HAMEG HM8125 User Manual
Operating Instructions
General Information ................................................. 23
Safety.......................................................................23
Symbols ...................................................................23
Operating conditions ............................................... 23
Warranty ..................................................................23
Controls for the HM8125 ........................................ 24
Accessories Supplied with HM 8125 ...................... 24
Basic concept of the HM 8125 ............................... 25
Frequency Standard ................................................ 25
Installation................................................................25
GPS Reference Location ......................................... 25
Getting Started ........................................................25
Table of contents
GPS Frequency Standard
HM8125
Operation ............................................................... 26
Lock Lost .................................................................26
Menu Structure .......................................................27
Sub-Menu Description.............................................27
LOCAL ..................................................................... 27
DST .......................................................................... 27
UTC .......................................................................... 27
1 PPS (Status) ......................................................... 28
MEAS.......................................................................28
QLTY ........................................................................ 28
POS ..........................................................................28
LIST .......................................................................... 29
LOCK .......................................................................29
ACC .......................................................................... 29
RS-232 Interface .....................................................29
Notes for the DCF77-Code ...................................29
Complementing information to the
data used in the menus Buffered Data ...............29
Error messages .......................................................30
Lock-Lost Reports with
ACKN Key Depressed .......................................... 30
Notes for the DCF77-Code ...................................... 30
Use of GPS Receivers for Frequency
and Time Determination ......................................30
Functional Principles of the GPS System ...............31
Obtainable Accuracy of
Straight C/A -Code Receivers .............................. 31
Obtainable Accuracy for Receivers
with Carrier-Phase Measurements...................... 32
Limits for the Usable Accuracy ............................... 33
Differential Measurements (DGPS) ........................ 33
Änderungen vorbehalten / Subject to change without notice
ENGLISH 21
HM8125 GPS Time/Frequency-Standard
■ Ultra-precise Time, Frequency and Position
■ World-wide Operation
■ Ultra-precise 10 Mhz Output
■ Accuracy 1x10
-12
when tracking Satellites
The HM8125 is a time/frequency standard designed to
provide ultra-precise time, frequency and position. It is based
on the NAVSTAR Global Positioning System (GPS),
developed and deployed by the U.S. department of defense.
It is the most accurate radio navigation system ever developed
and enables users, world-wide, to determine the correct time
with a higher degree of accuracy than ever before.
The HM8125 automatically acquires and tracks the
satellites and calculates time, frequency and position
within 2 to 15 min. after power-up. Synchronization is
confirmed via a front panel LED indicator and the actual
deviation can be read on a 2x20 characters LCD screen.
The compact unit provides timing outputs to within 100
nanoseconds of UTC (Selective Availability not implemented) and frequency outputs accurate to 1x10
-12
when
tracking satellites. Time and position data are available on
the serial interface. This enables the use of the HM8125
in calibration set-ups with easy registration and documentation facilities.
The HM8125 produces a 2.048 MHz frequency output
which is locked to the GPS system. This allows applications in the telecommunication and PCM field. The
HM8125 can also measure external frequencies with an
accuracy of 3x10
-10
at a gate time of 1 second. For field
applications, the geographic position can be read from the
LCD screen. The HM8125 can synchronize a Rubidium
Oscillator and can operate as a stand-alone generator.
The HM8125 is shipped as a complete set including the
antenna, the converter and 15m of BNC cable.
■ Short-term stability 3x10
-10
at 2 second
Integration Time
■ 1 Pulse Per Second Output
■ Serial Communication Port RS232
■ Low Cost of Ownership
Specifications
(Ref. temperatur : 23°C ± 2°C)
Frequency Generation
Frequency output: 1kHz, 2.048MHz and 10MHz
Accuracy: ±3x10
Timing output: 1PPS (Pulse per Second)
Accuracy: 100ns to UTC or GPS time
Jitter: <5ns
Position: Latitude und Longitude (100m), Altitude (150m)
Accuracy: (Under "Selective Availability enabled") ±5m
Frequency measurement
Frequency input: 10 MHz ± 70ppm
Accuracy: 3x10
Input Sensitivity: typ. 30mV - 1V
Antenna: All-weather, outdoor mounting
Dimensions: Ø 4cm x 12cm (approx.)
Frequency converter: for cable runs up to 25m
Dimensions: 3cm x 7cm x 17cm (approx.)
