Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CM00485J
PRIORITIZATION OF STORED MESSAGES IN A
DIGITAL VOICE PAGING RECEIVER
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to paging
receivers, and more particularly, to a paging
receiver Por receiving information including analog
voice messages, digitizing the analog voice messages
and storing the voice messages in a memory for
playback.
2. Background of the Invention
Communications systems in general and
paging systems in particular using transmitted call
signals have attained widespread use for calling
selected receivers to transmit information from a
base station transmitter to the receivers. Modern
paging systems and paging receivers in particular
Aave achieved multifunction capabilities through the
use of microcomputers which allow the paging
receiver to respond to information having various
combinations of tone, tone and voice, or data
messages. This information is transmitted using any
number of paging coding schemes and message formats.
In the operation of such paging receivers,
important factors involved in their successful
operation is the portability of the receiver, the
limited energy available for the receiver, the
limited availability of the radio spectrum, the fast
response time required in today's active society,
and the number of paging receivers included in the
paging system. In such paging receivers, in order
that the drain on the battery may be minimized, the
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paging receiver is systematically turned off and
turned on to maximize the length of time energy is
available from the battery (battery saving). The
limited energy in which the paging receiver must
operate constrains the type of electronic circuitry
available for a paging receiver.
A typical voice type paging system uses analog
voice channels ~or the transmission and reception o~
voice messages. While certain types of paging
systems use binary signalling formats, transmission
in an analog form remains the most common technique
for voice signals. Prior art paging receivers that
receive analog representation of voice signals are
limited in several features that would be highly
desirable. These include the ability to store a
voice message in a reasonable size memory ~or recall
at a later time and the use of digital modulation
techniques to store and reconstruct voice messages
in the paging receiver. Digital processing of voice
messages is, in general, qualitatively superior to
analog processing for high sample rates. This is a
result of the fact that once the voice message is in
a digitally-represented ~orm, it is not subject to
the type of signal degradation that occurs in analog
processing. Thus, it is beneficial to represent the
voice message in digital form rather than as a
voltage subject to the type of distortion inherent
in analog processing techniques.
Problems with prior art analog voice paging
receivers include the ability to store a plurality
of voice messages, prioritize the voice messages,
and selectively recall~a voice message. Prior art
analog voice paging receivers have typically stored
the voice information on conventional analog
magnetic tapes (e.g. U.S. Patent Number 4,356,519).
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While such voice type paging receivers are
available, they ars typically commercially
unfeasible. Some of the reasons are the cost of the
electronic components, the low battery life from the
high drain of current required by the tape
mechanism, and the difficulty in operating in a
battery saving environment. Additionally, if a
sequence of messages is stored on the tape, the
recall o~ a single message is hampered by the
inability of the analog magnetic tape to randomly
select a single message.
A particular problem with stored voice paging
receivers is the situation in which the paging
microcomputer's memory is full and a message
received or previously stored is lost because of the
lack of memory available to store the message.
Therefore, it would be highly desirable to have a
stored voice paging receiver which prioritizes the
message~ in which higher priority messages are saved
at the destruction of lower priority messages.
SUMMARY OF THE INVENTION
It is therefore an object of the present
invention to overcome the problems of the prior art
analog voice paging receivers by providing a voice
paging receiver with stored digitized voice.
It is another object of the present invention
to provide a digital stored voice paging receiver
capable of receiving, digitizing, prioritizing, and
storing a plurality of voice messages for later
recall.
It is ~nother object o~ the present invention
to provide a digitized stored voice paging receiver
that selectively protects specified stored voice
messages at the expense of unprotected stored voice
messages.
~862~3
These as well as other objects and advantageous
features of the present invention will be apparent
and in part pointed out here after.
In general, a communication receiver, such as a
paging receiver for receiving analog information,
the information having at least one voice message,
includes a receiving means, a decoding mean~, a
memory means, and a conversion means. The receiving
and decoding means receives information signals,
including at least one voice message and control
sign~ls, decodes the information signals for
selectively enabling a receiver correlating to the
received control information, and decodes tha
information to recover the voice message. The
conversion means converts the analog voice
information to digital information, the digital
information being representative of a replica of the
analog voice message. The digital information is
then stored according to a predetermined priority
scheme in a memory of the selected receiver. In
response to user generated inputs, the paging
receiver selects a digitized voice message stored in
the memory of the receiver, reconverts the digitized
voice to an analog signal, and produces audible
voice information from the analog signal
representative of the original analog voice message.
In particular, the paging receiver system and
m`ethod of the present invention stores digitized
voice messages according to a predetermined priority
scheme. Specifically, a stored message is
associated with a status value, the status value
indicative of importance to the paging receiver
user. The method scans previously stored messages
and selectively stores new messages according to the
priority scheme, destroying less important messages
in sake of saving more important messages.
~2~2~
BRIEF DESCRIPTION OF THE DRAWINGS
_
For the purpose of illustrating the invention,
there is shown in the drawings an embodiment which
is presently preferred, it being understood,
however, that the invention is not limited to the
precise arrangement and instrumentality shown.
