GPS Timing Receiver for eMGW/MGW System Installation and Operation Manual February 2005 Alvarion P/N 214028 Symmetricom P/N 197-03850-02, Issue 1
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About this Guide Chapter 1 – System Description. This chapter gives an introduction to the GPS Receiver and describes the command channel and control-display-unit ports and the Alvarion hardware. Chapter 2 – Installation. This chapter describes how to install the GPS Receiver and position location. Chapter 3 – Operations. This chapter describes the system indicators and command channel operation. Appendix A –Technical Data. Appendix B – EMC Emissions and Immunity. Appendix C – Maintenance.
Contents Chapter 1 - System Description...............................................................1-1 Introduction ........................................................................................... 1-2 Command Channel and Control-Display-Unit (CDU) Ports ........................ 1-3 Alvarion Hardware .................................................................................. 1-4 GPS Receiver : Specification .........................................................................
Contents Cable and Power Connections.....................................................................2-17 Casing Ground Connection ......................................................................2-17 Antenna Connection ................................................................................2-18 Output (Timing/Frequency) Connection ...................................................2-18 Command Channel to Alvarion eMGW/MGW System...............................2-18 CDU-PC Connection........
Figures Figure 1-1: Alvarion GPS Timing Receiver ........................................................ 1-4 Figure 1-2: Output Connections ...................................................................... 1-5 Figure 1-3: 1PPS Pulse .................................................................................... 1-6 Figure 1-4: 2.048 MHz Signal .......................................................................... 1-6 Figure 2-1: Alvarion GPS Timing Receiver - Back ...................
Tables Table 2-1: J7 Pin Connection......................................................................... 2-19 Table 2-2: J8 Pin Connections ....................................................................... 2-20 Table 2-3: J21 Pin Connections ..................................................................... 2-21 Table 3-1: LED Display....................................................................................
1 Chapter 1 - System Description In this Chapter Introduction, page 1-2 Command Channel and Control-Display-Unit (CDU) Ports, page 1-3 Alvarion Hardware, page 1-4
Chapter 1 - System Description Introduction Optimized for the Alvarion eMGW/MGW System, the GPS Receiver is a complete, stand-alone, Global Positioning System (GPS) Time and Frequency generator. It has been designed to provide a stable signal source which possesses the long-term stability of a cesium clock, but at a fraction of the cost. This equipment provides an accurate Primary Reference Source (PRS) for applications requiring absolute timing/frequency accuracy.
Command Channel and Control-Display-Unit (CDU) Ports Command Channel and ControlDisplay-Unit (CDU) Ports The Command Channel rear panel port enables any commercially available PC (running Windows 95/98/NT/2000/XP and a terminal display program) to initialize, customize, and control the unit.
Chapter 1 - System Description Alvarion Hardware GPS Receiver: Specification The GPS Timing Receiver for the Alvarion eMGW/MGW System, includes fittings and attachments for the majority of installations. The GPS Receiver includes Motorola™ M12 technology forming its receiver section, plus the latest in PLD technology to provide the signal processing and digital support features.
Alvarion Hardware The positive and negative supply leads may be left floating or either one may be connected to Ground (encompassing the -48V telecommunications standard). We do not recommend connecting the positive or the negative supply leads to ground. A safety ground must be connected to the external case using the terminal provided (see Figure 1-2). An externally accessible fuse is provided on the rear panel. Normally, field replacement of the fuse is neither required nor recommended.
Chapter 1 - System Description 1PPS Pulse Format 2.048 MHz 1PPS Pulse 488ns 1 second New second mark New second mark Figure 1-3: 1PPS Pulse 2.048 MHz This signal may be used as a synchronization interface. The pulse is a continuous DC biased square wave with TTL compatible levels when driving a 50Ω load. V OH V OL 488ns V OH ≥ 2.4 Volts V OL ≤ 0.8 Volts Figure 1-4: 2.048 MHz Signal Time of Day This communication port utilizes an RS232 9-pin ‘D’ type female connector.