Divers: RS232 interface built-in
Power requirements: 110/220V ±15%; 45-60Hz, 45VA
Ambient temp.: +10°C to +40°C
Humidity: 10%-90%, no condensation
Dimensions: 285mmx85mmx365mm (WxHxD)
Weight: approx. 5kg
Safety: Class I, According to IEC 1010-1
-10
at 2 seconds measuring time
-12
at 24 hours measuring time
±1x10
horizontal; ±10m vertical (24 hours averaged)
-10
at 2 seconds measuring time
-10
at 0.2seconds measuring time
2x10
DCF77 output
22 ENGLISH
Änderungen vorbehalten / Subject to change without notice
General Information
Operating conditions
Immediately after unpacking, the instrument should be
checked for mechanical damage and loose parts in the
interior. If there is transport damage, the supplier must
be informed immediately. The instrument must then not
be put into operation.
Safety
This instrument has been designed and tested in
accordance with IEC Publication 1010-1 (overvoltage
category I, pollution degree 2), Safety requirements for
electrical equipment for measurement, control, and
laboratory use. The CENELEC regulations EN 61010-1
correspond to this standard. It has left the factory in a
safe condition. This instruction manual contains important
information and warnings which have to be followed by
the user to ensure safe operation and to retain the
oscilloscope in a safe condition.
The case, chassis and all measuring terminals are
connected to the protective earth contact of the
appliance inlet. The instrument operates according
to Safety Class I (three-conductor power cord with
protective earthing conductor and a plug with
earthing contact).
The mains/line plug shall only be inserted in a socket
outlet provided with a protective earth contact. The
protective action must not be negated by the use of an
extension cord without a protective conductor.
The instrument has been designed for indoor use.
The permissible ambient temperature range during
operation is +10°C (+50°F) ... +40°C (+104°F). It may
occasionally be subjected to temperatures between
+10°C (+50°F) and -10°C (+14°F) without degrading its
safety. The permissible ambient temperature range for
storage or transportation is -10°C ... +70°C .
The maximum operating altitude is up to 2200m. The
maximum relative humidity is up to 80%.
If condensed water exists in the instrument it should be
acclimatized before switching on. In some cases (e.g.
extremely cold oscilloscope) two hours should be allowed
before the instrument is put into operation. The
instrument should be kept in a clean and dry room and
must not be operated in explosive, corrosive, dusty, or
moist environments. The oscilloscope can be operated
in any position, but the convection cooling must not be
impaired. The ventilation holes may not be covered. For
operation the instrument should be used in the horizontal position, preferably tilted upwards, resting on the tilt
handle.
The specifications stating tolerances are only valid
if the instrument has warmed up for 30minutes
at an ambient temperature between +15°C (+59°F)
and +30°C (+86°F). Values without tolerances are
typical for an average instrument.
Warranty
The mains/line plug should be inserted before
connections are made to measuring circuits.
Whenever it is likely that protection has been impaired,
the instrument shall be made inoperative and be secured
against any unintended operation. The protection is likely
to be impaired if, for example, the instrument
• shows visible damage,
• fails to perform the intended measurements,
• has been subjected to prolonged storage under
unfavourable conditions (e.g. in the open or in moist
environments),
• has been subject to severe transport stress (e.g. in
poor packaging).
Symbols
ATTENTION - refer to manual
Danger - High voltage
Protective ground (earth) terminal
HAMEG warrants to its Customers that the products it
manufactures and sells will be free from defects in
materials and workmaship for a period of 2 years. This
warranty shall not apply to any defect, failure or damage
caused by improper use or inadequate maintenance and
care. HAMEG shall not obliged to provide service under
this warranty to repair damage resulting from attempts
by personnel other than HAMEG represantatives to
install, repair, service or modify these products. In order
to obtain service under this warranty, Customers must
contact and notify the distributor who has sold the
product.
Each instrument is subjected to a quality test with 24
hour "burn-in" before leaving the production. Practically
all early failures are detected by this method. In the case
of shipments by post, rail or carrier it is recommended
that the original packing is carefully preserved. Transport
damages and damage due to gross negligence are not
covered by the guarantee. In the case of a complaint, a
label should be attached to the housing of the instrument
which describes briefly the faults observed. If at the same
time the name and telephone number (dialing code and
telephone or direct number or department designation)
is stated for possible queries, this helps towards speeding
up the processing of guarantee claims.