FIG. 1 is a schematic diagram of a digitized
stored voice paging receiver embodying the present
invention.
FIG. 2 illustrates a plurality of messages in a
message queue.
FIG. 3 is a detailed flow chart illustrating a
method of the present invention for chronological
replacing messages.
FIG. 4 is a flow chart illustrating the record
routine of the method of FIG. 3.
FIG. 5 is a flow chart showing the play routine
o~ the method of FIG. 3.
FIG. ~ illustrates a plurality of messages in a
message queue useful in explaining a method for
protecting messages according to a priority scheme.
FIG. 7 is a flow chart for storing messages
according to a predetermined priority scheme.
FIG. 8 is a flow chart of the method of FIG. 7
for storing the new digitized voice message to a
memory position according to a predetPrmined
priority scheme.
FIG. 9 illustrates the play routine for the
method of FIG. 7.
DETAILED DESC IPTION OF THE PREFERRED EMBODIMENT
In order to best illustrate the utility of the
present invention, it is described in conjunction
with a communication receiver, such as a paging
receiver, capable of receiving, decoding, and
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storing transmitted analog or voice information. While
the present invention is described hereinafter with
particular reference ot a paging receiver, it is to be
understood at the outset of the description which follows
it is contemplated that the apparatus and methods, in
accordance with the present invention, may be used with
numerous other communication receiving systems.
The paging receiver system described herein is
associated with a paging system having a base station
terminal, responds to coded data information from the
base station terminal, and in turn, decodes, digitizes,
stores, and provides analog or voice messages to a user
during operation. With reference to the drawings in
general, there is illustrated a paging receiver 10 and a
method for receiving, decoding, digitizing and storing
voice messages transmitted from the base station
terminal. A detailed description of a paging receiver
capable of performing the operations as discussed with
reference to FIGS. 2-9 is disclosed in copending
application entitled "Digitized Stored Voice Paging
Receiver Having Single Input User Control", filed even
date herewith, having Canadian serial number 564,693.
Briefly, FIG. 1 shows a ~unctional block
diagram of a paging receiver of the present invention.
~5 The paging receiver 10 of the present invention includes
a receiving means 12, a decoding means 14, a memory means
50, a support module 40, an input switch module 42, a
voltage conversion means 20, and a converting means 38.
An antenna 24 receives paging information including
receiver control signals and analog information including
speech signals representative of a voice message.
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The antenna 24 is coupled to receiving means 12 that
is subject to the control of decoder 14. The
decoder 14 not only controls receiving means 12, but
may also operate receiving means 12 on an
intermittent basis to extend the life of battery 16
through voltage conversion means 20. The recsiving
means 12 detects the presence of electromagnetic
energy representing the paging information and
applies the information to the converting means such
as coder-decoder 38. The coder-decoder 38 converts
the received analog signals, such as real time audio
speech signals, to a stream of binary bits and
reconverts stored binary bits to a replica of the
original received analog signals, such as
synthesized audio speech signals.
In the illustrated embodiment, the coder-
decoder 38 (hereinafter referred to as CODEC)
provides for the digital-to-analog and analog-to-
digital conversion of speech signals. The CODEC 38,
such as an adaptive delta modulator, can convert or
encode an audio input signal to a digital data
stream for storage and reconvert or decode a digital
data stream to reconstruct an audio signal. In
particular, the CODEC 38 monitors the real time
audio signal on line 44 and compares it to a past
value that it has reconstructed and generates a
digital bit (sign) that indicates whether the
reconstructed signal's voltage level is higher or
lower than the present input value. The CODEC 38
then tries to adapt the reconstructed signal voltage
to mirror the present value at the audio input by
varying or modulating a current. The current
charges or discharges a capacitor (not shown) which
changes the reconstructed signal's voltage. The
digital output on line 46 is the sign bit which
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indicates whether the reconstructed signal is behind
the input or lower in voltage (logic NO/~) or ahead
of the input or higher in voltage (logic ~1~). The
CODEC's digital output is stored in memory 50 and
retrieved on line 48 to reconstruct a synthesized
audio signal on line 21, thus closely replicating
the real time audio signal in both amplitude and
frequency. One example of such a coder-decoder is
disclosed by N.S. Jayant in the publication
~Adaptive Delta Modulation with a One-Bit Memory~,
Bell System Technical Journal, Vol. 49, No. 2, March
1970. The CODEC 38 is designed to operate at
sampling rates (bit or clock rates~ of 1~ KHz, 25
KHz, and 33 KHz. The obvious implication of the
three rates is that for slower clock rates, longer
messages can be stored in a fixed amount of memory
at the expense of a lower signal to noise (S/N)
ratio. For example, at a 100 mV P-P 1 KHz signal at
the input, the signal to noise degradation is 11 dB
at 33 KHz, 14 dB at 25 RHz, and 23 dB at 16 KHz.
To conserve power, most of the CODEC 38 is
turned off when there are no read/write operations
to the memory. The output buffers and control logic
are always on since it may be necessary to monitor
the channel or provide a BEEP tone when there are no
messages stored. Keeping the buffers and control
logic on also eliminates the need for additional
current source controls to handle the switching of
an additional current source.
