Thanks a lot. Actually I have never been dreaming of being mentioned along with Dr. Drela.

While working on the previous post I had to get deeper into servo resolution. The result was discouraging.

Hitec HS-5125 digital servo. Datasheet states 1us dead-band width. Very nice number as it gives user 1400 steps and even exceeds the possibilities of 1024PCM. Actually only Futaba 2048PCM could fully exploit 1us resolution advertised for HS-5125.

I personally like these servos and use them a lot. However my feeling was that HS-5125 actual dead-band was wider than 1us. Being curiuos I decided to test real servo resolution.

Test bed.
Hitec HS-5125 v.1.04 digital servo
Hitec HFP-10 servo tester/ digital servo programmer

Results.

1. DB width test. Servo comes to user with factory default dead-band setting DB=2 (=6us). When I asked MikeMayberry from Hitec about my finding he explained it was a "typo" in manual and DB=2/DB=1 just mean the lowest possible settings, not 6us/3us.

2. Servo resolution test. It shows again 6us for factory default servo. User can improve resolution to 3us if he buys Hitec servo programmer and changes dead-band setting to DB=1. Even then 3us is far from advertised 1us. When I contacted MikeMayberry again and informed him about my second test results, the answer was:

My thoughts are that the servos are 1-2us out of the box and when reset with the programmer.
This is the first time this has been questioned so if the servos were only capable of a minimum of 6us then their performacne would be nowhere near as good as they are. I would suggest you search here and rcuniverse for your answer since you don't beleive what I say.
Mike.

So according to his instructions I ask gurus to point what was wrong with my tests and my interpretation. Better yet if somebody with proper test equipment could repeat these tests and publish their data.

To publish your comments/data and read the full story please follow the link: http://www.rcgroups.com/forums/showthread.php?t=575183