Michibiki QZSS Satellite Now Operating in Regular Mode

From: http://www.jaxa.jp/projects/sat/qzss/index_e.html

December 15, 2010 Updated
MICHIBIKI starts technical and application verifications
The first quasi-zenith satellite "MICHIBIK" has been under the initial
functional verification for about three months and, all the satellite
bus and onboard mission devices were confirmed as functioning.
As a result, JAXA moved the operation of MICHIBIKI to regular mode on
December 13 (Japan Standard Time,) and, accordingly, we will begin
technical and application verifications of the MICHIBIKI with all
organizations concerned.
Each organization already started partial technical verifications when
the health of their onboard device(s) and ground systems was
confirmed.
However, as JAXA switched all positioning signals to the standard code
at 11:48 a.m. on December 15 (JST,) full-scale technical and
application verifications will be performed by all the organizations.


Question: Is standard code = no message zero = healthy ?
If so then we now have one satellite with a healthy L2C, L5 and L1C
signals !
If I lived in Japan or Australia, that would have been the greatest x-
mas present I could ask for !

Regards,

Marcelo

This is how JAXA explains 'standard code':

* Standard code:
Positioning signals were set to a non-standard code during the initial
functional verification period; therefore, users were not able to
capture signals. By setting them to the standard code, experimental
users of the technical and application verifications can receive
signals. Aside from the standard code, we also set up an "alert flag"
which indicates that MICHIBIKI's positioning signals cannot be used
(an alert condition,) thus general users cannot use MICHIBIKI's
signals for their positioning calculation even if they acquire the
signals. This "alert flag" will be removed after the quality and
reliability of MICHIBIKI's signals are proved to satisfy the user
interface specifications of the Quasi-Zenith Satellite System. (We
plan to remove the alert flag in three to six months after starting
the technical verification. We may temporarily remove it during the
verification when experimental users require the removal for a test.)

I interpret this to mean the signals are transmitting actual
navigation data but they are not set usable for navigation. There's a
time line showing signals testing and verifications will continue well
into next year.

Broadcom, the chip maker for mobile phones, has recently tested a
standard GPS chip that is already designed for QZS. They defeated the
'alert flag' for the test. I suppose that chip utilizes the L1/CA
code.

I'm not aware of any consumer class receivers for L5 or L2C signals
although I have seen reference to survey receivers that track phase of
the L2C signal. My understanding of L2C on the IIRM and IIF
satellites is they still are not transmitting an actual CNAV message.
I guess that doesn't matter until 2/3 frequency commercial class
receivers begin to appear.

--- CHAS

Dear CHAS,

Ok, so now the QZSS signal is like an otherwise usable signal but with
a code zero message. About another 6 months for a freely usable
signal. Good !

Back to L2C, ... Exactly. There's no receivers because:
1 - L2C isn't fully healthy for GPS satellites, and the realistic IIF
launch schedule isn't very promising, just look at the constant
slipping of launch schedules !
2 - Not enough geometry - Right now there's just 8 GPS satellites that
could broadcast a healthy L2C signal, you're very lucky to have 3 of
those satellites in view at once
3 - semi-codeless stuff is good enough for most high accuracy uses,
that's 31 healthy birds
4 - There's not much demand for consumer class dual frequency
receivers. Current street maps aren't very accurate, and SBAS is very
helpful in providing clock, orbit and iono corrections. It won't take
long until we can receive SBAS corrections through cell networks on
urban areas.

But when all 3 QZSS satellites are operational, with 7 IIR-M + 1 IIF +
3 QZSS there should 4+ L2C signals in view in the 120W-180W longitude
area (actual range should be larger, they can receive QZSS signals in
Moscow, also because QZSS birds fly much higher than GPS orbits). Add
to that 4 extra IIF birds, and we start reaching the 6 in view
requirement for high accuracy.

Considering that an L1 C/A + L2C + L5 capable receiver with triple
frequency optimizations, the QZSS and IIF ranging can be determined
from an inch to a couple millimeters of iono uncertainty. With a multi-
path resistant receiver, Out of a sudden, new applications are
possible for very high accuracy positioning. Notice QZSS includes an
SBAS like signal, so apparently QZSS capable users will not see more
GPS like satellites, but also receive ephemeris and clock corrections
for GPS satellites as well. With QZSS augmentation, as soon as all IIF
birds are healthy, L5 will have 4-6 in view most times over Oceania
and the far East.

Yes, x-mas present isn't about having a device that uses the
signals... Is knowing that concrete progress is being made to GNSS
availability. Honestly I'm not too fond of the slow progress of GPS
modernization and the uncertainty of Galileo, while China and Russia
are launching satellites like there's no tomorrow. And China is
withholding their ICDs for as long as they can. We need truly open
GNSS systems, not dictatorship sponsored systems. QZSS is a ray of
light in the GPS modernization arena.

Let's just hope things will progress as scheduled there.

Current vendors of expensive semi codeless gear aren't looking forward
to patent free competition. There's no semi codeless receiver
knockoffs (mainly due to patents), but as soon as L2C gets closer to
IOC, QZSS coverage areas will essentially have a FOC L2C signal due to
the extra QZSS signals. Exactly in places where most knockoff
electronics come from. What I really want is cheap USB/bluetooth dual/
triple frequency receivers, dual/triple frequency versions of Anywhere
Map, dual/triple frequency versions of Garmin 696, and so on.

Regards,

Marcelo

As for L2C and L5 CNAV messages, then what does this means ?
Can the signal be ICD compliant without a useful CNAV message ?

2010115

NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2010115 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
FOR SVN 62/PRN 25 GPS MODERNIZED SIGNAL, DEFINED IN INTERFACE CONTROL
DOCUMENTATION AS L2C AND L5, ARE NOW AVAILABLE WITH THE FOLLOWING
CAVEATS:
-AVAILABILITY AND QUALITY OF THESE SIGNALS ARE NOT GUARANTEED AS WE
COMPLETE THE DEVELOPMENT OF THESE NEW CAPABILITIES
-ANY USE OF THESE SIGNALS AT THIS TIME IS AT THE USER'S OWN RISK
*** GENERAL MESSAGE TO ALL GPS USERS ***

The GPS satellites are transmitting Message Type (0) on L2C. With
reference to an InsideGNSS magazine article,

'Message Type 0 consists of a 12-second, 300 bit=96long message that
includes a preamble, satellite pseudorandom noise (PRN) number,
message type ID (=3D0), GPS time of week, a sequence of alternating 1s
and 0s, and a cyclic redundancy check (CRC) parity block. The GPS Time
of Week will change every 12 seconds, as will the CRC bits'.

http://www.insidegnss.com/node/914

--- CHAS