Browse Prior Art Database

RF SITE SELECTION BY UTILIZING THE DOPPLER EFFECT

IP.com Disclosure Number: IPCOM000007087D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2002-Feb-25
Document File: 2 page(s) / 74K

Publishing Venue

Motorola

Related People

Stan Jelavic: AUTHOR

Abstract

In the current trunking and cellular systems it is a requirement to select the site with the best Rf signal for better quality of voice communications, With the current procedures the Rfsignals are sam- pled and then filtered by some form of a low pass filter to eliminate the fast fading component.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 64% of the total text.

Page 1 of 2

MO7DROLA Technical Developments Volume 21 February 1994

RF SITE SELECTION BY UTILIZING THE DOPPLER EFFECT

by Stan Jelavic

STATEMENT OF PROBLEM

  In the current trunking and cellular systems it is a requirement to select the site with the best Rf signal for better quality of voice communications, With the current procedures the Rfsignals are sam- pled and then filtered by some form of a low pass filter to eliminate the fast fading component.

The problem is that the Rfsignal can also include

the slow fading component which is sometimes called shadowing (see Figure 1). The filter cutofffrequency has to be selected properly in order to preserve the slow fading component and to cut out the fast fad- ing components. If the cutoff frequency is selected too high, the fast fading component is more pro- nounced increasing the selection error. Similarly, if it is selected too low, it will mask the shadowing component causing the unit to completely miss the slow peaks and dips ofthe signal.

COMBINED SIGNAL

To summarize:

If is dijj'krrh fo ,selecr fhe RfSipd Strcqfh filrrr aclo~jkxpency.

Q Motorola, inc. 1994 27

[This page contains 14 pictures or other non-text objects]

Page 2 of 2

MOlWROLA Technical Developments Volume 21 February 1994

RESOLUTION

To summarize:

- Make the cutoff frequency selection dynamic depending on the speed of the vehicle.

PROCEDURE

In order to implement the solution, the follow- ing procedure is to be followed:

- Digitize the SignalStrength samples. - Do...