Positioning Leadership
APN-043 Rev 1 December 11, 2007
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L-band Tracking and Data Output without GPS
This application note describes the OmniSTAR demodulator features that allow the receiver to track L-
band signals without the assistance of GPS. It is only available with OEMV 3.300 firmware or later.
GPS signals are normally used to steer the receiver's Voltage Controlled Temperature Compensated Crystal
Oscillator (VTCXO). With a more accurate VTCXO, the L-band signal can be acquired more readily.
However, with the GPS signals gone, the receiver must use a wider and more efficient search algorithm to
find the L-band signal.
This feature introduces the NL model which has 1 L-band OmniSTAR-enabled channel. Table 1, below, is
the VERSION log’s Model Designators table. Refer to the OEMV Family Firmware Reference Manual,
available from our website at www.novatel.com
. There you can find details on the VERSION log and other
commands and logs mentioned in this application note.
Table 1 Model Designators
G 12 L1 or 12 L1/L2 GLONASS channels, frequencies to match GPS configuration
R Receive RT2 and/or RT20 corrections
I Synchronized Position Attitude Navigation (SPAN)
J SPAN supporting 200 Hz IMUs and IGI higher rate IMU (256.144 Hz)
S Reduces positions and measurement rates to 5 Hz, disables VARF and EVENT signals
A Application Program Interface (API)
L 1 L-band channel with CDGPS and OmniSTAR HP/XP capability
NL 1 L-band channel with OmniSTAR enabled and no position, velocity, time (PVT)
or raw data output
B 1 L-band channel with CDGPS and OmniSTAR VBS capability
F 50 Hz output
When the receiver tracks an L-band signal, CDGPS or OmniSTAR, it saves the TCXO offset in Non-
Volatile Memory (NVM). The TCXO offset is the difference between the assigned frequency and the
actual tracking frequency. This allows the receiver to track L-band signals more quickly in future restarts
by centering the search for the signal around the known TCXO offset. The offset data is stored in NVM
with type LBAND_TCXO_OFFSET. The receiver updates the offset in NVM whenever the L-band signal
is tracking and the offset measures 50 Hz away from the currently stored value.
See also the ASSIGNLBAND command, starting on Page 2, for the new OMNISTARNARROW mode in
Table 2 L-band Mode on Page 3. Compared to the OMNISTAR mode, this mode uses a narrower search
window, and the L-band TCXO offset information, to look for the L-band signal. The L-band TCXO offset
information is only used in OMNISTARNARROW mode.
The tracking field, Field #6, of the LBANDSTAT log, now has the IDLE possible value, see Page 5. See
also the LBANDSTAT log starting on Page 4.
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ASSIGNLBAND Command to set L-band satellite
communication parameters
You must use this command to ensure that the receiver searches for a specified L-band satellite at a
specified frequency with a specified baud rate. The factory parameter default is
ASSIGNLBAND IDLE.
Abbreviated ASCII Syntax: Message ID: 729
ASSIGNLBAND mode freq baud
Factory Default:
assignlband idle
ASCII Example 1:
assignlband cdgps 1547547 4800
ASCII Example 2:
assignlband idle
ASCII Example 3:
assignlband omnistarnarrow 1535137500 1200
Field
Field
Type
ASCII
Value
Binary
Value
Description
Binary
Format
Binary
Bytes
Binary
Offset
1
ASSIGNLBAND
header
- -
This field contains the
command name or the
message header depending
on whether the command is
abbreviated ASCII, ASCII or
binary, respectively.
- H 0
2 mode See
Table 2 L-band
Mode on Page 3
Set the mode and enter
specific frequency and baud
rate values
Enum 4 H
3 freq
1525000 to
1560000
or
1525000000 to
1560000000
L-band service beam
frequency of satellite (Hz or
kHz). See also Beam
Frequencies on Page 4
(default = 1536782 if the
mode is OMNISTAR)
Ulong 4 H+4
4 baud
300, 600, 1200,
2400 or 4800
Data rate for communication
with L-band satellite
(default = 1200)
Ulong 4 H+8
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Table 2 L-band Mode
Binary ASCII Description
0
1 OMNISTAR When you select OmniSTAR, enter a dedicated frequency and baud rate.
2 CDGPS When you select CDGPS, enter a dedicated frequency and baud rate.
3 IDLE When you select IDLE, the receiver is configured to stop tracking any L-band
satellites. The 'freq' and 'baud' fields are optional so that you may select IDLE
without specifying the other fields.
4 OMNISTARAUTO When you select OMNISTARAUTO, the receiver automatically selects the best
OmniSTAR beam to track based on the receiver’s position. This requires the
receiver to have a downloaded satellite list from an OmniSTAR satellite.
Therefore, a manual assignment is necessary the first time an OmniSTAR
satellite is assigned on a new receiver. After collection, the satellite list is stored
in NVM for subsequent auto assignments. Lists are considered valid for 6
months and are constantly updated while an OmniSTAR signal is tracking. If the
receiver has a valid satellite list, it is reported in a status bit in the LBANDSTAT
log, see Page 4.
