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MKHOD OF REDUCING DATA MODE TRANSMITTER TURN-ON TIME IN VOICE/DATA CAPABLE LAND MOBILE RADIOS

IP.com Disclosure Number: IPCOM000006764D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Jan-30
Document File: 3 page(s) / 137K

Publishing Venue

Motorola

Related People

Michael Alwine: AUTHOR

Abstract

Transmitter turn-on time (TTO) is defined as the terminal users, since it directly affects the inbound chan- time required from the instant that a Push-to-Talk (FIT) nel utilization and capacity. It is difficult to minimize is asserted to the time when the transmitted signal is data-mode lT0 in a two-way radio that is to be used folly stable and usable by a receiving unit. selectively for voice or data communication. In particu- lar, an efficient and cost effective method of reducing TTO can also be referred to as transmitter attack the effects of load pulling of the transmitter frequency time, and receiver-to-transmitter switching time when on TTO without degrading voice mode transmitter per- applied to a simplex radio transceiver. formance is needed.

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MO7WROLA INC. Technical Developments Volume 19 March 1993

MKHOD OF REDUCING DATA MODE TRANSMITTER TURN-ON

TIME IN VOICE/DATA CAPABLE LAND MOBILE RADIOS

by Michael Alwine

  Transmitter turn-on time (TTO) is defined as the terminal users, since it directly affects the inbound chan- time required from the instant that a Push-to-Talk (FIT) nel utilization and capacity. It is difficult to minimize is asserted to the time when the transmitted signal is data-mode lT0 in a two-way radio that is to be used folly stable and usable by a receiving unit. selectively for voice or data communication. In particu- lar, an efficient and cost effective method of reducing TTO can also be referred to as transmitter attack the effects of load pulling of the transmitter frequency time, and receiver-to-transmitter switching time when on TTO without degrading voice mode transmitter per- applied to a simplex radio transceiver. formance is needed.

It is desirable to minimize 'lT0 in mobile data appli- Figure 1 illustrates a typical breakdown of 'IT0 cations where a data channel is shared by many mobile timing.

TIME -

FIGURE 1. 'lT0 BREAKDOWN FOR SIMPLEX RADIO TRANSCEIVER

  If an adaptive tilter switching has been implemented to minimize the initial synthesizer lock-time upon fre- quency reprogramming, the largest contribution can become the segment at the far right due to load pulling of the transmitter frequency. When a radio transceiver begins to transmit by providing signal and appropriate DC bias to its power amplilier and associated gain blocks, large impedance changes seen at these stages usually result in at least some small load impedance change back at the Voltage Controlled Oscillator (VCO) that serves as both receiver local oscillator and transmitter exciter in simplex FM transceivers. Phase-locked loop (PLL) techniques arc usually used to provide frequency syn- thesis by phase-locking the VCO output to a stable ref-

erence. When the VCO load is changed, its output fre- quency shifts. The PLL reacts to correct the frequency error, but this additional reaction time results in increased 'lT0. PLLs optimized for voice transmissions do not provide sticiently fast correction of this frequency error for efficient data mode operation.

The invention provides a method for solving this problem.

BACKGROUND

Figure 2 shows a simplified diagram of a PLL fre- quency synthesizer.

0 Motorola. 1°C. ,993 85

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0 M MO-LA

INC. Techni...