The receiving means 12 is further coupled by
line 23 to a support module 40. Operating in
response to decoder 14, the real time audio signal
on line 23 is applied to support module 40 which
supplies analog or digital signals to one of
annunciation transducers 32-36. In particular,
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decoder 14 controls support module 40 to apply
either the real time audio signal on line 23 or the
synthesized audio signal on line 21 to speaker 36.
~n practice, lines 21 and 23 may be a single line.
S Decoder 14 is associated with memory means 50
which serves to include information for decodiny the
received information and for storing information
received from CODEC 38. The CODEC 38 provides the
analog-to-digital conversion of speech signals on
line 46 which are stored in memory 50 as digital
voice messages. A plurality of digital voice
messages can be stored in memory 50 along with the
status of each voice messaga. For example, a voice
message may have either a read or unread status.
The decoder 14 also functions to alert the paging
user, store, recall, and playback voice messages.
The paging receiving of FIG. 1 has the
capability of storing selective call voice messages
for providing them to support module 40 according to
the state of a plurality of inputs, such as the
statP of the control switches of input module 42. A
switch interface 18 provides input capability for
control switches 54-60. Illustratively, control
switch 54 is an on/off switch for controlling power
from battery 16. Control input 55 is a volume
control for speaker 36. Control switch 56 is a play
~witch for playing back voice messages previously
digitized and stored in memory 500 Control switch
58 is a reset switch to reset the paging receiver
system and monitor the real time audio signal.
Control switch 60 is a mode switch for operating the
decoder in one of three modes. These modes are the
silent, push to listen (PTL), and normal modes.
Considering FIG. 1 in somewhat further detail,
the battery 16 is shown connected to decoder 14
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through a switch interface 18. Battery 16 provides
power to decoder 14 through a voltage conservation
means 20, such as a DC to DC converter. Decoder 14
is additionally connected to a code memory 22
further including regions designated function select
and pager ID. The enclosure of code memory 22 with
a broken line indicates a possibility that such a
device can be made removable and therefora separable
from the rest of the system. Another output 62 of
decoder 14 is coupled to support module 40 to
provide the necessary controls for generating alerts
on one of alert transducers 32-36. The alert
transducers may take the form of an illumination
means 32 and 33, such as an LED, a vibration motor
34, a visible display counter 3S, and an audio
speaker 36. Output 62 also controls whether real
time audio signals on line 23 from receiving means
12 or synthesized audio signals on line 21 from
CODEC 38 are applied to audio speaker 36.
It is to be understood that decoder 14 may
function entirely by a microsequencer or
microcomputer 26. Microcomputer 26 is shown to be
further comprised o~ a microprocessor 28 and a read
only memory (ROM~ 30. The ROM 30 includes the
necessary instructions to operate microprocessor 28
to perform the functions as described in FIGS. 2-9.
The operation of the paging receiver shown in
FIG. 1 is such that the receiving means 12 is
capable of receiving messages in any of several
message ~ormats through an antenna 24. The decoder
14 responds to the receive signals to analyze the
data and select one of several decoding schemes for
appropriately decoding the incoming information
received by receiving means 12. As with all paging
devices, the resulting decoded signal is tested for
6Z~
comparison with a designated pager address contained
in code memory 22. On detecting correspondence
betwePn the received and decoded signal and the
address in code memory 22, the decoder instructs the
CODEC 38 to digitize the real time analog signal and
provide the digitized signal to the decoder 14 for
storage in one of a plurality of message locations
or slots in memory 50. An alert output signal is
produced by the decoder 14 to generate an alert
indicating to the pager user that a message has been
received and stored. In particular, the alert
output signal from the decoder 14 is supplied to
support module 40 to produce a signal on one of a
plurality of transducers 3~-36 indicative of the
receipt of the message. Specifically, upon the
receipt of a messa~e, an unread message indicator 32
is activated and an unread message counter 35 is
incremented. Additionally, if all message slots are
full, a memory full indicator 33 is activated.
Table 1 illustrates the number of messages that
can be stored in the paging receiver using
particular confiyurations of memory when the CODEC
is operating at a specific bit rate. Even though
the table lists specific memories, it is to be
understood that numerous other memories can be used
in the practice of the present invention.
Continuing with the above described table, referring
to the 1 megabyte CMOS DRAM, if the paging receiver
is configured for two messages and the CODEC is
operating at 25 kilobytes per second (KBPS), Table 1
illustrates that 20 seconds of voice information can
be stored in one message slot. ~s is evident from
Table 1, the CODEC operates in a plurality of
operating rates such as 16 KBPS per secondl 25 KBPS
per second, and 32 XBPS per second. The operating
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rates can be selected by jumper connections within
the paging receiver or by switches external to the
paging receiver.
