Author: claimsbot

1. A method of encoding a video signal representing a sequence of pictures to form an encoded video signal, the method comprising:
generating an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and
providing the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.
2. A method according to claim 1, comprising generating the error concealment algorithm type indicator to indicate either a temporally-predictive or a non-temporally-predictive type of error concealment algorithm.
3. A method according to claim 1, comprising generating the error concealment algorithm type indicator by:
comparing a first picture of the sequence or a part thereof with a second picture of the sequence;
calculating a measure of similarity between the first picture or said part thereof and said second picture; and
comparing the measure of similarity with a predetermined criterion of similarity.
4. A method according to claim 2, comprising generating the error concealment algorithm type indicator by:
comparing a first picture of the sequence or a part thereof with a second picture of the sequence;
calculating a measure of similarity between the first picture or said part thereof and said second picture; and
comparing the measure of similarity with a predetermined criterion of similarity.
5. A method according to claim 4, comprising:
generating the error concealment algorithm type indicator to indicate that a non-temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof, when the measure of similarity does not meet the predetermined criterion of similarity; and,
generating the error concealment algorithm type indicator to indicate that a temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof when the measure of similarity meets the predetermined criterion of similarity.
6. A method according to claim 5, comprising updating the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity.
7. A method according to claim 5, comprising including the error concealment algorithm type indicator in a picture header.
8. A method according to claim 5, comprising encoding the video signal according to the H.263 standard and including the error concealment algorithm type indicator in the Supplemental Enhancement Information of the standard.
9. A method according to claim 5, comprising updating the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity, and leaving the error concealment algorithm type indicator unchanged when the measure of similarity meets the predetermined criterion of similarity.
10. A method according to claim 5, comprising using a scene identifier as the error concealment algorithm type indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene.
11. A method according to claim 5, comprising using a scene identifier as the error concealment algorithm type indicator, the scene identifier having one of two values, with pictures from adjacent scenes having non-identical scene identifier values.
12. A method according to claim 5, comprising including the error concealment algorithm type indicator in a picture segment header andor a macroblock header.
13. A method according to claim 5, comprising generating the error concealment algorithm type indicator to indicate a type of error concealment algorithm to be applied to a specified rectangular area of a picture.
14. A method according to claim 13, comprising generating multiple error concealment algorithm type indicators for a picture, each error concealment algorithm type indicator being specific to one of a plurality of non-overlapping rectangular areas of the picture.
15. An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus being configured to:
generate an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and
provide the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.
16. An apparatus according to claim 15, wherein the apparatus is configured to generate the error concealment algorithm type indicator to indicate either a temporally-predictive or a non-temporally-predictive type of error concealment algorithm.
17. An apparatus according to claim 28, wherein the apparatus is configured to generate the error concealment algorithm type indicator by:
comparing a first picture of the sequence or a part thereof with a second picture of the sequence;
calculating a measure of similarity between the first picture or said part thereof and said second picture; and
comparing the measure of similarity with a predetermined criterion of similarity.
18. An apparatus according to claim 16, wherein the apparatus is configured to generate the error concealment algorithm type indicator by:
comparing a first picture of the sequence or a part thereof with a second picture of the sequence;
calculating a measure of similarity between the first picture or said part thereof and said second picture; and
comparing the measure of similarity with a predetermined criterion of similarity.
19. An apparatus according to claim 18, wherein the apparatus is configured to:
generate the error concealment algorithm type indicator to indicate that a non-temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof when the measure of similarity does not meet the predetermined criterion of similarity; and
generate the error concealment algorithm type indicator to indicate that a temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof when the measure of similarity meets the predetermined criterion of similarity.
20. An apparatus according to claim 19, wherein the apparatus is configured to update the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity.
21. An apparatus according to claim 19, wherein the apparatus is configured to include the error concealment algorithm type indicator in a picture header.
22. An apparatus according to claim 19, wherein the apparatus is configured to encode the video signal according to the H.263 standard and to include the error concealment algorithm type indicator in the Supplemental Enhancement Information of the standard.
