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Spectracom 2804A Handbook

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SPECTRACOM Type 2804A
GPS MASTER CLOCK
SPECTRACOM
6A Beechwood, Lime Tree Way,
Chineham Business Park,
Basingstoke. RG24 8WA
Tel: +44 (0) 1256 303630
Fax: +44 (0) 1256 466713
Email: info@spectracom.co.uk
http://www.spectracom.co.uk
Designed and manufactured in the U.K.

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Summary of Contents for Spectracom 2804A

  • Page 1 SPECTRACOM Type 2804A GPS MASTER CLOCK SPECTRACOM 6A Beechwood, Lime Tree Way, Chineham Business Park, Basingstoke. RG24 8WA Tel: +44 (0) 1256 303630 Fax: +44 (0) 1256 466713 Email: info@spectracom.co.uk http://www.spectracom.co.uk Designed and manufactured in the U.K.
  • Page 3 The appropriate code letters are appended to the basic unit number to indicate the variant. EXAMPLE: If a 2804A basic unit were fitted with a 5MHz, Rubidium-Atomic reference oscillator and also the standard Synthesiser option, it would be designated 2804AFRS.

  • Page 5: Table Of Contents

    Drg. No. 3719-6345 dc-support (input) connector--J2 ............6 Drg. No. 3719-6344 dc output/alarm-2 connector--J3 ............8 GENERAL DESCRIPTION ..................10 Drg. No. 3870-7330 -- Functional Block Diagram -- 2804A ........... 12 OPERATING INSTRUCTIONS ...................14 Connecting Power sources ..................14 Status following Power-up ..................14 MANUAL OPERATION -- VIA FRONT PANEL ............15...
  • Page 6 UK customers should contact Spectracom for disposal instructions. Customers in other EU countries should contact the importers for disposal instructions.
  • Page 7 HAZARD LIST 1. HIGH VOLTAGE PRESENT IN EQUIPMENT -- Possibility of Electric Shock Safety notes 1(a) Before connecting or operating the unit ensure that the supply voltage/s and frequency are within the limits specified for the equipment. The rear-panel a.c. voltage-selector switch must be correctly set before applying a.c.

  • Page 8: Specification

    = Earth J2 7-way profDIN socket POWER CONNECTOR (d.c. input) Use optional (See Drg. No. 3719-6345) Connect only to Spectracom Battery support unit or equivalent protected supply, using approved cable. Voltage range +22V to +32V d.c. SIGNAL CONNECTORS DATA INTERFACES...
  • Page 9 SIGNAL CONNECTORS continued SIGNAL INTERFACES " Timecode Outputs : J15 (Output A) J16 (Output B), BNC, 50 ohm source Both connectors carry same code group User-selectable (from Panel or Com Port): Timecode (1) = IRIG-A, IRIG-B, XR3, 2137 Default: IRIG-B Internal link-configurable for Modulated or Unmodulated code types.
  • Page 10 C +/-10C (typical) ±3 in 10E10 C ± 10C 2804A GPS drift-corrected performance / at quasi-constant temperature in the range 26 Frequency (10MHz) Accuracy (24hr averaging) 5 in 10E11 (ref USNO) Stability (typical distribution, 1000 sec avg. 95% probability) ±1 in 10E10...

  • Page 11: Drg. No. 3870-7329 -- Block/Wiring Diagram Type 2804A

    Drg. No. 3870-7329 -- Block/Wiring Diagram Type 2804A ZCAT1518 -0730 ZCAT1518 -0730...
  • Page 12 BLANK PAGE...

  • Page 13: Drg. No. 3719-6345 Dc-Support (Input) Connector--J2

    + ve This drawing and any information disclosed herewith are not to be copied, used or disclosed in whole or part without the written permission of Spectracom. a division of Orolia Global Services Ltd CAD CORELDRAW 5 3719 22 05 98...
  • Page 14 BLANK PAGE...

  • Page 15: Drg. No. 3719-6344 Dc Output/Alarm-2 Connector--J3

    ALARM 2 This drawing and any information disclosed herewith are not to be copied, used or disclosed in whole or part without the written permission of Spectracom. a division of Orolia Global Services Ltd CAD CORELDRAW 5 3719 22 05 98...
  • Page 16 BLANK PAGE...

