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Address:
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127.127.29.u |
Reference ID:
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GPS |
Driver ID:
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GPS_PALISADE |
Serial Port:
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/dev/palisadeu |
Serial I/O:
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9600 baud, 8-bits, 1-stop, odd parity |
This documentation describes version 7.12 of the GPS Firmware and version 2.46 (July 15, 1999) and later, of the driver source.
Platform | Operating System | NTP Sources | Accuracy |
i386 (PC) | Linux | NTP Distribution | 10 us |
i386 (PC) | Windows NT | ftp://ftp.trimble.com/pub/ntp | 1 ms |
SUN | Solaris 2.x | NTP Distribution | 50 us |
Hewlett-Packard | HPUX 9, 10, 11 | http://us-support.external.hp.com | 50 us |
Various | Free BSD | NTP Distribution | 20 us |
Palisade generates a PPS synchronized to UTC within +/- 100 ns. The Palisade's external event input with 40 nanosecond resolution is utilized by the Palisade NTP driver for asynchronous precision time transfer.
No user initialization of the receiver is required. This driver is compatible with the following versions of Palisade:
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The 12 conductor (dia. 10 mm) power and I/O cable must be routed from the rooftop site to the NTP server and properly strain relieved.
Palisade's port B provides a TSIP (Trimble Standard Interface Protocol) interface for diagnostics, configuration, and monitoring. Port B and the PPS output are not currently used by the Palisade NTP reference clock driver.
The user is expected to provide a symbolic link to an available serial port device. This is typically performed by a command such as:
ln -s /dev/ttyS0 /dev/palisade0Windows NT does not support symbolic links to device files. COMx: is used by the driver, based on the refclock unit number, where unit 1 corresponds to COM1: and unit 3 corresponds to COM3:
Configuration without event polling:
#------------------------------------------------------------------------------
# The Primary reference
server 127.127.29.0 # Trimble Palisade GPS (Stratum 1).
# Set packet delay
fudge 127.127.29.0 time1 0.020
# and set flag2 to turn off event polling.
fudge 127.127.29.0 flag2 1
#------------------------------------------------------------------------------
The driver requests an event time stamp at the end of each polling interval, by pulsing the RTS (request to send) line on the serial port. The Palisade GPS responds with a time stamped event packet.
Time stamps are reported by the Palisade with respect to UTC time. The GPS receiver must download UTC offset information from GPS satellites. After an initial UTC download, the receiver will always start with correct UTC offset information.
Nov 14 16:16:21 terrapin ntpd[1127]: Palisade #0: message
Label | Definition | Default Value |
DEVICE | The serial port device to be used by the driver | /dev/palisadeu |
PRECISION | Accuracy of time transfer | 1 microsecond |
CURRENT_UTC | Valid GPS - UTC offset | 13 |
SPEED232 | Host RS-232 baud rate | B9600 |
TRMB_MINPOLL | Minimum polling interval | 5 (32 seconds) |
TRMB_MAXPOLL | Maximum interval between polls | 7 (128 seconds) |
Byte | Item | Type | Meaning |
0 | Sub-Packet ID | BYTE | Subcode 0xAD |
1 - 2 | Event Count | INTEGER | External event count recorded (0 = PPS) |
3 - 10 | Fractional Second | DOUBLE | Time elapsed in current second (s) |
11 | Hour | BYTE | Hour (0 - 23) |
12 | Minute | BYTE | Minute (0 - 59) |
13 | Second | BYTE | Second (0 - 59; 60 = leap) |
14 | Day | BYTE | Date (1 - 31) |
15 | Month | BYTE | Month (1 - 12) |
16 - 17 | Year | INTEGER | Year (4 digit) |
18 | Receiver Status | BYTE | Tracking Status |
19 | UTC Flags | BYTE | Leap Second Flags |
20 | Reserved | BYTE | Contains 0xFF |
21 | Reserved | BYTE | Contains 0xFF |
Leap Second Flag Definition:
Bit 0: (1) UTC Time is available
Bits 1 - 3: Undefined
Bit 4: (1) Leap Scheduled: Leap second pending asserted by GPS control segment.
Bit 5: (1) Leap Pending: set 24 hours before, until beginning of leap second.
