RF CURRENT

Welcome to RF Current, a weekly electronic newsletter focusing on Broadcast technical and F.C.C. related issues. This newsletter is part of The RF Page @ www.transmitter.com, a web site devoted to TV Broadcast RF engineering. For more information see the What is... guide to the R.F. Page site.

Issues are dated each Monday, although recently I've needed an extra day(week) or two to complete each issue. Articles may be posted earlier if time permits or if there is a major, breaking story.

<<< Back to August 28 - Issue 229

September 4, 2000 - Issue 230 Final Edition

FCC Satellite Applications Accepted for Filing (Sept. 1)
The FCC International Bureau's Satellite Policy Branch listed applications accepted for filng. Astrolink filed an amendment to its application for modification of its Ka-band satellite system requesting authority to performace TT&C operations in extended C-band frequencies. Astrolink also seeks a limited waiver of the extended C-band freeze to permit the licensing of a single earth station to perform the TT&C functions in the requested extended C-band frequencies.

PanAmSat requested Special Temporary Authority to conduct in orbit testing of the PAS-1R C/Ku-band hydbrid satellite at 61.5 degrees West Longitude for up to 90 days, commencing at launch.

Additional details are available in Satellite Policy Branch Report No. SAT-00054. This link requires a PDF reader to view the page.

FCC Allows Part 15 Spread Sprectrum 2.4 GHz Hopping Channels up to 5 MHz (Aug. 31)
In a controversial decision (see the EE Times article below in Other Items), the FCC amended Part 15 of its rules for frequency hopping spread spectrum devices in the 2.4 GHz band (2400 - 2483.5 MHz) to allow hopping channels with a wider bandwidth. The FCC's Report and Order said, "The wider bandwidths will permit these systems to provide higher data speeds, thereby enabling the development of new and improved consumer products such as wireless computer local area networks and wireless cable modems."

Supporters of direct sequence spread spectrum devices generally opposed the modification of the rules. The change in the rules is simple. Section 15.247 of the FCC Rules limits the power of frequency hopping spread spectrum systems to 1 Watt in the 2.4 GHz band. Systems are required to use a minimum of 75 non-overlapping hopping channels and each channel cannot have a 20 dB bandwidth greater than 1 MHz. The FCC also requires the average time of occupancy on any frequency be limited to 0.4 seconds or less in any 30 second period.

Under the amended rules, power and occupancy time are reduced as channel bandwidth and the number of hopping channels are reduced. The power is reduced proportionately as bandwidth is increased. For example, a system with a hopping channel with a 5 MHz bandwidth (5x that authorized earlier) is limited to an output power 1/5 of that authorized for a 1 MHz channel. For the 5 MHz hopping channel, the output power limit is limited to 200 mW. For any 1 MHz portion of the spectrum, the occupancy time cannot exceed the 0.4 second in 30 seconds limit. For a system with seventy five 5 MHz wide channels, the FCC said the channel occupancy time could be no greater than 0.02 second per hop, assuming each of the 75 hopping channels would be used at least once during a 1.5 second period.

The new Section 15.247 paragraph (a)(1)(iii) states: "Frequency hopping systems in the 2400 - 2483.5 MHz band may utilize hopping channels whose 20 dB bandwidth is greater than 1 MHz provided the systems use at least 15 non-overlapping channels. The total span of hopping channels shall be at least 75 MHz. The average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 30 second period."

Refer to the First Report And Order, ET Docket 99-231 for more information.

DTV - CEA Defines Digital TV (Aug. 31)
The Consumer Electronics Association (CEA) announced more detailed definitions for DTV products. The variety of DTV monitors, set-top boxes and receivers with DTV tuners led CEAb to categorize DTV products as HDTV - High Definition Television; EDTV - Enhanced Definition Television; and SDTV - Standard Definition Television. These three categories are applied to monitors, tuners and receivers. The CEA Board agreed the new definitions should be used by all manufacturers and retailers, replacing generic terms such as "DTV-ready" or "HDTV-ready".

Receivers and tuners in all three categories must be able to receive ATSC terrestrial digital transmisisons and decode all ATSC Table 3 video formats. HDTV and EDTV receivers and tuners must be able to receive and reproduce and/or output Dolby Digital Audio. SDTV receivers must be able to receive and reproduce usable audio. SDTV tuners must receive and reproduce, and/or output Dolby Digital Audio.

