Brandywine GPS4 User manual

MANUAL P/N 900000038 REV 2.2
1
User Guide
GPS4 Satellite Synchronized Time & Frequency
Standard
Model GPS4
P/N 001-0045
Revision 2.2
November 2004
Brandywine Communications
1153 Warner Avenue
Tustin, CA 92780
[phone]
[phone]
http://www.brandywinecomm.com

MANUAL P/N 900000038 REV 2.2
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Revision History
REVISION DATE COMMENTS
2.1 08-29-03 Preliminary release of GPS4 user guide.
2.2 11-02-04 Revision of entire GPS4 user guide.

MANUAL P/N 900000038 REV 2.2
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Table of Contents
1 Introduction............................................................................................................................... 5
2 Product Specifications.............................................................................................................. 6
2.1 Power Requirements......................................................................................................... 6
2.1.1 Standard .................................................................................................................... 6
2.1.2 Power Option 1 .......................................................................................................... 6
2.1.3 Power Option 2 .......................................................................................................... 6
2.2 Outputs.............................................................................................................................. 6
2.2.1 PPS ............................................................................................................................ 6
2.2.2 10 MHz....................................................................................................................... 7
2.2.3 Synthesizer ................................................................................................................ 7
2.2.4 Status Indicators ........................................................................................................ 8
2.3 Inputs................................................................................................................................. 8
2.3.1 System Reset............................................................................................................. 8
2.3.2 Antenna...................................................................................................................... 8
2.4 Environmental ................................................................................................................... 8
2.5 GPS Receiver ................................................................................................................... 8
2.6 Serial Control .................................................................................................................... 8
2.6.1 Control Port................................................................................................................ 9
2.6.2 TOD Port.................................................................................................................... 9
2.6.3 Serial Option 1 ...........................................................................................................9
2.6.4 Serial Option 2 ...........................................................................................................9
2.7 Hardware Status ............................................................................................................... 9
2.8 Physical ............................................................................................................................. 9
2.9 Connectors and Indicators .............................................................................................. 10
3 Installation .............................................................................................................................. 11
3.1 Thermal Considerations .................................................................................................. 11
3.2 Power Supply Connections ............................................................................................. 12
3.3 Unit Mounting .................................................................................................................. 13
3.4 Serial Interface Connections ........................................................................................... 14
3.5 Interfacing to the Serial Port............................................................................................ 14
3.5.1 RS232 ...................................................................................................................... 14
3.5.2 TxD2 ASCII Time of Day Output.............................................................................. 15
3.5.3 RS422 ...................................................................................................................... 15
3.6 Antenna Installation......................................................................................................... 15
3.6.1 Location ................................................................................................................... 15
3.6.2 Exposure to High RF Fields..................................................................................... 15
3.6.3 Lightning Protection ................................................................................................. 16
3.6.4 Antenna Cable Factors ............................................................................................ 16
3.6.5 RF Loss.................................................................................................................... 16
4 Operating Instructions ............................................................................................................ 17
4.1 Scope of Section ............................................................................................................. 17
4.2 Operation......................................................................................................................... 17
4.3 Serial Data Communication ............................................................................................ 20
4.4 Control TxD1/RxD1 ......................................................................................................... 20
4.4.1 TxD1 / RxD1 User Commands and GPS4 Responses ........................................... 21
4.5 Message Formats ........................................................................................................... 24
4.5.1 Time and Date with Status, Position Averager Status, and Output Status.............. 24
4.5.2 Pulse Output Data and Command........................................................................... 26
4.5.3 Dilution of Precision Values and Satellites Used ..................................................... 29
4.5.4 Time Code and Serial Data Output Formats ........................................................... 30
4.5.5 Frequency and Phase Controller Data .................................................................... 33
4.5.6 Health Status of Satellites........................................................................................ 39

MANUAL P/N 900000038 REV 2.2
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4.5.7 Leap Second Information......................................................................................... 40
4.5.8 Location and Signal-Noise Ratio of Satellites.......................................................... 41
4.5.9 Firmware Version Number....................................................................................... 42
4.5.10 Offset of Local Time Data and Command ............................................................... 43
4.5.11 Position of GPS Antenna ......................................................................................... 45
4.5.12 Software Reset Command....................................................................................... 46
4.5.13 Additional Information .............................................................................................. 47
4.5.14 Request Precision Time........................................................................................... 48
4.6 TxD2/RxD2 Messages .................................................................................................... 50
4.7 IRIG B and AFNOR NF 2 87-500 Time Code Output ..................................................... 52
4.8 NASA36 Time Code Output Option ................................................................................ 55
4.9 2137 Time Code Output Option ...................................................................................... 57
4.10 VELA Time Code Output Option ..................................................................................... 58
5 Maintenance and Calibration.................................................................................................. 59
5.1 Scope of Section ............................................................................................................. 59
5.2 Routine Maintenance ...................................................................................................... 59
5.3 Fault Finding ................................................................................................................... 59
6 Diagrams ................................................................................................................................ 60

