Masterclock GPS 500 User manual

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
2
DISCLAIMER
Information contained in this document is
subject to change without notice.
Masterclock, Inc. (hereinafter MC) makes
no warranty of any kind with regard to this
material, including, but not limited to, the
implied warranties of merchantability and
fitness for a particular purpose. MC shall
not be liable for errors contained herein or
for incidental or consequential damages in
connection with the furnishing,
performance, or use of this material. MC is
not responsible for legislative changes to
the Daylight Saving Time (DST) rules, nor
to the systems relying on accurate time,
which may be affected by such changes.
Issues related to legislative changes to the
DST rules are not covered under the
Masterclock, Inc. limited warranty. See
important limited warranty information
on page 7.
ADVISORY NOTICE
CONCERNING THE
GPS SATELLITE SYSTEM
AND THE GPS 500
GPS REFERENCE DEVICE
Depending on many factors beyond the
control of MC, the signals that are
received from the GPS satellites are
subject to interference, fading, satellite
failure and other influences that could
cause the GPS 500 to generate erroneous
time and/or date information and, under
some conditions, could prevent it from
generating a Time Code signal and/or
cause it to generate an erroneous Time
Code signal. It is the responsibility of the
user to determine the adequacy and
suitability of this device for the intended
use.
TABLE OF CONTENTS
Installation .................................................... 3
Operation ...................................................... 5
Antenna Location ......................................... 7
Diagram ...................................................... 12
Interval Blanking ......................................... 13
Limited Warrant and Exclusions ........... ..... 13
Hardware Service ...................................... 14
Contact ...................................................... 14
GPS 500 FEATURES
 Generates SMPTE / EBU or
IRIG-B Time Codes
 Synchronized to atomic clock in GPS
satellites
 -11.5 to +12 hour time zone offsets in
30-minute increments
 Automatic daylight saving (US & Canada
time standard)
 Multiple outputs
 NMEA/Kinemetrics / Truetime serial
protocol output
 Wide power supply input range:
12 to 48 VDC
 Switch compatible time zone, DST
 Switch compatible interval blanking
in the Schneider Ion Meter®
 Switch compatible format and baud rate
To ensure a successful installation to your local
grounding and electrical specifications, your GPS
500 was thoroughly tested with its antenna prior
to shipment.

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
3
Installation
PLEASE FOLLOW THESE 4 STEPS TO INSTALL
YOUR NEW GPS 500
STEP 1:
CONFIGURE THE GROUND JUMPER [J5]
AND SWITCHES
Prior to plugging in your clock, unscrew the two screws at the
back of the GPS 500 and gently pull it out to expose the circuit
board.
Set the four banks of eight DIP switches and other items using
the chart (next page) as your guide.
By default the J5 ground jumper is On. In this state the GPS-500’s
system ground is connected to the Earth Ground (J4, pin 3).
Removing the J5 ground Jumper will cause the GPS-500’s system
ground to be floating or a virtual ground.
STEP 2.
SECURE THE BOARD
Replace the circuit board within the case, and replace
the two screws to secure the back.
STEP 3.
CONNECT THE SMA ANTENNA CABLE AND
9-PIN OUTPUT CONNECTOR
Connect the GPS pre-amplified antenna to the GPS-500’s
SMA input with a coaxial cable.
Load the 9-pin terminal block (J2) according to your application’s
specifications and the inputs/outputs and switches diagram (p.
6).
STEP 4.
CONNECT THE POWER CORD
Important: First ensure that the J5 ground jumper is configured
to your specifications before connecting power. Connect power
to the 3-pin terminal block according to the inputs/outputs and
switches diagram (p. 6).
Time Reference
 When synchronized a GPS500’s accuracy is as accurate
as a GPS satellite atomic clock
 After initial synchronization, should the GPS500 lose
GPS signal it will revert to an internal calibrated
oscillator
 Accuracy when not synchronized:
internal TCXO ± one minute per year
Outputs
 SMPTE Time Code
 SMPTE, EBU, 24, 25 or 30 FPS
 IRIG-B Time Code
 IRIG-B - 1 kHz modulated, level - 5 Vpp
 IRIG-B – unmodulated, single ended 5 V
 PPS (Pulse Per second)
 5 V-TTL, Accuracy ± 1 µs (when
synchronized)
 Serial Output
 NMEA
 Time code information via RS-232/485
 Kinemetrics/Truetime protocol
 Date
 Date encoded references (IRIG 1344 and SMPTE
309M)
Connectors
 Output : 9-pin terminal block
 Power plug: 3-pin terminal block
 Antenna: SMA female
Physical
Size:
5.5 x 4.13 x 1.5 in
Weight:
17.3 oz
14 x 10.48 x 3.81 cm
490.5 g
Case
 Cover - off-white aluminum
 Front/rear panel - clear anodized aluminum
Compliance
 CE marked – Available for sale in EU
 FCC, Part 15, Class B, emissions
Power Supply
 12 VDC external wall mount supplied,
UL & CE listed
 115/220, 50/60 Hz
 Supplied with US, Euro-plug, British or AUS/NZ
- others optionally available
Antenna Options
 Basic antenna package includes magnetic GPS
antenna and 15’ (5m) of cable
 Standard antenna package includes marine GPS
antenna, mounting kit, and 50’ (15m) of cable.
Operating Parameters
 Temperature: 0 to +70°C
 Humidity: Up to 90% (non-condensing at +25°C)

