Perform Radiated & Conducted EMI pre-compliance testing at your
facility up to 1 GHz.
Com-Power PC-114 EMI emissions test system is a ideal solution performing pre-compliance EMC testing from 9 kHz - 1 GHz.. It has essential equipment needed for radiated and conducted EMI emissions measurements. The system includes a spectrum analyzer, antennas, near field probes, a preamplifier, LISN and a non conductive antenna tripod.
Pre-compliance testing in EMC is a commonly used term not easy to define. In general, it implies testing done prior to formal testing for legal compliance. Formal legal compliance is performed at a faqcility designed and equipped with test instrumentation that is fully compliant with the applicable EMC standards. Such facility and instrumentation is capital intensive and can be expensive even to rent and not easily available. Compliance testing is performed per exacting requirements of the Standards and other reference documents adherering to the test methods and last detail. In addition, the test facility may require to be accredited by an accreditation body such as NVLAP, A2LA. Often it is desirable to know prior to compliance testing at such facility, whether a product is close to compliance and also how close. Precompliance testing is specially useful for specifications such as FCC, Part 15, EN 55022 or EN 55011 (CISPR 22 or CISPR11). Pre-compliance testing usually means using the full compliance methods but making a few educated compromises in use of site or equipment to reduce costs and testing time. Here are some benifits of precompliance testing.
- Pre-compliance testing reduces the risk of failing certification.
- Pre-compliance testing allows you to make changes during the design phase.
- Fixing problems after compliance testing is much more expensive and time consuming than fixing them during the design stage.
- Pre-compliance testing can focus on the areas that you are concerned that may cause problems.
- Pre-compliance testing concentrates on identifying solutions rather than finding problems.
- You learn better design techniques to avoid future compliance.problems.
For many years, most commercial test standards required testing on an Open Area Test Site (OATS), but ambients are becoming noisier, especially due to urban expansion and density of transmitters. It is becoming difficult to find a convenient site for an OATS which does not suffer from very high levels of ambient noise. However, pre-compliance testing can achieve results close to compliance testing (depending on the care that is taken). For pre-compliance purposes, it is common to measure at a distance closer than that specified by the standard. Measuring at a closer distance allows the use of smaller test sites, and reduces the impact of ambient signals. A distance correction factor to test data is applied and is justifiable approach for pre-compliance testing.The PC-114 pre-compliance test includes a tripod that can hold the antenna 1 meter in height and can be easily moved to desired test distance.
Measurement uncertainty is not just an accepted concept for EMC compliance testing, but is required by most test standards. The same idea can be applied to determine measurement uncetainties in pre-compliance measurements. Calibration data for all the equipment, cables, and antennas, and normalized site attenuation (NSA) data could be used to determine the measurement uncertainty. When the precompliance data is compared to the compliance data, the uncertainty can be verified. The second way is to use a Comb Generator as reference for’ testing. Take Comb Generator measurement at a test lab with known measurement uncertainties and compare the output to your own site. The differences between the full compliance measurement results and the results obtained on your own site can be used as a correction factor and applied to all measurements made on the pre-compliance site. The PC 114 test system includes a Comb Generator. You can also use the Comb Generator quick measurement before each test to verify repeatability of your test results.
The system also includes a set of Near Field Probes. They do not require any special calibrated test facility and mostly immune to ambient noise. Once you've made your baseline measurements at a EMI Lab to determine failing frequencies, you can take the product back for troubleshoot at the factory. You can experiment with design modifications and repeated near-field measurements to reduce the emission levels. Once the emissions levels successfully reduced, the product can be taken back to the EMI lab for additional compliance measurements. This process will reduce the cost of the overall product compliance process.