PC-based V.22bis data-scope with native soft-modern implementation

Abstract

Despite the availability of more advanced options, low speed modem standards such as the 2400 bits per second V.22bis are still employed in various sectors. Examples include payment terminals, set-top boxes and vending machines. There are just a handful of applicable diagnostic products on the market, and none provide a compact, easy to use and non-intrusive solution to the call and data monitoring requirements of developers and modem integrators. In this work, we design and implement LineScope, a software based solution that addresses the above-mentioned shortcomings. Written in C#, it has at its core a substantial soft-modem implementation, together with diagnostic instrumentation and data tracing facilities. Targeting the payment terminal sector, the application can handle connections with the various handshake quirks prevalent in the industry. It features both synchronous and asynchronous decoding capability, with detailed link layer protocol tracing. It also performs reasonably well with moderate impairments. Real-time performance on an obsolete Pentium III class machine is attainable with a safe margin. In conclusion, our successful implementation demonstrates that today's managed code can be used effectively for signal processing applications.