[Touch Pro, Fuze General] whyfish2001:
My testing

I tried to be systematic about the changes. I made the registry changes one at a time and checked between each change, to see which change really made the difference. (This is because I have the feeling that the changes are guesses whose side-effects aren't well understood. I don't think they are all necessary.) I systematically tried some of the other changes I found on reading the voluminous posts and listed my results below (it would be so nice if everyone listed their phone, their rom, their software, etc... so the group testing could be somewhat systematic (and doubly nice if peole wouldn't post fluff like "I'll try this soon").

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Phone:

HTC Sprint Touch Pro

ROM 1.03.651.3 (stock rom)

Radio 1.03.15F​

GPS Software:

TomTom 6.032

Googlemaps 2.2.0.19​

Lag:

Lag is about 1 to 1.5 seconds second.​

Things that didn't work:

1. Changing the log file per the instructions:

> 1. disable A-GPS

> 2. disable GPS logging

> 3. logfile name must be empty

> 4. old logfile name must be empty

> 5. maximum size of logfile must be 0

> 6 delete the files : \windows\GPSLogFile.txt and \windows\GPSLogFileBack.txt​

2. The following changes didn't seem to make any difference, and I decided keep the original values.

> - HKLM\SYSTEM\CurrentControlSet\GPS Intermediate Driver\Drivers\SleepOnNoData -> 100 (default is 1000) --- The discussion at (http://xdaforums.com/showthread.php?p=3013753) suggests this is a bad setting, anyway.

> - HKLM\SYSTEM\CurrentControlSet\GPS Intermediate Driver\Multiplexer\MaxBufferSize -> 512 (by default not present, you have to create it)​

3. Changing the baud rate on COM 4 made no difference. I tried rates from 4800 to 384000.
​

Things that worked (more or less):

1. Using an external TomTom Bluetooth GPS fixes the problem.

2. HKLM\SYSTEM\CurrentControlSet\GPS Intermediate Driver\Drivers\GpsOneDevice\PollInterval -> 100 (default is 1000) -- this change made the most difference. It made things better, but didn't fix the lag completely.

3. - HKLM\SYSTEM\CurrentControlSet\GPS Intermediate Driver\Drivers\InputBufferSize -> 512 (default is 4096)

- HKLM\SYSTEM\CurrentControlSet\GPS Intermediate Driver\Drivers\OutputBufferSize -> 512 (default is 4096) --- these two changes made very little (if any) difference. But I decided to keep them.
​

Conclusions:

0. No one has done very careful tests. It's the blind leading the blind here. Caveat Emptor.

1. Not likely to be a CPU usage issue (per http://xdaforums.com/showthread.php?t=420460). I don't expect (but I am not 100% certain) that fetching the data from an external GPS versus fetching it from the internal chip should make a difference to the CPU usage.

2. Some of the registry fixes are an improvement, but not a complete fix. There is still a significant lag of roughly .5 - .75 seconds.

3. Using an external bluetooth GPS is much better, so I think it's a hardware or communication buffer issue.

4. Tests with googlemaps are difficult, because I have registration (i.e. alignment) problems. Sometimes, it seems that the maps are offset and sometimes not. I wouldn't recommend using googlemaps for tesing.​

Things I'd like to know:

1. Can this be reproduced on other stock Sprint TPs ?

2. Some people report that things are completely fixed.

Are you really getting no lag at all?

It is the tip of the arrow in Tomtom or the middle of the arrow that is aligned with where you are?

Does your real position and GPS-indicated position match at all speeds?

3. Does the \Drivers\GpsOneDevice\PollInterval -> 100 (default is 1000) change change the batter drain?​