Contents
Features
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Tamper-proof, highly accurate time.
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Displayed time is offset from GPS time by
only 12 ms max.
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Second-to-second accuracy is within 6 ms.
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Every second displayed is straight from the
GPS satellites, not just updated once an hour or once a day.
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Serial time code output through an RS-422
interface on regular 2-conductor shielded cable.
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Daylight Savings/Standard Time switch.
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Local time display uses large, bright LED
digits and can be switched between 12 and 24 hour modes.
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Bar graph display of number of satellites
that the receiver is locked to.
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LED indicators and verbose display of error
conditions including an audible alarm.
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Able to generate NPR, SMPTE
(optional), or DQS (optional) time codes.
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BCD time code output.
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A 'through' port that outputs data from the
GPS receiver to interface the master clock to a computer terminal for monitoring.
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Open-collector outputs for: every 5 minutes
of the hour, odd/even seconds, odd/even minutes, top of the hour single
pulse, and bottom of the hour double pulse.
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User programmable Time Zone Offset.
Advantages
Highly Accurate Time The GPS-1
generates highly accurate time that is traceable to standard time kept
by the US Naval Observatory. The time that is displayed on the clock is
off by only 12 ms from GPS time, which is far more accuracy than is
required for most broadcast applications. Second-to-second accuracy is typically
within 6 ms. Tamper-proof Aside
from generating highly accurate time, the time is tamper-proof.
In many work environments, there always seems to be those individuals who
re-adjust the clock to what they think is the real time, based on
for example, what their watch says. This, of course creates problems in
such environments such as television and radio studios that depend on accurate
time for their broadcasts. Our GPS-1 master has no controls to adjust time,
other than Time Zone Offset jumpers located inside the unit. Basically,
what you see is what you get, which is highly accurate time, straight from
the U.S. Military Global Positioning Satellite network. Up to 2 Levels of Timekeeping Redundancy When the
GPS-1 is used with our remote time displays,
you get a level of timekeeping redundancy, because if for whatever reason
the GPS-1 goes offline, our time displays will keep time by themselves
until it resynchronizes with the master clock. If one of the optional time
code generators are installed in the GPS-1, you get a second level of redundancy,
because those generators will maintain time if the GPS-1 goes offline as
well as our remote time displays. Military Grade, 12 Channel GPS Receiver The GPS
receiver is the 'Smart Antenna' manufactured by Canadian Marconi Company
and is capable of tracking up to 12 GPS satellites simultaneously. It is
a self-contained receiver and antenna in one single weather-proof housing
that is designed for harsh environments which meets or exceeds MIL-STD-810E
specifications. Operating temperature range is -30 °C to +75 °C (
-22 °F to +167 °F ). Full specifications of this receiver can be
found here.
Description The GPS-1
is designed for those installations where highly accurate, digital only
time displays are needed. It fits into standard racks occupying only 1
rack-unit. The local display is viewable up to a distance of 12 ft. (4
m). The standard GPS-1 package
consists of:
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GPS-1 Master Clock.
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'Smart Antenna' GPS receiver
which includes the receiver and antenna in one weather-proof package.
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50 ft. (15.2 m) of data cable
to interface the receiver to the master clock. Longer cable lengths up
to 4000 ft. can be added to this.
The serial
time code output on a standard GPS-1 is NPR time code which is ASCII based,
transmitted using an RS-422 interface. The time is transmitted in 24-hour
format, at a rate of 1 Hz. Of course, this does not mean that the
time will be displayed only in 24-hour mode on our remote
time displays since all of our time displays are capable of being switched
to 12-hour mode as well. Optional SMPTE and DQS
time code generators are available as well for customers who either prefer
or already have displays that decode these time codes.
A BCD
output is provided for customers who wish to interface the master clock
to a video keyer to put accurate time onto video.
The 'through'
port is basically a data splitter that reroutes data coming into the clock
from the GPS receiver back out for monitoring or troubleshooting the receiver
remotely using a computer terminal. It also puts out a 1PPS (Pulse Per
Second) signal that is accurate to ±200 ns from GPS time.
Finally, there
are open-collector pulse outputs for:
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Every five minutes of the hour.
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Odd and even seconds.
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Odd and even minutes.
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Top-of-the-hour.
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Bottom-of-the-hour double pulse.
These outputs
can be used to turn on or off devices at specific times, indirectly drive
impulse clocks, or to provide on-air 'beeps' respectively. Any number of these
outputs can be combined to provide a single output that serve multiple
functions to a single device. With just
a flick of a switch, the GPS-1 is also capable of switching not only its
local display, but all of the remote time displays
attached to it, to either Standard Time or Daylight Savings Time instantly.
This makes a strong argument for customers who currently use impulse driven
analog clocks and who are considering switching to all-digital time displays
because of their advantages over analog clocks. Those customers who do
have impulse driven analog clocks are all too familiar with the pain and
aggravation associated with adjusting them to either time standard. It
is a time and labor consuming task to re-adjust those clocks twice a year,
which can generally only be done during off-peak hours. Also, because digital
clocks switch instantly, it avoids the confusion that is often encountered
when inadvertently reading time from an analog clock while it's being re-adjusted. The front
panel display array consists of the time readout (which can be switched
between 12 and 24 hour modes), a bar graph of 12 green LED's indicating
the number of satellites that the GPS receiver is locked to, and three red
LED's indicating error conditions: complete loss of satellite lock, loss of receiver
communications, and an indication that the errors occurred although they have
corrected themselves. During these error conditions, the time readout
will also display the error verbosely. Time Zone
Offset jumpers inside the unit allow the time to be offset to any time
zone from Universal Coordinated Time (formerly Greenwich Mean Time) up
to 31½ hours through a binary addition of 6 bits. The GPS
receiver can be mounted on a roof top, the top of a vehicle, or in a satellite
dish farm with a clear view of the sky (weather conditions will not affect
satellite reception) using either a 1" diameter pipe with 1-14 UNS thread
or 3, 10-32 UNF screws with mounting hardware (provided on request).
Specifications Display: 0.8"
(20.3 mm), bright red LED.
Dimensions:
1 rack-unit --- 19" W x 1.75" H x 8.25" D (483 x 44.5 x 210 mm).
Accuracy:
Displayed
time and open-collector outputs are offset from GPS time by 12 ms max.
Second
to second accuracy is typically ±200 ns.
Time code outputs:
NPR time
code: ASCII at 9600 baud, 8N1, at a rate of 1 Hz.
Optional
SMPTE generator: 30 fps only, no drop frame.
Optional
DQS generator: Pulse-width modulated, 30 Hz.
Time code interface (all
codes): RS-422 - balanced, low Z.
Time code output drive capacity:
50 remote time displays, up to 4000 ft.
Receiver to Clock Interface:
RS-422 - balanced, low Z.
'Through' port:
RS-422 - balanced, low Z.
Open-collector outputs:
Max.
per output: 50V DC, 500 mA
Pulse
widths: 500 ms.
Bottom-of-the-hour
double pulse widths: 500 ms on - 500 ms off - 500 ms on.
BCD output:
TTL level.
1PPS output:
RS-422, ±200 ns from GPS time.
Power: 12VAC,
1A Specifications for the Smart
Antenna GPS receiver can be found here.
Ordering Info When placing an order with us, please refer
to the model numbers below:
GPS-1 --- This is the standard package
that includes the master clock, Smart Antenna receiver and 50 ft. of data
interface cable.
SMPTE-1 --- Optional add-on to
generate SMPTE time code.
DQS-1 --- Optional add-on to generate
DQS time code. |
