Attachment technical

technical

SUBMISSION FOR THE RECORD submitted by ViaSat

technical annex

2008-01-09

This document pretains to SAT-MOD-20071204-00168 for Modification on a Satellite Space Stations filing.

IBFS_SATMOD2007120400168_615860

555 Eleventh Street, N.W., Suite 1000 Washington, D.C. 20004-1304 Tel: + I ,202.637.2200 Fax: + I .202.637.2201 www.Iw.com FIRM I AFFILIATE OFFICES L AT H A M& W AT K I N 5 LLP Barcelona New Jersey Brussels New York Chicago Northern Virginia Frankfurt Orange County Hamburg Paris January 9,2008 Hong Kong San Diego London San Francisco Los Angeles Shanghai Madrid Silicon Valley Marlene H. Dortch Milan Singapore Secretary Moscow Tokyo Munich Washington, D.C. Federal Communications Commission 445 12th Street, SW Washington, DC 20554 Attn: Andrea Kelly, International Bureau Kathryn Medley, International Bureau Re: ViaSat, Inc. Application to Modify Space Station License (S2737) FCC File No. SAT-MOD-2007 1204-00168 Dear Ms. Dortch: On December 4,20007, ViaSat, Inc. (“Viasat”) filed the above-referenced Application to modify its existing license to launch and operate a communications satellite (“VIASAT-KA 1”) at the 77.3” W.L. orbital location to provide fixed satellite service. Section 6.2 of the Technical Annex to Exhibit C of the Application addresses two-degree compatibility of VIASAT-KA 1 transmissions in the 28.1-28.35 GHz band, which is available for uplink transmissions only. While Section 6.2 properly includes a C/I calculation for the uplink direction, it also includes a superfluous C/I calculation for the downlink direction. The inclusion of this downlink C/I calculation has the potential to cause confwsion. Accordingly, ViaSat respectfully requests that the text included in Attachment A be substituted in place of the version of Section 6.2 included in the Technical Annex. ViaSat also requests that this submission be uploaded into the International Bureau Electronic Filing System (“IBFS”) and associated with FCC File No. SAT- MOD-2007 1204-00168. Please contact the undersigned should you have any questions in this matter Respectful1yAubmitted, John fJanka Elizabeth R. Park Jarrett S. Taubman Counsel for ViaSat, Inc.

Attachment A: Substitute Text for Section 6.2 of Technical Annex 6.2 Two-Degree Compatibility Demonstration for the 28.1-28.35 GHz Band Currently there are no operational GSO Ka-band satellites that use the 28.1-28.35 GHz band within two-degrees of the 77.3" W.L. location, nor are there any pending applications before the Commission for use of the 28.1-28.35 GHz band by a GSO satellite within this arc. In order to demonstrate two-degree compatibility, the 125 MHz carrier contained in Table 4-1 has been assumed as both the wanted and victim carriers. Since the assumed uplink input power densities for both the wanted and victim carriers are therefore identical, the uplink C/I is simply the difference between the on-axis gain and the off-axis gain. The uplink C/I margin is calculated as follows: ( C / I ) ~ ~ ~=-G,~, , , - (29-25*iOg(e)) - C/N - 12.2 = 64.4 - (29-25*10g(2)) - 6.1 - 12.2 = 24.6 dB The calculated margin is quite large and clearly demonstrates two-degree compatibility. The large margin is not surprising given the size of the gateway antennas. Note the above calculation did not take into account any advantage for topocentric-to-geocentric conversion.


Document Created: 2008-01-15 11:11:40
Document Modified: 2008-01-15 11:11:40
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