23. An apparatus according to claim 19, wherein the apparatus is configured to use a scene identifier as the error concealment algorithm type indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene.
24. An apparatus according to claim 19, wherein the apparatus is configured to use a scene identifier as the error concealment algorithm type indicator, the scene identifier having one of two values, with pictures from adjacent scenes having non-identical scene identifier values.
25. An apparatus according to claim 19, wherein the apparatus is configured to include the error concealment algorithm type indicator in a picture segment header andor a macroblock header.
26. An apparatus according to claim 19, wherein the apparatus is configured to generate the error concealment algorithm type indicator to indicate a type of error concealment algorithm to be applied to a specified rectangular area of a picture.
27. An apparatus according to claim 26, wherein the apparatus is configured to provide multiple error concealment algorithm type indicators for a picture, each error concealment algorithm type indicator being specific to one of a plurality of non-overlapping rectangular areas of the picture.
28. An apparatus according to claim 19, wherein the apparatus is configured to update the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity, and to leave the error concealment algorithm type indicator unchanged when the measure of similarity meets the predetermined criterion of similarity.
29. A portable radio communications device including at least one of an apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal and an apparatus for decoding an encoded video signal representing a sequence of pictures, the apparatus for encoding a video signal being configured to:
generate an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and
provide the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture, and

the apparatus for decoding an encoded video signal being configured to:
receive an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator being separate from an indication of an encoding mode for the picture;
use the received error concealment algorithm type indicator as the basis for choosing a particular error concealment algorithm of the type indicated; and
apply the chosen error concealment algorithm to conceal an error in the picture or said part thereof.
30. An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus comprising one or more functional units for:
generating an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and
providing the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.
31. An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus comprising a processor configured to control:
generation of an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and
provision of the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.
32. An apparatus for decoding an encoded video signal representing a sequence of pictures, the apparatus comprising a processor configured to control:
reception of an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator being separate from an indication of an encoding mode for the picture;
choice of a particular error concealment algorithm of a type indicated by the received error concealment algorithm type indicator; and
application of the chosen error concealment algorithm to conceal an error in the picture or said part thereof.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1. A method for optimizing binary codes in a language having access to a zoned decimal type variable, comprising:
detecting, for each variable, an area including access to a zoned decimal type variable and not including an instruction that possibly causes a side effect, from said binary codes read into a memory; and
performing, in said detected area, at least one of a process for converting said zoned decimal type variable to a binary type variable and a process for deleting packunpack code such that a converted result does not change even upon a condition that the packunpack code is deleted from said binary codes.
2. The method according to claim 1, further comprising deleting a code of a residue calculation instruction for digit alignment from said binary codes after said step of performing said process.
3. The method according to claim 2, wherein said step of deleting a code of a residue calculation instruction comprises the steps of:
(A) upon a condition that said variable is an n1-digit variable and further a condition n1\u2267n2 is satisfied for a residue calculation instruction for making the variable an n2-digit variable, deleting a code of a residue calculation instruction for making said variable an n1-digit variable;
(B) upon a condition that case (A) does not apply,
(a) upon a condition that said variable is unsigned,
(a1) upon a condition that operations of addition, multiplication, or subtraction are continuous in said detected area and only in case the range of operations in which it can be guaranteed that no binary calculation overflow occurs is known at the time of compilation, deleting, from said binary codes, a code of a residue calculation instruction other than a code of the last one residue calculation instruction among the guaranteed continuous operations;
(a2) upon a condition that case (a1) does not apply, guaranteeing that the number of digits is correct before an operation that does not satisfy (a1);

(b) upon a condition that said variable is signed,
(b1) upon a condition that operations of addition, multiplication, or subtraction are continuous in said detected area and only in case the range of operations in which it can be guaranteed that a sign does not change during the continuous operations and that no binary calculation overflow occurs is known at the time of compilation, deleting, from said binary codes, a code of a residue calculation instruction other than a code of the last one residue calculation instruction among the guaranteed continuous operations; and
(b2) upon a condition that case (b1) does not apply, guaranteeing that the number of digits is correct before an operation that does not satisfy (b1).