  • Page 17: General Description

    The functional Block diagram is depicted in Drawing No 3870-7330 on the following page. Two data interfaces are available for use between the 2804A and the user's system; these interfaces are RS232 Duplex ports, designated Com Port 1 and Com Port 2. The connectivity at these ports, and their functional details are described fully in later sections.
  • Page 18 BLANK PAGE...

  • Page 19: Drg. No. 3870-7330 -- Functional Block Diagram -- 2804A

    Drg. No. 3870-7330 -- Functional Block Diagram -- 2804A...
  • Page 20 BLANK PAGE...

  • Page 21: Operating Instructions

    OPERATING INSTRUCTIONS Connecting Power sources The 2804A is intended for continuous powering from either 230V or 115V (nominal) 50Hz/60Hz ac supplies, according to the setting of the rear-panel a.c. voltage selector switch. +24V (nominal) d.c. supplies may also be used, either as the primary power source, or as back-up.

  • Page 22: Manual Operation -- Via Front Panel

    ±30 , both vertically and horizontally. It is recommended that the 2804A unit should be rack-mounted at a height corresponding to nominal eye- level to give best all-round readability and to avoid partial obscuration of the display characters by the window edges.

  • Page 23: The Display Page Sequence

    The Display Page Sequence The 2804A has a total of more than twenty five different display pages, that are used for various purposes including the display of data, control of the unit, and interrogation of its status. These pages are selected for display manually by means of the dedicated control button marked PAGE.

  • Page 24: The Mode Page

    MANUAL OPERATION The MODE page The choice of menu to be displayed is made on the page. MODE As each Menu is explored via the button, the sequence always passes through PAGE page which appears in each menu, allowing the user to switch to the MODE MAIN TEST...

  • Page 25: Drg. No.3870-7049 -- 2804A Display Pages -- Sequence Diagram

    Drg. No.3870-7049 -- 2804A Display Pages -- Sequence Diagram A Division of Global Services Ltd 2804 DISPLAY PAGE SEQUENCE DIAGRAM POWER ON or RESET INITIAL PAGE MODE PAGE PANEL LOCK / UNLOCK MAIN TEST MAIN MENU TEST PAGES MENU MENU...
  • Page 26 BLANK PAGE...

  • Page 27: Display Page -- Name List

    MANUAL OPERATION Display Page -- Name List NOTE: indicates page may be omitted -- dependant on options fitted MAIN MENU PAGE NAME FUNCTION MODE Allows Menu choice, & Panel Lock/Unlock STATE Current status of unit TIME Current UTC & Local Date/Time EVENT Recent 'external event' Date/Time log GPS 1...

  • Page 28: Display Page -- Characteristics

    MANUAL OPERATION Display Page -- Characteristics The Display Pages are illustrated in Drg No.3870-7051 (Sheets 1, 2, 3), below. These sheets show the typical appearance of pages within each menu; arbitrary data values are depicted. General Features All pages are designed to provide best readability within the constraints of a 2 x 40-character presentation space.
  • Page 29 All pages. This drawing and any information disclosed herewith are not to be copied, used or disclosed in whole or part without the written permission of Spectracom. a division of Orolia Global Services Ltd 03 10 01 3870 - 7051...
  • Page 30 BLANK PAGE...

  • Page 31: Main Menu

    If the unit is operating with a dc-blocked splitter feed or with an external dc-blocked GPS Amplifier, the 2804A software will clear the ANTENNA FAIL indication as soon as a valid Fix is achieved, regardless of the Antenna feed-current measurement.

  • Page 32: Description, Time Page

    MANUAL OPERATION Other items that may be shown on the STATE page relate to optional-fit items; these are: Rb LOCK Indicates that the optional Rubidium oscillator assembly [R option] has locked its internal PLL. This keeps its output frequency accurate with reference to the microwave frequency from the atomic physics package SYNTH LOCK Indicates that the optional Synthesiser card [S option]...

