QRS external timing

[Andre' Kesteloot]

Rik Strobbe wrote:

> Hello group,
>
> Recently there have been some requests to be able to let an external (and
> accurate) timing source control the PC clock while running QRS.
> I had a look at it and a basic 'external time control' was rather easy to
> implement.
> In version 3.06 beta 1 it is possible to connect a accurate timing source
> to  COM port CTS pin (on a D9 connector : pin 8, on a D25 : pin 5). At this
> moment it must be a 1 minute clock source (maybe more posibilies later).
>
> You can download this version from :
> http://www.qsl.net/on7yd/QRS/qrs306b1.zip
>
> In SETUP you can click on TIME to get to the external clock menue. There
> you have 3 possibilies :
> - DISABLE : no external clocking
> - ABSOLUTE : the PC clock will increment 1 minute for every pulse at CTS
> (compared to time at the previous pulse).
> - ADJUSTING : a pulse at CTS will adjust the PC clock to the closest minute
>
> May sound complicated, therefore an example :
>
> 1. Before starting QRS you have to set the PC clock as accurate as you can
> (by hand using the default windows device for setting the clock or using
> software that sets the PC clock based on DCF77 or similar).
>
> 2A. If you select ABSOLUTE then QRS will take a 'reference time' at the
> first pulse on CTS and from then on will increase time by 1 minute for
> every pulse. In the time between the pulses the PC clock will run at its
> own pace.
> eg. Assume 14:25:36 is taken as reference time. At the next CTS pulse the
> clock will be set to 14:26:36, then to 14:27:36 etc ...
>
> 2B. If you select ADJUSTING then QRS will also take a 'reference time' at
> the first CTS pulse but from then on will only adjust the clock on every
> CTS pulse.
> eg. Assume 14:25:36 is taken as reference time. At the next CTS pulse QRS
> reads the PC clock, let's say 14:26:35 -> this will be adjusted to 14:26:36.
>
> The difference between the 2 options is that if (for whatever reason) there
> is a CTS pulse missed that in the ABSOLUTE mode the PC clock will be 1
> minute wrong while in the ADJUSTING mode the clock will be set correct as
> long as the in the time between 2 CTS pulses it hasn't gone wrong more than
> 30 seconds in its own pace.
>
> One could use an atomic clock or GPS to generate the 60 second timing, but
> for the mere mortals a simple Xtal oscillator + divider train will do (keep
> the error less than a second over a period of several days).
> Keep in mind that the pulses must exactly come in a 60 second interval, but
> that there is no need that the pulse comes just on a full minute.
> Finaly : the pulse applied to CTS must be positive and have a width between
> 10us and 10ms.
>
> If there is sufficient feedback I am willing to continue and make more
> flexible external timing possibilies.
>
> 73, Rik  ON7YD