4. The method according to claim 2, further comprising reducing an operation strength of each remaining residue calculation instruction in said binary codes after said step of deleting a code of a residue calculation instruction for digit alignment from said binary codes,
wherein said operation strength is reduced by replacing said residue calculation operation with the following equation:
result=(numerator<denominator&&numerator>=0)?numerator:(numerator%denominator).
5. The method according to claim 3, wherein said step of guaranteeing in (a2) comprises generating a code of a residue calculation instruction for guaranteeing that said number of digits is correct before said operation that does not satisfy (a1), and inserting said generated code of said residue calculation instruction into said binary codes.
6. The method according to claim 3, wherein said step of guaranteeing in (b2) comprises generating a code of a residue calculation instruction for guaranteeing that said number of digits is correct before said operation that does not satisfy (b1), and inserting said generated code of said residue calculation instruction into said binary codes.
7. The method according to claim 1, wherein said step of detecting comprises:
generating a set, hereinafter also referred to as GEN(B), of variables accessed after an instruction that possibly causes a side effect in each block of said binary codes, and a set, hereinafter also referred to as KILL(B), containing all variables in each block in case said instruction that possibly causes a side effect exists, said KILL(B) being an empty set in case an instruction that possibly causes a side effect does not exist;
determining a set, hereinafter also referred to as IN(B), of variables at the beginning of each block from a set, hereinafter also referred to as OUT(B), of variables at the end of each block, said GEN(B), and said KILL(B);
setting set information modified at each instruction in each block as additional information for said instruction in said block, said set information being determined on the basis of said IN(B); and
regarding an area in which each variable is continuous as an area not including said instruction that possibly causes a side effect for said variable with respect to said additional information set for each instruction.
8. The method according to claim 7, wherein said generating comprises:
determining whether an instruction in each block is an access to a variable and whether said instruction possibly causes a side effect;
repeating said determination for each instruction in the order of execution; and
generating said GEN(B) and said KILL(B) from a result of said determination.
9. The method according to claim 7, wherein said OUT(B) and said IN(B) are determined from the following data flow equations:
OUT(B)=(IN(B)\u2212KILL(B))\u222aGEN(B);and
IN(B)=\u2229N\u03b5Pred(B)OUT(N),

wherein the OUT(N) is a set of variables at the end of a block N immediately before a block B being processed with said equations, the variables being accessed after an instruction that possibly causes a side effect.
10. The method according to claim 7, wherein said step of setting comprises:
determining whether an instruction in each block is an access to a variable and whether said instruction possibly causes a side effect and modifying said set information of the IN(B);
setting said set information modified at each instruction in each block as the additional information for said instruction in said block, said set information being determined on the basis of said IN(B); and
repeating said determination and said modification of said set information of said IN(B) for each instruction in the order of execution.
11. The method according to claim 1, wherein said process for deleting the packunpack code from the binary codes comprises:
for a variable for which a write operation is performed in said area not including an instruction that possibly causes a side effect, deleting, from said binary codes, a code other than the first and last type conversion instructions among packunpack codes for said zoned decimal type variable in said area not including an instruction that possibly causes a side effect; and
for a variable for which a write operation is not performed in said area not including an instruction that possibly causes a side effect, deleting, from said binary codes, a code other than the first type conversion instruction among packunpack codes for said zoned decimal type variable in said area not including an instruction that possibly causes a side effect.
12. The method according to claim 11, wherein said process for deleting the packunpack code from the binary codes further comprises:
in response to deleting said code other than said type conversion instruction(s), further deleting a sign processing code associated with said deleted code from said binary codes.