  • Page 33: Description, Fault Page

    MANUAL OPERATION GPS 2, shows two lists of satellite data. The upper row of numbers represents the satellite PRN (identity codes) that are currently available (according to the Almanac). The lower row shows the 'signal level' that is current for each of the satellites that is actually being received.
  • Page 34 BLANK PAGE...
  • Page 35 All pages. This drawing and any information disclosed herewith are not to be copied, used or disclosed in whole or part without the written permission of Spectracom. a division of Orolia Global Services Ltd 3870 - 7051 03 10 01...
  • Page 36 MANUAL OPERATION BLANK PAGE...

  • Page 37: Set Menu

    SPECIAL state definition allows the Auxiliary Alarm signal to operate in a dual-role mode that is not implemented in a standard 2804A unit. The lower-right field allows the 'beep' sounder (Buzzer) to be suppressed in any situation where it might prove to be annoying to the user.

  • Page 38: Description, Dst Page

    MANUAL OPERATION Note that the Time Zone definition is not connected with any Daylight Saving (DST) offset that may also apply in certain locations and at certain times of year; this is dealt with completely separately. See DST Page definition below. The Day of Week, Date and Time values in the top line can also be user-defined when it is desired to run the unit with the output Time epoch set in the Past or the Future.

  • Page 39: Description, Pps Page

    The remaining item on the PPS page is the EVENT field. This allows the user a choice of operating mode for the event marking (time-tag) facility in the 2804A. The unit will log an Date/Time reading for each input event; the timescale used may be UTC or LOCAL.

  • Page 40: Description, Freq Page

    Remote Display output port at J27. The type of display unit to be driven is defined in the TYPE field as Spectracom 419 or LEC. These display units groups use different data encoding. The 419 selection covers all Spectracom types including the 1405.

  • Page 41: Description, Ser 1 Page And Ser 2 Pages

    This page allows user setting of the Alarm output signal delays (hold-off times). There are two alarm signal channels from 2804A, one is the ALARM (contact) relay connection at J19 and the other is a separate TTL signal that is output via the D.C.OUTPUT connector for signalling an Alarm state to an external Autochangeover/Distribution unit.
  • Page 42 BLANK PAGE...
  • Page 43 All pages. This drawing and any information disclosed herewith are not to be copied, used or disclosed in whole or part without the written permission of Spectracom. a division of Orolia Global Services Ltd 3870 - 7051 03 10 01...
  • Page 44 BLANK PAGE...

  • Page 45: Test Menu

    MANUAL OPERATION TEST MENU SEE Dwg No 3870-7051 Sheet 3 NOTE: THE TEST MENU INCLUDES SOME SETTING FACILITIES THAT ARE OPERATIONALLY SENSITIVE. ARBITRARY OR ACCIDENTAL ADJUSTMENTS TO SOME PARAMETERS MAY CAUSE INCORRECT OR ERRATIC BEHAVIOUR OF THE UNIT; CAUTION IS THEREFORE REQUIRED IN SPECIFIC CASES. SIGNIFICANT EXAMPLES IN THIS MENU ARE: THE SOFTWARE RESET FIELD IN THE TEST PAGE THE F-ADJ FIELD IN THE OSC 1 PAGE [IF R OPTION IS FITTED]...
  • Page 46 MANUAL OPERATION the other parameters do not apply to a Quartz oscillator.

  • Page 47: Description, Osc 2 Page

    MANUAL OPERATION Description, OSC 2 Page This page defines various control-loop parameters for the reference oscillator. For both Quartz and Rubidium Reference oscillators, the parameters shown are of oscillator / Control-loop parameter / input register / TYPE GAIN DAC STEP The user-settable field RESYNC DELAY defines the duration allowed for a GPS signal-loss before the...

  • Page 48: Description, Hist 1And Hist 2 Pages

    This can cause problems if user's software that is reading the time data is configured to reject a seconds-count value of greater than 59 as illegal. An alternative method of encoding a leap second is therefore provided in the 2804A, where the closing seconds of the minute are counted as 57, 58, 59, and 59.
  • Page 49 MANUAL OPERATION...

  • Page 50: Front Panel Led Indicators

    FRONT PANEL LED INDICATORS FRONT PANEL LED INDICATORS In addition to the main alphanumeric display window, the 2804A has a group of seven discrete LED indicators that are located to the left of the front panel. These provide an independent monitoring facility giving an immediate indication of the units' operational state, without the necessity to read the main display or to operate the buttons.