Änderungen vorbehalten / Subject to change without notice
ENGLISH 23
Controls for the HM8125
LCD Display, 2x20 Symbols
10MHz Input for Frequency Measurements
Menu Keys
LED Indicator: “Data Changed”
LED Indicator: “Lock-Lost”
Acknowledge Key
DCF 77 Output
1 second Pulse, Square Wave
Output-Impedance: 1kΩ, 4Vpp
UTC or GPS Timing Output
1pps (pulse per sec.), Square Wave
Output-Impedance: 1kΩ, 4Vpp
Accessories Supplied with HM 8125
A HM 8125 receiver
B Frequency converter
C Antenna
D BNC to BNC cable 15 m (between converter and HM 8125)
E Type N to SMA cable 3 m (between antenna and converter)
F Adapter cable SMA to BNC (between converter BNC cable and HM 8125)
G BNC coupler (if D is BNC to BNC and not BNC to SMA)
H Manual, power cord and software for RS-232 interface
1kHz Output, Square Wave;
Output-Impedance: 1kΩ, 4Vpp
2.048MHz Output, Square Wave;
Output-Impedance: 50Ω, 2.5Vpp
10MHz Output, Square Wave;
Output-Impedance: 50Ω, 2.5Vpp
Power On LED Indicator and Power Switch
Rear elements of the HM 8125
Mains Input, Voltage Selector and Fuse
Antenna Input Connector (BNC)
Relay Contact Output for “Lock-Lost”
24 ENGLISH
Änderungen vorbehalten / Subject to change without notice
Basic concept of the HM 8125
Frequency Standard
The HM 8125 is a time- and frequency-standard to generate highly precise time, frequency and position data. The
accuracy is based on the NAVSTAR Global Positioning System (GPS) that was developed and is operated by the
US Department of Defense. The GPS consists of 24
satellites with cesium standards to guarantee the accuracy.
The satellite signals are transmitted worldwide. From these
transmitted signals, the HM 8125 calculates its actual place
of operation. Once this is found, the internal oscillators of
the HM 8125 are slaved to the time standard of the GPS.
Installation
The HM 81215 instrument should be installed (if possible)
in a climate-controlled area. The supplied 15 m BNC to
BNC cable is connected between the connector on the
rear of the instrument and to the remote antenna
converter. This cable length can be extended up to 40 m
and by use of an optional pre-amplifier to 100/ 200m.
From the end of the BNC cable connect the BNC to SMA
adapter cable to the antenna converter by use of the
BNC coupler (Barrel). The antenna is connected by use
of the type-N to SMA cable to the antenna converter.
The antenna must be installed on a pole in a vertical
position. The antenna converter must be installed within
3 m and preferably in a room. Even though the converter
is in a weathertight enclosure, it will be better to give
the converter the additional protection of a room or a
separate enclosure. The power to the antenna is supplied
via the coaxial cable from the antenna converter. The
antenna must be installed to give a clear 180 degree
horizontal field of view at the height of the antenna. No
obstructions must be in front of the antenna to ensure
optimum operation of the HM 8125.
GPS Reference Location
In general approximately 8 satellites are “visible” when
the antenna location is optimum. To determine the
accurate location of the HM 8125, four “visible” satellites
are required. The internally stored location is at the final
checkout (factory) of the HM 8125. This location will first
come up upon initial use. Normally the initial “place”
doesn’t correspond to the actual “place” at the operation
location. During initial use of the HM 8125, it may take
up to 30 minutes to determine the geographic reference
coordinates of the newly installed HM 8125. This time
period is strongly dependent upon the “visibility” of the
satellites. The duration of initial geo-referencing can be
shorted by entering the known coordinate data of the
actual location.
Getting Started
The following instructions are meant as a guideline to
quick and easy setup the HM 8125 for the initial operation.
To start operation the above given installation instructions
must be observed. The initial position by default is the
geographical location of the Hameg factory in Frankfurt,
Germany. This position is used as the initial position by
the instrument after power-up on delivery. When the
installation has been done correctly and the antenna has a
good “view” on the satellites, the instrument should lock
after approx. 15 min. regardless of the operation location.
However, in some cases when the installation of the
antenna is not optimum, the unit may fail tracking sufficient
satellites for locked operation.
In this case the following instructions might possibly help
to set-up the instrument correctly.
Be sure to have the geographical location data of your
position on hand. A tolerance of 1,5 oder 5° degree is
acceptable. After “Power-on” the main menu appears
on the LCD.
HM8125 GPS STANDARD
TIME FREQ RECVR STAT
Press the “RECVR”-key to access the “Receiver”-menu.
RECEIVER:
TRACK USE POS
By pressing the “USE”-key the “Use”-menu is reached.
USE averag’d position
(using inital pos)
Due to the reason that the instrument cannot use the
“averaged” position unless it has precisely located 4
satellites, the “entered” position mode should be used
in the beginning. Pressing the “up”-key twice prepares
the use of the position of the actual location.
USE entered position
(using inital pos)
After confirmation by means of the “Enter”-key, the LCD
changes to:
USE entered position
(not yet verified!)
This menu is left via “ESC”. In the “RECVR”-menu which
appears now, press the “POS”-key, which displays the
“POS”-menu.
entered:50°05.297’N
0118m 008°38.813’E
Änderungen vorbehalten / Subject to change without notice
ENGLISH 25
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