Railway Performance Society Magazine - Milepost

Speed apps

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msimister

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Speed apps - Posted: September 15, 2014 - 4:55 PM Quote and reply
I apologise if this has been raised previously, but I have downloaded two free apps onto my Samsung Galaxy S4 smartphone called DidiHUD and Speed which use GPS satellites to tell your speed. I have checked their accuracy against my stopwatch in both Australia and England and against a driver's cab digital speedo in Australia and they seem to be accurate. Has anyone else tried such things and does anyone know how they compare with full GPS devices?
Regards,
Malcolm

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djackman

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Re: Speed apps - Posted: September 24, 2014 - 8:30 PM Quote and reply

msimister said:
Has anyone else tried such things and does anyone know how they compare with full GPS devices?


I currently use a Nexus 7 (2013) and a GPS MAP 64s. I haven't yet been able to do a full evaluation but under normal conditions both are fine, though both have their quirks (e.g. the Nexus is much quicker getting first fix, for example). Once warmed up the 64s seems to be more accurate but is doesn't usually make a lot of difference in our terms (and it seems that both are usually more accurate than the mileposts).

When it does make a difference is longer journeys and/or "difficult" (e.g. anti-glare coated windows) stock. Either one or both of the units will fail to pick up any signal inside the train, and the "proper" GPS (with a GA25MCX external antenna attached) works more of the time than the Nexus - but there are occasions when the Nexus is working quite happily yet the 64s is struggling. The "proper" GPS is also better at acquiring new satellites (which means it will keep going beyond the couple of hours it takes to travel sufficiently that the satellites already acquired have moved out of view)

David


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