What is DigiHUD Speedometer?
DigiHUD Speedometer is an Android app designed to show speed and distance information based on the location data received from your device’s GPS receiver. It’s an ongoing project and will continue to evolve over time.
The free version will continue to have bug fixes as required but will not receive any additional features.
Pro will continue to improve with additional features.
In the future it’s hoped to also have an iOS version available.
Why did you make it?
Back in early 2012 I saw a speedometer app running on a friend’s iPhone that worked really well and thought I’d have a go at writing a similar app for my Android phone. The app I saw had a green digital readout of our speed, as well as a few bits of other information. The display also flipped so it could be used as a Heads-up display in the car windscreen. Cool app I thought.
It was one of those “I’m sure I can do that” moments. It was my first dip into Android/Java development but I soon became hooked.
Who is it for?
Currently only Android devices, including tablets (and hopefully smartwatches eventually), however I’m starting to look at iOS development with a view to one day porting DigiHUD to iPhone/iPad.
I want it to be available to as many devices as possible and will continue to try to support Android 2.3 and up.
Some features may not be available on some versions of Android depending on what parts of the framework are required.
How does it work?
The app ‘listens’ for location data coming from the GPS receiver, which in turn depends on getting enough signals from the GPS satellite array to ‘fix’ your location. This location data contains the current position (latitude and longitude), speed, heading, altitude etc. It then translates this data into your required unit (MPH/miles etc) and displays it using images.
That’s essentially all the app does and therefore is totally at the mercy of the quality and accuracy of the GPS data it receives. It doesn’t perform any fancy maths to try to reduce the lag that is always present when calculating speed as I’m not confident that this would work reliably or be of benefit to every device.
What information does it collect from my device?
No data is collected and sent from the device. I should have updated this a long time ago as the app hasn’t included any analytics or third-party SDKs for many years.
How accurate is it?
It will only ever be as accurate as the data coming from the GPS receiver.
The better the GPS signal then the better the accuracy will be. The higher the sensor refresh rate the lower the lag will be (both the free and Pro versions have been tested and work perfectly with external high refresh rate GPS receivers).
When near buildings, under foliage or with an obscured view of the sky the accuracy will be reduced. Inside tunnels and buildings it’s very unlikely to get any usable signal at all. If you’re sat indoors don’t expect to see accurate data, the signal will be so weak the location will probably be jumping all around your location giving a false speed reading.
With a clear view of the sky and a high accuracy reading the app has been found to show within +/-1MPH of UK roadside Police speed signs on a Samsung Galaxy S3 in a windscreen holder.
Don’t think that because the speed doesn’t match the speed shown by your vehicles speedometer that the app is inaccurate; vehicle manufacturers usually design the speedometer to read high (to account for tyre wear and other environmental variables) so that if you’re travelling at the speed limit your actual speed is several percent slower.
Having said that, don’t rely on it for your speed if it’s accuracy is unknown (read this post).
A small snippet from The Car Expert about car speedometer accuracy (UK specific):
The UK law is based on the EU standard, with some minor changes. A speedo must never show less than the actual speed, and must never show more than 110% of actual speed + 6.25mph. So if your true speed is 40mph, your speedo could legally be reading up to 50.25mph but never less than 40mph. Or to put it another way, if your speedo is reading 50mph, you won’t be doing more than 50mph but it’s possible you might actually only be travelling at 40mph.
To ensure that they comply with the law and make sure that their speedometers are never showing less than true speed under any foreseeable circumstances, car manufacturers will normally deliberately calibrate their speedos to read ‘high’ by a certain amount. As your satnav is not the designated device by which a car’s speed is measured, it does not need to incorporate any fudge factoring.
If you’d rather show the speed matching your vehicle’s speed the Pro version allows a percentage offset to be applied to the speed.
Why is there a screen burn-in warning, and what is burn-in? Other apps I use don’t have this warning.
Screen burn-in can happen on some types of screen and can cause permanent damage when a still image is displayed for a long period of time.
The display can exhibit areas of discolouration or darkening.
After many many hours of testing the app over the last two years one of my devices (a Samsung Galaxy S3) does now show some burn-in, which can be seen as a slight yellowing of the display where the speed and other information is displayed in landscape mode. Another older device (an HTC Wildfire) has no burn-in at all. The Samsung has an AMOLED screen whereas the HTC has an IPS screen.
Because of this I thought it worth making people aware of the potential for damage when using any app that displays a still image for a long period of time.
PC Pro magazine did a great article on AMOLED displays. Erica Griffin also shows burn in on a Nexus 6 after a few days.
Please check your device documentation for more information on whether your device may be susceptible.
Can I use it when walking, cycling, jogging, or in an aircraft, boat, train or hot air balloon?
Yes, as long as your device can pick up a good GPS signal you can use it almost anywhere.
It will work from as slow as .75 up to 999 MPH/KPH/KTS. I have personally recorded a speed of 704 MPH on a flight from Miami to London.
Will the screen go off when I'm using it?
When in full-screen mode the display will be kept on by the app. In Window mode it depends on the app that it’s running on top of.
I have a high accuracy external GPS receiver. Will DigiHUD work with it?
Yes. I’ve had reports that the app works with external GPS receivers and I’ve recently bought a Garmin GLO Bluetooth Receiver to test DigiHUD’s support for these devices. From my own testing I’ve found that the app works perfectly at a refresh rate of up to 10 times per second.
How well it works will depend on factors like the speed of the device running the app and the speed of updates that Bluetooth can handle. I’ve found that even on an old HTC Wildfire S it keeps up with the GPS updates without issue.
The Pro version is currently being updated to indicate when external data is being used, or GPS data from the internal receiver.
Does it have adverts?
No.
Will it work with Privacy Guard enabled, or other third-party privacy apps?
Privacy Guard, which is built in to some versions of Android, will stop DigiHUD working if it’s enabled for the app.
Other apps may also prevent it working if they block other app’s access to the device location.
Why has it put two icons in my app drawer?
The free version installs an icon for both full-screen and window modes.
After receiving feedback from Pro users the window mode icon was removed (in the Pro version) and replaced with the ability to create a shortcut directly to window mode if it’s required. In Android Lollipop a Widget will appear that can be added to a homescreen, which opens the app in Window mode.