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SA.22c Rubidium Oscillator

Designer Reference and User Guide Revision D

38

7.9.2

Initialization

During initialization, the algorithm sets up variables based on the time constant (TC) and damping factor
(DF). The SA.22c checks for 1PPS input once per second, and if present, it enters the holdover state.
Automatic mode is used when the time constant is set to 0. The SA.22c 1PPS is in the initialization state
when no 1PPS is applied. The j command shows the 1PPS count.

Figure 22 • SA.22c Initialize State

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Содержание SA.22c

Страница 1: ...Designer Reference and User Guide SA 22c Rubidium Oscillator...

Страница 2: ...3 3 External Interfaces and Grounding 9 3 4 Electrical Interface 9 3 4 1 1PPS Input and Output 9 3 4 2 Lock Signal 9 3 4 3 Service Signal 9 3 4 4 Frequency Control Signal 10 3 4 5 ACMOS Output Frequen...

Страница 3: ...6 1 4 Serial Interface Initialization 28 7 Appendix One Pulse Per Second Source Connection 30 7 1 Connection Requirements 30 7 2 Background 30 7 3 1PPS Functions 30 7 4 System Requirements 31 7 5 1PPS...

Страница 4: ...Register table was updated For more information see SA 22c and x72 Output Control Register see page 27 1 2 Revision C Revision C was published in February 2018 In revision C of this document the powe...

Страница 5: ...produce a stable and accurate time along with a frequency reference The SA 22c can be integrated into time and frequency systems it operates on low power 10 W at 25 C operating The design is successf...

Страница 6: ...be used In addition to controlling the operation of the oscillator the microprocessor s built in firmware allows an external host computer to communicate with the embedded controller through a serial...

Страница 7: ...SA 22c Pin Assignment and Function Chart Pin Signal Type Function 1 VSS GND Power and signal return ground all ground pins must be connected 2 VDD PWR 15 Vdc power input all power pins must be connec...

Страница 8: ...ient still air convection 10 C to 75 C Table 2 SA 22c Design Absolute Maximum Ratings Symbol Characteristic and Condition Value Unit VDD Supply relative to ground 15 Vdc Input 5 VCC Supply relative to...

Страница 9: ...V VIL Low level input voltage DIN 0 0 8 V 1PPSIN 0 0 8 V VOH High level input voltage DOUT SERVICE Lock at IOH 0 33 mA at IOH 0 mA 3 5 5 5 25 V FACMOS 1PPS OUT at IOH 3 5 mA 3 5 5 5 25 V VOL Low leve...

Страница 10: ...values for total quiescent power dissipation of SA 22c Figure 4 Total SA 22c Quiescent Power Dissipation Typical free convection The following figure shows the typical API level Figure 5 Typical AP1 L...

Страница 11: ...rding thermal humidity and dust challenges 3 2 1 Thermal Tape The base plate of the SA 22c must have good thermal contact to the mounting surface so that the operating base plate temperature can achie...

Страница 12: ...nding approach offers ESD protection and low spurious emissions however it may lead to ground loop issues Workarounds commonly used to break DC ground loops at a higher level of integration are Using...

Страница 13: ...enabled through the MSIP refer to Appendix Microsemi Serial Interface Protocol see page 25 The external analog frequency control is a sampled input with a typical response time constant of 154 ms Not...

Страница 14: ...bility The SA 22c is designed with a life of ten years of operation without retuning To accomplish this the major mechanisms impacting the need for maintenance were addressed Thus each SA 22c is desig...

Страница 15: ...ps describe how to power up the SA 22c Caution To avoid damage to the SA 22c do not apply power to the unit in reverse direction Verify the SA 22c voltage requirement see Appendix Using the Developer...

Страница 16: ...s 5 10 at 25 C typical 11 Note Signals appear at the outputs immediately after power is applied to the unit but these output signals are not stable until the oscillator is locked After 7 5 minutes the...

Страница 17: ...se and amplitude information which permits continuous regulation of the VCXO frequency The servo section converts the photo detector current into a voltage then amplifies demodulates and integrates it...

Страница 18: ...EA Technical Support ftd emeasupport microsemi com For EMEA Sales ftd emea_sales microsemi com 4 5 2 Contact 4 5 2 1 USA Americas Asia and Pacific Rim Microsemi FTD Services and Support 3870 N First S...

Страница 19: ...to date list of materials Note Use a power supply with leads or interface cable to connect the adapter test board to the main power To avoid potential damage to the adapter test board and the SA 22c e...

Страница 20: ...oard is designed to deliver power to and retrieve signals from the SA 22c The adapter test board allows you to electrically integrate the SA 22cto an existing system via J2 The following illustration...

Страница 21: ...s locked 15 1PPS IN Input 1PPS input positive edge triggered 16 DOUT Output UART data out at ACMOS logic levels 17 Not available 18 Not available J2 is a 26 pin Molex receptacle connector used for del...

