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

Type

ASCII

Value

Binary

Value

Description

Binary

Format

Binary

Bytes

Binary

Offset

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

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

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.

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.

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

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Field

Field Type Data Description Format

Binary

Bytes

Binary

Offset

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

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

3 0x0008

4 0x0010

5 0x0020

Reserved

6 0x0040 Bit Timing Lock 0 = Not Locked, 1 = Locked

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

11 0x0800

12 0x1000

13 0x2000

14 0x4000

Reserved

15 0x8000 Error 0 = Good, 1 = Error

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Table 4 OmniSTAR VBS Status Word

Nibble # Bit # Mask Description Bit = 0 Bit = 1

0 0x0001 Subscription Expired

False True

1 0x0002 Out of Region False True

2 0x0004 Wet Error False True

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

7 0x0080 No Time False True

8 0x0100

9 0x0200

10 0x0400

11 0x0800

12 0x1000

13 0x2000

14 0x4000

Reserved

15 0x8000 Updating Data False True

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

3 0x0008

Reserved

4 0x0010 HP not authorized

Authorized Unauthorized

5 0x0020 XP not authorized

Authorized Unauthorized

6 0x0040

7 0x0080

8 0x0100

9 0x0200

10 0x0400

11 0x0800

12 0x1000

13 0x2000

14 0x4000

15 0x8000

Reserved

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.

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Table 6 HP/XP Status Word

Nibble # Bit # Mask Description Bit = 0 Bit = 1

0 0x00000001 Subscription Expired

False True

1 0x00000002 Out of Region False True

2 0x00000004 Wet Error False True

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

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

N3-N5 12-23

24-25

Reserved

26 0x04000000 Static Initialization Mode False True

28-30

Reserved

31 0x80000000 Updating Data False True

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

Type

ASCII

Value

Binary

Value

Description

Binary

Format

Binary

Bytes

Binary

Offset

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

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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