IDEOGRAPHICAL CHARACTER SIGNALLING SYSTEM

Abstract: An ideographical character signalling system (2), such as an ideographical character paging system, comprising input means (4) for inputting a plurality of first and second different types of ideographical characters, said input means including coding means (84) for coding both said first and second types of ideographical characters according to a first code, and signal processing means (10) for receiving a data signal comprising said first and second types of ideographical characters coded according to said first code, said signal processing means comprising code converting means (88) for selectively coding the coded first type of ideographical characters according to a second standard code. A signal receiver (34), for receiving data signal comprising a plurality of coded ideographical characters, and having character generating means (52) for generating for display only the most frequently used ideographical characters together with a special character symbol if a rarely used character is received, is also disclosed.

Description: IDEOGRAPHICAL CHARACTER SIGNALLING SYSTEM FIELD OF THE INVENTION This invention relates to an ideographical character signalling system and more particularly to an ideographical character paging system. Background of the Invention In countries having languages comprising ideographi -1 characters such as China, Japan, Taiwan, paging systems which can transmit, receive and display the ideographical characters are required. Such paging systems are well known: however, several problems have arisen in the development of these ideographical paging systems. Typically a ideographical paging system comprises a character entry device, a terminal for control and coding functions and display pagers. Each one of a predetermined selection of characters of the language has an associated code, comprising one or more bytes, according to an industrial coding standard. A display pager on receiving a signal having a number of coded bytes decodes the signal according to the industrial code used, reads the corresponding characters from its character generating memory and displays the characters. However, the standard codes used to code the characters vary from one country to another. For example, the standard code in Taiwan is different to the standard code in China. Also, in some cases, there are multiple coding standards " within the same country. Therefore, for each of the coding standards different pager models in the paging system are required to be used, even when the same character set has been coded. This makes the ideographical paging system increasingly expensive. The Japan Industrial Standard (JIS), Peoples Republic of China (PRO , and Taiwan industrial coding standards have been developed to cover a particularly large number of characters. However, in order to code each one of these characters approximately 7000 words are needed which require two-mega-bits (2M bits) of Read Only Memory (ROM) for formatting. As a result excessive memory space is needed to incorporate all these characters into the character generating ROM of the pager. Another problem associated with an ideographical paging system arises due to the incompatibility of the character sets which ca be entered into the entry device, processed in the terminal and displayed in the display pager: this is a direct result of the memory capacity limitation of the terminal and character generating ROM of the pager. Since it is not practical to incorporate all the characters of the language into the system, especially into the memory of the character generating ROM, only a selection of characters are incorporated into the system. The number of characters incorporated depends on the memory capacity, therefore the selection can vary between the entry device with a larger capacity, the terminal and the character generating ROM. Thus, a problem occurs when a rarely used character is entered via the entry device into the system and the entered character is not one of the predetermined selection of characters stored in the character generating ROM of the pager (such a character will be referred to as an 'illegal' character hereafter) . When the pager receives an 'illegal* character, irrespective of whether the following characters are 'illegal' or not, the data decoding is interrupted and no further characters will be displayed. Since the same result occurs when the pager or the system malfunctions, the user of the pager has no information as to why the displayed message is incomplete. Thus, it is an object of the present invention to provide an improved ideographical signalling system wherein the above problems are overcome. Summary of he Invention In accordance with a first aspect of the present invention there is provided an ideographical character signalling system comprising: input means for inputting a plurality of first and second different types of ideographical characters, said input means including .coding means for coding both said first and second types of ideographical characters according to a first code; signal processing . means for receiving a data signal comprising said first and second types of ideographical characters coded according to-said first code, said signal processing means comprising code converting means for selectively coding the coded first type of ideographical characters according to a second standard code. In accordance with a second aspect of the present invention there is provided a signal receiver for use within an ideographical character signalling system for receiving data signals comprising a plurality of coded ideographical characters, each one of said ideographical characters being one of a first or second different type of ideographical character, said first type of ideographical character being coded according to a second standard code and said second type of ideographical character being coded according to a first code, said signal receiver comprising: decoding means for decoding each one of the plurality of coded ideographical characters; character generating means for generating said first type of characters for display; control means for determining the type