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Table 1
Message Length as a Function of Bit Rate
and Memory Size
One 256R CMOS DR~M
Number of
Messages 16 KbPS25 KbPS32 :KbPS
1 16 second10 second8 second
2 8 second5 second 4 second
T~o 256~ CMOS DRAMs
Number of
Messaqes16 KbPS 25 KhPS 32 KbPS
10 1 32 second 20 second16 second
2 16 second 10 second 8 second
4 8 second 5 second ~ second
One 1 Meg CMOS ~RA~
Number of
Messages16 KbPS 25 KbPS 32 XbPS
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1 64 second 40 second32 second
2 32 second 20 second16 second
4 16 second 10 second 8 second
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The following flow charts refer to the
operation of microprocessor 28. The programs are
stored in ROM 30 in a predetermined sequence to
cause the operation of the microprocessor 28 for
storing, protecting, and reading the messages in
accordanoe with the following flow charts. Other
routines for the operation of the paging receiver
are included in the ROM, however, the routines are
not described herein since they are not needed for
the understanding of the invention.
FIGS. 2-5 relate to a method for storing and
retrieving messages in a chronological order without
regard to the status value of a message. FIGS. 6~9
relate to a method for storing and retrieving
messages according to a predetermined priority
scheme, depending on status value and order of
receipt. For FIGS. 6-9, the status values of the
messages illustratively take the form of unread,
read, and empty, with unread having the highest
priority (thus last to be destroyed). It is
understood, however, that other status values may be
used and the above ussd status values are not to be
construed as limiting either the scope of the
invention or the scope of the disclosure.
Re~erring to FIG. 2, there is shown an
illustrated example of the plurality of message
slots in the digital stored voice paging receiver of
the present invention. For purposes of
illustration, four message slots are shown.
However, it is to be understood that more than four
message slots or as ~ew as two can be used with the
paging receiver of the present invention, the number
of message slots being limited only by the size of
memory.
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For clarity, the address of each message slot
is labelled A, B, C, and D. Considering the
example, then, message slot two (2) is associated
with address "Bn. Also associated with each message
slot is an unread/read tag which indicates whether
the message is unread or read. Each message slot is
capable of storing a digitized voice message for a
time period, depending on the size of memory and
number of message slots as explained with reference
to Table 1. To illustrate two sample messages, FIG.
2 shows a read digitized voice message "CALL KEN AT
11:00n occupying address ~A" and an unread digitized
voice message nCALL CLAUDINE AT 4: 30 PM~ occupying
address ~B~.
To explain the method of chronologically
playing back the most recent to the oldest message
and the recording over oldest to most recent
message, three address pointers (MESSAGE POINTER,
MOST RECENT MESSAGE POINTER, and PLAY POINTER) which
illustratively point to address A through D of the
four message slots example illustrated in FIG. 2 are
used. The plurality of message slots are referred
to as a message queue with address ~A~ being the
beginning of the queue and address "D" being the end
of the queue. Reference will continually be made to
FIG. 2 for explaining the flow charts of FIGS. 3-5.
In general, FIGS. 3-5 describe the method of
storing messages in a plurality of message slots and
replaying the messages in chronological order. The
messages are played in chronological order from the
most recently received message to the oldest
received message without regard to the status of the
message slots (unread versus read). The paging
receiver system achieves this capability by storing
the messagPs in the message queue in a forward
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direction, such as beginning to end, and retrieving
the messages from the queue in a reverse direction,
such as end to beginning. The position for storing
and playing in the queue are controlled by separate
pointers. ~hen a boundary of the queue is reached
by either pointer, the method sets the pointer to
the opposite end of the queue.
For purposes of illustration, the pointer~
discussed are a MESSAGE POINTER, a MOST RECENT
MESSAGE POINTER, and a PLA~ POINTER. The MESSAGE
POINTER being the storage pointer that points to the
next message slot in which a message can be stored.
If there are less messages stored than the maximum
number of slots in the message queue, the MESSAGE
POINTER points to the next empty message slot. If
- the message queue is full, the MESSAGE POINTER
points to the oldest message slot. The PLAY POINTER
points to the message slot to be played. The MOST
RECENT MESSAGE POINTER points to the most recent
message received to give a starting point for the
PLAY POINTER.
ln the operation of the system, the paging
receiver is initially powered up or reset, step 100.
A force reset is indicative of the microprocessor
2S being reset by user interaction or a microcontroller
when a malfunction occurs. The mPthod begins by
inikializing all ~he message slots to the read
state. The variable MAX is set to the maximum
number of m~ssage slots, stPp 102. Referring to the
above described example of FIG. 2, MAX is equal to
four. The method then sets the MESSAGE POINTER to
point to the beginning address or, in the example of
FIG. 2, address "A~ A message count being a count
of the number of messages received is initially set
to zero, step 104. The MOST RECENT MESSAGE POINTER
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which points to the address of the most recent
message is initialized to the beginning address such
as address "An, step 106~ The paging receiver then
goes into the standby state 108, waiting for
incoming information or activation of the play
switch.
If incoming information is detected, the system
is directed to the record routine. In the record
routine, the system stores the digitized voice
message in the message 510t pointed to by the
MESSAGE POINTER. Reference is made to FIG. 4 ~or a
more detailed discussion for recording the message.