1
This OmniSTAR mode does not use the TCXO offset information (see also
OMNISTARNARROW in the row below).
5 OMNISTARNARROW When you select OMNISTARNARROW, enter a dedicated frequency and baud
rate.
For re-acquisitions of the L-band signal, the receiver uses a 1500 Hz search
window and the stored TCXO offset information.
To remove the TCXO offset information from NVM, use the FRESET
LBAND_TCXO_OFFSET command. A standard FRESET command does not do
this, see Page 10.
1
The receiver always tracks an available local beam over a global beam. The receiver constantly
monitors the satellite list to ensure it is tracking the best one and automatically switches beams if it
is not. You can view the satellite list by logging the OMNIVIS log. Refer to the OEMV Family
Firmware Reference Manual.
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Beam Frequencies
You can switch between OmniSTAR VBS and CDGPS by using the following commands:
Use CDGPS
assignlband cdgps <freq> 4800
psrdiffsource cdgps
Use OmniSTAR VBS
assignlband omnistar <freq> 1200
psrdiffsource omnistar
Where
<freq> is determined for CDGPS or OmniSTAR as follows:
1. CDGPS beam frequency chart:
• East 1547646 or 1547646000
• East-Central 1557897 or 1557897000
• West-Central 1557571 or 1557571000
• West 1547547 or 1547547000
2. The OmniSTAR beam frequency chart can be found at http://www.omnistar.com/chart.html
.
For example:
Eastern US (Coverage is Northern Canada to southern Mexico) 1530359 or 1530359000
LBANDSTAT
Log to output L-band status information
This log outputs status information for a standard L-band, OmniSTAR XP (Extra Precision) or OmniSTAR
HP (High Performance) service.
Message ID: 731
Log Type: Asynch
Recommended Input:
log lbandstata ontime 1
ASCII Example:
#LBANDSTATA,COM1,0,73.5,FINESTEERING,1314,494510.000,00000000,c797,1846;
1551488896,43.19,62.3,0.00,0082,0000,7235,11,0,0000,0001,7762,04000000,0
*93f7d2af
- 5 -
Field
#
Field Type Data Description Format
Binary
Bytes
Binary
Offset
1
LBANDSTAT
header
Log header H 0
2 freq Measured frequency of L-band signal (Hz) Ulong 4 H
3 C/No Carrier to noise density ratio (dB-Hz) Float 4 H+4
4 locktime
Number of seconds of continuous tracking (no
cycle slipping)
Float 4 H+8
5 Reserved Float 4 H+12
6 tracking
Tracking status of L-band signal (see Table 3 L-
band Signal Tracking Status on Page 6)
Hex 2 H+16
7 VBS status
Status word for OmniSTAR VBS (see Table 4
OmniSTAR VBS Status Word on Page 7)
Hex 2 H+18
8 #bytes Number of bytes fed to the standard process Ulong 4 H+20
9 #good dgps Number of standard updates Ulong 4 H+24
10 #bad data Number of missing standard updates Ulong 4 H+28
11
Reserved (the hp status 1 field is obsolete and has been replaced
by the longer OmniSTAR HP Status field. The shorter legacy status
here is maintained for backward compatibility)
Hex 2 H+32
12 hp status 2
Additional status pertaining to the HP or XP
process (see Table 5 OmniSTAR HP/XP
Additional Status Word on Page 8)
Hex 2 H+34
13 #bytes hp Number of bytes fed to the HP or XP process Ulong 4 H+36
14 hp status
Status from the HP or XP process (see Table 6
HP/XP Status Word on Page 9)
Hex 4 H+40
15 Reserved Hex 4 H+44
16 xxxx 32-bit CRC (ASCII and Binary only) Hex 4 H+48
17 [CR][LF] Sentence terminator (ASCII only) - - -
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Table 3 L-band Signal Tracking Status
Nibble # Bit # Mask Description Range Value
0 0x0001
1 0x0002
Tracking State 0 = Searching, 1 = Pull-in,
2 = Tracking, 3 = Idle
2 0x0004
N0
3 0x0008
4 0x0010
5 0x0020
Reserved
6 0x0040 Bit Timing Lock 0 = Not Locked, 1 = Locked
N1
7 0x0080 Phase Locked 0 = Not Locked, 1 = Locked
8 0x0100 DC Offset Unlocked 0 = Good, 1 = Warning
9 0x0200 AGC Unlocked 0 = Good, 1 = Warning
10 0x0400
N2
11 0x0800
12 0x1000
13 0x2000
14 0x4000
Reserved
N3
15 0x8000 Error 0 = Good, 1 = Error
- 7 -
Table 4 OmniSTAR VBS Status Word
Nibble # Bit # Mask Description Bit = 0 Bit = 1
0 0x0001 Subscription Expired
2
False True
1 0x0002 Out of Region False True
2 0x0004 Wet Error False True
N0
3 0x0008 Link Error False True
4 0x0010 No Remote Sites False True
5 0x0020 No Almanac False True
6 0x0040 No Position False True
N1
7 0x0080 No Time False True
8 0x0100
9 0x0200
10 0x0400
N2
11 0x0800
12 0x1000
13 0x2000
14 0x4000
Reserved
N3
15 0x8000 Updating Data False True
2
Contact OmniSTAR for subscription support. All other status values are updated by collecting
OmniSTAR data for 20-35 minutes.
