M-TTY Tools


The M-TTY tools were developed at DSPG to support field studies of TTY transmission over digital wireless telephones. They are being distributed to the TTY Forum in the hope that they may be of some use to companies testing TTY over wireless networks in field conditions.

The M-TTY tools permit semi-automated data collection in mobile conditions. A laptop or notebook computer is attached by USB cable to a model of TTY that consumers would typically use for wireless telephone conversation.

Using the Mobile TTY Test Software, the tester can launch bi-directional scripts, which will alternate sides automatically after the GA characters. The text passes via serial connection to the TTY and then via audio connection to the handset. Incoming text is captured from the TTY by the laptop.

Data on call conditions can be entered into the TTY Test Software, and these conditions along with a time stamp are saved into a database format suitable for import to Excel or similar software. The software separates the two sides of the conversation for separate scoring of each side. This is done to assist in diagnosis of errors.

SCORE by Lober and Walsh (licensed for use by the TTY Forum in testing TTY over wireless telecommunications), and CTM_SCORE (from 3GPP TS 26.231 CTM Minimum Performance Specification) are supported; a utility program provided in the Gallaudet package runs both scoring programs and integrates the output with data on call conditions supplied by the tester.

Wireless-to-wireline or wireless-to-wireless calls are supported, depending on the number of modified TTYs available (two are needed for wireless-to-wireless calls).