of each one of said plurality of ideographical characters, said control means in response to said first type of ideographical character selecting said first type of ideographical character from the character generating means and said ' control means in response to said second type of ideographical character providing a special character symbol; and display means for displaying the selected ideographical characters and special character symbols. Thus, it will be appreciated that since the signal processing means of a ideographical character signalling system covering one area, for example Taiwan, changes the coding of the data signal from a first code (i.e. the standard code for the Taiwan area) to a predetermined second standard code which is the same for all the different areas, one signal receiver can be used within all the areas despite the fact they all have different industrial coding standards . In a preferred embodiment, the pager comprises a character generating ROM in which only the most frequently used characters of the ideographical language are incorporated. Such characters are referred to as 'legal' characters hereafter. Thus, by reducing the number of characters which can be selected according to the second standard code, the size of the ROM in the pager can be reduced which in turn provides for a substantial reduction ■ in cost . It will also be appreciated that since the second aspect of the present invention provides means to display a special 'illegal' character symbol when the pager receives an 'illegal' character, the data decoding will not be interrupted on receipt of an 'illegal' character thereby enabling all the characters of a message to be displayed. / Brief Description of the Drawings A preferred embodiment of present invention will now be described, by way of example only, with reference to the accompanying drawings. . Figure 1 shows a schematic diagram of the ideographical character paging system in accordance with the present invention. Figure 2 is.a schematic diagram of a display pager which forms part of the ideographical character paging system of Figure 1. Figure 3 shows a diagrammatic representation of- the address organization of the character generating ROM of the pager of Figure 2. Figure 4 comprises a detailed flow-chart of one implementation of the preferred embodiment of the invention. Figure 5 comprises a detailed flow-chart of a second implementation of the preferred embodiment of the invention. Figure 6 comprises a detailed flow-chart of an implementation of the display pager in accordance with a second aspect of the present invention. Detailed Description of the Drawings Referring firstly to Figure 1, in a preferred embodiment the ideographical character paging system 2 comprises an entry device 4 coupled to a terminal 10. The entry device 4 may be, for example, a personal computer (PC) 12 having a keyboard 18 for keying in the characters of a particular ideographical language. Once a character has been keyed-in, the PC will select a code for the character from its memory (not shown) according to the particular coding standard which is used: The selected code may be one or two bytes. The coding standard used depends on the area covered by the ideographical character paging system and varies from area to area. The Chinese character TT has, for example, according to the JIS coding standard an a sociated code of 3221- " (HEX) . The PC 12 communicates with the terminal 10 via a MODEM 24. The terminal 10 comprises a signal code controller 14 which contains an address conversion table (not shown) . The address conversion table converts the coded words into addresses according to a universal standard code M. Different address conversion tables are implemented for the various ceding standards cf the different areas and are arranged so that irrespective of the coding of the coded words the resulting data signal generated by the address conversion tables is coded according to the universal standard code. M. For the previous example, the code 3221 (HEX) which represents the Chinese character *τ will be converted into the address 'ABCD' (HEX) . The terminal 10 is coupled to a base station 30 having an antenna 32 for transmitting and receiving coded data signals. The ideographical character paging system 2 further comprises a plurality of pagers only one of which 34 is shown. Referring now also to Figure 2, the pager 34 comprises an antenna 36 coupled to a first RF amplifier 38 which is coupled to a second RF amplifier 44 via a first mixer 40 connected to a first oscillator 42. The second RF amplifier 44 is coupled to a filter 46 via a second mixer 48 connected to a second oscillator 50. The filter 46 is SUBSTITUTE SHEET coupled to a microcomputer 52 via a demodulator 54 and a data filter 56. The microcomputer 52 is coupled tc internal Random Access Memory (RAM) 60 and to a graphic display 58 which displays the data signal received at the antenna 36 of the pager 34 once it has been decoded by the microcomputer 52. Such a pager is well known in the art. In the preferred embodiment of the invention a character generating ROM 62 is also coupled to the microcomputer 52. The character generating ROM 62 stores only the most frequently used characters of the ideographical language (i.e. the 'legal' characters) so as to reduce the size of the memory. For example, 1M bits of ROM can store 4096 characters which is sufficient to cover the 'legal' characters. The character generating ROM 62 is arranged in a 16 x 16 byte dot matrix pattern. The address for each character stored in the character generating ROM 62 is identical to the coding of the same character according to the universal standard code M. Figure 3 shows the address organization for the location of one character, for example the character *τ, of the plurality of characters in the character generating ROM 62. As has been mentioned above the character I has a code 'ABCD' (HEX) according to the universal standard code M which is therefore the starting address 70 of the character *? in the character generating ROM 62. The starting address 'ABCD' (HEX) is followed by 32 bytes of pixel patterns 72 (ABCD1, ABCD2, ABCD3, ABCD4, etc.) which go to