Data Dump from the Summit

March 3, 2011

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Once this week’s Munich Satellite Navigation Summit got rolling, the information began flowing — sometimes in bits and pieces, sometimes in a flood.

Russia’s GLONASS program raised the curtain a few inches more on its plans to add CDMA signals to its FDMA satellite, beginning with the GLONASS-K launched last week and continuing on to a full set in orbit by 2020.

At the L1 frequency (1575 MHz) favored by civil service providers, GLONASS will offer a BOC(1,1) — discarding the BOC(2,2) option that had disturbed guardians of U.S. military signals. And, according to GLONASS deputy designer Grigory Stupak, a BPSK(10) signal will eventually appear at the GPS L5 band centered at 1176.45.

Meanwhile, China plans to send up four more Compass/BeiDou-2 satellites this year (cooling down only slightly from 2010’s five launches).

The issue of interference and jamming kept cropping up everywhere, including a panel discussion on spectrum issues and another session organized by the Civil GPS Service Interface Committee’s internation subcommittee.

In the former, Mitre Corporation’s Chris Hegarty noted that a rush to judgment may have accompanied LightSquared’s FCC-augmented fast track to install high-powered terrestrial wireless service next to GPS spectrum. Early tests on the effect of the transmitters may not have been drawn up as carefully as desirable, in part because technical information on LightSquared’s plans has not been forthcoming.

“Until we have some better test data . . . it would be premature to draw any conclusions,” Hegarty said.

Nonetheless, he also pointed out that the risk of interference would probably be greater for high-end, wideband GNSS receivers that track the carrier phase out to signal sidelobes than for inexpensive mass-market receivers whose two-megahertz tracking would be further away from LightSquared. Moreover, the low-cost receivers, which typically operate in multi-RF technology devices (including cellular and Bluetooth signals), already have more filtering in place.