[time-nuts] GPSDO simulation tool

Chris Albertson albertson.chris at gmail.com
Sun Mar 23 14:05:57 EDT 2014

On Sat, Mar 22, 2014 at 8:18 PM, Don Latham <djl at montana.com> wrote:
> Hi Tom et.al.   Isn't the simulator "easily" convertible to the real thing?
> That is, data inputs should be convertible somehow to data streams from
> physical devices?
> Don

This is a very common development method, not just with GSPDOs but
with anything like say a couple robots I'm building.  At first you
simulate the physical hardware.   I can write a function called
"GetMotorSpeed()" and at first it simply always returns a constant
"5.0" and that is good enough.  Later I make it read a file and
finally I make it read some hardware interface that connects to a
sensor but the sensor is just a test fixture on my desk.  Later I
integrate the sensor in to the robot.  I have a few sensors on my desk
right new  (sonar and IR distance sensors)  Almost 100% of
professional level work is done this way.

At work I've seen this same method used for air defense missiles,
radars and "everything".  At first you write the code and run it on a
desktop computer because it is so easy to do,  But as the software
matures you need more and more realistic hardware until finally you
are running one the actually target hardware on a real (inert)

Actually most projects keep the test environment with all the sensors
on the desk connected with the rats nest of wires because you can test
some scenarios and odd cases that are hard otherwise, like automated
fault detection, cooling system failures, EMI problems and so on.

It's a pretty common way to build stuff, the software begins it's life
on a Linux or UNIX PC then eventually gets put into some tiny micro
controller.   When you make a change you first test on the PC before
mooing the change down to the target environment.

All that said a GPSDO can simple enough that yu can short cut this and
go straight to the target hardware.  But I think or hope we will see a
more complex generation of GPSDO that have a LCD display, user
interface and built-in network services.  You can't short cut
something like that.

Chris Albertson
Redondo Beach, California

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