WO1999052284A1

WO1999052284A1 - Method and apparatus for providing elapsed time indicators in electronic devices

Info

Publication number: WO1999052284A1
Application number: PCT/US1999/007683
Authority: WO
Inventors: Andrew G. Drexler
Original assignee: Scientific-Atlanta, Inc.
Priority date: 1998-04-07
Filing date: 1999-04-06
Publication date: 1999-10-14

Abstract

A communication system (100), such as a cable television system, having electronic devices includes at least one device (200) that records an elapsed time value indicative of a time during which the device (200) has been operational. The device (200) includes a processor (205) for controlling operations of the device (200) and a memory (220) into which the elapsed time value is periodically recorded by the processor (205).

Description

METHOD AND APPARATUS FOR PROVIDING ELAPSED TIME INDICATORS IN

ELECTRONIC DEVICES

INVENTORS: Andrew G. Drexler

FIELD OF THE INVENTION

This invention relates generally to time recording mechanisms, and more specifically to time recordings by electronic devices.

BACKGROUND OF THE INVENTION

Communication systems, such as cable television systems, include a variety of different types of electronic devices. For instance, cable television systems typically include a headend that may be installed in a populated facility. The headend transmits signals that are routed away from the facility to subscriber residences and businesses. The transmission equipment often includes hubs for splitting signals, nodes for converting optical signals to radio frequency (RF) signals, amplifiers for amplifying the signals, and taps for splitting off the signals to provide subscriber drops. Failure rates for these electronic devices are often not easy to determine due to a lack of reliable data and the variety of methods used to calculate such failure rates. In particular, the date from which such devices are considered active is subject to interpretation. By way of example, the supplier and/or customer could consider the active date of a particular shipment of devices to be the ship date, the receive date, the date on which a particular shipment is removed from storage, the installation date, etc. Field failure rates are then determined from this date, and such failure rates are often used for deciding warranty costs, price estimates, estimation of penalties, and other commercial decisions.

Thus, what is needed is a more accurate and uniform way to determine dates associated with installation and failure of electronic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a communication system, such as a cable television system, according to the present invention.

FIG. 2 is an electrical block diagram of an electronic device included within the communication system of FIG. 1 according to the present invention. FIG. 3 is a flowchart illustrating an operation of a processor included within the electronic device of FIG. 2 according to the present invention.

FIG. 4 is a flowchart illustrating another operation of the processor in accordance with the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 is a block diagram of a communication system, such as a cable television system 100, including a plurality of devices, some of which include processing capability. More specifically, when the communication system comprises a cable television system 100, the system 100 includes a headend 105 for receiving satellite signals, demodulating the signals down to baseband, then retransmitting the signals to subscriber equipment located at subscriber residences and businesses. The headend 105 can, for instance, transmit optical signals over fiber optic cable 110 to a node 1 15 located in the field for converting the optical signals to radio frequency (RF) signals. The radio frequency signals are further transmitted over coaxial cable 120 to additional remote equipment, such as taps 125 for splitting off the signal to provide subscriber drops and amplifiers 130 for amplifying the signal for even further transmission throughout the system 100. Subscriber equipment, such as set top terminals 135, coupled to the taps 125 provide cable television service to subscribers. Failure rates for devices included within the system 100 can vary, and the methods for determining such failure rates can also vary. As mentioned briefly hereinabove in the Background of the Invention, failure rates of a type of device are often relevant in determining device price, warranty provisions, contract penalties, and other failure-related commercial and design factors. Therefore, an accurate and uniform determination of device failure rates is important to manufacturers, distributors, and customers. However, conventionally, failure rates of the device are determined in a variety of ways and from a variety of dates, such as installation date, ship date, receive date, etc., which has led to confusion and dispute.

Devices according to the present invention, on the other hand, include an elapsed time indicator for accurately recording an elapsed time during which the device has actually been operational. As a result, determination of a time before the device has failed, and thus of failure rate, is possible with much greater accuracy and certainty. Furthermore, as will be discussed in greater detail below, such an elapsed time indicator can be done inexpensively and, in most cases, without the addition of further hardware as long as the device has processing and storage capability. With reference to the communication system of FIG. 1, most, if not all, of the headend equipment 105, taps 125, terminals 135, and other system devices can include the elapsed time indicator of the present invention.