IP incoming information is not detected, eventually
the play switch may be activated, step 112. If the
play switch is activated, it is determined whether
the message count is equal to zero, step 114. If
the message count is equal to zero, the play switch
has bee~ activated with no messages being received
and the system outputs a memory empty tone, step
116. The method then loops back to the standby
state 108 to wait for incoming information or ~or
activation of the play switch. Referring back to
step 114, if the message count is not equal to zero,
this implies a message has been received by the
system and stored in the message queue. The system
is then vectored to the play routine as described in
FIG. 5 to play back the message.
Referring to FIG. 4, there is shown a method
for storing messages received by incoming
information. The method begins by determining if
the message count is equal to the maximum number of
message slots. That is, have all the message slots
b~en filled. Initially, the message count is set to
zero and if the message count is less than the
maximum number, this implies an empty message slot
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is available. If the message count is less than the
maximum number of message slots, the message count
is incremented by one, step 122.
Referring back to step 120, if the message
count is equal to the MAX, then the message count is
not incremented. Thus, when the message count
reaches MAX, this indicates that a message is
contained in every slot. Therefore, upon play back,
the system recognizes that each message slot
includes a message to be played back. It is then
determined whether the MESSAGE POINTER is gr~ater
than the maximum address, step 124. If the NESSAGE
POINTER is not greater than the maximum address,
this implies that a MESSAGE POINTER queue rollover
has not occurred. A queue rollover is when a
POINTER reache~ the beginning or end of the message
queue and is then set to the bottom or top of the
queue, respectively. If a MESSAGE POINTER queue
rollover has not occurred, the ~ESSAGE POINTER is
less than or e~ual to the maximum address and the
MOST R~CENT MESSAGE POINTER is set to the address of
the next message slot available pointed to by the
MESSAGE POINTER, step 126. Also at this time, the
PLAY POINTER is set to the NOST RECENT MESSAGE
POINTER ~o permit the playing back of messages from
the most recent message. If the M~SSAGE POINTER is
yreater than the maximum addres~, then a MESSAGE
POINTER queue rollover has occurred and the MOST
RECENT MESSAGE POINTER is set to the beginning
address, step 130. Additionally, the MOST RECENT
NESSAGE POINTER is initialized to the beginning
address. The MESSAGE POINTER is then incremented to
point to the next available message slot, step 128.
Referring to our simplified example of FIG. 2,
two messayes are shown to be recorded in addresses
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NA~ and nB~. We note that the MESSAGE POINTER
points to address nc~ which is the next available
message slot. When new informa~ion is received, the
MOST RECENT MESSAOE POINTER is set equal to the
MESSAGE POINTER such as address "C", step 126. The
MESSAGE POINTER is then incremented to the next
available address, step 128. If the MESSAGE POINTER
is pointing to "E~ at step 124, then the MOST RECENT
MESSAGE POINTER and MESSAGE POINTER are set to
address ~A~.
To recapitulate, at a queue rollover, the
MESSAGE POINTER is set back to point back to address
"An. Referring back to step 124, this is
accomplished by determining if the MESSAGE POINTER
is greater than or egual to the maximum address.
Thus, if the MESSAGE POINTER has been incrsmented
beyond address ~Dn, the MESSAGE POINTER is then set
to point to the beginning address such as address
aA~. This is accomplished by setting the MESSAGE
POINTER to the beginning address and setting the
MOST RECENT MESSAGE POINTER to the beginning
address, step 130. The MESSAGE POINTER is then
incremented to the next available message slot which
would be ~B7, step 128.
Continuing with the discussion of the record
routine, if the paging receiver is in the silent
mode or PTL mode, then the message is tagged to the
~unreadN state, steps 132-134. Referring back to
step 132, if the paging receiver is in the normal
mode, then the message is tagged to the ~read~
state, step 136. Tha message is then recorded into
the slot pointed to by the MOST RECENT MESSAGE
POINTER.
Thus, in our example of FIG. 2, the new message
is stored in address "Ca which is pointed to by the
NOST RECENT MESSAGE POINTER. The system then
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continues to store the incoming information until
the amount of memory available for the slot is
reached, step 140, the timeout depending upon the
amount of memory and bit rate of the CODEC as
illustrated in Table 1. If the timeout is not
reached, recording continues and it is determined
whether there is new incoming information, step 14~.
If new information is detected before the present
message is completely stored, the system stops
recording and repeats steps 120-140 to record the
new incoming information in the next available
message slot. Eventually, the timeout for recordiny
message is reached and the system returns to the
standby state 108.
To brie~ly summarize, the record routine stores
the messages in a first direction, such as beginning
to ending, in the message queues. The record
routine first determines the next available message
slot and then stores the message in that slot.
Since there are a limited number of message slots,
when the upper limit of the message queue is
reached, the method rolls the pointers back to the
beginning of the message queue to begin storage at
the beginning of the message queue. In addition to
restarting at the beginning of the message queue,
upon receiving incoming information, the record
routine determines if the system is in the silent,
PT~ or normal mode. I~ in the PTL or silent mode,
the m~ssage slot is tagged ~unreadn~ If the system
is in the normal mode, the message is tagged ~read~.
