Abstract
The combined analogue locked-loop universal modulator (CALLUM) is an RF transmitter topology which produces a linear output through the use of non-linear but highly efficient RF power amplifiers. This is achieved through careful phasing of two constant-envelope vectors, each derived from voltage-controlled oscillators. The system up-converts and amplifies a baseband signal within a closed-loop feedback scheme. The optimal CALLUM system requires complex baseband processing, but a simplified version, known as CALLUM2 can be implemented using simple analogue circuitry. This paper provides some insight into the behaviour of such systems and gives results from an experimental CALLUM2 system in response to a modulating signal compatible with that used in the TETRA standard
Original language | English |
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Pages | 137 - 140 |
DOIs | |
Publication status | Published - Aug 1998 |
Bibliographical note
Terms of use: Copyright © 1998 IEEE. Reprinted from Proceedings of IEEE Radio and Wireless Conference, 1998. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Bristol's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected].By choosing to view this document, you agree to all provisions of the copyright laws protecting it.
Name of Conference: Radio and Wireless Conference, 1998 (RAWCON 98)
Venue of Conference: Colorado Springs, CO
Keywords
- VCO-derived synthesis
- land mobile radio
- radio transmitters
- TETRA standard
- VHF circuits