Commercial Wireless Solutions Week Case Study: API's Filter Mitigates BAS Interference for Major Telecom Company

by Jaymie Murray 16. February 2015 15:27

Over the years, API Technologies has built a solid reputation among wireless service providers by solving even the most challenging interference issues. API's range of filter designs for the telecom industry offer a host of customizable topologies and models that can be modified and adapted to meet the specific needs of the customer. One such customer, a major telecom company, struggled with significant and persistent issues concerning Broadcast Auxiliary Service (BAS) interference in Electronic News Gathering (ENG) trucks. After several other companies tried and failed to rectify the situation, the telecom company engaged API Technologies. The result? Find out in this case study:

Case Study: API Technologies’ Filter Mitigates BAS Interference for Major Telecom Company Challenge A major telecommunications company that provides wireless, internet, and digital television services was experiencing a persistent and complex issue with television Broadcast Auxiliary Service (BAS) interference. One particular major network affiliate in a large metropolitan area was having severe problems with their Electronic News Gathering (ENG) trucks. The frequencies used by these trucks to transmit news video back to the station were experiencing severe interference problems. The interference was so severe that the company had to contact several filter manufacturers to attempt to mitigate the situation, to no avail. However, when they contacted API Technologies, a company that had previously successfully solved a similar problem by using an Advanced Wireless System (AWS) and Broadcast Auxiliary Service (BAS) interference mitigation filter (CMN719 2.1 GHz Band Reject Filter), API was confident that they could solve this issue. Solution After only three months of design iterations and lab calculations, API’s first filter prototypes were sent out for field testing. While a significant improvement was seen, it was not quite enough to allow the BAS receivers to function properly. The prototype filters were then sent back to API, minor re-tuning adjustments were made, and the units were shipped back to the customer, all within the span of one week. The interference problem was identified as Out Of Band Emissions (OOBE) and was remedied with API’s customized CMN719 2.1 GHz Band Reject Filter. Result Within a month the telecom company had sent out a directive to all of their regional offices which described this problem, API’s filter solution, and the requirement to install the filters at all cellular sites that may be impacting the BAS receive frequencies. Within only eight months, affiliates in nine different regions ordered over a thousand filters to finally solve their BAS interference issues.After solving this major issue for this customer, it brought to light an interesting possibility: if this telecom provider was experiencing this problem, there is a good chance that television networks and their affiliates around the country are being affected by OOBE without even realizing it or knowing that it can be easily rectified using API’s CMN719 2.1 GHz Band Reject Filter. API's CMN719 2.1 GHz Band Reject Filter API’s reputation for designing and delivering some of today’s most challenging bandreject filters is the reason why engineers trust us with their designs. Choosing from a wide assortment of topologies, including lumped element, cavity, ceramic, waveguide and suspended substrate, our engineers match the optimum topology to your requirements. The customizable CMN719 2.1 GHz Band Reject Filter features 2030 to 2109.5 MHz passband, 1.60 dB max insertion loss, 16 dB min return loss, and 60 dB min    2110.6 – 2121.5 MHz rejection. To learn more about this model and API's other filters for wireless communications, visit

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RF/Microwave & Microelectronics

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