  • Page 51: The Control & Monitoring Ports

    THE CONTROL & MONITORING PORTS THE CONTROL & MONITORING PORTS J6, Com-1 Port and J5, Com-2 Port -- Connectivity These two RS232 serial interfaces are connected via 9-way 'D' type sockets (DE9S), J5 and J6 on the units rear panel. Pin designations are shown below and in Drg.
  • Page 52 BLANK PAGE...

  • Page 53: Drg. No. 2840-4228 -- Serial (Rs232) Connectors

    Drg. No. 2840-4228 -- Serial (RS232) Connectors / USED AT COM PORT 1 AND COM PORT 2...
  • Page 54 BLANK PAGE...

  • Page 55: Com Port Operating Modes

    THE CONTROL & MONITORING PORTS Com Port operating modes Each COM port can operate in two distinct modes, these are referred to as Stream and Remote. Because the ports port operate independently from one another, one can be set for Stream mode when the other is in Remote mode, if this is required.

  • Page 56: Stream Mode -- Fixed-Format Output

    THE CONTROL & MONITORING PORTS Stream Mode -- fixed-format output The data transmitted in the STREAM mode allows the display of date/time and position messages on a 'dumb' RS232 terminal, or a PC using a Terminal Emulator programme. See below for example of format. ASCII character strings are transmitted as follows: At every second -- a Time-Date message, Every 10 seconds -- a Position and Satellite-data message...
  • Page 57 THE CONTROL & MONITORING PORTS Notes:-- If the unit is operating in the GPS timing mode, the prefix UTC will be replaced by the prefix GPS. See CONTROL COMMAND section for definition of UTC and GPS time. (ii) 'Position' is shown as <Latitude><Longitude><Height> Latitude being xx yy.abcN Longitude being xxx yy.abcW...

  • Page 58: Remote Mode Command Set

    THE CONTROL & MONITORING PORTS Remote Mode Command Set The command format used on the serial RS232 control ports is: [ASCII letter character/s] [byte string (parameter)] [delimiter] Note: Command identity letter/s may be in upper case or lower case. The parameter string is required only on certain commands. The standard delimiter character is Carriage Return (ASCII 0DH).

  • Page 59: Command Summary

    THE CONTROL & MONITORING PORTS Command Summary The following standard commands are recognised in the REMOTE mode. (i) Interrogation Commands These Commands are used to read information from the unit on a routine basis; they do not affect the normal operation of the unit. Format Command Name <CR>...
  • Page 60 THE CONTROL & MONITORING PORTS (ii) Control & Configuration Commands These are commands used to set-up the operating mode of the unit according to requirements. Care should be exercised when using any 'Set' commands, particularly where the unit is operational in a performance-critical situation.

