Other Satellite Navigation Systems - Understanding GPS: Principles and Applications - page 628

Designs for the antenna and power amplifiers for both the communications and
navigation services must address the changes in gain and footprint associated
with significant eccentricity in the planned elliptical orbits. At the time of this writ-
ing, plans for the technical solution to these related problems were not available
in the public domain. With plans for mobile communications and audio/video
broadcast in S-band, data services and TT&C in the K u -band, and navigation sig-
nals in L-band, each QZSS spacecraft will need to carry an impressive array of
antennas [77].

11.3.6 Ground Support
Ideas concerning the satellite signal-monitoring stations essential to GPS aug-
mentation service are three tiered and exceedingly complex. They will, where possi-
ble, draw on existing resources and on occasion serve dual or multiple functions.
Monitoring of the overall satellite navigation service in Japan will be provided by
1,200 stations with the capability to receive GPS, the augmentation signals from
QZSS, and any future independent ranging signal that may be provided by QZSS
satellites in the future. These sites already exist in part, in association with a network
of locations for tracking GPS carrier phase under Japan's Geographical Survey
Institute [72].

11.3.7 User Equipment
Little or nothing has been said about development of user equipment capable of
addressing consumer demand for both the mobile (principally automotive) commu-
nications market as well as the augmented GPS service. With the whole force of the
Japanese consumer electronics industry at hand, however, it is highly unlikely that
either quality or manufacturing of user equipment will cause a stumble in the
program.

11.3.8 Reference Systems
The QZSS system plans to use the Japanese Geodetic Datum JGD-2000, based on
regional measurements taken in support of the ITRF. Much existing documentation
in Japan still relies on the Tokyo-1927 datum, requiring a corresponding transfor-
mation for these users where needed. Timing corrections and a match-up to
WGS-84 datum for complete GPS overlay and compatibility are planned. 2

11.3.9 Navigation Services and Signals
Services provided by QZSS may actually emphasize communications, with S-band
for broadcast of audio and video, K u -band for data and TT&C, and L-band for the
navigation signals. No explicit specification has been given yet for data bandwidth,
though filings with the ITU in 2002 set some limitation [72].
News about the status of QZSS in late 2004 suggested some decisions remain
unsettled about what services will be offered. An impasse between the Japanese gov-

2. Japanese Geodetic Datum JGD-2000 is derived from the ITRF.