make up the character ΪT. In operation if the data signal received by the antenna 36- of the pager 34 is decoded and includes the address ABCD, then, under the control of the microcomputer 52, the 32 byte pixel pattern of the character *τ will be loaded into the internal RAM 60. During a further cycle of the microcomputer 52 the pixel patterns will be outputted to the graphic display 58 in order to display the character *τ. The ideographical paging system 2 operates in the following manner. A character is keyed into the PC 12 using the keyboard 18. The PC codes the character by selecting a code for the character from its memory (not shown) according to a particular coding standard. The selected code may be one or two bytes. The coded data signal is then transmitted via the MODEM 24 to the signal code controller 14 of the terminal 10. Before converting the coded word(s) into an address according to the universal standard code M, the signal code controller 14 decodes the word(s) and checks that the character is one of the 'legal' characters stored in the character generating ROM 62 of the pager 34. If a 'legal' character is keyed into the entry device 18, then the signal code controller 14 converts the coded word(s) into an address using the conversion table (not shown) . The address data outputted from the signal code controller 14 is used to modulate a carrier signal in the terminal 10. The modulated signal is transmitted by the antenna 32 to the pager 34. If, however, an 'illegal' character is keyed into the entry device 18 and coded by the PC 12, the signal code controller 14 will detect an 'illegal' character when it attempts to perform the conversion. The terminal 10 will then search in a look-up table (not shown) for a replacement character having the same meaning. If a replacement is found the signal code controller 14 converts the coded word(s) of the replaced character into an-address using the conversion table ■ (not shown) and the output address data signal is transmitted by the antenna 32 to the pager 34 as described above. If no replacement character is found then the coded wofd(s) of the 'illegal' character will be used to modulate the carrier signal which is then transmitted to the pager 3 . A data signal received at the antenna 36 of the pager 34 is decoded. The decoded data word(s) comprise at least one starting address 70 of one character in the character generating ROM 62. Under the control of the microcomputer 52, once a location in the character generating ROM 62 has been addressed the 32 byte pixel pattern of the selected character is loaded into the internal RAM 60. During a further cycle of the microcomputer 52, the pixel patterns will be outputted to the graphic display 58 in order to display the selected character. If an 'illegal' character transmitted from the terminal 10 is decoded,the pager will replace the 'illegal' character by a special symbol from the character generating ROM 62 which will be subsequently displayed on the graphic display 58. Thus, the user of the pager will be able to determine if the special symbol is displayed, that one character is missing due to the capacity limitation of the character generating ROM- rather than a malfunction due to either a hardware or software problem. In addition, since data decoding is not interrupted when the pager receives an 'illegal' character which is subsequently represented on the graphic display by the special symbol, a complete message can be displayed. The complete message displayed will comprise the special symbol and the 'legal' characters and thus, the user should be able to decipher the whole or most of the message. When characters of a message are entered into the ideographical paging system, the entry system can operate in one of two ways.: automatic message entry or manual message entry. The automatic message entry operation of the entry device 4 and terminal 10 of the ideographical paging system of Figure 1 is illustrated in the flow-chart 80 of Figure 4. Figure 4 is described with respect to one character of the plurality of characters which make up a message. It will be appreciated, however, that the routine is repeated for all the characters of the message. The automatic message entry operation starts at 82. The character is entered into the entry device 4 and the character is coded according to the coding standard X, block 84. Coding standard X may be any one of the JIS, PRC or Taiwan coding standards. A verification that the character is a 'legal' character is initiated at 86. If the character is found to be 'legal*, the routine branches to convert the character from coding standard X to universal coding standard M, at block 88. The character coded according to universal coding standard M is outputted to the terminal 10, at block 90. If the character is found to be 'illegal', a search is made at block 92 for a replacement character which has the same meaning. If a replacement character is found the 'illegal' character is replaced by the replacement character at 96 which is then converted from coding standard X to universal coding standard M, at block 88. The replacement character coded according to universal coding standard M is outputted to the terminal 10, at block 90. If no replacement character is found the 'illegal' character coded according to standard coding X is outputted to the terminal 10, at block 90. The coded character outputted to the terminal 10 is-" encoded and transmitted to the pager 34, at block 98. The manual message entry operation of the entry device 4 and terminal 10 of the ideographical paging system of Figure 1 is illustrated in the flow-chart 100 of Figure 5. Figure 5 is described with respect to one character of the plurality of characters which make up a message. The manual message entry operation starts at 102. The character is entered into the entry device 4 and the character is coded according to the coding standard X, block 104. A verification that the character is a 'legal' character is initiated at 106. If the character is found to be 'legal' the routine branches to convert the character from coding standard X to universal coding standard M, at block 108. The character coded according to universal