Pendulum GPS-12, User Manual

Page: 6 / 62

Introduction
Cesium-controlled
Frequency via Satellites
The GPS-controlled frequency standards
GPS-12(R) and the GLONASS/GPS-con-
trolled frequency standard GPS-12RG deliver a
precision frequency and time reference every-
where in the world. They gain their long-term
frequency stability from Cesium standards in
the navigation satellite systems GPS and
GLONASS. They are also designed to provide
very high short-term stability and are cost-effi-
cient and extremely
accurate frequency
standards.
These reference sources are very suitable as fre-
quency standards in the telecommunication and
electronics industry. They fit both as stationary
frequency references - for instance in test sys-
tems and as local references in the design depart-
ment - and as portable, highly accurate reference
sources for field use.
These instruments are off-air frequency stan-
dards with an internal architecture according to
Figure 1-1. They have one antenna input and a
number of optional frequency outputs.
There is also an option for disciplining with an
external 1 pps source, e.g. an in-house cesium
standard.
Optional I/O Boards
The GPS-12X comes as standard with two
2.048/1.544 MHz square wave outputs and one
1 pps pulse output with approx. 10 µs duration.
The GPS-12RG has also 3 x 10 MHz and
1 x 5 MHz outputs. See Option 70B below.
There are six options to choose from, options
70B, 71B, 72B, 73B, 74B and 79/01. All but the
79/01 allow for four extra frequency outputs to
be mounted. Any combination of none, one or
two of these units is possible. Only one
79/01can be mounted.
Option 70B gives 3 x 10 MHz and 1 x 5 MHz
sine wave outputs, 1 V
RMS
in 50
W
. The
GPS-12RG is as standard equipped with one
such option.
Option 71B gives four sine wave outputs,
1V
RMS
in 50
W
, of resp. 10 MHz, 5 MHz, 1
MHz and 0.1 MHz.
Option 72B gives 2 x 2.048 MHz clock outputs,
±1.2
V square wave in 75
W
, plus
2 x 2.048 Mbps data outputs (G.703:10), for
telecommunication testing and clock synchro-
nization.
Option 73B gives 4 x 13 MHz square wave out-
puts with TTL levels in 50
W
.
Option 74B gives 2 x 1.544 MHz plus
2 x 1.544 Mbps outputs for SONET
applications.
Option 79/01 gives 2 x 10 MHz sine
wave outputs, 1 V
RMS
in 50
W
, plus
1 x 1 pps output, TTL levels in 50
W
,
plus 1 x 1 pps disciplining input, TTL
levels.
1-2
Preface
Satellite
Receiver
Refererence Out Phase
Comparator
Local
Oscillator
(VCO)
Figure 1-1 Simplified block diagram of the GPS-12X.