[ltp] Re: hdapsd during Intercity Express ride

[Elias Oltmanns]

Jan Girlich <vollkorn@cryptobitch.de> wrote:
> Am Montag, den 12.10.2009, 20:48 +0200 schrieb Martin Steigerwald:
>> Hi!
>
>> 
>> I am currently traveling with a Intercity Express - mail will be sent 
>> later, cause no internet access in the moment - and found a cumbersome 
>> problem: There have been extreme lags during most common operations.
>
> I had the same problem during a bus ride. The system is rendered useless
> because of vibrations like from car engines.

>From a mathematical point of view, I have serious doubts that the logic
implemented in hdapsd is the right thing(TM). The problem is, as far as
I'm aware, that we don't know exactly what the data returned by the
accelerometer is supposed to represent, i.e. whether any kind of
mathematical preprocessing is performed. I seem to remember that Shem
performed some experiments when (s)he made changes to hdapsd. Whether
real rides by bus or train had been among those tests, I don't recall.

>> On Windows there is an option to ignore continued vibrations from such a 
>> situation - we checked with a laptop from a co-worker. Is there such a 
>> knob for hdapsd? I thought about
>
> I don't know about any options, but I haven't looked into it, yet.
>
> But I also think the thresholds are set way too sensitive and hdaps kind
> of 'overreacts'.

What thresholds exactly? Have you tried the -s option yet? If you work
on bus / train frequently, it might be worthwhile fiddling with this
option and reporting your results to this list.

Regards,

Elias