  • Page 61: 2804A Command And Response Detail

    THE CONTROL & MONITORING PORTS <CR> Reset 2804A COMMAND AND RESPONSE DETAIL. RAD<CR> Read Alarm Delays Response RADabcd<CR><LF> Where a is the Relay GPS delay b is the Relay control delay c is the Auxiliary GPS delay d is the Auxiliary control delay and a,b,c,d are hexadecimal values coded as follows ‘0’...
  • Page 62 COMMAND & RESPONSE LIST RCM<CR> Read Current Mode and Status Response RCMabcdefghijk<CR><LF> Where abcdefghijk is a 11 digit hex value whose bits relate to the current mode and status a bit 3 = Relay alarm output state – 0 = relay off (alarm) ; 1 = relay on a bit 2 = Auxiliary alarm state –...
  • Page 63 COMMAND & RESPONSE LIST RDS<CR> Read Daylight Saving Time Parameters Response RDSms,ddmmyyyy,eennzzzz<CR><LF> Where m = 2 – Automatic mode m = 1 – Manual mode m = 0 – Off s = 2 - +2 hour time shift s = 1 - +1 hour time shift ddmmyyyy is the start date of summer (daylight saving) time eennzzzz is the end date of summer (daylight saving) time REG<CR>...
  • Page 64 COMMAND & RESPONSE LIST RFM<CR> Read Fault Mask Response RFMa<CR><LF> Where a has the fault mask with bit assignments as follows a bits 3,2 – not used a bit 1 = AC power low – 1 = masked a bit 0 = DC power low – 1 = masked RFS<CR>...
  • Page 65 COMMAND & RESPONSE LIST RGS<CR> Read GPS Status Response RGSabcdefgh<CR><LF> Where abcdefgh is an 8 digit hexadecimal number bit assignments/values as follows a = 0 not used b = 0 – Doing position fixes b = 1 – No GPS time b = 2 –...
  • Page 66 COMMAND & RESPONSE LIST RLS<CR> Read Leap-Second data Response RLSyyyymmddoonn,cc,mf<CR><LF> Where yyyymmdd = Date of next Leap-second [00000000 if none scheduled] oo = Previous Leap-second offset (00 to FF hexadecimal) [00 if none scheduled] nn = Next Leap-second offset (00 to FF hexadecimal) [00 if none scheduled] cc = Current Leap-second offset (00 to FF hexadecimal) [0Dhex=13 secs in Y2002]...
  • Page 67 2 = Time select – 0 = UTC ; 1 = Local a bit 1 = 0 – Not used a bit 0 = Type select – 0 = Spectracom ; 1 = LEC RS1<CR> Read Serial 1 Configuration Response RS1abc<CR><LF>...
  • Page 68 COMMAND & RESPONSE LIST RTZ<CR> Read Time Zone Response RTZshhmm<CR><LF> Where shhmm is the time offset between UTC and local time s = sign digit (‘+’ or ‘-‘) hh = Hours (00 to 23 decimal) mm = Minutes (00 to 59 decimal) RUT<CR>...
  • Page 69 COMMAND & RESPONSE LIST SADabcd<CR> Set Alarm Delays Response SADabcd<CR><LF> Where abcd (4 digit hexadecimal) represent the alarm delays as described for the RAD command above The delay settings are stored in non-volatile memory. SCBaaaaaa<CR> Set Control Bits Response SCBaaaaaa <CR><LF> Where aaaaaa (6 digit hexadecimal) are the control bits inserted into the IRIG timecode as described for the RCB command above The control bits are set to zero when the unit is reset...
  • Page 70 COMMAND & RESPONSE LIST SLSm<CR> Set Leap Second Mode Response SLSm <CR><LF> m = Mode – 0 = ITU (59,60) ; 1 = non ITU (59,59) N.B. restrictions apply to the date set via this command and it will be overwritten by the GPS received data Only the mode is stored in non-volatile memory SOVvvvv<CR>...
  • Page 71 COMMAND & RESPONSE LIST SSFaaaaaaaaaa<CR> Set Synthesiser Frequency Response SSFaaaaaaaaaa <CR><LF> Where aaaaaaaaaa is a 10 digit decimal number representing the current synthesiser frequency with a resolution of .01 Hz. N.B. THE DATA ENTRY IS LIMITED IN THE RANGE 0000000000 TO 1299999999. WITH STANDARD FILTER SETTINGS IN THE SYNTHESISER MODULE, THE FREQUENCY RANGE IS LIMITED TO 11MHZ +1-3DBM (13MHZ +1/-6DBM) The synthesiser frequency is stored in non-volatile memory STCa<CR>...
  • Page 72 COMMAND & RESPONSE LIST Wabcdef<CR> Wrap interface test command Response abcdef<CR><LF> Where abcdef is an alphanumeric string This command echoes the input data omitting the leading W character Change interface mode no delimiter reqd Response NONE This command changes the mode of the interface from Stream to Remote or vice-versa. The command does not affect the other port : Changes to the other port configuration can be made via the SS1 or SS2 command as above.
  • Page 73 COMMAND & RESPONSE LIST @Habccdddd<CR> Set Hardware configuration Response @Habccdddd<CR><LF> Where abccdddd are as described above for the read command. Any alteration to these parameters can seriously affect the operation of the unit. @T<CR> Start tests Response NONE This command enables the display test, which is performed at power up, to be repeated.

