Verif-I Ltd
GPS Synchroniser
Operating and Software instructions
Firmware versions 2v14 to 2v27 and 3v80
Verif-i Limited
Manual Version 1.00 revision 0
June 2016
Chiltern House
Marsack Street
Caversham
Reading
RG4 5AP
United Kingdom
Tel
+44 118 972 2236
Fax
+44 118 947 9743
Email info@verif-i.com
Web www.verif-i.com
Copyright
This manual is provided as an aid to use of the GPS Synchroniser kit and its software.
Users of the software are free to print copies for the above purpose only. This manual
may not be distributed to third parties without the prior written consent of Verif-i Ltd.
 2016 Verif-i Ltd.
2
Contents
1 Introduction
1.1
4
Timing Considerations
4
2 External Connections
5
3 Operation
6
3.1
Data Format
4 Firmware Version 3v80
5 Using GPS Sync 1.1 Software
5.1
5.2
5.3
5.4
5.5
Download Memory
Changing Trigger polarity
Live Data
Reset GPS Module
GPS to UTC
6 Using GPSSerial2 Software
6.1
6.2
Transferring Results to a PC Using GPSSerial2
Changing Trigger Polarity Using GPSSerial2
7 Using Terminal Software
7.1
7.2
Transferring Results to a PC Using Terminal Software
Changing Trigger Polarity using Terminal Software
7
8
9
10
12
13
15
16
18
18
20
22
22
23
8 Specifications
24
9 Adjusting the Precision Clock
25
10 Setting GPS Receiver Parameters
26
11 Cable Diagrams
30
3
1
Introduction
The GPS Synchroniser is designed to measure the time at which events occur to near
microsecond accuracy using a precision oscillator in conjunction with the GPS network.
The GPS Synchroniser operates automatically and autonomously. Each time it
receives an external trigger signal, the date and time are recorded in a non-volatile
memory, transmitted via the serial port and displayed on the unit.
The non-volatile memory has a capacity of 4095 records (8191 for software 2v20 and
above) which is organised on a last in, last out basis.
The unit is triggered by a nominal 5 volt TTL level. The polarity (rising or falling edge)
is programmable via the serial port.
The contents of the memory can be transferred to a PC using the serial port.
There is an internal test facility to check and adjust the precision clock.
1.1 Timing Considerations
The GPS Synchroniser records a single event in any second. The information is
displayed and written to memory during the following second. The unit is ready to
record the next event during the second afterwards. Thus the maximum repetitive
recording rate is one event every two seconds.
4
2
External Connections
PC Serial Connector
12 Volt Supply
Antenna Connector
Input Trigger Connector
GPS Seconds LED
5
3
Operation
1.
Place the antenna in a suitable location and connect to the GPS Synchroniser.
The base is magnetic and the arrow should point upwards.
2.
Connect the unit to a 12 Volt supply. The following display appears:
GPS SYNC 2v14 02
Waiting for TB
This indicates that the unit is waiting for a trigger input. The LED on the end
panel will flash once a second indicating that the GPS unit is functioning.
The figure on the upper right of the display indicates the number of satellites
that the system is using for calculation; this is refreshed once a second. The
system must use at least one satellite to produce a valid time.
If there is a problem with the antenna connection the number is replaced by a
two-letter code:
OC
UC
NV
The antenna current is too high (possible short circuit)
The antenna current is too low (possible open circuit)
The antenna status cannot be determined.
3.
Connect the trigger signal to the unit. When a trigger is received the following
display appears:
Trigger polarity
Event time - microseconds
“U” - UTC Time
“G” - GPS Time
45743 us
+
U 17:05:34 11 05
Event time - hours
minutes and seconds
Available
Satellites
Satellites used in time
calculation
6
The data is also output from the serial port. It can be captured on a PC using
GPSSerial 2 (software on the supplied CD) or a terminal utility such as “Hyperterminal”.
The parameters should be set to:
9600 bits per second
8 data bits
No parity
1 stop bit
No flow control
The cable is not supplied with the unit. The wiring diagram is on page 30.
3.1 Data Format
Typical output data string via serial port:
012 289238 us + U 12:14:31 11 03 15/02/2005
012
289238 us
U
+
12:14:31
11
03
15/02/2005
Serial Number of the unit
Event time – microseconds
Time is UTC (or ‘G’ for GPS – see page 12)
Trigger is on positive transition (or ‘-’ for negative)
Event time hours, minutes and seconds.
Number of visible satellites
Number of satellites used for calculation
Event date, day, month and year
7
4
Firmware Version 3v80
This version of the software adds two extra items of information to that provided by
version 2vXX.


The time stamp is also recorded in microseconds in GPS time. This is the
elapsed time in microseconds since 00h00 on 6th January 1980. This
information is not added to the real-time output string.
