Browse Prior Art Database

SIGNALLING SCHEME FOR WIRELESS DIGITALLY MODULATED ENCRYPTION SYSTEMS

IP.com Disclosure Number: IPCOM000008940D
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2002-Jul-25
Document File: 2 page(s) / 101K

Publishing Venue

Motorola

Related People

Norbert Röttger: AUTHOR [+2]

Abstract

A signaling scheme is proposed which makes use of user-definable bits in the data protocol of wireless digitally modulated encryption systems. PL informa- tion can be represented by different bit patterns.

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@ MmROLA

Technical Developments

SIGNALLING SCHEME FOR WIRELESS DIGITALLY MODULATED ENCRYPTION SYSTEMS

by Norbert Riittger and Jiirgen Schmidt

ABSTRACT

  A signaling scheme is proposed which makes use of user-definable bits in the data protocol of wireless digitally modulated encryption systems. PL informa- tion can be represented by different bit patterns.

INTRODUCTION

  This paper describes how current and future digi- tal-wireless-communication systems using encryption methods can benefit from the application of traditional analogue private-line (PL) functionality. The idea is applicable to all such communication systems. The systems reserve user-definable data bits, which are free for the proposed Crypt0 PL functionality. Traditional PL functionality is implemented by use of sub-audible tone frequencies (<300Hz) that get summed to the voice signal during transmission.

PROBLEM(S) TO BE SOLVED

  A common problem in encryption systems is the limited number of encryption keys and the effort need- ed to administer the encryption keys for large systems.

  Current encryption systems cannot use traditional analogue PL signaling, because it would disturb the encryption modulation in the RF channel. In general, the PL functionality would be desirable in such sys- tems too. For details of the PL functionality and appli- cations please read the Motorola wireless product descriptions. The implementation of highly desirable multiple PL signaling systems is currently not possible, without adding a special expensive decoder, with the technology (HCll software decoder) that is used in current products from Motorola's Radio Paging Group.

PROPOSED SOLUTION TO THE PROBLEM(S)

  Traditional analogue PL occupies a sub-audible frequency range below 300Hz of the analogue FM audio spectrum. There are different fixed frequencies defined, from which one is added to the transmitted (TX) signal of the transmitting radio during the voice communication, This PL tone is decoded by all the radios listening to the same RF channel. If the rcceiv- ing radio detects its programmed PL frequency a cer- tain function can be enabled, e.g. open squelch.

  The idea now proposed is a "Crypt0 PL" algorithm which makes use of user-definable bits in the data pro- tocol of wireless digital mo...