Note: Descriptions are shown in the official language in which they were submitted.
A METHOD FOR AUTOMATICALLY UPDATING A PERSONAL COMPUTER
SYSTEM TIME CLOCK OVER A TELEPHONE LINE
FIELD OF THE INVENTION
The present invention relates to a personal com-
puters time management syctem, more particularly, to amethod of automatically updating of the PC system time
clock when an incoming telephone call i5 received.
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BACKGROUND OF THE INVENTION
Most of today's computers have built in real-time
clocks. By using a battery, these clocks keep time even
while the computer is turned off. Although these clocks
are stable, they are generally not very accurate. Thus,
the user must regularly update the time of the clock.
One present way to insure the accuracy o~ the local
PC clock requires an expensive time broadcast receiver PC
card. This card contains a time broadcast receiver for
receiving a radio signal. The radio signal contains time
information that the card decodes and synchronizes the
local cloc~. This system has two primary disadvantages.
First, the high cost of the time broadcast receiver PC
card. Second, the need for proper reception of the radio
wave usually including an antenna system.
The clock maintained by the telephone company is
extremely accurate. Until recently, the only way for the
public to receive the local telephone company ti~le was to
call the "time" number and listen to the time. The
listener then must enter the new time into the computer.
Obviously, there is a time lag between listening to the
time and entering the time into the computer. Errors in
entry are also possible.
With calling number identification (CID) service,
Frequency Shift Keying (FSK) data is sent over the phone
lines to the telephone service customer. The telephone
system time stamps the FSK data as it is sent out. The
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present invention uses this information to update the PC
clock.
Prior to the present invention, no inexpensive means
to automatically keep the system clock in a personal com-
puter (PC) synchroni2ed with the real local time existed.
Therefore, it is the objective of the present invention
to provide a technique to cause the automatic updating of
the PC system time clock when an incoming FSK data stream
occurs on the telephone line to which the accessory card
is attached.
SUMMARY OF THE INVENTION
In order to accomplish the objective of the present
invention there is provided a method for automatically
updating a local clock on a personal computer when a
ringing signal is received. This method uses the highly
accurate time stamp sent by the local phone company in
FSK data streams such as the calling number identifica-
tion (CID) data stream to automatically cause the PC
system clock to be updated each time an FSK data stream
containing a local data and time field occurs on the
attached line. The telephone system transmits a data
packet to the personal computer immediately after ringing
the telephone. Data in the data packet represents the
time of the telephone system's clock when the data packet
was sent. This data, after being received by the PC, is
decoded and then used to update the PC clock. Finally, a
user interface is provided that allows the user to enable
or disable the automatic updating of the PC clock.
DESCRIPTION OF THE DRAWINGS
A better understanding of the invention may be had
from the consideration of the following detailed descrip-
tion taken in conjunction with the accompanying drawings,
in which:
FIG. 1 is a system block diagram of the card's rela-
tionship to the host PC, external power supply, incoming
telephone line and extension telephones.
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~ FIG. 2 is a dlagram showing the hardware aspects of
the accessory card.
FIG. 3 is a screen image of the clock setup
function.
FIG. 4 is a flow chart of the sequence of events
that occur when an incoming call occurs accompanied by a
calling number ID data stream~
FIG. 5 is a diagram showing the format of a Single
Data Message CID data stream.
FIG. 6 shows the actual content of a sample packet
for a Single Data Message CID data stream.
FIG. 7 is a diagram showing the format of a Multiple
Message CID data stream.
DESCRIPTION OF TH~ PREFERRED EMBODIMENT
The present invention is part of a hardware and
software package that comprises a complete single-line
call management system. The hardware, as shown in figure
1, consists of a PC card. Generally, the environment is
a personal computer with monitor, keyboard, and mouse
101, the card 102, and standard telephone line with some
type of FSK data service 103.