Referring next to FIG. 2, an electrical block diagram of an electronic device 200 including an elapsed time indicator is shown. The device 200 comprises a processor 205 for controlling operations of the device 200, a clock 210 for providing current time values, a port 230 for receiving power for powering the device 200, and storage capabilities. More specifically, the device 200 can include an operational memory 225, such as a random access memory, for storing device parameters, including a programmed time value. Another memory, i.e., an elapsed time memory 220, can be included for storing elapsed time values. Preferably, the elapsed time memory 220 is a non-volatile memory or other type of memory that retains information in the absence of power. Alternatively, the elapsed time memory 220 could be coupled to an optional backup battery or other power source for powering the elapsed time memory 220 even once the device 200 has failed.

FIG. 3 is a flowchart illustrating an operation of the processor 205 included in the device 200. The processor 205, at step 305, receives a current time value from the clock 210, which could be a real-time clock or could provide values that are converted to real time values in a known manner. The processor 205 then, at step 310, references the programmed time value that is stored in the operational memory 225. When, at step 315, a comparison of the programmed time value and the current time value with a last stored elapsed time value, if any, reveals that a predetermined amount of time has passed, the processor 205, at step 320, writes the current time value into the elapsed time memory 220. For instance, during normal operation, the processor 205 could, at step 315, determine whether the current time value minus the last recorded elapsed time value is greater than or equal to the programmed time value. If so, the predetermined amount of time has elapsed, and the current time value is written, at step 320, into the elapsed time memory 220. In such a situation, the current time value can overwrite the previously stored elapsed time value to function as the new elapsed time value, or a succession of time values could be recorded in the elapsed time memory 220.

As mentioned, the device 200 according to the present invention provides an elapsed time indicator in a convenient and relatively inexpensive manner as compared to similar prior art devices. Such prior art devices that record operational time must include sufficient capacitance on the microprocessor board to allow the microprocessor to complete a shut down routine and store time-to- failure data, and insufficient capacitance can prevent the storage of any time whatsoever. Alternatively, prior art devices can include a method to warn the microprocessor of impending loss of power and a device, such as a capacitor, to provide power for a long enough period to permit recording of a time in memory. These prior art devices require additional hardware, such as capacitors, watch-dog timers, and voltage and current sensors, that can prohibitively increase the cost and complexity of such devices. Furthermore, the prior art methods may be undependable since unexpected power losses or failures and insufficient stored power can lead to the absence of any recorded time at all.

Upon first operation of the device 200, the elapsed time indicator process could be initiated in several ways. For instance, the elapsed time memory 220 could be preset with a time value equivalent to zero, in which case the flowchart of FIG. 3 would provide functionality to record a first elapsed time as soon as the time period indicated by the programmed time value had passed. Alternatively, the processor 205 could be programmed to record, immediately upon power up, the current time value into the elapsed time memory 220, after which the procedure set forth in FIG. 3 could be followed.

The programmed time value is preferably indicative of a period of time, such as an hour, a day, a week, etc., passage of which triggers recording of a new time value in the elapsed time memory 220. The programmed time value could, for example, be preset by the manufacturer of the memory 220 or the device 200, or the programmed time value could be a customer- programmable value. In either case, as long as the device 200 is operational, a new elapsed time value is written into the elapsed time memory 220 every time the time period indicated by the programmed time value has elapsed. If the device 200 fails in a manner that prevents correct operation, further recordings of elapsed time will not occur. Therefore, a technician can access the elapsed time memory 220 to read the most recent (or the only) recorded elapsed time value. This value will conveniently provide an accurate indication of the amount of the time that the device 200 has actually been operational. As a result, failure rates for the particular type of device 200 can be determined based upon accurate and uniform information, thereby avoiding disputes that could otherwise arise.