Bit 6: (1) GPS Leap Warning: 6 hours before until 6 hours after leap event
Bit 7: (1) Leap In Progress. Only set during the leap second.Tracking Status Flag Definitions:
Code | Meaning | Accuracy | Receiver Mode |
0 | Receiver is Navigating | +/- 1 us | Self Survey |
1 | Static 1 Sat. Timing Mode | +/- 1 us | 1-D Timing |
2 | Approximate Time | 20 - 50 ms | Acquisition |
3 | Startup | N/A | Initialization |
4 | Startup | N/A | Initialization |
5 | Dilution of Position too High | 5 ppm | Self Survey |
6 | Static 1 Sat. Timing: Sat. not usable | 5 ppm | 1-D Timing |
7 | No Satellites Usable | N/A | Self Survey |
8 | Only 1 Satellite Usable | 20 - 50 ms | Self Survey |
9 | Only 2 Satellite Usable | 20 - 50 ms | Self Survey |
10 | Only 3 Satellites Usable | 20 - 50 ms | Self Survey |
11 | Invalid Solution | N/A | Error |
12 | Differential Corrections | N/A | N/A |
13 | Overdetermined Fixes | +/- 100 ns | Timing Steady State |
Byte | Item | Type | Meaning |
0 | Sub-Packet ID | BYTE | Subcode 0x0B |
1 - 2 | Event Count | INTEGER | External event count recorded (0 = PPS) |
3 - 10 | UTC / GPS TOW | DOUBLE | UTC / GPS time of week (seconds) |
11 | Date | BYTE | Day of Month |
12 | Month | BYTE | Month of Event |
13 - 14 | Year | INT | Year of event |
15 | Receiver Mode | BYTE | Receiver operating dimensions: 0: Horizontal (2D) 1: Full Position (3D) 2: Single Satellite (0D) 3: Automatic (2D / 3D) 4: DGPS reference 5: Clock hold (2D) 6: Over determined Clock |
15 - 17 | UTC Offset | INTEGER | UTC Offset value (seconds) |
18 - 25 | Oscillator Bias | DOUBLE | Oscillator BIAS (meters) |
26 - 33 | Oscillator Drift Rate | DOUBLE | Oscillator Drift (meters / second) |
34 - 37 | Bias Uncertainty | SINGLE | Oscillator bias uncertainty (meters) |
38 - 41 | Drift Uncertainty | SINGLE | Oscillator bias rate uncertainty (m / sec) |
42 - 49 | Latitude | DOUBLE | Latitude in radians |
50 - 57 | Longitude | DOUBLE | Longitude in radians |
58 - 65 | Altitude | DOUBLE | Altitude above mean sea level, in meters |
66 - 73 | Satellite ID | BYTE | SV Id No. of tracked satellites |
Note: If driving the RS-422 inputs on the Palisade single ended, i.e. using the Green and Gray connections only, does not work on all serial ports. Use of the Palisade NTP Synchronization Interface Module is recommended.
The 12 pin connector pinout definition:
Face the round 12 pin connector at the end of the cable, with the notch turned upwards.
Pin 1 is to the left of the notch. Pins 2 - 8 wrap around the bottom, counterclockwise to pin 9 on the right of the notch. Pin 10 is just below the notch. Pins 10 (top), 11 (bottom left) and 12 (bottom right) form a triangle in the center of the connector.
Pinouts for the Palisade NTP host adapter (Trimble PN 37070) DB-25 M connector are as follows:
DB-25M | Conductor | Palisade | Description |
1 | Red | 1 | Power |
7 | Black | 9 | Ground |
9 | Black/White | 12 | PPS - |
10 | Green | 8 | Transmit Port A (T-) |
11 | Brown | 4 | Transmit Port B (T-) |
12 | Gray | 7 | Receive Port A (R+) |
13 | Orange | 3 | Receive Port B (R+) |
21 | Orange/White | 11 | PPS + |
22 | Blue | 10 | Transmit Port A (T+) |
23 | Yellow | 5 | Transmit Port B (T+) |
24 | White | 6 | Receive Port A (R-) |
25 | Violet | 2 | Receive Port B (R-) |
Questions or Comments:
Sven Dietrich
Trimble Navigation Ltd.
(last updated July 29, 1999)