraded by the vendor by changing the firmware, which makes it possible to add new features. Or it may be difficult to complete a custom test. These devices also lack the necessary integration capabilities, such as data stream storage playback or multi-instrument synchronization.
In response to new trends, a software-defined modular test architecture that meets industry standards is becoming the mainstream in the industry, and it has been gradually adopted. Modular instruments have the following advantages:
1. Greater test system flexibility. Can use a variety of application software for product upgrades.
2. Higher test system performance. Significantly increase the throughput of the test system, so that instruments from different instrument suppliers can be closely coordinated and integrated, such as precision DC voltmeters, high-speed analog and digital, and RF signal generation and analysis.
3. Lower test system investment. It can reduce initial capital investment and maintenance costs while supporting multiple test requirements to reuse instruments.
4. Longer test system life. Due to the adoption of industry standards, this will enable technology upgrades to improve performance to suit future testing requirements.
It can be divided into two parts: modular hardware and flexible and powerful software. Users can choose from the modular hardware provided by the DC to RF precision measurement software, including application development environment, such as graphical development platform LabVIEW and Visual C++, can also use the test management software to manage the test process, such as TestStand.
Modular instrumentation achieves cost savings because it takes full advantage of the growth in the semiconductor industry and shares chip costs with other large-scale industries such as consumer electronics, telecommunications, and automotive electronics. With the rapid development of semiconductor technology, NI can use existing commercial ADC/DAC chips to achieve 7-inch DC measurement accuracy up to 2.7GHz RF signal acquisition. In addition to modular hardware, the previously mentioned requirements for synchronization between data streams and instruments are increasing, and therefore a new, more powerful hardware platform is also needed. PXI (PCIeXtensions for Instrumentation), developed in 1997, was introduced as an open industry standard to meet the increasing complexity of instrumentation systems. PXI combines rugged, modular, and compact cPCI features with the addition of special synchronization triggers and software compatibility features. The PXI platform currently supports more than 1,000 modular instruments, including signal generators, high-speed digitizers, high-speed digital I/O, DMMs, RF measurement and generation, switch modules, data acquisition, image acquisition, and motion control, as shown in Figure 3. As shown.
National Instruments offers audio and video analyzers, signal generators, and RF vector signal generators/analyzers. With the associated device drivers and software toolkits, modular instruments and independent instruments have as many functions to perform audio, video, and RF testing. NI's audio analyzers (dynamic signal analyzers) feature 24-bit sampling resolution, differential inputs, and built-in anti-mirroring filters for high-fidelity audio measurements, while high-speed digitizers and signal generators achieve high-quality requirements Video test. Take the audio test as an example. The test content of the audio analyzer includes: amplitude and frequency response, signal quality data, RMS, Gain, signal crosstalk, total harmonic distortion, SINAD, total harmonic distortion plus noise, dynamic range, sound level measurement, etc. .
Application Development Environments (ADEs) such as NI LabVIEW and LabWindows/CVI software play a key role in the test system architecture. The ADEs used to develop test and measurement applications are very versatile. With these tools, test system developers can communicate with multiple instruments, integrate test items, display information, interconnect with other application software into database or chart generation, etc. . The NI LabVIEW Audio and Video Toolkit provides a flexible set of audio and video measurement and analysis functions. Take a video test as an example. A video signal generator of a modular instrument is used. The video pattern icon is set by software. Therefore, a non-ideal signal can be designed to test the robust performance of the product, such as changing the timing and level, or adding Filter, or introduce noise. In addition, through the video signal triggering function built into the high-speed digitizer, video signals can be easily obtained from different consumer electronics products such as set-top boxes, DVDs, and digital video cameras, including different video formats: NTSC, PAL, SECAM, and standard HDTVs. And you can add new test items as needed.