Alvarion Hardware LEDs A set of three function (or mode) indicators are located on the front panel. These consist of colored LEDs configured to illuminate as described in the Indicators section, page 3-2. Input / Output Message Format Three RS-232 communication interfaces are available from the GPS Receiver, a time output port, a Command port, and a CDU port. The Time of Day channel is a uni-directional output, with the PC report/control port being bi-directional.
2 Chapter 2 - Installation In this Chapter: Installation, page 2-2 Position Location, page 2-22
Chapter 2 - Installation Installation Installing a basic system will require the following: Mounting of the antenna and the 2 lightning arrestors Connecting a power supply to the GPS Receiver Interconnecting the antenna, the 2 lightning arrestors, the GPS Receiver, and a PC. Connecting the Command Channel and CDU ports to a PC. Installing the TSIP compatible Software to the PC.
Installation Figure 2-2: Typical Antenna Mounting CAUTION DO NOT allow the pole or other surfaces to extend higher than the underside of the antenna. Such a condition would impair signal reception. The most important consideration in selecting a position for the antenna is the presence of objects which obscure the sky or horizon. Where possible, there should be no obstruction to a full view of the sky.
Chapter 2 - Installation Be especially wary about mounting the antenna directly onto the fascia of a flat roof. To overcome this situation, elevate the pole about 1 meter above the flat surface. A satellite prediction program may usefully be employed to check a potential installation, and also to identify directions in which obstructions may be a particular source of problems. The antenna is connected to the GPS Receiver by a coaxial cable fitted with TNC connectors at each end.
Installation There is no way to provide 100% protection for electronic equipment from direct strike damage. It is possible however, to reduce the likelihood of damage from near strike induced fields by ensuring the installation obeys some fundamental rules. Lightning arrestors are not 100% efficient, a residual attenuated electrical pulse being transmitted down the antenna cable, may still contain sufficient energy to damage equipment within the building.
Chapter 2 - Installation Case 2 In case that the GPS antenna is not exposed to direct lightning hit it is recommended to use the regular protection set on the antenna side and at the indoor side. Minimize the exposure of the antenna cable to electrically induced fields. This is easily achieved by feeding the cable down the center of the pole used to mount the bracket. Ensure all conduits exposed to induced fields are of heavy gauge, welded seam construction, and are properly grounded.
Installation Having thereby passed a large proportion of the lightning discharge current to earth, it is then necessary to make provision to deal with the lesser current flows.
Chapter 2 - Installation At the GPS Receiver Unit After taking the precautions described previously in the antenna installation, it should be understood that a destructive residual current may still be present in the cable coming down from the antenna to the GPS Receiver unit. A second lightning arrestor must be installed near to the GPS Receiver to further dissipate any remaining lightning energy.
Installation Figure 2-4: Example of Connections GPS Timing Receiver Installation and Operation Manual 2-9
Chapter 2 - Installation The Lightning Arrestor The lightening arrestor kit contains 5 parts: 1. The Lightning Arrestor quantity 2. 2. Grounding cable. 3. 1 meter coax cable. 4. Bracket for mounting the lightning arrestor on the mast - see Figure 2-3. 5. N type to TNC Adaptor. – optional depending on lightning arrestor connector type. The lightning arrestor will be delivered in one of the following options with TNC connectors or with N-Type connectors (as given in the picture below).
Installation Detailed Installation procedure Installing the Surge Protection Install the lightning arrestor on the mast as shown in Figure 2-3. Install the Surge Protector device and the grounding cable on the backside of the rack – as shown below. Tighten well using M8 screw. Figure 2-6: Installation of Lightening Arrestor on Mast Connecting the N-type to TNC adaptor Connect the TNC to N-type adaptor (part of the kit) on the “surge” side – if the lightning arrestor has N-type connectors.
Chapter 2 - Installation Figure 2-7: Connecting the TNC to N-type Adaptor Connecting the Grounding Cable Connect the other side of the grounding cable to a grounding source of the rack. NOTE A good ground system is required for proper installation and operation. The lightning arrestor is only as good at suppressing impulses as the electrical ground system that is connected to the unit.
