Some users experience the following problem:
Using Workbook (or AlphaTeach) with an interactive LED display or interactive whiteboard, they dot an 'i' or cross a 't', or just draw a very short hypen or dash on the canvas - and it does not appear on the page. The behaviour does not occur if using a mouse: the shortest of strokes, or just dots, appear OK on the Workbook canvas when made with the mouse instead of the touch device.
To help with troubleshooting: There are several potential sources for this behaviour (short ink strokes and dots not being drawn), the most obvious being:
- Hardware filters touches – All touch systems have filters built in to their firmware which are designed to eliminate noise. By noise I mean spurious touches: a touch signal which is not a “real” touch signal. Different suppliers adjust these filters for greater or lesser sensitivity depending on the market. (In Australia for example, we’re all aware of their problem with flying insects…. And being able to neglect the effect of a fly landing on the display without consequence to a human finger’s input, is of some advantage there!) The kind of filter which is of greatest concern is looking at the minimum “touch-down-and-drag” distance before a signal is passed as a “real” touch intention. Obviously, the drag component of this algorithm will impact on such real-world needs as placing a dot over an “i” or crossing a “t”….
- Hardware reduces touch sampling - In addition, the device “samples” the touches at a prescribed rate. This sampling rate may drop under certain circumstances – eg if the usb transmission bandwidth is inadequate, or if the device is instructed by a driver to drop its sampling rate. Obviously, reducing the sampling rate increases greatly the likelihood that a dot over the “i” or a stroke over the “t” is overlooked and not reported.
- Connectivity – The interactive display’s connection to the computer (via usb cable in most cases) is a point of vulnerability. Every touch, every drag, every mouse action is communicated over this cable. In addition, the device may have to send other data over the cable, or the cable may also be connected to a hub and be handling data from other devices (eg video feeds) causing bandwidth constraints. USB is tolerant of noise such that a poor signal can simply mean less sampling of the touch gets through to the computer. In other words: if your usb cable is too long, or if there are several connection points (sockets etc), or there is some other source of noise, or there is too much data being sent over the one USB connection, then the available “bandwidth” is compromised and touch responsiveness will drop: ie not just lag, but also actual data loss occurs. One of the very first symptoms of this to the user is the inability to make short ink strokes or dots.
- Computer & OS - Touch signals from your device pass through the usb port into your computer and are interpreted by Windows (or other OS) through a queueing system. Sometimes, if the computer is light on processing and there’s a lot of demand placed on it, then it can take some time for the queue of inputs to be processed. This generally presents as a delay and catch-up of mouse actions rather than as missing inputs (such as a missing ink dot or stroke). – So I doubt this is the issue!
- Drivers - Drivers installed on the computerwill directly influence thesampling and filtering of touch signals. Sometimes a driver will reduce sampling rates or filter noise, perhaps in response to the bandwidth available for communications with the device. We see both responsiveness impacts and also filtering leading to data loss, resulting from drivers interpreting the touch signals.
- Software – There are a few cases in which the application software’s design will impact on whether or not it acts on touch information being received. Efficient touch application software today will use the touch functionality built into Windows 7, 8 and 10 in preference to the standard HID (Human Interface Device) drivers used for mouse or other pointing devices. Workbook / Alphateach interfaces correctly with the native Windows touch functionality. The software will need to input the touch signals from the queue, and interface with drivers which control the touch device.
Categories: Workbook / AlphaTeach, Admin / IT.