QPI Active Filtering for Improved EMI performance
for Thermal Imaging Camera (EN60945 Compliant)
Modern thermal imaging technology is capable of both sensing infrared radiation and then converting the thermal energy into an image for a video output. The video can then be used to help pilots and drivers navigate and detect objects in the dark, and in fog, or detect warm objects against a cooler background when it is completely dark (such as a cloudy, moonless night). Thermal imaging is often used in naval vessels, fixed-wing aircraft, helicopters, and armored fighting vehicles. In warfare thermal imaging technology provides three significant advantages. First, the imager itself is nearly impossible for the enemy to detect, as it detects energy that's already there, and doesn't have to send out any energy of its own. Second, it sees heat, which is hard to camouflage. Thirdly, thermal imaging systems can see through smoke, fog, haze, and other atmospheric obscurants better than a visible light camera can.
A Picor customer was designing a thermal imaging device for video over IP application. And due to the nature of the application, it needed to comply with EN60945 EMI limits, which is a compliance standard which applies to Maritime Navigation and Radio Communication Equipment and Systems. The compliance limit on this standard is 10dB lower than the Class B limit for frequencies above 5 MHz, which creates a greater challenge for an EMI designer.
The application required a filter compatible with a 24 V input converter, at a power level of less than 150 W. For this application, the designer was looking to replace a passive discrete design with a Picor QPI-3LZ filter. The customer requested a QPI evaluation board which allowed them to evaluate the performance of the filter in a matter of days rather than weeks. The evaluation demonstrated that the QPI filter was able to provide a greater margin of compliance than the passive design both at higher frequencies, as well as the lower frequencies. Another important factor in selecting the QPI filter was the size. The small size (1” x 1”) of the QPI filter made it possible to easily fit the device within the same area that had previously been allocated for a passive design.
Made in USA
