User-Programmable Scrambler IC to Protect Audio Systems Against Security Breaches

Recognising the growing need to protect communication systems from the threat of being compromised by unauthorised parties, CML Microcircuits has introduced the CMX7158. Based on the company’s proprietary FirmASIC® technology, so as to facilitate configuration, this compact user-programmable scrambler IC is optimised for inclusion in multi-function audio systems, as well as handheld wireless/cellular equipment.

Maintaining elevated levels of audio quality, it can rapidly switch between clear and scrambled voice modes via a programmable frequency inversion point, with minimal delay being experienced. Furthermore, its completely independent Tx and Rx signal paths mean that this IC is capable of full duplex operation.

Thanks to FirmASIC, a Function Image™ is generated in which the CMX7158’s functional parameters are defined. This is loaded to the system upon power-up/device initialisation – either from the system’s host microcontroller (across the C-BUS interface) or through an attached serial flash memory. Dual-tone multi-frequency (DTMF) encode/decode, Selcall signalling and VOX detection on both channels are among the other main features encompassed.

Key applications for the CMX7158 include cellular radio accessories. Bluetooth headsets, wired/wireless access control systems, plus private mobile radio (PMR) and land mobile radio (LMR) radio hardware, as well as legacy wireline telephony. Supplied in a space-saving 48-pin VQFN package, it supports low power operation (drawing from a 3.0V-3.6V source, with power conserving modes available). The numerous analogue audio interfaces incorporated make integration into existing system designs very straightforward. To assist engineers during the development process, CML offers the PE0402 evaluation board to accompany the CMX7158.