Re~erring briefly back to FIG. 3, if the play
switch is activated and the message count is greater
than zero, then the method proceeds to the play
routine as illustrated in FIGo 5. In the play
routine, the messages ars retrieved from the message
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queue in a second direction opposite the first
direction of the record routine. The method begins
by determining if this is the last message, step
160. The last message is determined by deciding if
a tPmp count variable is e~ual to the message count.
If the system has reached step 160 from the standby
state 108, the temp count variable is zero. If the
temp count variable is zero, the message count will
be greater than zero, and the system is vectored to
step 162. It is then determined whether this is the
first message, step 162. The first message is
determined by analyzing the temp count variable. If
the temp count variable equals zero, then this is
the first message and the method proceeds to step
164. If the temp count variable is not equal to
zero, this indicates that the play switch has been
activated during the playback of the previous
message and the user desires ts hear the next
message.
Referring back to step 164, if the temp count
variable is zero, this is the first message and the
temp count variable is incremented by one.
Additionally, the message slot is tagged to ~read~.
The mPssage is then played from the position pointed
at by the PLAY POINTER, step 166. Note the PLAY
POINTER is set to the most recent address in the
record routine and that address is played back.
The method then determine~ if the message has
been played for the timeout period, step 168. If a
timeout has not occurred, then it is determined
whether the play switch has been activated during
the playing back of the message, step 170. If it
has not, then incoming information is checked, step
172. If no incoming inPormation is present, then
the system loops back to determine if a timeout has
86~0
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occurred, step 168. Thus, the system will play back
the message until a timeout or forced timeout (such
as reset switch) occurred, the play switch is
activated, or incoming in~ormation is detected. If
the play switch is not activated, nor inc~ming
information detected, the message will eventually
play in its entirety. The system then sets the temp
count variable to zero and sets the PLAY POINTER
equal to the MOST RECENT MESSAGE POINTER, step 174.
The system then returns to the standby state 108.
If the user desires to play back more than the
first message, the play switch is activated during
the playing of the present message, step 170. In
this case, the method is vectored bacX to step 160.
In this instance, it is determined whether this is
the last message. If it is the last message, the
temp count variable is set equal to zero and the
PLAY POINTER is set to the MOST RECENT MESSAGE
POINTER, step 174. If this is not the last message,
then the system detsrmines if this is the first
message of the queue, step 162. Since the temp
count variable has now been incremented and this is
not the ~irst message in the queue, the PLAY POINTER
is decremented, step 176. Note that decrementing
the PLAY POINTER sets the pointer in the opposite
direction of the MESSAGE POINTER. This insures that
the next most recent message is played bac~.
Referring to our simplified example of FIG. 2,
if the first message at address nBn is being played,
and the play switch is activated during the playing
back oP the message at address ~B~, the PLAY POINTER
which has been pointing to address ~Bn is now
decremented to address nA~ and the next most recent
messaga is played bacX. I~ the PLAY POINTER reaches
the beginning o~ the message queue, the PLAY POINTER
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is set to the end of the message queue, step 178.
Referring back to FIG. 2, if the next message to
play back is in address "Dn, the play switch is set
to address ~D~. The temp count variable is then
incremented, the message slot set to ~read~, and the
message is played back from the position pointed to
by the PLA~ POINTER, step 166.
~ hus, the play message routine plays messages
back in a chronological order from the most recent
to the oldest. This is accomplished by decrementing
the PL~Y POINTER which is set during the record
routine to equal the MOST RECENT MESSAGE POINTER
when the recording is done by incrementing the
MESSAGE POINTER. Referring to FIG. 2, if the PLAY
POINTER reaches the beginning of the queue, such as
address "A~, the PLAY POINTER is set to the end of
the message queue or address ~D~, thus playing the
messages back in a chronological order. The
requirement for playing back the next most recent
message is that the play switch must be activated
before the timeout of the playing of the current
message occurs. For example, if the third oldest
message is played back, the play switch must be
activated consecutively three times within a timeout
period. It should be noted that when each message
is played back, the timeout period is reset.
Referring to FIG. 6, there is shown an
illustrated example of the plurality of message
slots in the digital stored voice paging receiver of
a method for prioritizing the messages between
"read~ and "unread~ status. For purposes of
illustration, Pour message slots are shown.
However, it is to be understood that more than four
message slots can be used with the present
invention, the number of message slots being limited
.
129~6~
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only by the size of memory and bit rate of the
COD~C. For illustrative purposes, the address of
each message slot is labelled A, B, C, and D.
Considering the example, then, message slot two (2)
is associated with address B. Also associated with
each slot is an unread/read status tag which
indicates whether the message is unread or read.
Also associated with these message slots is a queue
order variable. The queue order is representative
of the order when the message was received when
compared to the other messages. For example, if a
message has a queue order of 4, this signifies that
this is the oldest message, while a queue order of 1
signifies that this is the youngest message. Each
message slot is capable of storing a digitized voice
message for a timeout period, depending upon size of
memory and number of message slots, as previously
explained with reference to Table 1.