MANUAL P/N 900000038 REV 2.2
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1 Introduction
The GPS4 disciplined time and frequency standard is a device that offers many
desirable features. Utilizing signals from the Global Positioning System, the unit
provides highly accurate time, synchronization, and frequency functions. The
unit may operate in either GPS or UTC time mode. Local time offsets may be
programmed into the unit in resolutions of minutes. A brief outline of the unit’s
features is described below.
•PPS Output: This 1 PPS output provides a TTL output level into 50 ohms.
This output is available on the front panel BNC connector labeled “PPS”.
•10 MHz Output: This 1 Vrms sinusoidal output is available on the front
panel BNC connector labeled “10MHz”.
•Synthesizer Output: This is a frequency output option that is factory
configurable to produce one of three different frequencies (19.6608 MHz,
1.544 MHz, and 2.048 MHz). This output is available on the front panel
BNC connector labeled “SYNTH”. Other frequencies may also be
synthesized so please contact Brandywine Communications for more
information on a particular frequency.
•IRIG B Time Code Output: This is a time code output used to distribute
time of day information to other devices. This output is available by an
internal link selection (DC level shift code output or modulated time code
output). It is available on the front panel BNC connector labeled “CODE”.
Other time code formats are possible so please contact Brandywine
Communications for more information on a particular time code.
•Serial I/O: The GPS4 features one bi-directional control port and one
dedicated output port used to provide time of day (TOD) information. The
TOD output is an ASCII data string that is outputted each second shortly
after the 1 PPS. These serial ports may be factory configured for either
RS232 (bi-polar) or RS422 (differential) signal levels.

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2 Product Specifications
2.1 Power Requirements
CONNECTOR DESCRIPTION
Connector Type MR series locking type AMP 1-640508-0
Pin 1 Positive
Pin 2 Chassis ground
Connector Pin
Pin 3 Negative
2.1.1 Standard
STANDARD DESCRIPTION
Input Voltage/Current 15 VDC @ 1.4 A maximum and 0.5 A steady state
Isolation None
2.1.2 Power Option 1
OPTION 1 DESCRIPTION
Input Voltage/Current 18 - 36 VDC @ 1 - 0.5 A maximum and 0.5 - 0.3 A steady state
Isolation 500 VDC
2.1.3 Power Option 2
OPTION 2 DESCRIPTION
Input Voltage/Current 36 - 60 VDC @ 1 - 0.34 A maximum and 0.5 - 0.2 A steady state
Isolation Isolated, 500 VDC
2.2 Outputs
2.2.1 PPS
PPS DESCRIPTION
Rate 1 pulse per second
Drive Output TTL into 50 ohm load
Reference Rising edge referenced to UTC (USNO)
Width 1 ms
Connector BNC female
±150 ns to UTC after the stabilization period of 24 hours – static and
time locked
Accuracy
Standard deviation of 34 ns
Less than 8 us/8 hr after the learning periodHoldover
Can be influenced by the antenna delay compensation

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2.2.2 10 MHz
10 MHz DESCRIPTION
Frequency 10 MHz
Period 100 ns
Waveform Sinusoid (standard) or square (link selectable)
Drive Level 1 Vrms (minimum) into 50 ohm load
Harmonics < 30 dB
100 Hz -140 dBc/Hz
1000 Hz -150 dBc/Hz
Phase Noise
10 KHz -155 dBc/Hz
1 sec 1 x 10
-11
10 sec 1 x 10
-11
100 sec 8 x 10
-12
Stability (Short Term)
1000 sec 1 x 10
-11
Long term 5 x 10
-12
while locked over 24 hours Accuracy
Holdover 1 x 10
-10
average during 24 hours
2.2.3 Synthesizer
SYNTH OPTION 1 DESCRIPTION
Frequency 19.6608 MHz
Connector BNC female
Drive Level Single ended, HCMOS
Duty Cycle 50/50 ± 10%
Long term 5 x 10
-12
while locked over 24 hoursAccuracy
Holdover 1 x 10
-10
average during 24 hours
SYNTH OPTION 2 DESCRIPTION
Frequency 2.048 MHz
Connector BNC female
Drive Level Single ended, HCMOS
Duty Cycle 50/50 ± 10%
Long term 5 x 10
-12
while locked over 24 hoursAccuracy
Holdover 1 x 10
-10
average during 24 hours
SYNTH OPTION 3 DESCRIPTION
Frequency 1.544 MHz
Connector BNC female
Drive Level Single ended, HCMOS
Duty Cycle 50/50 ± 10%
Long term 5 x 10
-12
while locked over 24 hoursAccuracy
Holdover 1 x 10
-10
average during 24 hours