Not only that, based on the LabVIEW development environment, some third-party vendors also provide more powerful and professional test software, such as the Danish-based MicroLEX() company, a member of NI's System Alliance, and its video testing software product VideoMASTER provides a complete Solution, with powerful video analysis capabilities, suitable for analog video signal, composite video signal, S-video and digital high-definition television signal measurement analysis. The VideoMASTER uses the NI 5122 digitizer, a 14-bit, 100M sample rate, and a two-channel digital converter with composite and S-terminal control. For HDTV applications, MicroLEX also offers optional terminal blocks. Figure 4 is a powerful video analysis tool for MicroLEX.
Application Examples The following are two application examples to illustrate how the modular instrument solution to the actual challenges.
A. TV Tuner Test Challenge: Design an automated, cost-saving, time-saving, scalable, full-featured test system for TV tuners.
Solution: Produce a variety of standard RF TV test signals with NI LabVIEW software and NIPXI-5671VSG, use NI-PXI 5122 high-speed digitizer for audio and video parametric testing, and NIM-Series data acquisition card (DAQ) control tuner during testing The status of the work, as well as TestStand software to achieve the upper test management, and complete database interaction and data statistical analysis capabilities. As shown in Figure 5.
Figure 5 TV Tuner Production Line Test This is a typical audio video and RF test application. The test task is to perform an analog tuner line test. By using high-performance modular instruments and flexibly developed software, TV test patterns can be generated at any radio frequency channel, power level, modulation depth, and television signal standard. High-speed digitizers perform high-performance testing of audio and video quality. In the test procedure, 10 non-linear video measurements and 5 audio measurements ensure that each product meets the customer's high measurement quality requirements. Typical video tests include sync and pulse amplitude, chroma/luma gain, differential gain, and differential phase. Typical audio tests include gain, noise level, signal-to-noise ratio, and total harmonic distortion.
The test program can be easily extended to digital television standards through software modifications. In the audio and video signal generation section, the PXI-5671 vector signal generator has a strong software-defined radio capability, with an output frequency range up to 2.7 GHz and 20-MHz real-time broadband. Through software settings, test engineers can set different types of digital encoding and modulation types, and can also increase the distortion of the test signal. In the audio and video signal quality analysis section, the 14-bit, 100-MHz PXI-5122 has a digitizer with built-in video triggering, which can provide 14-bit resolution and a distortion-free range of more than 75 dB for video testing, and its range can surpass today's greatness. Some standard video analyzers. This solution has been adopted by many major television companies at home and abroad.
Compared with the solution of the modular instrument, the test method of the traditional desktop instrument requires many instruments such as an audio/video signal generator, an RF frequency synthesizer, an audio/video analyzer, an oscilloscope and a spectrum analyzer to achieve the test target. Equipment costs are high and testing time is longer. In addition, it is very difficult for traditional instrument architectures to support new TV standards.
B, Bluetooth headset test challenge: Design a comprehensive audio RF automation test platform for Bluetooth headset product terminal testing, while reducing budget and saving test time.
Solution: Use the NIPXI-4461 audio signal analyzer to simulate the generation of audio test signals, collect and receive the analysis audio signals to complete the video test, use the NI-5660 vector signal analyzer to complete the Bluetooth RF test, and use the digital multimeter NI4070 to achieve the basic circuit current and voltage test The entire test system is completed by a PXI chassis system. As shown in Figure 6 and Figure 7.
With the development of communication and computer technology, wireless technology with low cost and low power consumption has rapidly developed and gradually replaced the cable connecting users. Bluetooth has gradually grown up and is widely used. Bluetooth headsets are a good example of a combination of audio and wireless technology. For many headset manufacturers, adding Bluetooth to the headset means that they will need to add a separate Bluetooth test station to the production line, and its expensive price will significantly increase the cost of the test. In the modular instrumentation solution, all audio and Bluetooth terminal functional tests can be unified into one PXI test station, which can significantly reduce the time and cost.