To illustrate a method of prioritizing between
read and unread messages by protecting unread
messages over read messages, the discussion which
follows uses address pointers (MESSAGE POINTER and
MOST MESSAGE RECENT MESSAGE POINTER) which
illustratively point to addresses A through D of the
four message slot example illustrated in FIG. 6.
The plurality of message slots is referred to as a
queue with the address A being the beginning of the
queue and address D being the ending of the queue.
Reference will continually be made to FIG. 6 for
explaining the flow chart of FIGS. 7-9.
In general, FIGS. 7-9 describe a method for
storing messages in a plurality of message slots,
the messages stored according to a priority scheme
in which the priority scheme replaces read messages
before unread messages. Upon play back, the
-
~Z9~ 0
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messages are played in chronological order, whether
they are read or unread, from the most recent
received message to the oldest received message.
For purposes of illustration, the method uses the
MESSAGE POINTER and a MOST RECENT MESSAGE POINTER as
previously defined. The MESSAGE POINTER points to
the next "read~ message slot in which a message can
be stored. The MO5T RECENT MESSAGE POINTER points
to the youngest message in the message queue.
In general, the system stores messages only in
empty slots. When empty slots become unavailable,
the system stores a message only in ~read~ slots,
leaving unread messages protected. In playback, the
system scans the queue order and retrieves the
messages according to the queue from youngest to
oldest.
In the operation o~ the system, the paging
receiver is initially powered up or reset, step 200.
A forced reset is indicative of the microprocessor
being reset by user interaction or a microcontroller
because of a malfunction condition. The method
hegins by initializing all the message slots to the
empty status. This enables all the me~sage slots to
be overwritten by incoming messages. The variable
MAX is set to the maximum number of message slots.
Referring to the above described example of FIG. 6,
MAX is set equal to four. The message then sets the
MESSAGE POINTER to the beginning address o~ the
message queue. The MOST RECENT MESSAGE POINTER is
also initialized to point to the beginning address,
such as address A. A message count being a count of
the number of messages received is initially set to
zero, step 204. The paging receiver then goes into
the standby state, ~08, awaiting for incoming
information or activation of the play switch.
:
-
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-26~
If incoming information is detected, the system
is directed to the record routine. Xn the record
routine, the system protects unread messages by
allowing only read message to be overwritten by
incoming infoxmation. For a detailed discussion of
the record routine, attention is directed to FIG. 8.
If incoming information is not detected, eventually
the play switch may be activated, step 212. I~ the
play switch is activated, it is determined whether
the message count is equal to zero, step 214. I~
the message count is equal to zero, the play switch
has been activated with no messages being received
and the system outputs a memory empty tone, step
216. The method then returns to the standby state
208 to wait for incoming information or ~or
activation of the play switch. Referring to step
214, if the message count is not egual to zero, a
message has been received by the system and is
stored in the message gueue. The ~ystem is then
vectored to a play routine to play the message as
disclosed in FIG. 9.
Referring to FIG. ~, there is shown a method
for storing messages received by incoming
information according to a prioritization scheme.
The prioritization scheme protects unread messages
while permitting destruction of read or empty
message slots. The method begins by determining if
the message count is egual to the maximum number of
message slots, step 220. This determines if there
are any empty message slots available. If there are
empty message slots available, the message count is
incremented, step 222. Again, it is determined
whether there are any empty message slots available,
step 224. In this case, the queue order o* all
stored messages are incremented, step 227. This
~L29~
-27-
step effectively ages all the stored messages by
increasing the queue order of all stored messages.
The MOST RECENT MESSAGE POINTER is then set to the
next message slot available pointed to by the
MESSAGE POINTER, step 228. The MESSAGE POINTER is
then incremented to the next message slot available
and the queue order for that slot set to the
youngest, step 230.
It is then determined whether the system is
operating in either the silent or PTL mode, step
232. I~ the system is operating in the silent or
PTL mode, then the message is tagged ~unread~, ~tep
234. If the system is operating in the normal mode,
then the message slot is tagged ~read~, step 236.
The message is then stored into the slot pointed to
by the MOST RECENT MESSAGE POINTER, step 23B. The
system then continues to record the incoming
information until the amount of memory available for
the slot is reached, st2p 24G. If the timeout for
the slot is not reached, recording continues and it
is determined whether new incoming informatioh is
available, step 242. If new information is detected
before the present message is stored, the system
stops recording the present message and repeats
25 steps 220 through 240 to record the new incoming
information in the next available message slot.
Eventually, the timeout for recording messages is
reached, and the system returns to the standby state
208.
Referring back to step 224, if there are no
empty message slots available, this indicates that a
message queue rollover has occurred. If a message
queue rollover has occurred, this indicates that
previously stored message information must be
destroyed to accommodate the new incoming
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-28-
information. The method then determines if any read
messages are available, step 226. If no read
messages are available, then the system will store
the incoming information in the oldest message slot
available even if the slot is unread. This is
determined by scanning the queue order and
retrieving the address of the message slot with the
highest queue order value, the highest queue order
value being the oldest message. The queue order for
this slot is then set to zero, step 244. The
MESSAGE POINTER is then set to the oldest message
slot, step 246. The system then ages all the queue
order values, sets the MOST RECENT MESSAGE POINTER
to the MESSAGE POINTER, steps 226-230. Continuing,
the method determines if the paging receiver is in a
silent or PTL mode, sets the message slot to read or
unread and stores the message in the appropriate
slot, steps 232-242.
