# Scintillation / Timing Accuracy

**URL:** <https://learn.safran-navigation-timing.com/t/scintillation-timing-accuracy/598>\
**Category:** Skydel Discussion\
**Created:** [May 4, 2022, 12:21pm UTC](https://learn.safran-navigation-timing.com/t/scintillation-timing-accuracy/598 "2022-05-04T12:21:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mventresca](https://avatars.discourse-cdn.com/v4/letter/m/3e96dc/32.png) [@mventresca](https://learn.safran-navigation-timing.com/u/mventresca)\
**Post date:** [May 4, 2022, 12:21pm UTC](https://learn.safran-navigation-timing.com/t/scintillation-timing-accuracy/598/1 "2022-05-04T12:21:39Z")

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Customer Question:  
_I was able to simulation a scintillation event using Skydel API! The only thing I would maybe like to improve on is the timing accuracy with which my python script sends commands to the simulation engine. I would like the commands to go to the simulation at a rate of 100Hz but every so often the script gets delayed by 1-2 hundredths of a second because of the other tasks running on the computer. Do anyone have any suggestions for making this timing more accurate and deterministic?_

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**Author:** ![pmleveel](https://yyz2.discourse-cdn.com/flex030/user_avatar/learn.safran-navigation-timing.com/pmleveel/32/35_2.png) [@pmleveel](https://learn.safran-navigation-timing.com/u/pmleveel)\
**Post date:** [May 4, 2022, 3:23pm UTC](https://learn.safran-navigation-timing.com/t/scintillation-timing-accuracy/598/2 "2022-05-04T15:23:15Z")

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Hi Marco,

There are 2 types of commands in the API, _call_ and _post_ commands. Both types can take a timestamp as a parameter.

The _call_ method is blocking and this calling mechanism is referred as synchronous. This means that it will stop the script execution until Skydel returns a result (pass or fail). Since these commands stop the execution of the script it is not recommended to set a timestamp (otherwise the script will wait until the timestamp of the command is reached).

The _post_ method is not blocking and this calling mechanism is referred as asynchronous. It is recommended to set a timestamp for these commands to tell Skydel when to apply the command. The _post_ command is stored in Skydel’s internal memory and **precisely** applied at the timestamp value (with a millisecond resolution). Execution of other tasks on the computer will not affect the time of application of the command.

You can check the example\_basic.py script in the ./Skydel-SDX/API folder for an example of the _post_ command with timestamp:

Line 35/36 of the script:

> #When simulation elapsed time is 9.567 sec, change satellite 32 power to -25 dB (relative to nominal power)  
> cmd1 = sim.post(SetPowerForSV(“GPS”, 32, -25, False), **9.567** )