It’s not enough to have smart gadgets. Any gadget that wants to attract the attention of consumers must not only be intelligent but also networked. Networking means that there must also be wireless capabilities in the design. Wireless technology has brought many new design possibilities and is beginning to appear in some unusual places. Here are some interesting examples:
· Startup company Velo Labs is developing a solar-powered bicycle lock that can be hung on a Wi-Fi network and sent to the bicycle's smartphone when the motion detector of the lock detects that the bicycle may be stolen. alarm.
· A new intelligent electric toothbrush from Oral-B uses wireless technology to capture information about the user's brushing habits, which is expected to be part of the dental record. This is not a good thing to be judged by consumers.
Of course, the significance is that thousands of products on the shelf, at work or to be imagined will use some kind of low-power wireless function to meet consumer demand, or may become part of the so-called Internet of Things.
The most challenging part of all of these networking needs is that product manufacturers must learn how to add wireless capabilities to their products, but many manufacturers have little RF experience. The most common and practical method is to use pre-packaged WLAN modules directly in the design. It is not surprising that the market for these modules is growing at a double-digit rate and is expected to continue to grow.
Although the use of wireless modules eliminates many technical problems, as shown in Figure 1, many decisions still need to be made. The most critical and difficult task is to ensure that the final product meets complex FCC and international regulatory requirements. Conformance testing is an exhaustive test that takes a long time, and failure to test at this stage of product development can lead to costly redesigns and product launches.
As shown in step 6 of the flowchart, regulatory pre-consistency checks are critical to avoiding these worst-case scenarios. Fortunately, you can use economical, familiar test equipment internally to perform pre-compliance testing to ensure that products with wireless technology achieve a high probability of passing the conformance test for the first time. The goal is to identify potential problems ahead of time and reduce the risk of high test failures during the compliance test phase.
Figure 1. Using a wireless module reduces design complexity, but it also involves many important steps, the most critical of which is to ensure regulatory compliance testing during the design phase.
Since the first wireless transmission, spectrum radiation has been a topic of concern for design engineers. Regulatory agencies around the world have set radiation limit limits that specify the method of measurement for conformance testing. Formal certification must be completed before the product can be sold, must be completed in an independent laboratory, costing between $5,000 and $10,000 per day, and does not include travel and other expenses.
The use of commercially available modules, even those that have been self-certified, does not necessarily make the task of obtaining certification much easier. This is because it is also necessary to test and quality check the fully assembled product. Design issues such as PC board layout, antenna design and orientation or system interaction may result in products failing to meet certification requirements.
By using the instrument, these problems can be easily identified at the design stage. These instruments not only allow designers to perform a full range of pre-compliance tests on their own test benches, but also help designers identify the root cause of problems that may cause a product to fail formal testing.
Pre-conformance testing and overall consistency
Pre-compliance testing is performed after the wireless module system is integrated to identify any problem areas in the design. Pre-compliance testing does not necessarily need to correspond to every international standard, as the goal is simply to identify potential problems and reduce the risk of testing failures during the expensive conformance testing phase. The equipment used does not necessarily include every function and specification required by the standard. If the test results use sufficient margin, the accuracy and dynamic range may be lower than the receiver that meets the standard.
A universal spectrum analyzer with universal filters and detectors is a good starting point for pre-certification and EMI emissions testing. However, for a more complete analysis, it is best to use a WLAN-specific test and authentication solution that supports the full range of tests and analysis required by the IEEE 802.11 standard. Especially when combined with a hybrid domain oscilloscope and combined with vector signal analysis software, such a solution allows designers to correlate events in the time domain with frequency domain analysis to quickly identify issues that can lead to product certification failures. For example, glitch that occurs only during wake-up in the time domain may cause out-of-band radiation in the frequency domain.
A common problem usually involves comparing the quasi-peak (QP) detectors used in comprehensive conformance testing with the simpler peak detectors typically used in pre-conformance testing. In fact, at the beginning of the test, the external laboratory typically scans with a simple peak detector to find problem areas that are above or near the specified limits. For signals that are close to or above the limit, they will perform a quasi-peak measurement.
The quasi-peak detector is a special test method specified by the EMI measurement standard. The quasi-peak detector is used to detect the peak (quasi-peak) after signal envelope weighting. It weights the signal based on signal duration and repetition rate. The higher the frequency of signal generation, the higher the quasi-peak measurement data compared to the incident pulse.
Figure 2: This example illustrates the effect of peak and quasi-peak detection on signals at 8 μs pulse width and 10 ms repetition rate. The quasi-peak is 10.1 dB lower than the peak.
A good rule of thumb is that the quasi-peak will always be less than or equal to the peak detection and will never be greater than the peak detection. Therefore, you can use peak detection for EMI debugging and diagnostics. You don't need to be accurate to the EMI department or lab scan level because they are all relative. If your lab reports using a quasi-peak detector display design that exceeds 3 dB and the peak detection shows more than 6 dB, then you need to implement a patch that reduces the signal by -3 dB or more.
This article is selected from the Electronic Consumers Network August "Wireless Communications Special Issue" Change The World column, please indicate the source! 
Sensor Dustbin Automatic Dustbin
Sensor Dustbin Automatic Dustbin,Automatic Sensor Recycling Dustbin,Stainless Steel Sensor Automatic Dustbin,Automatic Sensor Dustbin
NINGBO ZIXING ELECTRONIC CO.,LTD. , https://www.zixingautobin.com