13. The method according to claim 1, wherein:
said process for converting said zoned decimal type variable into said binary type variable comprises estimating a cost difference before and after said conversion process and performing said conversion process upon a condition that an estimated cost after said conversion process is lower than an estimated cost before said conversion process, and
said process for deleting the packunpack code from said binary codes is performed for a part not subjected to said conversion process as a result of calculation of estimation of said cost difference.
14. The method according to claim 13, wherein said cost difference before and after the conversion process is determined with the following equation:
cost difference=a difference in cost of accessing a variable by an instruction between a case in which said variable is a zoned decimal type variable and a case in which said variable is a binary type variable, multiplied by the frequency of execution of said instruction+a cost of converting into said binary type variable multiplied by the frequency of execution of entering each detected area+a cost of converting into said zoned decimal type variable multiplied by the frequency of execution of exiting from each detected area+a cost of a residue calculation instruction for digit alignment multiplied by the frequency of execution of said residue calculation instruction.
15. The method according to claim 1, wherein said instruction that possibly causes a side effect is one of an instruction that possibly causes process inconsistency upon a condition that said zoned decimal type variable is converted into said binary type variable, and an instruction that possibly causes process inconsistency upon a condition that the packunpack code is deleted.
16. The method according to claim 1, wherein said instruction that possibly causes a side effect is at least one of:
an instruction that executes an instruction out of a compilation scope;
an instruction that possibly causes an exception observable from an application; and
an instruction that changes at least one of a base address register and an index register of the variable.
17-19. (canceled)
20. A computer program product for optimizing binary codes in a language having access to a zoned decimal type variable, the computer program product comprising:
a computer readable storage medium having computer readable non-transient program code embodied therein, the computer readable program code comprising:
computer readable program code configured to perform the steps of a method according to claim 1.

1. A Push To Talk (PTT) over Cellular (PoC) system for establishing and managing a multimedia PoC session for performing a multimedia call service, the PoC system comprising:
a session establishment request PoC client for transmitting a session participation request (INVITE) message containing media type and media attribute information to a PoC server; and
the PoC server for storing the media type and media attribute information contained in the INVITE message, and if a first response message is received, transmitting a response message, which indicates that media types contained in the first response message are in a transportable state, to the session establishment request PoC client in order to establish a PoC session supporting only the media types set for media transmission in the first response message.
2. The PoC system of claim 1, wherein the PoC server compares the media types contained in the first response message and the stored media types, and if the media types are all the same, the PoC server transmits a response message, which indicates that all the stored media types are in the transportable state, to the session establishment request PoC client.
3. The PoC system of claim 2, wherein the PoC server inserts User Datagram Protocol (UDP) port numbers assigned to transportable media and a media feature value indicating that corresponding media types can be transmitted in the response message that is to be transmitted to the session establishment request PoC client.
4. The PoC system of claim 1, wherein the PoC server compares the media types contained in the first response message and the stored media types, and if the media types are not all the same, the PoC server transmits a response message, which indicates that only the media types contained in the first response message are in the transportable state, to the session establishment request PoC client.
5. The PoC system of claim 4, wherein the PoC server inserts User Datagram Protocol (UDP) port numbers assigned to transportable media and a media feature value indicating that corresponding media types can be transmitted in the response message that is to be transmitted to the session establishment request PoC client.
6. The PoC system of claim 1, wherein if a response message received in response to the INVITE message is not the first response message, and if media types contained in the response message are a portion of media types supported by a session established between the session establishment request PoC client and the PoC server, the PoC server does not update the session.
7. The PoC system of claim 1, wherein if a response message received in response to the INVITE message is not the first response message, and if media types contained in the response message are different from media types supported by a session established between the session establishment request PoC client and the PoC server, the PoC server updates the session so that the newly supported media types are in the transportable state.
8. The PoC system of claim 7, wherein when the PoC server updates the session so that the newly supported media types are in the transportable state, the PoC server performs the session update according to media attributes of the stored media types.
9. The PoC system of claim 7, wherein the PoC server transmits a re-INVITE message containing UDP port numbers assigned to the media types newly supported for the session update to the session establishment request PoC client.