The position in WGS 84 format. This is raw GPS information (not DGPS).
Typical output data string via serial port (real-time):
254 147080 us + U 10:12:35 08 02 28/08/2013 N 51d 26m 27.17s W
00d 20m 36.00s
The output data is a single line. The format is the same as version 2vXX on the
previous page with the addition of coordinates in degrees, minutes and seconds.
Typical output data string via serial port (transferred data):
254 1061719971147080 us + U 10:12:35 08 02 28/08/2013 N 51d 26m
27.17s W 00d 20m 36.00s
The output data is a single line. The format is the same as the real-time version with
the addition of the ten digits to the time stamp corresponding to GPS time.
It should be noted that the sixteen digits of the timestamp are always in microseconds
in GPS time. The next part of the time section in HH:MM:SS DD/MM/YY format is in
UTC time or GPS time as indicated by the ‘U’ or ‘G’ character in the output string.
There is a difference between the two (17 seconds in May 2016) due to the addition of
leap seconds to UTC time. This can be seen with the example data below showing
the same event recorded on two different units. Unit 253 was set to GPS time and 254
to UTC time. The initial 16 digit values are the same but the HH:MM:DD format time
on unit 253 is 16 seconds ahead of unit 254.
253 1061719973147009 us + G 10:12:53 08 03 28/08/2013 N 51d 26m
27.20s W 00d 20m 35.89s
254 1061719973147009 us + U 10:12:37 08 02 28/08/2013 N 51d 26m
27.17s W 00d 20m 36.00s
8
5
Using GPS Sync 1.1 Software
This software has been designed to work on the Microsoft’s .NET framework which is
built into all versions of Windows after Vista. It will also work on XP if service pack 1 is
installed.
9
5.1 Download Memory
The Download Memory module is designed to allow the user to download all data
currently stored on the GPS Synchroniser via the supplied blue cable. To avoid
missing data the serial port should be set up and the GPS Synchroniser connected to
the PC using the blue cable before power is applied to the GPS Synchroniser.
Note that data is not erased from the memory when it is read so data download can be
repeated if necessary.
Before connecting power to the GPS Synchroniser select which serial port the GPS
Synchroniser is connected to using the drop down list on the Select Com Port control.
This list can be refreshed if the serial port is attached to the PC after the module has
been started, e.g. if a USB to Serial converter is connected to the PC after the software
has been launched.
10
Data downloaded from the GPS Synchroniser can be saved into a Tab Separated
Value (TSV) text file. Alternately this data can be saved with no formatting. This is
selected by checking the save format check box which will indicate the save format
which is currently selected. When saved in TSV this allows data to be easily imported
into spreadsheet programmes such as Microsoft Excel. An example of the TSV format
is shown below:
GPS
Serial:
Serial
No.
microsecond
value
us
11
867318
11
975701
11
No. Lines
Read:
Trigger
Polarity
Firmware
type:
Timing
Mode
Time
us
+
U
us
+
U
8199
2
Sats.
seen
Sats.
used
11:30:28
12
6
11/11/2015
11:30:30
12
6
11/11/2015
Date
Once the serial port has been selected click the Connect button.
The software then prompts for the folder and file name in which to save the downloaded
data. This file’s location and name is displayed in the text box at the bottom of the
window under the Received data text box.
Power should then be applied to the GPS Synchroniser to initiate the download.
While the data is being transferred by the GPS Synchroniser the user will be able to
see the incoming data as well as a line count to indicate the progress.
Data download can be cancelled at any time by clicking the Disconnect button which
will close the serial port.
11
After data download is complete a timing test is continuously performed. While the
timing test is in progress the trigger polarity of the GPS Synchroniser can be changed,
see section 5.2 below.
If downloading data from more than one GPS Synchroniser, it is recommended that
the software be closed and restarted. This will clear the received data table and the
line count for the new unit.
5.2 Changing Trigger polarity
After data download is complete, as described in section 5.1 above, the trigger polarity
of the GPS Synchroniser can be changed.
When the download is complete the GPS Synchroniser automatically performs a timing
test. The timing test counts the number of microseconds counted by the GPS
Synchroniser over two PPS seconds to give an indication of the accuracy of the GPS
crystal (see section 9). This test repeats indefinitely until stopped by the operator.
While the timing test is in progress the polarity of the signal used to trigger the GPS
Synchroniser can be changed by clicking the Change Polarity button. If the button was
clicked while the data download was in progress the software will remember this and
will start this procedure once the download is complete.
When the Change Polarity button is acknowledged by the software the Positive or
Negative polarity buttons are enabled as appropriate to enable the polarity to be
changed.
