Harry's GPS Suite Forum

Hi, I've been using HLT for a few years now, across multiple iPhones and have always had great results with it. I recently bought a Kiwi 3 Bluetooth module, which after a few small changes in expert settings, is now working great (and after the most recent v20.0.18 update, I NEVER have to unplug/re-plug it to get it recognized, which was a rare occurrence as it was). However, I have noticed that A: it's not quite synced up with my video like everything else is (all the data from internal sensors such as GPS and accelerometer), and B: the update rate is typically given as something like "18/4", with the first number typically between 15-19, and the second between 3-4. I know I can probably get the data synced up better by playing with the delays in expert settings, but I'm wondering if this update rate makes sense? I'm running this with a 2012 Honda Civic Si, using the ISO 15745-4 protocol, 29 bits at 500kbps. I've played with the expect settings EXTENSIVELY, and did a little research, I'm positive this is the right protocol since it works fine and gives what *appears to be* a decent/appropriate update rate, but I want to be sure. Most of all, I want to know why the update rate is given as 2 numbers; in all my reading throughout these forums, everybody else seems to give their OBD update rate as a single number. Thanks for the help and clarification!

EDIT: As a side note, I noticed that I can crank up the accelerometer refresh rate all the way to 100Hz, which I've done; is there any downside to this? I'm currently on an iPhone 6S w/ 128GB storage, so if the only downside is additional system load and storage for the extra data points, I should be fine, right? Thanks for clearing this up as well, I'm trying to really get the most out of my data collection devices!

A: you need to adjust sensor delays to configure your overall sync. Search the forum for "sensor delay" please.
B: "18/4" makes sense for a CAN bus. Please change "CAN Multi Requests (ELM327)" to 3 PIDs / adaptive in case you haven't yet. LapTimer uses an update rate notion counting an update for a "complete set of parameters", not individual parameters. So 18 means 18 PIDs/s received and 4 full sets of PIDs. The later is the one exchanged here on the forum mostly. The earlier is the marketing number many use

- Harry

Changing the accelerometer update rate does not increase the number of data points. That's always determined by the GPS data rate. What it does, though is change the filter time constant for the accelerometer data. I prefer the somewhat noisier but, in my opinion, more accurate high data rate values, particularly for autocross where acceleration changes rapidly.