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<<< Back to February 14 - Issue 201
February 21, 2000 - Issue 202 Final Edition
- DTV - Brazil Releases Detailed DTV Test Report
- ANATEL, the Brazilian National Agency of Telecommunications, has released its full report on its testing of the ATSC, DVB-T and ISDB terrestrial digital TV modulation systems. See the February 14, 2000 RF Current for information on the testing and the preliminary results. The full report is available, in Portuguese at http://www.anatel.gov.br/index.asp?link=/biblioteca/publicacao/relatorio_tvdigital_cp216.htm. The web page links to over twenty report sections in Adobe Acrobat Format (PDF). See last week's RF Current article for a link to a Portuguese to English translator.
Although the ANATEL press release and preliminary report indicated the ATSC 8-VSB system would have to improve before it could be considered, the field test results actually showed 8-VSB performing better than the Sinclair and Motorola tests in the U.S. indicated. These results, however, were not obtained with the new Nxtwave and Motorola 8-VSB demodulators but with a professional receiver from Zenith. In the report, Figura 8: Percentual de recepção nos pontos críticos in Capítulo V - Análise dos Resultados, shows reception was possible in 50 percent of the situations with ATSC using the Zenith receiver, in none of the tests with the Nxtwave or Motorola chips, in only 15 percent of the situations using DVB-T 2k, and in 100 percent of the situations when DVB-T 8k or ISDB was used. The ATSC 8-VSB system retained its 4-dB advantage in C/N in the lab tests. In field tests, the advantage dipped to as small as 2.7 dB when the "A-chip" was compared with DVB-T and was not an issue in the "intermediário", "indoor" and SFN tests where the ATSC system did not work at all. The best case ATSC required C/N was 16.0 dB for the "outdoor" tests. The "A Chip" was one dB worse. The C/N required for DVB ranged from 19.7 dB outdoors to 23 dB or more indoors and in the intermediate range to 32.4 dB for the SFN configuration (Single Frequency Network).
In multipath testing, the 8k carrier COFDM DVB-T modulation method was the clear winner. While DVB-T 2k modulation was better than 8-VSB, Figure 3 in the Análise dos Resultados shows much less improvement than DVB-T 8k. While the Japanese ISDB modulation method based on COFDM performed better than DVB-T 2k in some tests, it required over 2 dB more receive signal level than DVB-T and over 3 dB more signal than the ATSC 8-VSB. Peak power requirements were the lowest for ATSC, at 6.66 dB above average, and worst for ISDB at 8.54 dB above average.
All proponents can find something to support their argument in the report. Overall, it appears DVB-T 8k did the best, with ISDB a close second and and DVB-T 2k and ATSC 8-VSB in more distant third and fourth places. Before rushing to judgement, at least review Capítulo V - Análise dos Resultados to get an overview of the results of the testing. In Figura 6: Relação eco-portadora em função da velocidade, the relative performance of the four systems is easily compared.
- FCC Satellite Applications (Feb. 18)
- In its February 16 Satellite Applications Accepted for Filing (pdf), the FCC's International Bureau listed two applications requesting consent for a transfer of certain satellite authorizations from Columbia Communications Corporation to CCC Merger Sub, Inc., which is a wholly-owned subsidiary of GE American Communications (GE Americom). The applications requested transfer of Columbia's C-band license at 37.5 degrees West Longitude (WL), a C-band license at 47 degrees WL, and a license to construct, launch and operate a C-band satellite at 47 degrees WL and a hybrid C/Ku-band satellite at 172 degrees East Longitude. If the FCC approves the merger, Columbia would become a wholly-owned subsidiary of GE-Americom. The merger would give GE Americom an international presence it now lacks.
There are several complex issues surrounding the merger, including Columbia's requests to add Ku-band to some of its C-band only satellites. See the Adobe Acrobat document above for complete details.
In the February 18 Satellite Applications Accepted for Filing, there is an application from Colubmia Communications requesting extension of its construction milestone for its new C-band satellite at 47 degrees WL until two weeks after the FCC acts on the pending application to transfer control of Columbia to GE Americom.
In other applications, Eutelsat asked the FCC to add three of its satellites to the "Permitted Space Station" list created earlier by the FCC. Orbital Communications Corporation (ORBCOMM) requested a Special Temporary Authority "to commerce commercial operation using its recently launched plane of satelllite prior to action on Orbcomm's pending request for modification."
- SATELLITE - Microsoft And Gilat Announce Plans for Two-Way VSAT High-Speed Internet Access Service (Feb. 16)
- People who desire high speed internet access may have another option if a new announced by Gilat Satellite Networks LTD and Microsoft performs as planned. The Gilat Press Release said its Gilat-To-Home satellite service provides a two-way, always-on connection with " Internet access speeds up to 10 times faster then normal modem speeds, with burst rate considerably higher." This implies an average speed between 240kbps and 530kbps if today's modem technology was used for the comparison. Because the service is two way, a telephone connection is not required. The system will use "very small aperture terminal" or VSAT dishes for the service. Typically these are one meter or less in size.
Gilat-To-Home will use Microsft's MSN for internet access as part of a complete hardware and service package. The MSN Internet Access satellite offering will be available directly from Microsoft and through retailers such as Tandy Corporation's RadioShacks. Gilat said trials of the 2-way satellite service have begun and wide availability is expected by the end of 2000. The Press Release did not mention a price for the hardware and service.
- OTHER Items of Interest
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