Lap timing

[nick]

I wish to purshase a lap timing unit a was undecide which to get, Lap beacon or a Gps Beacon, I see more benifts in logging for the Gps unit ,but will it work as well as a lap beacon in all conditions ie (bad weather etc), Also what is the accury of the Gps ? ie (metres,cm, mm)

[Apex Speed Tech]

We've used GPS exclusively in the AMA Superbike Championship with excellent results. Wouldn't go back to the optical beacon ever.

[Dragon]

Motec has stopped selling the 10Hz and 20 hz GPS units.

We have had beacon problems with GPS when weather was bad, or when the car had to run under bridges.

We now keep both GPS and BR2 and select which one to use based on conditions.

Good news for Motec!

[chelspeed]

They've stopped selling the Standard 10 Hz and 20 Hz GPS, ref GPS-BL1, part numbers 41301 and 41302 respectively. But I'm told the Professional 10 Hz and 20 Hz models, no ref no, part numbers 41303 and 41304 is still available. Hope that's right because I've just ordered one.

[JamieA]

We have stopped selling the 10 and 20hz units, as the supplier could no longer supply the units to us, for no other reason. If we could still buy them, we would be still selling them!

We still sell the 5hz GPS with works just fine for lap times.

Why GPS beacons?

You get speed, track position and lap time, all for about half of the cost of a transmitter and reciever.

The BR2 reciever and BTX transmitter are more expensive, but also more accurate. There isnt much in it, as previously mentioned, but absolute accuracuy only comes from the IR method.

-Jamie

[Holmz]

I have a GPS-BL1 unit in 10Hz mode, that I got in Dec 2008.

There might not be much of a difference between the Australian and US version except that the US version can take advantage of WAAS (I think) which us only available in the US.
Since I use want to use the unit in 2 continents I have been toying with the idea of the US version.

Bottom line is that I would sell the GPS-BL1 order to get the Professional version - if anyone is interested in it... (Otherwise I'll be happy keeping it)

[chelspeed]

> WAAS (I think) which us only available in the US

WAAS (wide area augmentation service or similar) is only available in US. But Europe has EGNOS (European geo-stationary navigational overlay system) which is directly equivalent. Amazingly enough it's the same standard and frequency etc so that a box designed for WAAS will also use EGNOS. There are also two other systems, MSAS in Japan and GAGAN in India. Lots of stuff here.

I've got the 10Hz version of the US Race Grade box and in UK I get the Diff and DGPS lights on fairly regularly. Not sure of the benefit because you can't get a log of Diff and DGPS, just the number of satellites, so hard to compare what I log with whether DGPS was working or not.

My Garmin navigator in the same location regularly reports accuracy of 2 or 3m but how reliable this is I'm not sure.

[IDP]

viewtopic.php?f=26&t=89&p=1073#p1073

See AlanB's reply in this topic regarding logging DGPS.

[chelspeed]

Thanks for the heads up, hadn't seen that before, must have been before I subscribed. I'll be on it reprogramming the datalink first thing tomorrow.

Googled $GPGGA and variable 8 is "horizontal dilution of precision" or the relative accuracy of the horizontal precision so I'll try for that too.

Worked a treat first time, why am I always surprised when these things work as intended? I got 9 sats, 2 for status for a DGPS fix and 1.1m "dilution".

Thanks again to all.

[toby]

If you lose satellites for part of a lap but always have them over the start/finish line, will the lap time still be accurate? In other words, is the lap time based on the atomic clocks in the GPS satellites? I realise that lap distance and drive line analysis would be incorrect in this instance. In other words, is it necessary to use I/R beacons as well as GPS if there is any doubt about loosing satellites?