Why does the location keep jumping on NAVFone?

Recently, there has been 1-star reviews and feedback that the NAVFone apps for iPhone is lousy because the GPS is not working properly. So we investigated and tested and finally decided we better attempt to answer the question: Why does the location keep jumping on NAVFone?

GPS position is calculated based on signals from satellites in the sky. Generally 3-12 satellites can be visible by the GPS chip in the mobile devices. When the chip is receiving less than 4 signals, the GPS position becomes invalid or highly inaccurate.

Inaccuracy has also been experienced when there are many glass façade buildings in the vicinity. GPS signals get reflected off the glass panels and when received by the GPS receivers, produce inaccurate results. This can happen in areas with tall glass façade buildings.

Bad weather and thick tree cover also reduce the accuracy of the GPS signals, causing a delayed response on the navigation apps. Sometimes, the location is delayed up to 3 sec during rain storms.

Specifically for iPhone, the Location Service is provided by phone. It is very much beyond the control of the developers. Besides the limitation of the GPS position as highlighted above, when there is no GPS, the iPhone Location Service switches automatically to the AGPS position.

The AGPS position is normally the mobile or WiFi base station which the mobile phone is connected to. Hence whenever there is no GPS position, it bounces from building to building, or landmark to landmark. All apps utilising the Location Service face the same problems. When that happens, you can observe inaccuracy of up to several hundred metres from the actual location. This is commonly terms as a 'location jump'.
In our testing, we have experienced these occurrences when:
(1) Inside tunnel such as CTE and KPE
(2) Underground or covered carpark and driveways
(3) Along highly built up areas with tall buildings, such as the Shenton Way, Robinson Road, Cecil Street and the Raffles Place vicinity.

AGIS has tested the apps on several iPhone devices with the same result. We also tested the NAVFone with other navigational software and noticed the same location error.

Nonetheless, we are still looking into the issues and coming up with solutions that could filter or minimise the inaccuracy. Meanwhile, we hope to get the understanding and support of our users - we are working to improve our apps all the time.

At least for one thing, you can be assured NAVFone or NAVFDrive would bring you to your destination :)