***OFFICIAL*** poast you’re Dragy street vids thread!!!
05-02-2019, 10:47 AM
#22
10 Second Club
Thread Starter
05-02-2019, 11:30 AM
#23
What are the reasons? I've seen numerous examples where its within .1 in the quarter mile and within 2MPH in the half mile of actual timing equipment. I agree its not a 100% replacement, but certainly close enough to have some fun in winter when track is closed or to know how a car performs that the owner doesn't want to take to the track for whatever reason.
Keeping this short, the issues are A) the GPS receiver has a 10Hz refresh rate...that is 10 times a second, so calculating times to .0x when you only refresh every .x is no bueno, and B) the inherent error in commercial grade GPS is ~5 meters. I've talked to multiple people who have one and they can run multiple passes back to back on multiple occasions and sometimes they line up and sometimes they dont. Shoot, being a tenth off a track time is awesome....just not when people are trying to claim records with it, which is the new craze. I've seen at least one instance of a platform claiming first in the 11's because their Dragy said they ran an 11.95. Sorry go to the track and back it up.
The new L5 band of GPS will give accuracy to less than 1ft and they already have 100 Hz GPS receiver's available but they have other issues (noise). Yes the current Dragy also has an accelerometer and timing, which also all have error, and again the sampling rate is too low to perform proper filtering and analytics on it to throw out outliers during a run. For reference, I designed and built a ruggedized data acquisition device that samples in the 10's of kilohertz so I have some clue about this despite what Hammer's 3rd grade posts would have you think
05-02-2019, 11:37 AM
#24
10 Second Club
Thread Starter
As I said above, its great for a ballpark. The problem is that on other platforms people are using these things to replace drag strip times and claim "first to xx et/xxx mph".
Keeping this short, the issues are A) the GPS receiver has a 10Hz refresh rate...that is 10 times a second, so calculating times to .0x when you only refresh every .x is no bueno, and B) the inherent error in commercial grade GPS is ~5 meters. I've talked to multiple people who have one and they can run multiple passes back to back on multiple occasions and sometimes they line up and sometimes they dont. Shoot, being a tenth off a track time is awesome....just not when people are trying to claim records with it, which is the new craze. I've seen at least one instance of a platform claiming first in the 11's because their Dragy said they ran an 11.95. Sorry go to the track and back it up.
The new L5 band of GPS will give accuracy to less than 1ft and they already have 100 Hz GPS receiver's available but they have other issues (noise). Yes the current Dragy also has an accelerometer and timing, which also all have error, and again the sampling rate is too low to perform proper filtering and analytics on it to throw out outliers during a run. For reference, I designed and built a ruggedized data acquisition device that samples in the 10's of kilohertz so I have some clue about this despite what Hammer's 3rd grade posts would have you think
Keeping this short, the issues are A) the GPS receiver has a 10Hz refresh rate...that is 10 times a second, so calculating times to .0x when you only refresh every .x is no bueno, and B) the inherent error in commercial grade GPS is ~5 meters. I've talked to multiple people who have one and they can run multiple passes back to back on multiple occasions and sometimes they line up and sometimes they dont. Shoot, being a tenth off a track time is awesome....just not when people are trying to claim records with it, which is the new craze. I've seen at least one instance of a platform claiming first in the 11's because their Dragy said they ran an 11.95. Sorry go to the track and back it up.
The new L5 band of GPS will give accuracy to less than 1ft and they already have 100 Hz GPS receiver's available but they have other issues (noise). Yes the current Dragy also has an accelerometer and timing, which also all have error, and again the sampling rate is too low to perform proper filtering and analytics on it to throw out outliers during a run. For reference, I designed and built a ruggedized data acquisition device that samples in the 10's of kilohertz so I have some clue about this despite what Hammer's 3rd grade posts would have you think
05-02-2019, 12:08 PM
#29
As I said above, its great for a ballpark. The problem is that on other platforms people are using these things to replace drag strip times and claim "first to xx et/xxx mph".
Keeping this short, the issues are A) the GPS receiver has a 10Hz refresh rate...that is 10 times a second, so calculating times to .0x when you only refresh every .x is no bueno, and B) the inherent error in commercial grade GPS is ~5 meters. I've talked to multiple people who have one and they can run multiple passes back to back on multiple occasions and sometimes they line up and sometimes they dont. Shoot, being a tenth off a track time is awesome....just not when people are trying to claim records with it, which is the new craze. I've seen at least one instance of a platform claiming first in the 11's because their Dragy said they ran an 11.95. Sorry go to the track and back it up.
The new L5 band of GPS will give accuracy to less than 1ft and they already have 100 Hz GPS receiver's available but they have other issues (noise). Yes the current Dragy also has an accelerometer and timing, which also all have error, and again the sampling rate is too low to perform proper filtering and analytics on it to throw out outliers during a run. For reference, I designed and built a ruggedized data acquisition device that samples in the 10's of kilohertz so I have some clue about this despite what Hammer's 3rd grade posts would have you think
Keeping this short, the issues are A) the GPS receiver has a 10Hz refresh rate...that is 10 times a second, so calculating times to .0x when you only refresh every .x is no bueno, and B) the inherent error in commercial grade GPS is ~5 meters. I've talked to multiple people who have one and they can run multiple passes back to back on multiple occasions and sometimes they line up and sometimes they dont. Shoot, being a tenth off a track time is awesome....just not when people are trying to claim records with it, which is the new craze. I've seen at least one instance of a platform claiming first in the 11's because their Dragy said they ran an 11.95. Sorry go to the track and back it up.
The new L5 band of GPS will give accuracy to less than 1ft and they already have 100 Hz GPS receiver's available but they have other issues (noise). Yes the current Dragy also has an accelerometer and timing, which also all have error, and again the sampling rate is too low to perform proper filtering and analytics on it to throw out outliers during a run. For reference, I designed and built a ruggedized data acquisition device that samples in the 10's of kilohertz so I have some clue about this despite what Hammer's 3rd grade posts would have you think
05-02-2019, 12:18 PM
#31
Ahh yes I agree with that, you can't claim a drag racing track record without a timeslip period! But I could see if both parties are using dragy, I suppose they could claim the "dragy record" for whatever that's worth. Really all the records themselves have gotten out of control, seems everyone in racing wants a participation trophy. Whatever happened to just racing to have fun? That's how I would classify this device, to have fun but not a replacement for a time slip.
Meh, its as close as you can get without trying to do DA correction on your timeslip....and much more repeatable than GPS.
05-02-2019, 12:24 PM
#33
11 Second Club
Hams is funny. Trying to look special?? That is not a bone stock firehawk period. I drove my 01 SS for two years "stock" except for replacing the stamped steel suspension components. So my car wasn't really stock. Also with 25.6" rear tire, 3.42 gear, & 6k rpm it should pull to 130+ in fourth. Looks like you got them 4.11 gears rollin as only 118mph in fourth.
05-02-2019, 12:27 PM
#34
10 Second Club
Thread Starter
Hams is funny. Trying to look special?? That is not a bone stock firehawk period. I drove my 01 SS for two years "stock" except for replacing the stamped steel suspension components. So my car wasn't really stock. Also with 25.6" rear tire, 3.42 gear, & 6k rpm it should pull to 130+ in fourth. Looks like you got them 4.11 gears rollin as only 118mph in fourth.
05-02-2019, 12:41 PM
#36
05-02-2019, 12:59 PM
#40
11 Second Club