coding standard M is outputted to the terminal 10, at block 110. If the character is found to be 'illegal', a search is made at block 112 for a replacement character which has the same meaning. If a replacement character is found the 'illegal' character is replaced by the replacement character at 116.which is then converted from coding standard X to universal coding standard M at block 108. The replacement character coded according to universal coding standard M is outputted to the terminal 10, at block 110. The operation so far has been identical to that described with reference to Figure 4. However, if no replacement character is found, the person who operates the entry device 4 can choose at block 118 whether to send the message or not. If no message is to be sent, the message is aborted at 120. If the message is to be sent, the 'illegal* character coded according to standard coding X is outputted to the terminal 10, at block 110. The coded character outputted to the terminal 10 is encoded and transmitted to the pager 34, at block 122. The operation of the pager 34 of Figure 2 is illustrated in the flow-chart 130 of Figure -6. The operation starts at block 132. The data signal received at the antenna 36 of the pager 34 is decoded, at 34 and a parity check is initiated at- 136. If, after completing the parity check, no error in the data is detected the routine branches to determine if the decoded data is a 'legal' character, at 140. If the character is found to be 'legal' the character is read from the character generating ROM 62 into the internal RAM 60 at block 142. The stored character in the RAM 60 is then outputted to the graphic display at block 144. If the character is found to be 'illegal' the 'illegal' character symbol is displayed at the graphic display, block 14-6. If, after completing the parity check, an error in the data is detected the routine branches to determine if the error is correctable, block 148. If the error is correctable, the error corrected at block 150, and the data is checked to determine if the corrected data is a legal character, at 140. If the character is found to be 'legal' the character is read from the character generating ROM 62 into the internal RAM 60 at block 142. The stored., character in the RAM 60 is then outputted to the graphic display at block 144. If the character is found to be 'illegal' the 'illegal' character symbol is displayed at the graphic display, block 146. If the error cannot be corrected, the bad data character symbol is displayed at the graphic display 58, block 152. In summary, by converting the coded characters to a universal coding standard in the pager terminal, the preferred embodiment of the first aspect of the present invention allows for one pager model to be used in different areas using different coding standards. In addition, since the preferred embodiment utilizes a character generating ROM which stores only the most frequently used characters the size of the character generating ROM can be reduced. The preferred embo . diment of the second aspect of the present invention enables a complete, message to be displayed, including 'illegal' character symbols if a rarely used character is part of the message. Thus, the use.r of the pager will be able to decipher the whole or most of the message, even if rarely used characters form part of the message. What is claimed is :

Claims: Claims 1. An ideographical character signalling system comprising:' input means for inputting a plurality of first and second different types of ideographically characters, said input means including coding means for coding both said first and second types of ideographical characters according to a first code; signal processing means for receiving a data signal comprising said first and second types of ideographical characters coded according to said first code, said signal processing means comprising code converting means for selectively coding the coded first type of ideographical characters according to a second code. 2. An ideographical character signalling system according to claim 1 wherein said first type of ideographical characters are the most frequently used characters of a language. 3. An ideographical character paging system comprising an ideographical character signalling system according to claim 1. 4. A signal receiver for use within an ideographical character signalling system for receiving data signals comprising a plurality of coded ideographical characters each one of said ideographical characters being one of a first or second different type of ideographical character, said first type of ideographical character being coded according to a second standard code and said second type of ideographical character being coded according to a first code said signal receiver comprising: decoding means for decoding each one of the plurality of coded ideographical characters; character generating means for generating said first type of characters for display; control means .for determining the type of each one of said plurality of ideographical characters, said control means in response to said first type of ideographical character selecting said first type of ideographical character from the character generating means and said control means in response to said second type of ideographical character providing a special character symbol; and display means for displaying the selected ideographical characters and special character symbols. 5. An ideographical character signalling system according to claim 4 wherein said first type of ideographical character comprises the most frequently used ideographical characters. 6. A signal receiver according to claim 4 wherein said character generating means comprises a Read Only Memory. 7. A signal receiver according to claim' wherein said control means comprises a microcomputer. 8. A pager for use in an ideographical character paging system wherein said pager comprises a signal receiver according to claim 4.

Inventors: KUNG PATRICK SHUANG, SCHWENDEMAN ROBERT JOHN, KUNG, PATRICK, SHUANG, SCHWENDEMAN, ROBERT, JOHN
Applicants: MOTOROLA INC, MOTOROLA, INC.
Application year: 1990
Main classification: G09G5
IPC codes: G06F3, G08B5, G09G5