Radiated And Conducted Signal Sources For Quick EMC Site Measurement EMC labs calibrate their radiated emissions test sites, instrumentation and accessories at least once a year. The calibration procedures are elaborate and time-consuming and may require other specialized test equipment and, in some cases, use of outside services. However, calibration does not prevent equipment malfunction in between calibrations such as damaged receivers, broken cables, poor connections, bad antenna, etc. To improve the measurement accuracy and reliability, you have to check these items at closer intervals. It could be a daily procedure. Performing a full calibration each time is expensive and daily is not practical.
The problems with equipment may not be noticed during EMC testing and incorrect measurement data may result. A quick test using a Comb Generator can avoid this situation. Monitoring a few frequencies regularly on the Comb Generator's broadband radiated output can verify the entire setup quickly and efficiently. Any potential problems with the test setup can be detected before leading to erroneous results. In addition, Comb Generator data gathered over a period of time will provide information about the measurement consistency of the site. This will increase your overall confidence in the measurements made on the site.
The Comb Generator can also be utilized to compare sites. Sometimes, questions arise when EUT emissions test data is not consistent between two test sites. A Comb Generator can be used to compare the sites. Analysis of the gathered data can be invaluable for the identification and mitigation of problems. EMC labs with multiple sites can utilize the Comb Generator as a standard to compare all the sites, increasing overall confidence in the measurement capabilities of the entire test facility. The Comb Generator is self-contained, compact and portable. Unlike other signal sources, it has no external cables that could potentially affect the radiated output. The Comb Generator is powered by internal rechargeable batteries. When the unit is turned on, all harmonics are present up to the maximum frequency of operation.
The Comb Generators use extremely stable components to minimize output variations. The output is uniformly radiated in all directions using monopole antennas. Although Comb Generators were designed for EMC site verifications, it can also be used as a signal source for applications such as the testing of cables, filters, as well as for shielding effectiveness of enclosures. CGC Series Comb Generators To Verify Conducted Emissions Setup The CGC-series Comb Generators were specifically designed for conducted emissions test setups employing Line Impedance Stabilization Networks (LISNs).
LISNs are used for EMC conducted emissions testing according to many worldwide standards, such as FCC Part 15, CISPR/EN, Mil-Std 461, etc. The Comb Generator output port is fitted with a Nema 5-15P plug for direct connection to the LISN EUT power port. By using the Comb Generator for pre-test site verifications, the test engineer can quickly identify any problems with the conducted setup before it is used for EUT measurements. The Application Note AN-104 provides more details on the Comb Generator. Not all test labs are the same, so their requirements may vary significantly. To accommodate a wider range of professional facilities, Com-Power manufactures several comb generators as part of our complete line of EMC radiated and conducted emissions testing equipment.
Several models are available on a number of our products. Generally, the different models perform the same function but may differ with respect to their frequency range of operation or configuration of the assemblies. All Comb Generator models feature convenient battery operation to eliminate power cables that can potentially affect its radiated output. A full charge can deliver up to 18 hours of use, and an automatic shut-off feature disables the output well before the battery voltage drops below the point at which the output would become unstable, thereby preserving the accuracy of your verification measurements.
Com-Power comb generators are lightweight and extremely portable without sacrificing durability. You can easily transport and set them up in remote locations for site comparisons and other EMC testing applications. A custom wooden box conveniently houses all required system components and documentation.
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