12
In the above example the GPS Synchroniser polarity is currently positive, as shown in
the bottom line of the display POL>+, so the Negative button is enabled to allow the
polarity to be changed to negative if required.
After the polarity has been changed the GPS Synchroniser should be powered down
and the blue cable removed before being used to record events.
5.3 Live Data
The Live Data module is designed to allow the user to monitor and record events
recorded by the GPS Synchroniser as they are received. The user should construct a
two wire serial cable, as described on page 30 of this manual, however the module will
also work with the supplied blue cable if the GPS Synchroniser is powered up before
the cable is attached (the download procedure automatically starts if a blue cable is
detected when the system boots).
13
The user should select which serial port the GPS Synchroniser is connected to using
the drop down list on the Select Com Port control. This list can be refreshed if the serial
port is attached to the PC after the module has been started e.g. if a USB to Serial
converter is connected to the PC after the software has been launched.
Please note that if the GPS Synchroniser has the Positioning firmware, version 3.80,
installed the Position Firmware box should be selected before the Connect button is
clicked.
Data received from the GPS Synchroniser can be saved into a Tab Separated Value
(TSV) text file. Alternately this data can be saved with no formatting. This is selected
by checking the save format check box which will indicate the save format which is
currently selected. When saved in TSV this allows data to be easily imported into
spreadsheet programmes such as Microsoft Excel. An example of the TSV format is
shown above.
Clicking the Connect button prompts the user to select the folder and file name in which
to save the data. This file’s location and name is displayed in the text box at the
bottom of the window under the Received data text box.
Power should then be applied to the GPS Synchroniser and timing data is output each
time an event is detected.
14
This shows that ten events were output to the PC. The events are also recorded into
the internal memory of the GPS Synchroniser and can be downloaded as normal, as
described in section 5.1.
5.4 Reset GPS Module
This module resets the parameters in the internal GPS module if they have been
corrupted for any reason (e.g. the internal battery becomes discharged after a long
period of storage). A symptom of parameter loss is an invalid time display such as
“55:55:55” or displaying “OC” when an antenna is connected.
This module uses the red cable is used to communicate with the PC. The GPS
Synchroniser should be powered up after the cable is connected.
The user should select which serial port the GPS Synchroniser is connected to using
the drop down list on the Select Com Port control. This list can be refreshed if the serial
15
port is attached to the PC after the module has been started e.g. if a USB to Serial
converter is connected to the PC after the software has been launched.
When the GPS Synchroniser has booted Clicking the Connect button resets the
parameters in the GPS module.
The GPS Synchroniser should be powered down and the red cable removed before
being used to record events.
5.5 GPS to UTC
This module selects whether event times are recorded in GPS or UTC time.
The red cable should be used to connect the GPS Synchroniser to the PC before the
GPS Synchroniser is powered up.
Select which serial port the GPS Synchroniser is connected to using the drop down list
on the Select Com Port control. This list can be refreshed if the serial port is attached
to the PC after the module has been started, e.g. if a USB to Serial converter is
connected to the PC after the software has been launched.
16
When the GPS Synchroniser has booted, clicking the Connect button interrogates the
GPS Synchroniser to get the current timing mode.
Currently GPS
Currently UTC
The above two images show how the software displays the current setting of the GPS
timing mode of the connected GPS Synchroniser. Depending on which timing mode is
currently being used the text below the COM port list will change accordingly. The
appropriate button will then be enabled so that the user can change between modes.
17
6
Using GPSSerial2 Software
GPSSerial2 a terminal application supplied with the GPS Synchroniser. It will run on
all versions of Windows from XP onward. It requires the .NET Framework to be
installed on the PC, this is usually done by default on Windows Vista and Windows 7
installations.
6.1 Transferring Results to a PC Using GPSSerial2
1. Connect the cable with blue connectors between the PC serial port and the GPS
Synchroniser.
2. Start GPSSerial2. If no serial port is found an error message is displayed and
the programme exits.
3. Select the appropriate serial port and baud rate in the drop boxes at the top left.
For a data transfer the baud rate should be 57600. If the serial port number is not
known (for example if a USB converter is being used) the Device Manager may
give useful information. Click on “Connect” to connect to the port.
4. Click on “Save” to select a filename and location for the transferred data. The
extension “txt” is automatically added.
5. Connect the GPS Synchroniser to a 12 Volt supply. The following display
appears:
GPS
SYNC
2v26
Exporting Data
The display on the PC should show the data arriving. The complete transfer takes
about 50 seconds (100 seconds for software 2v20 and above).
18
6. When the transfer is complete a display similar to the following appears on the
GPS Synchroniser, click on “Stop” to save the file:
1999999
Timer Test
The Timer Test is an internal test during which the number of the microseconds from
the internal precision clock is counted over a two second period from the GPS system.
