When it comes to the C-band repack, choosing the right filter is imperative. And I’m not just talking about a filter made to the appropriate specifications.
In addition to industry, legislative, and FCC outreach, the now-defunct C-Band Alliance (made up of the major satellite owners) spent large sums of money on research to develop a filter to impede 5G signals.
Going through countless versions and improvements, the CBA’s ultimate goal was the development of a filter that had more than twice the rejection of typical WiMax or TI filters.
The filter would also need to have a sharp rejection of 70db in just 20 MHz. Additionally, filters must produce these results and have a lower insertion loss than any filters it replaced.
The Idea of a Two Step Filter Solution is Born
The plan for the immediate clearing of 120MHz in the top 46 PEAs made the filter development and deployment more complex. In anticipation of the multi-phase clearing, the CBA developed a two-filter solution – the same solution now on the market.
The first, called the “red” filter, is a temporary filter which allows the bandpass of transponders 7 through 24, while rejecting all 5G transmissions of 70db or less, below 3.8 GHz. This filter also rejects transmissions above 4.22 GHz allowing it to replace existing radar -TI filters.
The “blue” filter is the permanent filter solution, allowing the bandpass of transponders 16 through 24 while rejecting all 5G transmissions of 70db or less, below 3.98 GHz. The blue filter also rejects transmissions above 4.22 GHz, allowing it to replace existing radar -TI filters.
Once all cable, television and radio networks are migrated above transponder 16, the red filters will be replaced. All non-filtered downlinks will be outfitted with the blue filter.
But with Every Rule, There is Always and Exception
Not everyone must adhere to a two-tiered red/blue filter solution.
The exception? Radio broadcasters.
Fortunately, SES has moved all commercial radio networks on SES-11 and faith-based networks on SES-2 to the higher transponders, while Intelsat has moved the Public Radio Satellite System to the higher transponders. Because of these early-transition efforts, radio broadcasters can skip the red filter completely and install the blue filter immediately.
TV and Cable MSO are not so fortunate. They likely must start with the red filter in the top 46 PEAs, then move to blue at the appropriate time
Ultimately, the timing of the installation of the blue filter will depend on the services used on the particular antenna and whether all of those services had migrated above 4.0 GHz. For these operators the monitoring of the transition periods to other satellites and higher transponders will be important.
Your Prime Concern
Protecting your C-band transmission is your objective. If you have any doubts or concerns about the blue filter / red filter approach, or the entire process of mitigating 5G interference at your site, please reach out to our team at LinkUp Communications. We’ll be happy to answer any questions you may have, or even handle the C-band filter installation for you.