Installation Figure 2-8: Connecting the RF TNC-type side to the “Equipment” side GPS Timing Receiver Installation and Operation Manual 2-13
Chapter 2 - Installation Connecting the Surge side Connect the 50m coax cable from antenna to the Lightning Arrestor device – to the Surge side (if the lightning arrestor has N-type connectors use the TNC to N-type adaptor as described in Figure 2-9).
Installation Connection Diagram 19 inch Rack RF cable L=1m To TNC RF connector (rear) GPS Receiver Ring lug Mounting screw PROTECTOR DGXZ+15TFTF-A RF cable To GPS antenna Ground cable AWG8 L=3m Ground Bus Figure 2-10: Lightening Protector Connection Diagram GPS Timing Receiver Installation and Operation Manual 2-15
Chapter 2 - Installation Mounting the GPS Receiver The GPS Timing Receiver is designed for integral mounting within a standard 19 inch telecommunications equipment cabinet. Mounting in Equipment Cabinets Two integral mounting flanges are provided on the ends of the front panel of the unit. All cable connections are made at the rear of the Timing Receiver. Refer to Figure 2-11.
Installation Cable and Power Connections Electrical installation must only be carried out by suitably qualified personnel. Particular attention should be given to protecting the site from the damaging effects of lightning strikes (refer to the section on Protection against Lightning on page 2-6). The GPS Receiver requires a minimum of four connections to be made: Chassis Earth Antenna Output (Timing/Frequency) Power Power supply voltage is to be a nominal 48Volts DC.
Chapter 2 - Installation CAUTION Ensure the casing ground connection is the FIRST connection made to the unit, and the LAST to be disconnected. Interference problems will be minimized by effective and direct ground connections. A screened data cable should be used and grounded at the GPS Receiver connector end. When fitting the host connector, it is desirable to connect both the screen and drain wires to a connector having 360° connectivity (no tails). Any other solution degrades the EMC performance.
Installation Table 2-1: J7 Pin Connection J 7 Connector PIN Connection, Function = Command Channel (as viewed at the GPS Receiver connector) Pin 1 not connected Pin 2 TX - CMD Pin 3 RX - CMD Pin 4 DTR - CMD Pin 5 Ground Pin 6 DSR - CMD Pin 7 TX - CDU Pin 8 RX - CDU Pin 9 Ground CDU-PC Connection These messages are of binary format. Users are unable to use a terminal emulator program to control the GPS Receiver unit through the CDU port.
Chapter 2 - Installation Time of Day Connection The Time of Day port outputs a message once every second. This output is NOT user configurable. Table 2-2: J8 Pin Connections J 8 Connector PIN Connection, Function = Time of Day (as viewed at the GPS connector) Pin 1 Not used Pin 2 TX data Pin 3 RX data Pin 4 DTR Pin 5 Ground Pin 6 DSR Pin 7 not used Pin 8 not used Pin 9 not used Use the cable provided with the Alvarion eMGW/MGW System for connection to the ‘TOD’ port.
Installation Table 2-3: J21 Pin Connections J 21 Connector 4-PIN Connector, Function = Power Cable Core color (viewed at the GPS Receiver connector) Pin 1 Not Connected N/A Pin 2 GND White Pin 3 Supply + Red Pin 4 Supply - Black For use on a negative supply connect ‘supply +’ to ground. For use on a positive supply connect ‘supply -‘ to ground. Figure 2-13: Female Power Connector (cable end view) The maximum power dissipated, at warm-up, does not exceed 20Watts.
Chapter 2 - Installation Position Location When extracting data from the Global Positioning System, there are four unknown variables which the GPS receiver must resolve: X position, Y position, Z position, and time. Each of these variables has an effect on the other. Therefore, before the GPS Receiver can produce an accurate time output, it must first obtain valid data for the other three values.