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2.2.4 Status Indicators
INDICATOR COLOR DESCRIPTION
POWER GREEN Indicates the system power is available
LOCKED GREEN Indicates the system time locked status
HOLDOVER YELLOW Indicates the system is in holdover operation
ALARM RED Indicates the system fault
2.3 Inputs
2.3.1 System Reset
SYSTEM RESET DESCRIPTION
Function Resets the system microprocessor
Level +5 V, active high (pin 4)
Pulse Width 2 ms minimum
Sink Current 30 mA maximum
2.3.2 Antenna
ANTENNA DESCRIPTION
Connector BNC female
Impedance 50 ohms
Bias Voltage 5 VDC
Bias Current 80 mA maximum
2.4 Environmental
ENVIRONMENTAL DESCRIPTION
Operating -10°C to +60°C
Maximum Rate Change 15°C per hour
2.5 GPS Receiver
GPS RECEIVER DESCRIPTION
Number of Channels 8 parallel
Band L1 (1575.42 MHz)
2.6 Serial Control
SERIAL CONTROL DESCRIPTION
Connector DE-9 female

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2.6.1 Control Port
CONTROL PORT DESCRIPTION
75 – 19200 baud selectable by the DIP switchBaud Rate
4800, N, 8, and 1 is factory setting
2.6.2 TOD Port
TOD PORT DESCRIPTION
Protocol Time of day (ASCII)
Baud Rate 19.2 K
2.6.3 Serial Option 1
SERIAL OPTION 1 DESCRIPTION
I/O Level RS232
2.6.4 Serial Option 2
SERIAL OPTION 2 DESCRIPTION
I/O Level RS422
2.7 Hardware Status
HARDWARE DESCRIPTION
Connector DB-9
Level Open collector – pulled to ground through 100 ohm resistor
Maximum Pull-Up Voltage 5 VDC
Maximum Current 30 mA
Status Time lock (pin 8)
Status Fault (pin 9)
2.8 Physical
PHYSICAL DESCRIPTION
Length 5.84 inches (148.3 mm)
Width 5.58 inches (141.7 mm)
Height 1.61 inches (40.9 mm)
Weight 1.5 lbs (0.7 kg)

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2.9 Connectors and Indicators
The GPS4 provides access to the power, I/O, and signal connectors on the front
panel of the chassis. These various connectors and indicators are described
below.
LABEL FUNCTION DETAIL
PWR Power input connector Pins are numbered from left to right so
Pin 1 = VDC, Pin 2 = chassis, and Pin 3 =
ground
PIN RS232
(STANDARD) RS422 (OPTIONAL)
1 No connection Control TX-Y
2 Control TX Control TX-Z
3 Control RX Control RX-A
4 Hardware reset Control RX-B
5 Ground Ground
6 TOD TX TOD TX-Y
7 No connection TOD TX-Z
8 Time locked Time locked
I/O I/O connector provides I/O
for serial communications
and hardware status
indicators. Hardware
statuses are open collector
transistors that pull low
when the described status
is true.
9 Fault Fault
LABEL FUNCTION DETAIL
POWER Power good indicator LED Green LED indicates that +5 V of power is
present.
LOCKED Time locked indicator LED Green LED indicates time and position data is
synchronized since power up. Turns off after 8
hours of no satellite reception.
HOLDOVER Holdover indicator LED Yellow LED indicates the unit is in holdover.
ALARM Alarm indicator LED Red LED indicates:
- Phase lock loop control voltage is within 10%
of its limit.
- Synthesizer lost lock.
- Processor malfunctions.
- 8 hours of no satellite reception.
PPS 1 PPS output, BNC female Output of 1 PPS at TTL levels into a 50 ohm
load. 1 ms wide and rising edge on time.
10MHz 10 MHz sine wave output,
BNC female
Output of 10 MHz at 1 Vrms (2.8 Vp-p)
minimum into a 50 ohm load.
SYNTH Synthesizer output, BNC
female
Output of synthesizer frequency, HCMOS
levels. Frequency is programmed at the factory.
CODE Time code output, BNC
female
IRIG B/AFNOR time code:
- Modulated 3 Vp-p and modulation ratio 3:1
nominal (LK1 2-3).
- IRIG B DC level shift.
- TTL level into 50 ohm load (LK1 1-2).
ANT GPS antenna input, BNC
female
The input connects to a L1 band (1575.42 MHz)
GPS antenna. The “input” provides a +5 VDC
bias voltage to the GPS antenna at up to 80 mA
of current to operate a low noise amplifier or line
amplifier.