Страница 22: ...ormation Table 7 SMA Connectors Signal Information SMA Signal Type Function J3 1PPS OUT Output 1PPS output may be enabled disabled digitally J4 1PPS IN Input 1PPS input positive edge triggered J5 FACM...

Страница 23: ...r board It also shows the connections used to access various inputs and outputs of the SA 22c depending on the option selected Figure 13 Block Diagram of Suggested Test SA 22C Set up Option 1 After th...

Страница 24: ...SA 22C Set up Option 2 It is recommended to power up 5 V first or simultaneous with the 15 V supply After the SA 22c unit receives power wait for a few minutes while the unit achieves atomic lock Duri...

Страница 25: ...ring this period the monitored lock signal must be HIGH After the unit achieves atomic lock the lock signal goes LOW The following figure shows the physical power supply wiring and jumper settings nee...

Страница 26: ...bidium Oscillator Designer Reference and User Guide Revision D 23 Figure 16 Power Supply and Output Options Option 1 allows you to directly power the adapter test board with 10 Vdc to 32 Vdc supplied...

Страница 27: ...SA 22c for operation the 5 Vdc must be applied before or simultaneous to the 15 Vdc For this option J7 is used for serial interface communications J3 J5 and J6 are used for signal outputs and J4 is u...

Страница 28: ...t contains a TTL to RS232 converter that allows interfacing to a PC 6 1 2 Run Mode Data Format Customer Mode SA 22c outputs are all decimal data as ASCII coded hex except for the echoed characters Do...

Страница 29: ...and w The following example shows the response to the command w for the SA 22c health data wellness r w AData SCont 6012 SerNum 3B8 PwrHrs 8A PwrTicks E291DB LHHrs 85 LHTicks 16CCE28 RHHrs 85 RHTicks...

Страница 30: ...ng the configuration information into the unit batch list file prior to testing 3 8 1PPS output enable 0 Enables 1PPS output 1 Disables 1PPS output Configuration is set either by entering the control...

Страница 31: ...amming 6 1 4 Serial Interface Initialization The serial interface is initialized as listed in the following tables Table 10 Run Mode Commands User Output to SA 22c Response to Host Command Name and De...

Страница 32: ...ion Command Data a a Goes to administration mode i Outputs 7 lines of banner same as power up information Displays unit Information r Run mode Enter run mode FC mode is disabled enabled Goes to run mo...

Страница 33: ...quire 1PPS signals to be synchronized within 2 s over long periods of time even when GPS signals are not available To achieve this performance system designers must combine the benefits of short term...

Страница 34: ...ollowed by a 1 see The g Command Typical performance data for this configuration is shown in see page 34 Flywheeling Recover with and 1PPS offset 1 sec see page 35 Flywheeling Recover with 1PPS offset...

Страница 35: ...ues must be between 0 25 and 4 Values less than 0 25 defaults to 0 25 while values over 4 defaults to 4 Tau or time constant expressed in seconds and determines the time constant of the PLL for follow...

Страница 36: ...d 7 6 2 The y Coefficients Factory Default If the factory default values of damping factor 1 and tau 400 are acceptable for the application no modifications to the y coefficients are required The SA 2...

Страница 37: ...for pin 14 but pin 12 is reserved for 1PPS lock indication only There is no service pin on the 1PPS LED versions The factory default modes set by the g command for each firmware version are 1PPS stan...

Страница 38: ...dication only 7 7 Flywheeling Recovery Example Normal In this test the SA 22c is synchronized to 1PPS before the following data set as shown in the following figure Antenna is removed at 0 hour and re...

Страница 39: ...rred to as the holdover state The SA 22c determines whether the 1PPS input is usable by calculating the rate of change in timing measurements that are taken once per second After a 1PPS input is quali...

Страница 40: ...ubidium Oscillator Designer Reference and User Guide Revision D 37 7 9 1 1PPS Algorithm High Level Flow Chart The following flow chart explains the 1PPS steer algorithm Figure 21 SA 22c 1PPS Algorithm...

Страница 41: ...les based on the time constant TC and damping factor DF The SA 22c checks for 1PPS input once per second and if present it enters the holdover state Automatic mode is used when the time constant is se...

Страница 42: ...nce and User Guide Revision D 39 7 9 3 Holdover During holdover 1PPS input statistics are accumulated and the results are calculated periodically CalcSlope State The sample size is set to 120 data poi...

Страница 43: ...vision D 40 7 9 4 Calcslope The frequency difference between the SA 22c and the 1PPS source is calculated and if the difference is 3 10 the state changes from holdover to JamSynch This state executes...

Страница 44: ...2c 1PPS input and if the difference is 1 s the state returns to holdover to collect a second data set When two consecutive slopes are in range the SA 22c s 1PPS output is synchronized to its 1PPS inpu...

Страница 45: ...dover If at any time a 1PPS input signal is more than 330 ns from its expected value the 1PPS algorithm returns to holdover state If the input source is stable the SA 22c further refines the input est...

Страница 46: ...y determine suitability of any products and to test and verify the same The information provided by Microsemi hereunder is provided as is where is and with all faults and the entire risk associated wi...

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