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
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SW1
controls
Serial Output Truetime and NMEA.
---------------------------------------------
1 Truetime Lock Indicator enable.
2 Truetime Interval Blanking enable. *see
section regarding inverval blanking, page 14
3 Disable output if GPS is not locked.
Applies to Truetime and NMEA only.
4 Truetime enable.
5 NMEA enable.
Select NMEA output messages:
678
000 = ZDA
001 = ZDA, GGA, GSA, RMC
010 = ZDA, GGA, VTG, GLL, GSA, RMC
011 = reserved
100 = ZDA, GGA, VTG
101 = reserved
110 = ZDA, GGA, VTG, GSV
111 = reserved
see also SW3-6,7,8
for serial baud rade
SW2
controls
Daylight Savings and Time Zone.
------------------------------------------------
Select the DST standard:
12
00 = no offset
01 = US/Canada Standard
10 = European Standard
11 = Mexico Standard
3 Makes the time zone offset negative
4 Adds 1/2 hour to the time zone offset
Set the time zone offset in hours:
5678
0000 = no offset
0001 = 1 hour
0010 = 2 hours
0011 = 3 hours
0100 = 4 hours
0101 = 5 hours
0110 = 6 hours
0111 = 7 hours
1000 = 8 hours
1001 = 9 hours
1010 = 10 hours
1011 = 11 hours
1100 = 12 hours
SW3
controls
Time Code and PPS control,
Time Quality control,
Baud of Truetime/NMEA output.
---------------------------------------------
1
0 = Output time code whether GPS
is locked or unlocked.
1 = Do not output time code when
GPS is unlocked.
2 Time Quality of IRIG-B 1344.
0 = Do not indicate Time Quality.
1 = Indicate Time Quality.
3, 4 = Reserved
5 PPS Output-see also SW4-6,7,8
0 = No PPS output if GPS unlocked
1 = PPS output will be from processor
if GPS unlocked.
Baud Rate of Truetime/NMEA output:
678
000 = 9600
001 = 19200
010 = 38400
011 = 57600
100 = 4800
101 = reserved
110 = reserved
111 = reserved
SW4 controls
Type, format and "Coded Expressions" of time code.
------------------------------------------------------
1
0 = SMPTE
1 = IRIG
US/Canada standard
2nd Sunday in March/
1st Sunday in November
2:00 AM local time
European standard
Last Sunday in March/
Last Sunday in October
1:00 AM UTC time
Mexico standard
1st Sunday in April
Last Sunday in October
2:00 AM local time
CONFIGURATION SWITCH SETTINGS
PPS output pulse width:
678
000 = ~ 200 milliseconds
100 = ~ 1 millisecond
010 = ~ 10 milliseconds
001 = ~ 100 milliseconds
23
when
IRIG
00 = IRIG B0 DCLS (PWM)
01 = IRIG B1 AM
10 = reserved
11 = Time Code output disabled
4,5 when
IRIG
00 = BCDtoy (IRIG Bx02)
01 = BCDtoy, SBS (IRIG Bx03)
10 = BCDtoy, BCDyear, SBS (IRIG
Bx04)*
11 = reserved
*Only time quality bits 20-23 set.
See SW3-switch 2.
Note: Seven (7) IRIG expressions
can be output by other Masterclock
generators, but GPS500 will output
only these 3:
toy = time of year.
BCD = Binary Coded Decimal.
SBS = Straight Binary Seconds.
23 when SMPTE
00 = SMPTE 30 frames per second
01 = SMPTE 25 frames per second
10 = SMPTE 24 frames per second
11 = Time Code output disabled
45 when SMPTE
00 = SMPTE - Leitch date encoding
01 = SMPTE - 309M Date Encoding
MM/DD/YY,
Time Zone included
10 = SMPTE - 309M Date Encoding
Modified Julian Date
(MJD),
Time Zone included
11 = reserved

