Begin forwarded message:
From: Paul Saffo <paul@saffo.com>
Date: May 13, 2008 10:13:48 AM EDT
To: David Farber <dave@farber.net>
Subject: GIOVE-B Transmitting its First Signals
A big step towards GPS III, which will enable dramatic new navigation
and life safety functions.
-p
GIOVE-B Transmitting its First Signals 08/05/2008
Following a successful launch on 27 April, GIOVE-B has begun
transmitting navigation signal on 7 May. This is a historic step for
satellite navigation since GIOVE-B is now, for the first time,
transmitting the GPS-Galileo common signal using a specific optimised
waveform, MBOC (multiplexed binary offset carrier), in accordance with
the agreement drawn up in July 2007 by the EU and the US for their
respective systems, Galileo and the future GPS III.
These GIOVE B signals, locked on-board to a highly stable Passive
Hydrogen Maser clock, will provide higher accuracy in challenging
environments where multipath and interference are present, and deeper
penetration for indoor navigation. It demonstrates that Galileo and
GPS are truly compatible and interoperable and that positioning
services will benefit all users worldwide. The quality of the signals
transmitted by GIOVE-B will have an important influence on the
accuracy of the positioning information that will be provided by the
user receivers on the ground. Onboard GIOVE-B carries a passive
hydrogen maser atomic clock, which is expected to deliver
unprecedented stability performance.
The signal quality can be affected by the environment of the satellite
in its orbit and by the propagation path of the signals travelling
from space to ground. Additionally, the satellite signals must not
create interference with services operating in adjacent frequency
bands, and this is also being checked. Galileo teams within ESA and
industry have the means to observe and record the spectrum of the
signals transmitted by GIOVE-B in real time. Several measurements are
performed relating to transmitted signal power, centre frequency and
bandwidth, as well as the format of the navigation signals generated
on board. This allows the analysis of the satellite transmissions in
the three frequency bands reserved for it.
Caption: A screen in the control room displays the spectra of signals
received from GIOVE-B shortly after the spacecraft began transmitting
navigation signals.
Website: http://www.esa.int/esaCP/SEMGVUZXUFF_index_0.html
http://www.gim-international.com./news/id3042-GIOVEB_Transmitting_its_First_Signals.html