Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

OVENIZED OSCILLATOR WARM UP INDICATOR

IP.com Disclosure Number: IPCOM000007789D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-24
Document File: 2 page(s) / 102K

Publishing Venue

Motorola

Related People

James Gehrke: AUTHOR [+4]

Abstract

Modem wireless communications base stations offen require a high stability frequency reference with significantly better than 1 ppm stability. This level of frequency reference performance requires a design based on a ovenized oscillator.

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 50% of the total text.

Page 1 of 2

Technical Developments

OVENIZED OSCILLATOR WARM UP INDICATOR

by James Gehrke, John Ft. Zanghi, Robert Sarocka and Lynn Heffley

BACKGROUND:

  Modem wireless communications base stations offen require a high stability frequency reference with significantly better than 1 ppm stability. This level of frequency reference performance requires a design based on a ovenized oscillator.

  The problem with the use of ovenized oscilla- tors is that there is a significant worst case warm up period needed to insure that the device is tempera- ture stabilized and on frequency. This is critical because FCC or other 'government regulations do not allow the base station to transmit until the sys- tem is known to be within frequency limits. The current way to do this is to force the station to wait the worst case 15 minutes before transmitting. This causes an unnecessary wait after any station reset to account for the longest oscillator stabilization from the lowest temperature. Since the timing is based on any control module reset, which takes place dur- ing most service operations, even though the ovenized reference will have been off only for a short period (or not at all for external references), the user will have to wait the maximum stabilization time to key and test the base station.

  A method is needed to determine when the ovenized oscillator is stabilized rather than always waiting the worst case period. The new approach solves the problem of long delay during the servic- ing of base stations with ovenized frequency references.

lized. The base station uses a TCXO oscillator as a Voltage Controlled Crystal Oscillator or VCXO. It is phase locked to the ovenized frequency reference. This network can monitor the control line of the TCXO. The TCXO is a temperature compensated oscillator that provides enough frequency stability to determine that the ovenized oscillator is not sta- bilized by the voltage of the phased locked control line and its rate of change. This voltage is sampled over time. Once the voltage falls within a certain window, the system looks for the rate of chan...