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
5
Operation
OPERATING THE GPS500 FOR THE FIRST TIME
When the GPS500 is initially powered up (after having
been shipped to a new location) the time to first fix
(time to acquire satellites and reference GPS time)
could be up to 25 minutes. However, the typical wait
time is 2 to 5 minutes. A variety of factors, including
atmospheric conditions, type of antenna, antenna
location and antenna cable length, may affect the
time to first fix.
Set the DIP switches to your desired settings
Upon powering up the device and acquiring a GPS
lock, the GPS 500 will output GPS time. After a few
minutes the device will receive the leap second
information (automatic) and self-adjust to output UTC
time.
When the GPS 500 unit is powered down, the GPS
navigation module within it maintains startup data
with an internal backup battery. The unit will restart
much faster if the location, time and number of
overhead satellites has not changed since the last
power down.
LED POWER INDICATOR AND GPS LOCK STATUS
The small green light on the faceplate of the GPS 500 is your
LED power indicator. After applying power the following
indications will be visible.
INDICATION: One blink per second
GPS is locked. Power is on.
INDICATION: Two blinks per second
GPS is not locked (it is freewheeling). Power is on.
The time reference is the internal clock.
INDICATION: Off No blinking
No power.

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
6
Antenna Location
INDOOR CAN BE A PROBLEM
Obstructions may block signal reception if your GPS
500 antenna is not properly located. Try to find an
unobstructed view of the sky. In some cases this can
be accomplished by placing the included basic
antenna adjacent to a window. However, in most
cases good reception will require mounting a
standard antenna outside of the building, perhaps on
a roof. It is possible that the system will operate
indoors and under certain obstructions, but this can
only be determined by trial and error, ultimately
leading to a successful installation.
BASIC ANTENNA INCLUDED
Your GPS 500 package comes complete with a basic
antenna. If a cable extension is required, lengths up to
500 feet with pre-amplified antennas are available
from Masterclock.
STANDARD ANTENNA OPTION
A more weather resistant antenna is available. It is the
Standard Antenna and it has the following specs:
Gain: 32dB pre-amplified
Voltage: 3.5-5 VDC - 27 mA(max)
Connector: SMA Female
Dimensions: 3.7dia x 5.5h in [9.3dia x 14h cm]
Weight: 6.7 oz (190 g)
Environment: -40° to +85°C with high humidity
Above: The basic antenna that comes with
your GPS 500 package.
Below: The standard antenna may be
purchased separately.
It mounts on a PVC pipe, typically outdoors.

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
7
GLOBAL POSITIONING SYSTEM AND PRECISE TIME
AND FREQUENCY
The Global Positioning System (GPS) is a worldwide radio-
navigation system formed from a constellation of 24 satellites
that continuously orbit the earth. Each GPS satellite has on
board several atomic clocks that are precisely synchronized to
Universal Time Coordinated (UTC) provided by the U.S. Naval
Observatory (USNO). Coded signals are broadcast by each of
the satellites with the exact time and position of the satellite.
All GPS receivers use an antenna to receive these signals. By
using a GPS receiver optimized for time and not position it is
possible to get extremely precise time synchronization with the
satellite’s atomic clocks.
GPS Antennas and Cables
The signals from the GPS satellites operate in the “semi-visible”
spectrum of the L1 band (1575.42 MHz) with a minimum signal
level of -162.0 dBW. With this very low signal strength the GPS
antenna must be able to “see” the sky to acquire the signals.
Practically speaking the antenna must have a clear view of the
sky and thus be mounted on a roof, or in some cases in a
window. The antennas are relatively small, coffee cup size or
smaller, and are connected to the GPS receiver typically via
coaxial cable.
Since the GPS signal is very weak the antenna usually
amplifies the signal to drive it through the cable to the
receiver. Antenna cable however offers some resistance and
the GPS signal strength will attenuate as it travels down the
cable. GPS receiver sensitivity is finite so if the cable length is
too long the signal will be too weak for the receiver to detect
it. Consequently it is very important to know the distance in
advance between the antenna and the receiver so that the
proper cable solution can be installed.
Antenna Types
There are two basic antenna types used with GPS timing
receivers; roof mounted and window mounted. The roof
mounted antenna is required for the more accurate GPS clocks
since at least three satellites are required to be in view at all
times to maintain timing accuracy, typically nanoseconds to
UTC. The window mounted antenna is applicable for the
network time servers which operate with a lesser degree of
accuracy, typically microseconds or in some cases low
milliseconds to UTC, and can function with as few as one
intermittent satellite in view. The roof mounted antenna is
always preferable since by nature of its location has the best
view of the sky. A variation on the roof antenna is the GPS
Down/Up converter used for very long cable runs. This is a
special GPS antenna that receives the GPS signal and down
Typical roof antenna mounting