Referring to figure 2, the interfaces to the card
` consist of a PC Interface 201 for connecting to the host
PC. A telephone line interface 208 connection. DC
isolation and lightning/power cross protection are pro-
vided for by the ~elephone line interface 208. An exter-
nal power source not shown in figure 2, is locally regu-
lated on the card and a well-defined power-on-reset sig-
nal is generated to reset the card's own microprocessor
at initial power-up. The portion of the cardls circuitry
that deals with interfacing to the PC 201 receives 5~
power (VCC-PC) from the PC and is not powered when the PC
is off.
The analog portion of the card 206, 207 and 209 con-
tains an off hook sensing circuit to determine telephoneline status, a DTMF generator and decoder, and an FSK
Bell 103 type modem to receive and decode the calling
number data. The digital portion of the card 202, 203,
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3 3
~04~ and 205 contains the microprocessor, RAM, ROM and
Phone interface receptively. Alternatively, Phone inter-
face 205 could hook directly to the PC via a serial port
or directly to the PC bus.
The present invention distinguishes this system from
existing FSK reception devices in that it provides a
method for updating the system clock of the PC by using
the time and date information contained in frequency
shift keying data strings sent by the telephone company.
This invention provides a very convenient and inexpensive
way to keep the PC system clock synchronized to local
time. The standard FSK string contains the month, day,
hour and minute corresponding to local time at the in-
stant the FSK string is sent from the telephone company
switching equipment. Assuming an incoming call occurs on
the attached line once a week and the automatic system
time update feature is enabled, the PC system time should
remain accurate to within a few seconds. This assumes
the accuracy of most personal computing devices at the
time of this patent application's writing.
First an overview will be given, followed by a more
detailed description. Referring first to figure 3, a
user interface on the PC allows the user to enabled this
feature. Assuming the feature is enabled as shown in
figure 3, the device will use incoming FSK data as a ref-
erence for updating the system clock of the PC. When the
device detects an incoming call with an accompanying FSK
data stream, it passes the FSK data on to the associated
PC software. The associated PC software reads the cur-
rent time and date contained in the FSK data. Next, thePC software updates the PC system clock to match the FSK
date and time sent from the telephone company.
Referring to figure 4, a flow chart showing the
logical execution of the PC software as it relates to
updating the PC system time is shown. When an incoming
call or other FSK event occurs 301, the FSK information
is collected by the accessory card and passed to the PC
port 302. After receiving the FSK information, the PC
software checks if the auto system time update feature
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has been enabled 303. If so, ~ tware uses the
time and date stamp included in the FSK string to update
(reset) the PC sys-tem clock 304. Processing then returns
to the calling point to continue processing o-ther infor-
mation contained in the FSK string 305.
Figure 5 shows the format of an FSK Calling Number
Identification (CID) string sent from the phone company
to the customer's equipment. This figure shows the
single message format CID data string as specified in the
Bellcore Technical Advisory, TA-NWT-000030 "SPCS-to-CPE
Data Transmitter Generic Requirements". Figure 6 gives a
more detailed description of the format of figure 5. In
figure 6, an e~ample data packet for "March 21; 2:05 PM;
Calling Number: ~914) 555-1234" is shown.
Figure 7 shows another format for CID data. This
figure shows the multiple message format CID data string
also specified in the Bellcore Technical Advisory, TA-
NWT-0000300 In the multiple message format, the date and
time are contained under a separate parameter specified
as parameter type 01 Hex.
An alternate embodiment allows the telephone system
to update a standalone clock. This embodiment replaces
the PC clock with a regular human readable clock. The
operation is similar to that of the PC embodiment with
some differences. The primary difference being that the
clock module must receive the information from the tele-
phone system and then update the local time of the time
module.
Although the preferred embodiment of the invention
has been illustrated, and that form described, it is
readily apparent to those skilled in the art that various
modifications may be made therein without departing from
the spirit of the invention or from the scope of the
appended claims.
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