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RF modem utilizing SAW device and pulse shaping

A modem and surface acoustic wave technology, applied in power oscillators, shaping networks in transmitters/receivers, AM carrier systems, etc., can solve the problems of low spectral density and noise of transmitted signals, achieve cheap packaging and reduce production costs , the effect of low power consumption

Inactive Publication Date: 2003-01-08
射频波有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The transmitted signal has low spectral density, and to a receiver without this code sequence, it appears as noise

Method used

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  • RF modem utilizing SAW device and pulse shaping
  • RF modem utilizing SAW device and pulse shaping
  • RF modem utilizing SAW device and pulse shaping

Examples

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Effect test

no. 1 example

[0096] Fig. 1 shows a block diagram of an RF modem constructed in accordance with a first embodiment of the present invention. An RF modem, generally indicated by reference numeral 10, includes transmit circuitry and receive circuitry. A portion of the modem, the SAW correlator, is shared by the transmitter and receiver.

[0097] The constructed RF modem 10 operates as pulse transmitter and pulse receiver. It is general-purpose in the sense that it can be applied to many different types of data communication systems, a few examples of which are described below. An RF modem can be used as a physical layer (PHY) within a layered communication system such as the ISO OSI communication stack.

[0098] For example, the transceiver RF modem 10 can be used to construct different types of communication systems, such as: on-off keying (OOK), pulse width modulation (PWM), pulse position modulation (PPM) or other types of pulse modulation. Please note that those skilled in the art can ...

no. 3 example

[0213] To achieve higher communication bit rates, other correlators and associated circuitry may be added to the first and second modem embodiments described above. In general, any number of correlators can be attached, where f i The correlation function or code of each correlator represented by (t) is orthogonal to the correlation functions of all other correlators. When the correlation functions (ie, codes) of the correlators are mutually orthogonal, each correlator transmits and receives independently of the other correlators. However, a sufficient number of correlation functions that satisfy the following criteria must be established.

[0214] i (t), fj(t)>=0, when all i≠j (5)

[0215] In other words, all codes must have a very low cross-correlation with each other, ie: around 0. For example, a skilled artisan can easily generate a plurality of linear FM codes that are approximately orthogonal to each other and have a cross-correlation with each other close to zero.

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PUM

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Abstract

A bidirectional direct sequence spread spectrum half-duplex RF modem which can be applied to transmit and receive numerous types of analog and digital pulse modulation. The modem incorporates two different SAW devices fabricated on a single monolithic substrate. A first SAW device is used as a resonator in the oscillator circuit while a second SAW device is used as the correlator for transmit and receive operations. The RF modem operates as an analog or digital pulse transmitter and receiver and is adapted to be generic and versatile enough to be used in many different types of data communication systems, such as OOK, PWM and PPM. The RF modem can be used as the physical (PHY) layer in a layered communication system such as the ISO OSI communication stack. In an alternative embodiment, the transmission bit rate is increased using a plurality of correlators wherein each is configured with a unique function (i.e., code) that is orthogonal with all other functions.

Description

technical field [0001] The present invention relates generally to radio frequency (RF) modems and, more particularly, to surface acoustic wave based spread spectrum RF modems incorporating upconversion circuitry and pulse shaping circuitry to limit the frequency output of transmitted signals. Background technique [0002] With the rapid growth of computer usage, the demand for peripheral devices and systems connected by wireless connection is also increasing. Currently, the number of wireless applications is growing at a high rate in areas such as security alarms, networking, data communications, telephony, and computer security. [0003] At present, there are many ways that wireless communication can be adopted, such as ultrasonic, IR and RF. The communication technology commonly used in RF wireless communication is spread spectrum technology. Spread spectrum communication is a communication technology that spreads a signal by spreading a signal over a frequency band much...

Claims

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Application Information

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IPC IPC(8): H04B1/707H04B1/7093H04L7/04H04L25/03H04L25/06H04L25/49H04L27/02
CPCH04L27/02H04L25/03834H04L25/4902H04B1/7093H04B1/70712H04L7/043H04L25/06H04W92/02
Inventor 戴维·本-巴萨特摩西·勒纳
Owner 射频波有限责任公司
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