We now understand how radio controlled clock synch procedure works. It was tested on my cluster from Audi 2002 D2 FL, software version D39 (your software can work differently).
This is what I calculated with a bit of trial and error:
* Cluster will make a synch sessions with DCF77 at 3am, 4am and 5am every day.
* Synch attempt will only start when ignition is off and cluster displays went to sleep mode by timeout.
* Each synch session lasts about 10-11 minutes. Cluster switches on receiver power only for the length of the synch session. Receiver power stays off all other time. Because it takes 1 full minute to get date and time information from DCF77 transmitter there are 9 or 10 opportunities/attempts to receive full good signal during each synch session.
* During synch session once the good signal is received, say from 2nd attempt, the synch session is prematurely terminated, cluster switches off receiver power, switches itself to radio controlled clock mode, displays antenna symbol, displays correct date and time and makes no further synch sessions during this day.
* If all synch sessions at 3am, 4am and 5am ended with failure cluster makes additional synch sessions after each trip. Definition of trip from cluster point of view: ignition goes on, then cluster receives some speed signal, ignition goes off, key is removed and cluster displays go to sleep mode by timeout. Immediately after that synch session starts.
* If all synch sessions ended with failure for the last 3 days cluster goes back to normal quartz clock mode.
* If cluster's power is switched off (remove fuse number 4 from yellow bank for couple of seconds and put it back) the cluster will forget radio controlled mode and will also forget about time shift from CET time to UK time.
Now, with all this in mind, we have a **quick** procedure to test how well your receiver is working in it's current location:
- If cluster is already in radio controlled clock mode remove fuse number 4 from yellow bank for couple of seconds and put it back. This will save waiting 3 days
- You will see something like 0:00 and 1.1.1999 depending on version of your cluster software.
- Switch ignition on, press Menu button on centre console and set time to 2:59am.
- Switch off ignition. Wait for cluster displays go to sleep mode by timeout. At '3:00am', with displays in off position, the synch session starts.
- You can now press 'Check' button on cluster (or open driver door) if you want to to return displays back on to keep tracking of progress. If receiver catches good signal (usually by about 3:03-3:04am) you will see CET time and date on your cluster:
(picture was taken 18:09 UK time. Time shift can be adjusted in Menu by changing hours figure. Time shift can be from +11 to -11 hours. In radio controlled mode cluster doesn't allow to set minutes and date. In future if cluster goes back to quartz clock mode after 3 days of no signal it will still remember the specified time shift and after next successful synch session it will take that into account when it goes back to radio controlled mode)
- If after 12 minutes of waiting the clock still shows 3:11am and 1.1.1999 that means synch session was unsuccessful, all attempts failed and it can mean many things: your car is parked in rubbish reception area or location of receiver in car is not optimal or receiver itself is rubbish.
So, now it takes only up to 12minutes to definitively know if sync works. This quickly allows to scan many places in car to find optimal location for receiver.
My target is to find receiver and location of receiver that synchs from 1st attempt.
Hope it makes sense
...To be continued...