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Table 5 OmniSTAR HP/XP Additional Status Word
Nibble # Bit # Mask Description Bit = 0 Bit = 1
0 0x0001 Solution not fully converged False True
1 0x0002
OmniSTAR satellite list
available
False True
2 0x0004
N0
3 0x0008
Reserved
4 0x0010 HP not authorized
3
Authorized Unauthorized
5 0x0020 XP not authorized
3
Authorized Unauthorized
6 0x0040
N1
7 0x0080
8 0x0100
9 0x0200
10 0x0400
N2
11 0x0800
12 0x1000
13 0x2000
14 0x4000
N3
15 0x8000
Reserved
3
This authorization is related to the receiver model and not the OmniSTAR subscription. To view
OmniSTAR subscription information use the LBANDINFO log, refer to the OEMV Family
Firmware Reference Manual.
- 9 -
Table 6 HP/XP Status Word
Nibble # Bit # Mask Description Bit = 0 Bit = 1
0 0x00000001 Subscription Expired
4
False True
1 0x00000002 Out of Region False True
2 0x00000004 Wet Error False True
N0
3 0x00000008 Link Error False True
4 0x00000010 No Measurements False True
5 0x00000020 No Ephemeris False True
6 0x00000040 No Initial Position False True
N1
7 0x00000080 No Time Set False True
8 0x00000100 Velocity Error False True
9 0x00000200 No base stations False True
10 0x00000400 No Mapping Message False True
N2
11
N3-N5 12-23
24-25
Reserved
26 0x04000000 Static Initialization Mode False True
N6
27
28-30
Reserved
N7
31 0x80000000 Updating Data False True
4
Contact OmniSTAR for subscription support. All other status values are updated by collecting
OmniSTAR data for 20-35 minutes.
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FRESET
Command to clear selected data from NVM and reset
This command clears data stored in NVM. Such data includes the almanac, ephemeris, and any user-
specific configurations. The commands, ephemeris, almanac, and L-band related data, excluding the
subscription information, can be cleared by using the STANDARD target. The model can only be cleared
by using the MODEL target. The receiver is forced to hardware reset. In addition, values entered using the
CLOCKCALIBRATE, or the ASSIGNLBAND OMNISTARNARROW, command can only be cleared by
using their respective targets. See also Table 7 FRESET Target on Page 11.
FRESET STANDARD (which is also the default) causes any commands, ephemeris, GPS almanac
and SBAS almanac data (COMMAND, GPSALMANAC, GPSEPHEM and SBASALMANAC in
Table 7 on Page 11) previously saved to NVM to be erased.
Abbreviated ASCII Syntax: Message ID: 20
FRESET [target
]
Input Example:
freset command
Field
Field
Type
ASCII
Value
Binary
Value
Description
Binary
Format
Binary
Bytes
Binary
Offset
1
FRESET
header
- -
This field contains the command
name or the message header
depending on whether the
command is abbreviated ASCII,
ASCII or binary, respectively.
- H 0
2 target
See Table 7
FRESET Target
on Page 11
Data to be reset by the receiver Enum 4 H
- 11 -
Table 7 FRESET Target
Binary ASCII Description
0 STANDARD
Resets commands, ephemeris, and
almanac (default). Also resets L-band
related data except for subscription
information.
1 COMMAND
Resets the stored commands (saved
configuration)
2 GPSALMANAC Resets the stored GPS almanac
3 GPSEPHEM Resets the stored GPS ephemeris
4 GLOEPHEM Resets the stored GLONASS ephemeris
5 MODEL Resets the currently selected model
11 CLKCALIBRATION
Resets the parameters entered using the
CLOCKCALIBRATE command
20 SBASALMANAC Resets the stored SBAS almanac
21 LAST_POSITION
Resets the position using the last stored
position
31 GLOALMANAC Resets the stored GLONASS almanac
38 LBAND_TCXO_OFFSET
Removes the TCXO offset information
from NVM (entered using the
ASSIGNLBAND command)
Final Points
If you require any further information regarding the topics covered within this
application, please contact:
NovAtel Customer Service
1120 – 68 Ave. N.E.
Calgary, Alberta, Canada, T2E 8S5
Phone: +1-800-NOVATEL (in Canada or the U.S.) or +1-403-295-4500
Fax: +1-403-295-4501
E-mail: support@novatel.com
Website: www.novatel.com