Position Location User Entered Position In an attempt to expedite the surveying process, the GPS Receiver may be given a position (e.g. entered manually). This user entered position is used to determine which satellites are currently in view. This can only occur when the GPS Receiver has acquired its first satellite, the date and time can then be determined. Utilizing a user entered position (and stored almanacs of the satellites), the satellites in view can be calculated.
3 Chapter 3 - Operations In this Chapter Operation, page 3-2 Indicators, page 3-2 Command Channel Operation, page 3-3
Appendix A - Technical Data Symmetricom(PPGPS Receiver Operation The installation of the system is described in detail in Chapter 2 - of this manual. A minimum requirement for operation of the GPS Receiver being the connection of the antenna, the lightning arrestors plus the grounding and power cables. Once powered, the GPS Receiver will automatically start to work and commence the Position Location sequence described on page 2-22.
Operation Table 3-1: LED Display Conditions Yellow (no GPS) Green (Osc. On) Red Alarm Warm-up mode (~ 6 minutes from switch-on) Off Off Flash After warm up – outputs but not valid (Stabilization) Off Flash Off Normal operating mode Off On Off On Off Off Recovery from Flywheeling (stabilization) Off Flash Off GPS Receiver failed self test Off Off On Firmware Update Download Process Flash Flash Off No power Off Off Off Flywheeling (in spec.
A Appendix A - Technical Data Symmetricom™ GPS Receiver GPS Timing Receiver: 12 channel C/A code, L1 frequency. Dimensions: 308mm W (12.14 inches) x 44.5 mm H (1.75 inches) x 213mm D (8.4 inches). Weight: 3 lb (1.4kg) approx. Power Requirements: Single power input. Voltage: 48V nominal (36 to 72V). Power Consumption: 12W @25°C (20W @ warm-up/cold environments). Antenna: 12VDC, Active type. (complies with ETS 300 019, Class 4.1 - non-weather protected locations).
Appendix A - Technical Data Symmetricom(PPGPS Receiver 1PPS Output: Locked Time error < 100ns when locked to GPS signals. Unlocked Accumulated time error: <100µs accumulated in 24 hours of unlocked operation. (Max 10°C / hour rate of change, between 0-60°C) Pulse Width 488ns negative Amplitude TTL compatible into a 50Ω load. Holdover Stability 3µs/3 hours from loss of satellites. 10µs/5 hours from loss of satellites. 15µs/8 hours from loss of satellites. 100µs/24 hours from loss of satellites.
Operation Indicators: LEDs 3 system status LEDs. Environmental Conditions: GPS Receiver Complies with ETSI 300 019-2-3, Class 3.1 (partly temperature-controlled locations). Operating temperature: 0°C to +60°C Storage temperature: -25°C to +85°C Humidity: 95% (Non-condensing) Antenna Complies with ETS 300 019-1-4, Class 4.1 (non-weather protected locations).
Appendix A - Technical Data Symmetricom(PPGPS Receiver Safety GPS Receiver complies with the following specifications when powered from a supply meeting SELV limits: EN 60950 UL 60950 GPS Timing Receiver Installation and Operation Manual A-4
B Appendix B - EMC Emissions and Immunity The GPS Receiver system has been tested to the following standards and specifications: EN 61000-6-3 - CE marked to this standard EN 55022 Class B - CE marked to this standard EN 61000-6-1 - CE marked to this standard IEC 61000-4-2 IEC 61000-4-3 IEC 61000-4-4 The receiver is designed to have sufficiently low conducted interference that the frame into which it is fitted will meet FCC Part 15, Sub-part B, Class B (conducted emissions). FCC Class B Notice.
Appendix B - EMC Emissions and Immunity However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures: Reorient or relocate the receiving antenna. Increase the separation between the equipment and receiver.
C Appendix C - Maintenance Clean the instrument, use only mild soap solution.
D Appendix D - The Global Positioning System (GPS) The Global Positioning System (GPS) is a military satellite based system developed by the U.S. Department of Defence (DoD) to provide global, all-weather, precise navigation and timing capability to users 24 hours a day. Civilian use of GPS is made freely available at the users own risk, but is subject to the prevailing DoD policy or limitations, and to an individuals understanding of how to use the GPS. However, current practice of the U.S.