  • Page 74: Inputs & Outputs -- Rear Panel Functionality

    J4 -- GPS Antenna Type: N This is the GPS L1 frequency input to the GPS receiver in the 2804A. In addition, it is the d.c. output feed to the LNA in the Antenna head, that requires a nominal +5V supply, supplied via the r.f. downlead.
  • Page 75 J27 -- Remote Display Type BNO Provides an RS422 drive to Spectracom Digital Remote Display units (or to other similar types that are supported). J28 -- Remote Display [optional second cable driver, not a standard fit] Provides a second RS422 drive to Spectracom Digital Remote Display units or to other similar types.

  • Page 76: Alarm Outputs

    TTL compatible logic signal which is connected via the dc output connector to provide an alarm state indication to a Spectracom Type 18xx ACU/Distribution unit. This signal is configured as high for fault. An alarm state will be initiated by the software under any of the conditions listed below: GPS Receiver is not providing a 2D or 3D fix.
  • Page 77 ALARM OUTPUTS The alarm logic is configured to distinguish between the situation where a CONTROL status failure occurs due failure situation where CONTROL failure occurs in isolation. This feature allows the alarm system to operate due to a GPS failure (the consequent CONTROL failure being ignored) or due to a CONTROL only fault.

  • Page 78: Event Logging (Time-Tag) Facility

    EVENT LOGGING (Time-Tag) facility The 2804A will record the time of an external event input from the users system. An event input may be made by a TTL pulse applied at the J29 (1pps input) connector or by sending a unique # (number sign) character, to either of the COM ports.

  • Page 79: Gps Receiver & Antenna

    10°. Antenna Installation The 2804A may be used with a Spectracom , Type 5b, GPS antenna. The Type 5b is currently supplied as a standard item. The Type 5b is a fixed pattern antenna that has a built-in low-noise preamplifier, powered via the co-axial RF downlead cable from a low-voltage d.c.
  • Page 80 BLANK PAGE...

  • Page 81: Drg. No. 1008-8020 - Type 5B Antenna Installation

    Drg. No. 1008-8020 - Type 5b Antenna Installation.
  • Page 82 BLANK PAGE...

  • Page 83: Electromagnetic Compatibility Notes

    Power The d.c. power input and output ports on SPECTRACOM equipment are intended only for direct connection to other SPECTRACOM units, normally mounted in adjacent, or near adjacent, positions.
  • Page 84 EMC NOTES...

  • Page 85: Statement Of Compliance For 2804A

    Statement of Compliance for 2804A DECLARATION OF CONFORMITY According to ISO/IEC Guide 22 and CEN/CENELEC EN 45014 A Division of Global Services Ltd Manufacturer’s Name: SPECTRACOM Manufacturer’s Address: 6A Beechwood, Lime Tree Way, Chineham Business Park, Basingstoke. RG24 8WA Declares under sole responsibility that the products as originally delivered:...
  • Page 86 BLANK PAGE BLANK PAGE...

  • Page 87: Appendix A -- Antenna Installation Guidelines

    APPENDIX A APPENDIX A -- Antenna Installation guidelines Spectracom 5 antenna assemblies are currently supplied for use with the 2804 unit. These items are described in a previous section of this Manual, GPS RECEIVER & ANTENNA Downlead cables are not normally supplied as standard with 2804 units because requirements vary from site to site.
  • Page 88 (which is one reason for having two antennas) then a common mounting could be said to be defeating the object. If the antenna is to be mounted in proximity to a third-party (non Spectracom) antenna, then a greater separation may be required.
  • Page 89 APPENDIX A...

  • Page 90: Appendix B -- Installation Solutions For Gps Downlead Cables

    Whilst not required as part of a normal antenna installation for an 2804, the following information is included for completeness. The Spectracom E244 cable (standard length 50 metres) is adequate for the majority of installations; where the cable run exceed 50 metres, custom-length variants of the E244 can be supplied up to 70 metres ( E244/70).
  • Page 91 For installations where protection against Lightning (LEMP event) is considered desirable, then suitable in-line protection units for the antenna Downlead are available (at extra cost) from Spectracom. Such devices will not protect the antenna against a direct strike, even one of low magnitude. Should this occur, the antenna will almost certainly be destroyed and will require replacement.

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