Referring next to FIG. 4, a flowchart illustrates an operation of the processor 205 for an embodiment of the present invention in which the clock 210 produces pulses of a given frequency. According to this embodiment, the processor 205 receives and counts, at step 405, clock pulses from the clock 210. The processor 205 also references, at step 410, a programmed number of pulses stored in the operational memory 225. When, at step 415, the number of clock pulses is equivalent (or greater) than the programmed number, the elapsed time value stored in the elapsed time memory 220 is incremented, at step 420. Thereafter, the clock pulse counter function of the processor 205 is reset, at step 425, and operation again begins at step 405. As illustrated by the process of FIG. 4, there are numerous ways to perform the counting/clock function of the present invention. For example, the clock 210 can, as mentioned, generate pulses of a predetermined frequency. When the programmed time value is equivalent to a programmed number of pulses, the processor 205 may not need to make any conversions to determine that the time for writing into the elapsed time memory 220 has arrived. If, on the other hand, the programmed time value is a real time value, e.g., twenty-four hours, the processor 205 can easily convert the number of clock pulses to a real time value given its known frequency. By converting the number of clock pulses, when necessary, to real time values, the processor 205 can also write a real time value into the elapsed time memory 220. However, it will be appreciated that any method of indicating operational time can be used. For instance, the elapsed time indicator 220 could merely be a counter that is incremented by a predetermined value each time the processor 205 performs the write operation. In such a situation, a technician or even equipment could perform a conversion of the elapsed time memory counter value to a real time value in the event of a device failure. It will further be understood that methods of "counting" can vary as well. When, for instance, the clock 210 outputs real time values, the processor 205 need only monitor the real time values as compared to a programmed real time value. Alternatively, an internal or external counter (not shown) could be incremented at each clock pulse until the number of clock pulses equals a programmed number or is equivalent to a programmed real time value. Any method or embodiment is acceptable as long as the processor 205 functions to periodically write into the elapsed time memory 220 a value by which an operational time of the device 200 can be determined.

It will be appreciated that the elapsed time indicator of the present invention can be included in any device that has processing and storage capabilities. As a result, implementation in devices that are included in many existing communication systems, such as cable television systems, is easy and inexpensive.

What is claimed is:

Claims

1. A device for recording operational time thereof, the device including: a memory for storing an elapsed time value; and a processor for recording the elapsed time value in the memory, the elapsed time value indicating an elapsed time from a time at which the processor became operational.

2. The device of claim 1, further comprising: a clock coupled to the processor for providing current time values.

3. The device of claim 1, wherein the memory is a non-volatile memory device.

4. The device of claim 1, further comprising a port for receiving power for powering the device.

5. The device of claim 2, wherein the memory comprises a counter, and wherein the clock provides pulses at a particular frequency.

6. The device of claim 1, wherein the memory comprises an elapsed time memory, and wherein the device further comprises an operational memory for storing device parameters.

7. The device of claim 6, wherein the operational memory further stores a programmed time value indicative of a time period, expiration of which triggers recording of the elapsed time value in the elapsed time memory by the processor.

8. The device of claim 1, wherein the device is included within a communication system.

9. The device of claim 1, wherein the device is included within a cable television system.

10. A communication system including remote devices, the communication system comprising: a device for recording an elapsed time value indicative of a time during which the device has been operational.

1 1. The communication system of claim 10, wherein the device comprises: a memory for storing the elapsed time value; and a processor for recording the elapsed time value in the memory.

12. The communication system of claim 1 1 , further comprises: a clock coupled to the processor for providing current time values.

13. The communication system of claim 12, wherein the memory is a non-volatile memory.

14. The communication system of claim 12, wherein the memory is a volatile memory, and wherein the device further comprises a backup battery coupled to the volatile memory.

15. The communication system of claim 12, wherein the memory comprises an elapsed time memory, and wherein the device further comprises an operational memory for storing device parameters.

16. The communication system of claim 15, wherein the operational memory further stores a programmed time value indicative of a time period, expiration of which triggers recording of the elapsed time value in the elapsed time memory by the processor.

17. The communication system of claim 10, wherein the communication system comprises a cable television system.

18. A method, in a device having a processor and a memory, for recording an elapsed time indicative of a time during which the device has been operational, the method comprising the steps of: storing a first elapsed time in the memory; determining that a predetermined amount of time has passed; and storing a second elapsed time in the memory.

19. The method of claim 18, wherein the determining step comprises the step of: referencing a programmed time value and a current time value; and determining from the programmed time value and the current time value that the predetermined amount of time has passed since storing the first elapsed time value.

20. The method of claim 18, wherein the step of storing the second elapsed time comprises the step of: overwriting the first elapsed time with the second elapsed time.

21. The method of claim 18, wherein the determining step and the storing steps are performed by the processor.

22. The method of claim 18, wherein the step of storing the first elapsed time occurs in response to the step of: receiving power to enable the processor of the device.