10. The PoC system of claim 7, wherein when UDP port numbers are assigned to all the media types in the initial session establishment, and when the PoC server receives a newly supported media type and transmits a message for updating to a media feature value indicating that the media type can be transmitted, the message for updating is a Media Burst Control Protocol (MBCP) message using a Real-time Transport Control Protocol (RTCP) channel.
11. A method of establishing and managing a multimedia Push To Talk (PTT) over Cellular (PoC) session for performing a multimedia call service in a PoC system comprising a session establishment request PoC client, at least one session participation PoC client, and a PoC server for establishing and managing the multimedia PoC session, the method comprising:
a first process, wherein the session establishment request PoC client transmits a session participation request (INVITE) message containing media type and media attribute information to the PoC server;
a second process, wherein the PoC server stores the media type and media attribute information contained in the INVITE message; and
a third process, wherein if a first response message is received, the PoC server establishes a PoC session by transmitting a response message, which indicates that media types contained in the first response message are in a transportable state, to the session establishment request PoC client.
12. The method of claim 11, wherein the third process comprises:
the PoC server comparing the media types contained in the first response message and the stored media types; and
if the media types contained in the first response message are the same as the stored media types, transmitting a response message, which indicates that all the stored media types are in the transportable state, to the session establishment request PoC client.
13. The method of claim 12, further comprising if the media types are not all the same as a result of the comparison, transmitting a response message, which indicates that only the media types contained in the first response message are in the transportable state, to the session establishment request PoC client.
14. The method of claim 12, wherein the PoC server inserts User Datagram Protocol (UDP) port numbers assigned to the transportable media in the response message that is to be transmitted to the session establishment request PoC client.
15. The method of claim 13, wherein the PoC server inserts User Datagram Protocol (UDP) port numbers assigned to transportable media in the response message that is to be transmitted to the session establishment request PoC client.
16. The method of claim 12, further comprising:
a fourth process, wherein if a response message received in response to the INVITE message is not the first response message, it is determined whether media types contained in the response message are a portion of media types supported by a session established between the session establishment request PoC client and the PoC server; and
a fifth process, wherein if it is determined that the media types contained in the response message are a portion of the media types supported by the session established between the session establishment request PoC client and the PoC server, the PoC server does not update the session.
17. The method of claim 16, further comprising if it is determined that the media types contained in the response message are different from the media types supported by the session established between the session establishment request PoC client and the PoC server, updating the session so that the newly supported media types are in the transportable state.
18. The method of claim 17, wherein when the PoC server updates the session so that the newly supported media types are in the transportable state, the PoC server performs the session update according to media attributes of the stored media types contained in the INVITE message.
19. The method of claim 17, wherein the PoC server transmits a re-INVITE message containing UDP port numbers assigned to the media types newly supported for the session update to the session establishment request PoC client.
20. The method of claim 17, wherein when UDP port numbers are assigned to all the media types in the initial session establishment, and when the PoC server receives a newly supported media type and transmits a message for updating to a media feature value indicating that the media type can be transmitted, the message for updating is a Media Burst Control Protocol (MBCP) message using a Real-time Transport Control Protocol (RTCP) channel.
21. A User Equipment (UE) for establishing and managing a multimedia Push To Talk (PTT) over Cellular (PoC) session for performing a multimedia call service in a PoC system, the UE comprising:
a data transmitter for performing transmission and reception of packet data with a PoC server; and
a controller for controlling the data transmitter to transmit a session participation request (INVITE) message containing media type and media attribute information required for session establishment, and if a re-INVITE message containing specific media type information supported in a current session is received, to transmit a response message in response to the re-INVITE message.
22. The UE of claim 21, wherein if an INVITE message is received, the controller controls the data transmitter to transmit a response message containing supportable media type information, in response to the INVITE message.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1. A circuit comprising:
an active pull-up device coupled to a one-wire bus, wherein the active pull-up device is configured to decrease the transition time of a voltage signal on the one-wire bus transitioning from a first voltage level to a second, higher voltage level; and
a level shift circuit coupled to the active pull-up device to circuit ground, said level shift circuit providing a substantially constant reference voltage level different than said circuit ground, wherein the active pull-up device is configured to operate with respect to the constant reference voltage level for decreasing the transition time of said voltage signal.