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
8
converts it to a lower frequency that is then sent down the
cable. Next to the GPS receiver is an up converter that converts
the signal back to the original frequency and delivers it to the
GPS receiver. This process is transparent to the GPS receiver.
Antenna Placement and Mounting
Roof Antenna Placement: When selecting a site for the roof
antenna, find an outdoor location that provides full 360-degree
visibility of the horizon. In most cases, this means locating the
antenna as high as possible, such as on the roof. Any
obstructions may degrade unit performance by blocking the
satellite signals. Blocked signals can increase the time for
satellite acquisition, or prevent acquisition altogether.
A short mounting mast and hose clamps are provided
with the roof antenna to mount the antenna to a pole
or the peak of a building. The antenna mounting mast
and clamps are well suited to attach the antenna to a
vent pipe or mast affixed to the roof. The pipe must
be rigid and able to withstand high winds without
flexing..
Typical roof antenna mounting
GPS Receivers can be susceptible to reflected GPS
signals called multipath. MultiPath interference is
caused by reflected signals that arrive at the antenna
out of phase with the direct signal. This interference is
most pronounced at low elevation angles from 10 to
20 degrees above the horizon. The height of the
mast/antenna may be extended upward to prevent
multipath interference. The antenna should also be at
least three to six feet (1-2 m) from a reflecting
surface.
Window Antenna Placement
The window mount antenna is suitable for use only with the
network time server products with appropriate versions of
firmware. For window mounted antenna installations it is best
to use a window with the best view of the sky. For windows
with equivalent views, orientations that face the equator are
preferred. Generally more satellites will be in view toward the
equator than away from it, east or west facing windows will
also work. Polar facing windows will also work but in general
are not preferred. Windows that have the best view of the sky
are always preferred regardless of orientation.
Attach the antenna above the window sill versus at the top of
the window. This will improve the upward visibility from the
antenna to the sky. Note that some window glazing
treatments may reduce or block the GPS signals, preventing
the time server from acquiring the time.
Placement is preferred in Window with clear view of sky
This window is not a preferred location due to line of sight obstructions

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
9
Antenna Cable Configurations/Options
Antenna cabling solutions typically vary depending on how far
the antenna is installed from the GPS receiver. 150 feet (45 m)
is the unaided cable length limit for many GPS timing receivers.
Adding a GPS inline amplifier extends the cable length an
additional 150 feet (45 m). Beyond 300 feet (90 m) alternative
methods may be used. Figure 3 highlights the cable lengths and
the antenna solutions that enable them.
In-line Amplifier
In-line amplifiers overcome signal attenuation in by amplifying
the GPS signal, adding an additional 150 feet (45 m) in cable
length. The inline amplifier attaches directly in line with the
antenna cable and uses the same power as the antenna; no
extra wiring is required.
GPS Down/Up converter
The GPS Down/Up converter makes cable runs of 250 to 1500
feet (75 m to 457 m) possible. GPS signal down conversion
requires a special GPS antenna and corresponding signal up-
converter. The antenna module converts the signal down to
a lower frequency that is less susceptible to attenuation, and
transmits it the length of the cable to the up-converter. The up
converter restores the signal to the normal GPS signal
frequency for the receiver. The down/up conversion process
is transparent to the GPS receiver. As with any precision GPS
timing receiver, only cable delay and down conversion delays
need to be entered into the receiver. Power is supplied
by the GPS receiver. In the case of Bus level GPS receivers an
external power supply is used. It is important to note that the
cable used in GPS down/up conversion is different than the
standard cable.
Fiber Optic Links
Fiber-optic connections function as a transparent link between
the antenna and GPS receiver equipment. These links eliminate
the limitations of copper systems by enabling longer
transmission distances while retaining the highest level of
signal quality. In addition, fiber optics provide several other
significant network advantages, including simplified network
design, ease of installation, and immunity from EMI/RFI and
lightning.