Referring back to step 226, if any read
mes~ages are available, the read messages are
destroyed to protect the unread messages. The
method determines the oldest read message available
by scanning the message slots, finding the read
messages and determining the read message with the
oldest queue order value, step 248. A temporary
variable is set equal to the oldest read message
queue order value and the queue order value of that
slot is then set equal to one representing the
youngest message, step 250. The MOST RECENT MESSAGE
POINTER is then set to the MESSAGE POINTER of the
slot, step 252. The method then increments all the
other queue orders which are less than the queue
order stored in the temporary variable from the
oldest read message slot. This effectively ages all
the message slots that have a queue order less than
Z9862~
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the found oldest read message slot. This preserves
the chronological order of the messages remaining.
The method then proceeds ko determine if the paging
receiver is set to the æilent or PTL mode as
previously described before.
To recapitulate, in general, the record routine
records incoming information into empty message
slots first and then into read messages if no empty
message slots are available and then into unread
message slo~s if no empty or read message slots are
available. The message slots are replaced in
chronological order from the oldest to the youngest.
Thus, the method preserves unread messages at tha
cost of read me~sages and preserves chronological
order for the paging receiver user.
Referring briefly back to FIG. 7, if the play
switch is activated and the message counter is
greater than zero, then the method proceeds to the
play routine as illustrated in FIG. 9. In the play
routine, the method begins by determining if this is
the last message, step 260. The last message is
determined by deciding if the temp count variable is
equal to the message count. If the system has
reached step 260 from the standby state 208, the
temp count variahle is zero. I~ the temp count
variable is zero, the message count will be greater
than zero, and the system then determines if this is
the first message in the queue, step 262. The first
message of the queue is determined by analyzing the
temp count variable. If the temp count variable
equals zero, then this is the ~irst message and the
method proceeds to determine the most recent message
to play back by analyzing the queue order variable.
The method retrieves the queue order variable for
the messages and determines the youngest queue order
.
~:9~620
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variable, step 268. The youngest queue order
variable is then stored in a temporary position to
be used later when searching for the next most
recent message, step 269. The method then
increments the temp count variable and sets the
message slot to the read status, step 270. The
method then begins playing the message from the
youngest queue order variable found, step 272. The
method then determines if the message has played
according to the timeout for the message, step 274.
If the message i5 not played back for the length of
time recorded, a timeout has not occurred. It is
then determined whether the play switch has been
actîvated during the playing back of the message,
step 276. If it has not, then incoming information
is checked, step 278. If no incoming information is
present, then the system loops back to determine if
a timeout has occurred, step 274. Thus, the system
will play back the message until a timeout or forced
timeout via the reset switch occurs, the play switch
is activated, or incoming information is detected.
If the play switch is not activated nor incoming
in~ormation is detected, the message will eventually
play in its entirety. The system then sets the
temporary counter to zero and sets the message
pointer equal to the MOST R~CENT MESSAGE POINTER,
step 266. The system then returns to the standby
state 208.
If it is desired to play back more than the
firs~ message, the play switch must be activated
during the playing o~ a message, step 27~. In this
case, the method is vectored back to step 260. In
this instance, it is determined whether this is the
last message. If it is the last message, tha temp
counter is set equal to zero and the MESSAGE POINTER
~;~986ZO
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equal to the MOST RECENT MESSAGE POINTER, step 266.
If this is not the last message, then the system
determines if this is the first message, step 262.
Since the temp count variable has now been
incremented and thi~ is not the first message, the
system retrieves the next most recent, step 264.
This is accomplished by incrementing the temporary
queue order variable stored in step 269 and scanning
the messages to retrieve the message corresponding
to this variable. The MESSAGE POINTER is then
pointed to the message with the next highest queue
order variable and the method proceeds again by
incrementing the temp count variable and setting the
message slot equal to ~read~, step 270.
Thus, the play routine plays messages back in a
chronological order by scanning the queue order
variable. The messages are played back from the
most recent to the oldest. This is accomplished by
scanning the queue order variable to determine the
youngest and oldest message.
Thus, there has been shown two methods for
prioritizing messages in a digital stored voice
paging receiver. In the first method, messages are
stored and retrieved in a chronological order. In
the second method, messages are stored and retrieved
according to a predetermined priority, depending
upon a status value associated with each stored
message and the order messages are received. It is
to be understood that other status values other than
unread, read, and empty may be used. For instance,
messages may be designated protect, unread, read,
and empty with protect being the highest priority
and empty being the lowest.
It should be apparent from the above
description that numerous variations can be made
~98~;Z~?
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from the preferred embodiment described herein
without departing from the scope of the invention.
Accordingly, this invention is not to be regarded as
limited to the embodiment disclosed therein but is
to be limiked as de~ined by the appended claims.
What is claimed is:
