I am following up in hopes that some of you smart fellas can offer suggestions. Recap: USAF Calls / emails asking to please identify all 5Ghz emitters operating on or near 5765Mhz and either turn them off or change RF settings to not fall under that category so that RFI to their tracking radar can be reduced. How the radar works: Apparently the radar has multiple modes for tracking / interrogating space-bound craft. In its primary mode, it sends a pulse out on 5672Mhz and then listens for the echo (normal radar operation). It then has another mode, where it sends an interrogation request to the vehicle (satellite / rocket etc) on 5690Mhz and then listens for a reply from the vehicle on 5765Mhz at least for some commercial space launches. DoD military launches etc. also are tracked / interrogated this same way but the listen freq. is something other than 5765Mhz (probably classified). So - the prob the USAF has with RFI is related to hearing the vehicle interrogation response on 5765Mhz - and only while sitting on the pad and the first few seconds of flight. A few seconds after launch, the gigantic parabolic dish (~65db gain on 5Ghz) with its <1deg beam-width has effectively muted out most of the RFI to the sides as it starts to track up. We (and others / cable company etc) worked with them to not only re-program our equipment we felt could be causing RFI to their radar, but to track down others we could see operating equipment centered on their 5765Mhz freq. We were able to continue this process until the radar was able to track / interrogate successfully, from what information I was relayed. We attempted to work with them to be good neighbors and hopefully avoid a situation where we were told all emitters regardless of their effect on the radar (even ones that were not causing them issues) would need to be removed from service in some fashion. Here we are today. The USAF has now decided to create a 60Km zone around each of their tracking radars and request that we not only keep equipment off the 5765Mhz they listen on but everything in the range from 5630 - 5800 Mhz just for good measure. I feel such a blanket request is not reasonable. Cut and past from their DoD Eastern Area Frequency Coordination Office: ===========
Mr WISP, I received the 5 GHz exclusion the range is requesting around their radars (Graphic available here: http://flhsi.com/files/radar.PNG ). The spheres are centered on each radar and have a radius of 60 km. No emitters in these spheres should be allowed to transmit from 5630 - 5800 MHz. I am drafting up a request for public notice to FCC today. When approved, I will let you know. =========== So my question is this.... Is it realistic or even remotely possible this becomes an FCC official rule? I would ask anyone / everyone with a vested interest in this (do you use 5Ghz?) to respond. Thank you for your time. Scott Carullo Technical Operations 855-FLSPEED x102 ---------------------------------------- From: "Scott Carullo" <[email protected]> Sent: Wednesday, May 07, 2014 12:02 PM To: [email protected] Subject: [WISPA] Air Force Base / KSC Launch RFI Question Good morning, We operate between two local Air Force bases and near KSC as well. We were notified recently that the AFB has resorted to using an older radar system that was previously retired due to the newer range radar system catching fire or something to that effect. During the two months or so the repairs are expected to take we have had several space launches scheduled during this window from CCAFS / KSC. The USAF has fired up the old radar and has recently contacted us asking about equipment we have in the area at customer premises. I asked the frequency coordinator what freq their radar uses he said the center freq was 5735 and that it had a very wide bandwidth of like 100 Mhz basically taking the whole ISM/UNII bands worth of spectrum in 5Ghz. So any way to the point... When the USAF shows up and says hey, I see you are using FCC approved equipment in accordance to the FCC spectrum rules the equipment was designed to operate in on freq 5765Mhz - but I need you to turn it off to see if its your equipment we are seeing - and if it is please change freq "preferably below 5600 MHz or above 5850 MHz" (actual quoted request). Obviously we can't accommodate their request for several reasons,most notably because the equipment nor the FCC allows it. I'm just curious if any of you have had anything like this happen and what your response was / would be. I try to be a nice neighbor and work with them any way possible but them trying to shut down the whole 5Ghz non-licensed upper band all our equipment uses (including every other cable and wireline providers wifi 5Ghz equipment in the county) to work their range RFI issues is a bit much and ultimately unattainable within the 3 days they have left prior to launch, IMO. Any insight or suggestions you smart fellers have would be appreciated. I am particularly interested in those more intimate with FCC rules regarding this situation. Do I have to comply? Do they have legal justification to just say - turn it off... etc Thanks... I appreciate your time in responding. Scott Carullo Technical Operations 855-FLSPEED x102
_______________________________________________ Wireless mailing list [email protected] http://lists.wispa.org/mailman/listinfo/wireless