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Lightning Arrestor
In-line lightning arrestors are mounted on a low impedance
ground between the antenna and the point where the cable
enters the building. They require no additional power or wiring
except the ground lead.
Cable Delay
GPS position as well as precise UTC time is determined at the
point the GPS signals are received at the antenna. Since the
antenna is typically attached to the GPS timing receiver via a
cable, signal propagation delays through the cable cause the
time calculated by the receiver to be slightly behind UTC. In
GPS clocks with nanosecond and microsecond accuracies this is
a critical factor. In products such as network time servers cable
delay is not important because time transfer over IP networks
degrades the time to the millisecond level.
Cable delay is a function of the cable type. RG-59 cable for
example typically delays the signal 1.24 ns/ft. For 50 feet of
cable (15 m) the delay would be 62 nanoseconds. Cable delay is
removed by advancing the antenna signal inside the GPS
receiver. In this example, advancing the signal +62
nanoseconds removes all cable latency. Solutions such as the
GPS Down/up converter also introduce signal latency but this
latency can also be removed by adjusting the signal. All
precision GPS timing receivers with nanosecond or
microsecond timing accuracy have the ability to compensate
for cable delay.
Advanced Planning
It is time well spent to estimate in advance the cable length
from the GPS antenna to the receiver for any planned
installation. Cable lengths that are too short or too long
can each introduce problems. In some cases adding an inline
amplifier and some extra cable may be a quick and economical
solution. In other instances retrofitting for a GPS down/up
converter may be necessary which will require installing a
different cable type. Keep in mind that some extra cable coiled
in a ceiling leftover from over estimating the cable length is not
necessarily negative. Provided you know the length of the total
cable, the cable delay can be accounted for and the timing
accuracy maintained.

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Inputs/Outputs and Switches Diagram

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GPS500 User Manual – Rev E – 2020.04.14 2484 W Clay St, St Charles, MO 63301
12
INTERVAL BLANKING
During the following noted periods the GPS500 does
not output a timestamp, per the request of our
customers needing these quiet intervals.
MID-INTERVAL INTERVAL
mm:ss - mm:ss
xx: 00:00 58:45 - 01:15
xx: 05:00 03:45 - 06:15
xx: 10:00 08:45 - 11:15
xx: 15:00 13:45 - 16:15
xx: 20:00 18:45 - 21:15
xx: 25:00 23:45 - 26:15
xx: 30:00 28:45 - 31:15
xx: 35:00 33:45 - 36:15
xx: 40:00 38:45 - 41:15
xx: 45:00 43:45 - 46:15
xx: 50:00 48:45 - 51:15
xx: 55:00 53:45 - 56:15
LIMITED WARRANTY
The following Masterclock, Inc. Product Warranty
extends only to the original purchaser.
Masterclock warrants every GPS 500 against defects in
materials and workmanship for a period of five years
from date of sale. If Masterclock receives notice of
such defects during the warranty period, Masterclock
will, at its option, either repair or replace defective
products.
Should Masterclock be unable to repair or replace the
product within a reasonable amount of time, an
alternate remedy shall be a refund of the purchase
price upon return of the product to MC. This warranty
gives the customer specific legal rights. Other rights,
which vary from state to state or province to province,
may be available.
EXCLUSIONS
The above warranty shall not apply to defects
resulting from improper or inadequate maintenance
by the customer, customer-supplied software or
interfacing, unauthorized modification or misuse,
operation outside of the environmental specifications
for the product, or improper site preparation and
maintenance (if applicable).

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13
WARRANTY LIMITATIONS
MASTERCLOCK MAKES NO OTHER WARRANTY, EITHER
EXPRESSED OR IMPLIED, WITH RESPECT TO THIS
PRODUCT. MASTERCLOCK SPECIFICALLY DISCLAIMS
THE IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.
In any state or province which does not allow the
foregoing disclaimer, any implied warranty of
merchantability or fitness for a particular purpose
imposed by law in those states or provinces is limited
to the one-year duration of the written warranty.
EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE THE
CUSTOMER'S SOLE AND EXCLUSIVE REMEDIES. IN NO
EVENT SHALL MASTERCLOCK BE LIABLE FOR ANY
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES, WHETHER BASED ON
CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.
In any state or province which does not allow the
foregoing exclusion or limitation of incidental or
consequential damages, the customer may have other
remedies.
HARDWARE REPAIR SERVICE
You may return your GPS 500 to MC for repair service
at any time. First, however, please contact the factory
at 1-636-724-3666 for a return authorization.
CONTACT US
Masterclock, Inc.
2484 West Clay Street
St. Charles, MO 63301 USA
website
www.masterclock.com
USA and Canada
1-800-940-2248
1-636-724-3666
1-636-724-3776 (fax)
International
1-636-724-3666
1-636-724-3776 (fax)
Sales
[e-mail]
Technical Support
suppor[email protected]om