Pulse or digital communications – Transceivers – Modems
Reexamination Certificate
1998-05-15
2001-09-04
Chin, Stephen (Department: 2634)
Pulse or digital communications
Transceivers
Modems
C379S398000, C379S404000
Reexamination Certificate
active
06285707
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates generally to communications cards such as PCMCIA-architecture style modem or network cards. More specifically the present invention relates to compensating for heat build-up or temperature changes therein.
2. The Relevant Technology
As computer housings have downsized, internal spatial restrictions have required the establishment of standards for the internal accessories of the computer. One set of standards applicable to memory cards has been developed by the Personal Computer Memory Card International Association (PCMCIA). This organization is comprised of hundreds of manufacturers of memory cards and related peripheral equipment. By convention, the PCMCIA has determined that the spatial standard for all memory cards used in down-sized computers should be restricted to a rectangular space approximately 55 mm in width, 85 mm in length, and either 3.3, 5 or 10.5 mm in depth.
To assure themselves of compatibility and spatial conformity with computers utilizing the PCMCIA standards, internal modem manufacturers have adopted these same spatial standards for their down-sized communications cards. Other communications cards complying with the PCMCIA standards include, but are not limited to, various network cards for use in a LAN or equivalents thereof.
No matter which style of communications card is used, because the size constraints imposed by the PCMCIA standard are so confined, heat has adversely been observed as building-up within the structure of the communications card. Where heretofore this problem was essentially non-existent because of adequate forced-air coolers and large, open spaces available for dissipating heat away from communications cards, this problem has become quite an industry-wide nuisance.
However, to compensate for this heat, many communications cards are configured with variable components dynamically adjusted according to temperature. For example, in a modem communications card, a digital signal processor (DSP) changes various filter coefficients according to line conditions and a measured temperature. In turn, this causes a corresponding change in modem gain. Although effective, modem communications cards experience numerous such changes because they typically require about a 10-15 minute warm-up period before a steady state temperature is achieved.
Detrimentally, adjustments of these components necessitate time-consuming retraining sequences and adaptive filtering to establish various line parameters, such as gain and equalization, between communicating modems. Moreover, it is even possible that during such retraining sequences the net character transmission throughput between the modems can be completely stopped.
Other proposed solutions for overcoming the adverse effects of heat build-up include various hardware implementations. With hardware, however, excessive board space is consumed in an already space-critical environment. Hardware also increases manufacturing costs in labor and component expense. Numerous required retraining sequences have also been reported with these devices.
Accordingly, it would be an advance to provide temperature compensation for communications cards while minimizing retraining sequences during periods of temperature change, especially heat build-up, within the communications card.
OBJECTS AND SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide improved temperature compensation for communications cards.
It is another object of the present invention to provide temperature compensation for communications cards that minimizes retraining sequences.
It is still another object of the present invention to provide temperature compensation for communications cards without consuming valuable board space therein.
It is yet another object of the present invention to provide economical temperature compensation for communications cards.
It is still yet another object of the present invention to provide temperature compensation for communications cards during periods of heat build-up before essentially steady-state temperature conditions are achieved.
In accordance with the invention as embodied and broadly described herein, the foregoing and other objectives are achieved by methods and apparatus that provide temperature compensation for communications cards, such as a modem or network card, to minimize retrain sequences between the communications card and another communications card during periods of heat build-up within the communications card. It is a feature of the invention to provide this temperature compensation regardless of the speed or temperature of arriving at a steady state temperature and regardless of the make of the communications card, host computer or computing temperature environment under examination.
In a preferred embodiment, a keyword between the communications card and a host computer is compared to provide unique heat compensation for these two devices that have generally different, but consistent, heating characteristics. If the keywords do not match, a plurality of original parameters are developed for the two devices in accordance with their heating characteristics. Later, this enables a faster compensation during periods of heat build-up. If the keywords match, this indicates that a set of original parameters have previously been developed, from which a plurality of initial parameters are set.
Thereafter, a temperature is monitored within the communications card so that whenever the monitored temperature exceeds a preselected threshold, temperature based adjustments occur. Preferably, the adjustments are additions of delta values to filter coefficients set for a DSP in a modem communications card. Preferably, the delta values correspond to a preselected temperature range and are stored in a look-up table in a fast storage device to minimize the time required to make adjustments from one temperature range to the next. This compensates for heat or temperature change in a fast manner, from which, the retraining sequences between the communications card and the another communications card is minimized. Character throughput therebetween is also improved.
In one embodiment, heat or temperature is sensed by a thermistor and provided to a codec or an A/D converter. The codec or A/D converter communicates with the DSP for retrieval of the delta values from a fast storage device whenever the temperature within the communications card exceeds some predetermined value.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
REFERENCES:
patent: 5440305 (1995-08-01), Sigmore et al.
patent: 5488638 (1996-01-01), Brown et al.
patent: 5506900 (1996-04-01), Fritz
patent: 5612677 (1997-03-01), Baudry
patent: 5809068 (1998-09-01), Johnson
patent: 5935466 (1999-08-01), Knudsen
Giles Rick
Tengan Curtis
3Com Corporation
Chin Stephen
Ha Dac V.
Workman & Nydegger & Seeley
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