The test result is also output on the RS 232 port. Values from 1999998 to 2000002 are
within specification. The precision clock can be adjusted if necessary (see page 11).
Software versions 2v22 and above will additionally display the number of satellites
used for calculation in the upper right hand corner.
19
6.2 Changing Trigger Polarity Using GPSSerial2
1.
Follow the procedure for transferring data on the previous page.
2.
When the data transfer is complete click on “Polarity”. After a few moments the
GPS synchroniser will return the prompt “POL>” in the display:
The ‘+’ character is the current setting; in this case the unit will trigger on a positive
edge.
To change the polarity, click on ‘Positive’ or ‘Negative’ as appropriate. The display will
confirm the chosen configuration.
20
The GPS Synchroniser will need to be restarted after this process.
21
7
Using Terminal Software
7.1 Transferring Results to a PC Using Terminal Software
1.
Connect the cable with blue connectors between the PC and the GPS
Synchroniser.
2.
Start a terminal utility such as “Hyperterminal” on the PC.
The parameters should be set to:
57600 bits per second
8 data bits.
No parity
1 Stop bit
No flow control
3.
The “Capture Text” facility or equivalent can be used to save the transferred
data in a file.
4.
Connect the GPS Synchroniser to a 12 Volt supply. The following display
appears:
GPS
SYNC
2v14
Exporting Data
The terminal display on the PC should show the data arriving. The complete transfer
takes about 50 seconds (100 seconds for software 2v20).
5.
When the transfer is complete the following display appears:
1999999
Timer Test
This is an internal test during which the number of the microseconds from the internal
precision clock is counted over a two second period from the GPS system. The test
result is also output on the RS 232 port.
Values from 1999998 to 2000002 are within specification. The precision clock can be
adjusted if necessary (see page 11).
Software version 2v22 will additionally display the number of satellites used for
calculation in the upper right hand corner.
22
7.2 Changing Trigger Polarity using Terminal Software
1.
Follow the procedure for transferring data on the previous page.
2.
When the data transfer is complete type ‘’ on the PC keyboard. The GPS
Synchroniser will return the prompt:
POL> +
The ‘+’ character is the current setting; in this case the unit will trigger on a positive
edge.
To change the polarity type ‘+’ or ‘-’ as appropriate.
Note
The GPS Synchroniser will only recognise the two characters ‘+’ and ‘-’. Any other
characters will be echoed to the terminal and the prompt will return, as in the following
example:
POL > + W
POL > + R
POL > + O
POL > + N
POL > + G
POL > + POL > In this case the sixth attempt was recognised and the polarity changed.
23
8
Specifications
Input:
Optically isolated to 1.5 kV
Input range 3.5 V to 12 V
Triggers on a positive or negative going transition, software selectable
Output:
RS232 - 9 pin D female with true RS232 levels
Accuracy:
± 5 microseconds for each event
Power Requirement:
9 V to 18 V DC 250 mA
Size:
100 x 250 x 45 millimetres
Weight:
430 grams
24
9
Adjusting the Precision Clock
1.
Remove the four screws holding the case together. The two upper screws are
accessible after removing the small plastic panel on the back of the case.
2.
Put the GPS Synchroniser into test mode as described on page 8.
3.
Adjust the potentiometer (indicated) until the display reads 2000000. The
display will typically vary by one or two counts. The front panel connector has
been removed in the image above for clarity.
Note
1
The GPS Synchroniser displays the result of a count every two seconds.
Sufficient time should be left between adjustments to allow the display to
refresh.
2
The adjustment should only be made with the antenna connected and the unit
capturing satellite data.
25
10 Setting GPS Receiver Parameters
Normally this should not need to be done. The GPS receiver has an internal battery
powered memory for saving parameters. The parameters are reset if they are lost for
any reason (eg battery failure) or it is required to change the time mode (UTC to GPS
or vice-versa). A symptom of parameter loss is an invalid time display such as
“55:55:55”.
It is suggested that the following method is used for both cases.
1.
Connect the GPS control cable (red connectors) between the PC and the GPS
Synchroniser.
2.
Power up both units and start the WinOncore12 software.
3.
Start the setup wizard from the button on the toolbar.
26
4.
Click “Yes” to continue
5.
Check the serial port settings and click “OK”
27
6.
The position information is not important since it is not used. Click “OK” to
continue.
7.
Choose GPS or UTC time mode (important). The date and time information is
not important; the receiver will correct it as soon as it receives valid satellite
data. Click “OK” to continue.
28
8.
Set the output message rate to “1”.
Note : This is an important parameter.
Click “OK” to continue.
9.
Click “OK” to finish..
29
11 Cable Diagrams
30
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