Tables It is a combination of the Universal Co-ordinated Time (UTC) traceable signal transmitted by the GPS satellites, used in conjunction with the Symmetricom™ GPS Timing Receiver, which has enabled an extremely accurate timing system to be developed. GPS satellites transmit a code for timing purposes, in addition to a ‘Navigation message’ which includes their exact orbital location and system integrity data.
Tables To measure the range from the satellite to the receiver, two criteria are required: signal transmission time, and signal reception time. All GPS satellites have several atomic clocks which keep precise time and these are used to time-tag the message (i.e. code the transmission time onto the signal) and to control the transmission sequence of the coded signal. The receiver has an internal clock to precisely identify the arrival time of the signal.
Tables The figures refer to 95% position fix accuracies, expressing the value of two standard deviations of radial error from the actual antenna position, this position being an estimate made under specified satellite elevation angle and PDOP conditions. Dilution Of Precision (DOP) is a measure of the satellite geometry, and is an indicator of the potential quality of the solutions.
Tables Precise Positioning Service (PPS) This service is only available to authorised users with cryptographic equipment and special receivers. Access is limited to the U.S. and Allied military, U.S. Government agencies, and selected civil users specifically approved by the U.S. Government Geodetic Datums Geodetic datums, and the co-ordinate reference systems based upon them, were developed to describe exact geographic positions for surveying, mapping, and navigation.
E Appendix E - Glossary 2D Two-dimensional 3D Three dimensional (i.e. including altitude) AGC Automatic Gain Control Almanac Data transmitted by each satellite, and which provides the approximate orbital information of all the GPS satellites constellation (i.e. a ‘timetable’). Antenna Also called ‘Aerial’, the device for receiving the radio signals. ASCII A standard digital format for alpha-numeric characters (American Standard Code for Information Interchange).
Tables CMD The Alvarion GPS unit’s Command Port. CMOS A type of semiconductor fabrication process (Complementary Metal Oxide Semiconductor), resulting in low power. CMOS devices require static protection during handling. CNO Carrier to Noise ratio (dBHz), a measure of signal quality. COM Port Communication port, e.g. PC serial communication ports COM1 etc.
Tables DSR Data Set Ready (serial communication handshaking) DTR Data Terminal Ready (serial communication handshaking) ECEF Earth Centred Earth Fixed.
Tables HDOP Horizontal Dilution of Precision. IC Integrated Circuit. ICD Interface Control Document I/O Input - Output IODE Issue of Data Ephemeris IRQ Interrupt Request Kalman Filter Mathematical process used to smooth out measurement errors of pseudo-ranges and carrier phases of tracked satellites. For example ‘8 states’ refers to filtering of position and time (i.e. x,y,z and t) and the rate of change of each. knot Nautical mile per hour L1 The 1575.
Tables NMEA National Marine Electronics Association. NMEA 0183 A serial communication standard defining hardware compatibility, message formats, and a range of standard messages. OTF ability to resolve integer carrier phase ambiguities in real-time while moving. n.mile International Nautical Mile (1852 meters; 6076.1 feet, 1.15 statute miles). ns, nSec Nanosecond, one thousandth of a microsecond (i.e.
Tables RF Radio frequency RFI Radio Frequency Interference RMS Root Mean Square RS232 Serial communication hardware standard (+/- 12v nom.
Tables TXD Transmit Data (serial communication from Data Terminal or ‘DTE’ to Data Communication Equipment or ‘DCE’) us, uSec Microsecond (u is frequently used for the Greek µ symbol denoting ‘micro’, one millionth part, 10-6) UTC Coordinated Universal Time UTM Universal Transverse Mercator UART Universal Asynchronous Receiver-transmitter (used in serial communications) VDOP Vertical Dilution of Precision WGS World Geodetic System (a world-wide Datum, GPS works in WGS84 which has superseded WG
