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Browse Prior Art Database

Time Division Pulse Modulation

IP.com Disclosure Number: IPCOM000061030D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Munoz-Bustamante, C: AUTHOR [+3]

Abstract

This article describes a time division pulse modulation (TDPM) method for infrared packet transmission. Several known methods exist for encoding data bits for transmission on various physical media. Among these techniques are the Manchester, non-return to zero (NRZ), NRZ inverted (NRZI) and group encoding. The method disclosed herein lowers the power consumption and increases the distance and data rate of infrared packet switched transmissions. With TDPM one light pulse encodes 4 bits (a nibble) of information by measuring the time between adjacent pulses. Referring to the pulse illustration of Fig. 1, given that the last pulse already occurred and used up 1000 ns for the LEDs to turn on and off, the next pulse begins at one of 16 allotted slot times.

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Time Division Pulse Modulation

This article describes a time division pulse modulation (TDPM) method for infrared packet transmission. Several known methods exist for encoding data bits for transmission on various physical media. Among these techniques are the Manchester, non-return to zero (NRZ), NRZ inverted (NRZI) and group encoding. The method disclosed herein lowers the power consumption and increases the distance and data rate of infrared packet switched transmissions. With TDPM one light pulse encodes 4 bits (a nibble) of information by measuring the time between adjacent pulses. Referring to the pulse illustration of Fig. 1, given that the last pulse already occurred and used up 1000 ns for the LEDs to turn on and off, the next pulse begins at one of 16 allotted slot times. These slot times are narrow and depend on the gate delays of modern gate array chips. For the purposes of this disclosure the slots are defined as 200 ns. The latter optical pulse becomes the previous pulse for the one to follow (i.e., each pulse acts as a stop timing signal for the current nibble and as a start timing signal for the next nibble). The advantages are data rate increases, the worst-case power is reduced by 4, and the information is carried by the positive edges only so pulse- width distortions can be ignored. From Fig. 1 these characteristics are indicated as follows: -Minimum time to transmit 4 bits is 1000 ns, i.e., 250 ns/bit or 4 Mb/sec. -Maximum time to transmit 4 b...