HDTV displays must have active vertical scanning lines of 720p (progressive), 1080i (interlaced), or greater and be capble of displaying a 16:9 image. EDTV displays must have active vertical scanning lines of 480p (progressive) or higher. SDTV applies to displays with active vertical scanning lines less than 480p. Aspect ratios are not specified for EDTV and SDTV displays.

HDTV tuners must output ATSC Table 3 720p and 1080i/p formats in the form of HD with minimum active vertical scanning lines of 720p, 1080i, or higher. They may also output HD formats converted to other formats or be a digital bitsream with the full resolution of the broadcast signal. EDTV tuners must be able to output ATSC Table 3 720p, 1080i/p and 480p formats with minimum active vertical scanning lines of 480p or provide a digital bitsream output capable of transporting 480p. The ATSC Table 3 480i format can be output at 480i. SDTV tuners output the ATSC Table 3 formats as NTSC.

More information on the new definitions may be found in the Press Release at the CEA News Room. Also see the TWICE article linked to in Other Items below.

SATELLITE - Satmex Solidaridad 1 Satellite Fails (Aug. 30)
Satmex announced its Solidaridad 1 satellite has ceased operation and is now considered irretrievably lost. The satellite was built by Hughes Space and Communications and launched in 1994. It experienced a failure of its primary control processor in April 1999 and had been operating on its back-up processor. The back-up processor failed Sunday, August 27. Engineers from both Satmex and Hughes continued efforts to recover the spacecraft, but by Tuesday evening the satellite's battery power supply was exhausted and the satellite was declared a full loss.

Satmex migrated Solidaridad 1's customers to other Satmex satellites and to satellites operated by Satmex's partner, Loral Skynet. Satmex is a member of the Loral Global Alliance. As of Wednesday, August 30, Loral said 86 percent of all utilized capacity and 95 percent of all users had been successfully migrated or assigned to these other satellites. The satellite was insured for US$250 million. Satmex intends to apply the insurance proceeds toward the construction and launch of a replacement satellite as well as for debt service, according to the Loral press release.

The failure brought to mind the failure of another Hughes satellite in May, 1998, when both of Galaxy IV's spacecraft control processors failed. Similar problems were later reported on other Hughes satellites. (See RF Current - May 1998.) Information on the Solidaridad 1 failure was obtained from the Loral press release Satmex's Solidarid 1 Satellite Lost.

INDUSTRY - Acrodyne Files Appeal to NASDAQ's Notification of Delisting (Aug. 29)
In a Press Release issued today, Acrodyne said it was nearing completion on its comprehensive review of the financial status of the Company. It expects to file its Form 10-Q for the quarter ended June 30, 2000 on or before September 18, 2000. Nat Ostroff, chairman and interim CEO of Acrodyne Communications, Inc., said, "We made the decision to pursue this intensive review course of action with the interests of all of our shareholders in mind. It has taken more time than originally anticipated to complete this inventory and financial review process."

In its August 14, 2000 press release Acrodyne Announces Deferral of Second Quarter 10Q Filng, Acrodyne said it "has determined that errors exist in the audited 1999 financial statements included in the Company's annual report on Form 10-K, and the interim financial statements included in the Company's report on Form 10-Q for the quarter ended March 31, 2000." The press release said, "The errors discovered to date relate solely to the Company's traditional analog product line. The Company believes that the errors will not affect its ability to support its customer base and vendor relationships, its distribution of the Rohde and Schwarz transmitters or the development of its new Quantum transmitter product line."

Because of the delay in the 10-Q filing, NASDAQ sent Acrodyne a delisting notice. Acrodyne has filed an appeal seeking review of the notice. Acrodyne's securities will not be delisted pending resolution of the appeal. Two shareholder class action lawsuits have been filed regarding issues in the press release. Nat Ostroff commented on the health of company, saying, "We have been talking with our customers and vendors throughout this process and we are strongly encouraged by their interest in our Quantum digital transmitter product line. This line is on target to begin shipping in the fourth quarter."

OTHER Items of Interest

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