2. The circuit of claim 1 wherein the one-wire bus is a hi-directional one-wire bus for hi-directional communications, and the active pull-up device switches from a first impedance to a second, lower impedance when the voltage signal rises above a designated threshold voltage level between the first and second voltage levels, for decreasing said transition time of the voltage signal due to parasitic capacitances on the one-wire bus.
3. The circuit of claim 2 wherein:
the voltage signal on the one-wire bus includes a bias signal equal to the reference voltage level; and
the active pull-up device has a voltage sense switch that is coupled to the level shift circuit, said active pull-up device being configured to initiate the decrease of said transition time when the voltage sense switch determines that a measured level of the voltage signal has risen above the designated threshold voltage level, said voltage signal being measured with respect to said reference voltage level.
4. The circuit of claim 2 where the level shift circuit is a diode with its cathode connected to circuit ground and its anode connected to a reference connection point of the active pull-up device.
5. The circuit of claim 2 further comprising:
at least one communication device coupled to the one-wire bus and configured to output said voltage signal for communicating over the one-wire bus, wherein the at least one communication device is configured to include a bias signal equal to the reference voltage level in the voltage signal.
6. The circuit of claim 5 further comprising:
a transceiver having a processor, wherein the transceiver is coupled to the one wire bus and is configured to communicate with said at least one communication device over said one-wire bus, wherein communication signals generated by the transceiver are biased by said reference voltage level.
7. A circuit comprising:
a level shift circuit connected to a circuit ground and configured to output a substantially constant reference voltage level different than said circuit ground; and
an active pull-up device coupled to the level shift circuit and to a one-wire bus for bi-directional communications wherein the active pull-up device is configured to output a first designated voltage level on the one-wire bus when a measured voltage level of a communication signal on the bus rises above a second designated voltage level, said second voltage level being less than the first voltage level said active pull-up device measuring the voltage level of the communication signal with respect to the constant reference voltage; and
wherein the active pull-up device decreases a transition time of the communication signal on the one-wire bus transitioning from the second voltage level to the first voltage level.
8. The circuit of claim 7 wherein:
the active pull-up device switches from a first impedance to a second, lower impedance when the measured voltage level of the communication signal on the bus rises above the second designated voltage level, for decreasing said transition time of the communication signal; and
the communication signal includes a bias signal equal to the reference voltage level.
9. The circuit of claim 8 wherein the level shift circuit is a diode with its cathode connected to circuit ground and its anode connected to a reference connection point of the active pull-up device.
10. The circuit of claim 7 further comprising:
at least one communication device coupled to the one-wire bus and configured to output said voltage signal for communicating over the one-wire bus, wherein the at least one communication device is configured to include a bias signal equal to the reference voltage level in the voltage signal.
11. The circuit of claim 10 further comprising:
a transceiver having a processor, wherein the transceiver is coupled to the one wire bus and is configured to communicate with said at least one communication device over said one-wire bus, wherein communication signals generated by the transceiver are biased by said reference voltage level.
12. A communication system comprising:
a one-wire bus for bi-directional communications:
a transceiver connected to the one-wire bus;
a communication device connected to the one wire-bus, wherein the communication device is configured to apply a voltage signal to the bus for communicating with the transceiver;
an active pull-up device connected to the one-wire bus and configured decrease the transition time of the voltage signal on the one-wire bus when transitioning from a first voltage level to a second, higher voltage level, when the voltage signal passes above a threshold level; and
a level shift circuit disposed between the active pull-up device and a circuit ground, said level shift circuit providing a substantially constant reference voltage level above or below said circuit ground, wherein the active pull-up device is configured to operate with respect to the constant reference voltage level, and wherein the voltage signal applied by the communication device includes a bias voltage equal to said constant reference voltage level.