Audio tests for headphones include Tx/Rx amplitude-frequency response, distortion, noise, isolation, and sensitivity. Typical RF tests include Bluetooth initial carrier frequency tolerance, RF output power, and sensitivity. NI provided this solution to a well-known domestic headset company, which reduced the test time by 40% and saved 30% of the cost.
Summary In the face of today's audio and video testing, increased product functionality complexity, reduced development cycles, and reduced budgets, engineers need to evaluate their current strategies and find better solutions to increase efficiency and reduce costs. Designing a new generation of audio and video test systems requires consideration of factors such as increased system flexibility, improved measurement performance, high throughput, reduced test system costs, and extended system life.
Modular hardware platforms are built on a widely adopted industry-standard platform. For example, PXI allows engineers to develop scalable test systems and tightly integrate instruments from different instrument vendors. In addition, it allows Engineers integrate current equipment investments to reduce initial investment costs. Software-defined measurement methods leverage the latest PC technologies such as multiple core processors and PCI Express. Next-generation test systems can significantly improve data throughput and can be scaled to meet the needs of different product upgrades. So the software-defined modular test architecture is an ideal solution.
First, more and more digital standards are emerging and replacing traditional analog standards. Taking the rapidly developing television standard as an example, traditional analog standards such as NTSC, PAL and SECAM are now being replaced by digital standards such as ATSC in the United States, DVB-T in Europe and ISDB-T in Japan. From March 1, 2007, the United States and Japan will no longer broadcast analog television signals. Although digital television provides viewers with higher quality and better fidelity, it brings more complexity to engineers responsible for design and testing. One of the factors is the variety of audio, video encoding and digital modulation methods. For example: MPEG-2, MPEG-4, H.264/AVC, VC-1, MPEG-2 AAC, AAC-Plus, PCM, AC3 , COFDM, QPSK and QAM. This technical complexity is leading, or requiring engineers to choose an optimal solution to deal with.
Second, with the rapid development of wireless communication technology, audio and video products often integrate wireless functions. People not only need to hear and see, but also need to communicate information wirelessly. Popular commercial products such as mobile phones, PDAs, wireless headphones, and even PS games are representative of the close integration of audio, video, and wireless communications. Of the many different wireless standards that exist in the market at the same time, it is still unclear who is the ultimate winner. Therefore, many devices are designed to be compatible with many different standards. An example of this is the Blackberry developed by Motion. As shown in Figure 1, it supports both GPS, GPRS, Bluetooth and HSCDS.
As a result of the rapid development of technology and the continuous drive of the market, today's test engineers need to apply new technologies to complete new product testing tasks in the shortest possible time. In general, test engineers face the following challenges:
1. The product design is more complex to meet the versatility of the product.
2. The development cycle is shorter and shorter in order to remain competitive and meet the needs of consumers.
3. The test budget is less.
Modular Instruments Traditional benchtop instruments are often more restrictive in terms of flexibility. For example, software processing and user interfaces are defined by the instrument supplier and can only be upgraded by the vendor by changing the firmware, which makes it possible to add new features. Or it may be difficult to complete a custom test. These devices also lack the necessary integration capabilities, such as data stream storage playback or multi-instrument synchronization.
In response to new trends, a software-defined modular test architecture that meets industry standards is becoming the mainstream in the industry, and it has been gradually adopted. Modular instruments have the following advantages:
1. Greater test system flexibility. Can use a variety of application software for product upgrades.
2. Higher test system performance. Significantly increase the throughput of the test system, so that instruments from different instrument suppliers can be closely coordinated and integrated, such as precision DC voltmeters, high-speed analog and digital, and RF signal generation and analysis.
3. Lower test system investment. It can reduce initial capital investment and maintenance costs while supporting multiple test requirements to reuse instruments.
4. Longer test system life. Due to the adoption of industry standards, this will enable technology upgrades to improve performance to suit future testing requirements.
It can be divided into two parts: modular hardware and flexible and powerful software. Users can choose from the modular hardware provided by the DC to RF precision measurement software, including application development environment, such as graphical development platform LabVIEW and Visual C++, can also use the test management software to manage the test process, such as TestStand.
Modular instrumentation achieves cost savings because it takes full advantage of the growth in the semiconductor industry and shares chip costs with other large-scale industries such as consumer electronics, telecommunications, and automotive electronics. With the rapid development of semiconductor technology, NI can use existing commercial ADC/DAC chips to achieve 7-inch DC measurement accuracy up to 2.7GHz RF signal acquisition. In addition to modular hardware, the previously mentioned requirements for synchronization between data streams and instruments are increasing, and therefore a new, more powerful hardware platform is also needed. PXI (PCIeXtensions for Instrumentation), developed in 1997, was introduced as an open industry standard to meet the increasing complexity of instrumentation systems. PXI combines rugged, modular, and compact cPCI features with the addition of special synchronization triggers and software compatibility features. The PXI platform currently supports more than 1,000 modular instruments, including signal generators, high-speed digitizers, high-speed digital I/O, DMMs, RF measurement and generation, switch modules, data acquisition, image acquisition, and motion control, as shown in Figure 3. As shown.
National Instruments offers audio and video analyzers, signal generators, and RF vector signal generators/analyzers. With the associated device drivers and software toolkits, modular instruments and independent instruments have as many functions to perform audio, video, and RF testing. NI's audio analyzers (dynamic signal analyzers) feature 24-bit sampling resolution, differential inputs, and built-in anti-mirroring filters for high-fidelity audio measurements, while high-speed digitizers and signal generators achieve high-quality requirements Video test. Take the audio test as an example. The test content of the audio analyzer includes: amplitude and frequency response, signal quality data, RMS, Gain, signal crosstalk, total harmonic distortion, SINAD, total harmonic distortion plus noise, dynamic range, sound level measurement, etc. .
Application Development Environments (ADEs) such as NI LabVIEW and LabWindows/CVI software play a key role in the test system architecture. The ADEs used to develop test and measurement applications are very versatile. With these tools, test system developers can communicate with multiple instruments, integrate test items, display information, interconnect with other application software into database or chart generation, etc. . The NI LabVIEW Audio and Video Toolkit provides a flexible set of audio and video measurement and analysis functions. Take a video test as an example. A video signal generator of a modular instrument is used. The video pattern icon is set by software. Therefore, a non-ideal signal can be designed to test the robust performance of the product, such as changing the timing and level, or adding Filter, or introduce noise. In addition, through the video signal triggering function built into the high-speed digitizer, video signals can be easily obtained from different consumer electronics products such as set-top boxes, DVDs, and digital video cameras, including different video formats: NTSC, PAL, SECAM, and standard HDTVs. And you can add new test items as needed.
Not only that, based on the LabVIEW development environment, some third-party vendors also provide more powerful and professional test software, such as the Danish-based MicroLEX() company, a member of NI's System Alliance, and its video testing software product VideoMASTER provides a complete Solution, with powerful video analysis capabilities, suitable for analog video signal, composite video signal, S-video and digital high-definition television signal measurement analysis. The VideoMASTER uses the NI 5122 digitizer, a 14-bit, 100M sample rate, and a two-channel digital converter with composite and S-terminal control. For HDTV applications, MicroLEX also offers optional terminal blocks. Figure 4 is a powerful video analysis tool for MicroLEX.
Application Examples The following are two application examples to illustrate how the modular instrument solution to the actual challenges.
A. TV Tuner Test Challenge: Design an automated, cost-saving, time-saving, scalable, full-featured test system for TV tuners.
Solution: Produce a variety of standard RF TV test signals with NI LabVIEW software and NIPXI-5671VSG, use NI-PXI 5122 high-speed digitizer for audio and video parametric testing, and NIM-Series data acquisition card (DAQ) control tuner during testing The status of the work, as well as TestStand software to achieve the upper test management, and complete database interaction and data statistical analysis capabilities. As shown in Figure 5.
Figure 5 TV Tuner Production Line Test This is a typical audio video and RF test application. The test task is to perform an analog tuner line test. By using high-performance modular instruments and flexibly developed software, TV test patterns can be generated at any radio frequency channel, power level, modulation depth, and television signal standard. High-speed digitizers perform high-performance testing of audio and video quality. In the test procedure, 10 non-linear video measurements and 5 audio measurements ensure that each product meets the customer's high measurement quality requirements. Typical video tests include sync and pulse amplitude, chroma/luma gain, differential gain, and differential phase. Typical audio tests include gain, noise level, signal-to-noise ratio, and total harmonic distortion.
The test program can be easily extended to digital television standards through software modifications. In the audio and video signal generation section, the PXI-5671 vector signal generator has a strong software-defined radio capability, with an output frequency range up to 2.7 GHz and 20-MHz real-time broadband. Through software settings, test engineers can set different types of digital encoding and modulation types, and can also increase the distortion of the test signal. In the audio and video signal quality analysis section, the 14-bit, 100-MHz PXI-5122 has a digitizer with built-in video triggering, which can provide 14-bit resolution and a distortion-free range of more than 75 dB for video testing, and its range can surpass today's greatness. Some standard video analyzers. This solution has been adopted by many major television companies at home and abroad.
Compared with the solution of the modular instrument, the test method of the traditional desktop instrument requires many instruments such as an audio/video signal generator, an RF frequency synthesizer, an audio/video analyzer, an oscilloscope and a spectrum analyzer to achieve the test target. Equipment costs are high and testing time is longer. In addition, it is very difficult for traditional instrument architectures to support new TV standards.
B, Bluetooth headset test challenge: Design a comprehensive audio RF automation test platform for Bluetooth headset product terminal testing, while reducing budget and saving test time.
Solution: Use the NIPXI-4461 audio signal analyzer to simulate the generation of audio test signals, collect and receive the analysis audio signals to complete the video test, use the NI-5660 vector signal analyzer to complete the Bluetooth RF test, and use the digital multimeter NI4070 to achieve the basic circuit current and voltage test The entire test system is completed by a PXI chassis system. As shown in Figure 6 and Figure 7.
With the development of communication and computer technology, wireless technology with low cost and low power consumption has rapidly developed and gradually replaced the cable connecting users. Bluetooth has gradually grown up and is widely used. Bluetooth headsets are a good example of a combination of audio and wireless technology. For many headset manufacturers, adding Bluetooth to the headset means that they will need to add a separate Bluetooth test station to the production line, and its expensive price will significantly increase the cost of the test. In the modular instrumentation solution, all audio and Bluetooth terminal functional tests can be unified into one PXI test station, which can significantly reduce the time and cost.
Audio tests for headphones include Tx/Rx amplitude-frequency response, distortion, noise, isolation, and sensitivity. Typical RF tests include Bluetooth initial carrier frequency tolerance, RF output power, and sensitivity. NI provided this solution to a well-known domestic headset company, which reduced the test time by 40% and saved 30% of the cost.
Summary In the face of today's audio and video testing, increased product functionality complexity, reduced development cycles, and reduced budgets, engineers need to evaluate their current strategies and find better solutions to increase efficiency and reduce costs. Designing a new generation of audio and video test systems requires consideration of factors such as increased system flexibility, improved measurement performance, high throughput, reduced test system costs, and extended system life.
Modular hardware platforms are built on a widely adopted industry-standard platform. For example, PXI allows engineers to develop scalable test systems and tightly integrate instruments from different instrument vendors. In addition, it allows Engineers integrate current equipment investments to reduce initial investment costs. Software-defined measurement methods leverage the latest PC technologies such as multiple core processors and PCI Express. Next-generation test systems can significantly improve data throughput and can be scaled to meet the needs of different product upgrades. So the software-defined modular test architecture is an ideal solution.
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