Abstract:
A method for Cellular Text Telephone Modem (CTM) signal transmission includes: converting a CTM transmitter signal carried in a first sampling rate to generate a transmission signal carried in a second sampling rate, wherein the second sampling rate is different from the first sampling rate; and outputting the transmission signal carried in the second sampling rate to a CTM receiver.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/139,920 filed on Mar. 30, 2015, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to signal transmission/reception, and more particularly, to a method for Cellular Text Telephone Modem (CTM) operation with sampling rate conversion, and a related machine readable medium. 
         [0003]    A text telephone (TTY) is one of the most commonly used applications by people who are not capable of communicating orally/aurally over the telephone. TTY is a device that uses texts (text signals) instead of voice (speech signals) to communicate over a telephone network. This enables people with hearing or speech difficulties to converse on the phone by typing messages; the signal generated by TTY is then transmitted to a Cellular Text telephone Modem (CTM) which allows a reliable transmission of text characters via the speech channel of a cellular phone system. 
         [0004]    CTM can only work in a narrowband frequency. Conventionally, the signal generated from the CTM for transmission over the telephone network is in a low sampling rate (e.g. 8 K), which results in poor communication quality. Thus, one cannot benefit from better communication quality under higher sampling rates. 
       SUMMARY 
       [0005]    One of the objectives of the present disclosure is therefore to provide a method for CTM operation which can adjust the sampling rates of the CTM signal to solve the above-mentioned problem. 
         [0006]    According to an implementation of the present disclosure, a method for Cellular Text Telephone Modem (CTM) signal transmission is disclosed, wherein the method comprises: converting a CTM transmitter signal carried in a first sampling rate to generate a transmission signal carried in a second sampling rate, wherein the second sampling rate is different from the first sampling rate; and outputting the transmission signal carried in the second sampling rate. 
         [0007]    According to an implementation of the present disclosure, a method for Cellular Text Telephone Modem (CTM) signal reception is disclosed, wherein the method comprises: receiving a transmission signal carried in a second sampling rate frequency; and converting the transmission signal carried in the second sampling rate to generate a CTM receiver signal carried in a first sampling rate, wherein the first sampling rate is different from the second sampling rate. 
         [0008]    According to an implementation of the present disclosure, a non-transitory machine readable medium having a program code stored therein is disclosed, wherein when executed by a processor, the program code instructs the processor to perform the following steps: converting a Cellular Text Telephone Modem (CTM) transmitter signal carried in a first sampling rate to generate a transmission signal carried in a second sampling rate, wherein the second sampling rate is different from the first sampling rate; and outputting the transmission signal carried in the second sampling rate 
         [0009]    According to an implementation of the present disclosure, a non-transitory machine readable medium having a program code stored therein, wherein when executed by a processor, the program code instructs the processor to perform the following steps: receiving a transmission signal carried in a second sampling rate frequency; and converting the transmission signal carried in the second sampling rate to generate a Cellular Text Telephone Modem (CTM) receiver signal carried in a first sampling rate, wherein the first sampling rate is different from the second sampling rate. 
         [0010]    These and other objectives of the present disclosure will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the implementations that are illustrated in various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a diagram illustrating an application of the CTM transceiver module according to an implementation of the present disclosure. 
           [0012]      FIG. 1B  is a diagram illustrating a CTM transceiver module according to an implementation of the present disclosure. 
           [0013]      FIG. 2  is a diagram illustrating a CTM communication progress according to an implementation of the present disclosure. 
           [0014]      FIG. 3  is a diagram illustrating the VCO mode and the HCO mode of the text phone according to an implementation of the present disclosure. 
           [0015]      FIG. 4  is a flowchart illustrating an operating flow of the CTM transceiver module according to an implementation of the present disclosure. 
           [0016]      FIG. 5  is a diagram illustrating an electronic device using the CTM transceiver module according to an implementation of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should not be interpreted as a close-ended term such as “consist of”. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
         [0018]      FIG. 1A  is a diagram illustrating an application of the CTM transceiver module  100  according to an implementation of the present disclosure. As shown in  FIG. 1A , the mobile phones  2 ,  4  are connected to the text telephones  1 ,  3  respectively, wherein the connection between the mobile phones and the text telephones may be through a psychical cable or in other approaches which is not limited in the present disclosure. Through each connection between the mobile phones  2 ,  4  and the text telephones  1 ,  3 , the text signal sent from the text telephones  1 ,  3  can be transmitted in a higher sampling rate for better quality via the CTM transceiver module  100  comprised in the mobile phones  2 ,  4 .  FIG. 1B  is a diagram illustrating a CTM transceiver module  100  according to an implementation of the present disclosure. As shown in  FIG. 1B , the CTM transceiver module  100  comprises a CTM module  101  and at least one sampling rate conversion (SRC) module (e.g. two SRC modules  102  and  103  in this implementation) , wherein the CTM module  101  is a conventional CTM, and the SRC modules  102  and  103  are arranged to adjust sampling rate of signals. For example, the CTM transceiver module  100  may be a software module executable on a processor-based system. The sub-diagram (A) of  FIG. 1B  illustrates the operation of the CTM transceiver module  100  being part of a transmitter for transmitting signals. In the sub-diagram (A) of  FIG. 1B , the CTM transceiver module  100  receives an input signal IS carried in a sampling rate SR 3 , wherein the input signal IS maybe a text telephone signal or a speech signal. The SRC module  102  generates a converted signal CS carried in a sampling rate SR 1  to the CTM module  101  according to the input signal IS, wherein the sampling rate SR 1  is a frequency in which the CTM module  101  can process, e.g. 8 KHz. The CTM module  101  processes the converted signal CS carried in the sampling rate SR 1  to generate a CTM transmitter signal CTMTS carried in the sampling rate SR 1  to the SRC module  103 . The SRC module  103  converts the CTM transmitter signal CTMTS carried in the sampling rate SR 1  to generate a transmission signal TS carried in a sampling rate SR 2 . In this way, even if the CTM module  101  can only process signals carried in the sampling rate SR 1 , e.g. 8 KHz, the proposed disclosure can still deal with input signals carried in an arbitrary frequency higher or lower than the working frequency of the CTM module  101 . 
         [0019]    The sub-diagram (B) of  FIG. 1B  illustrates the operation of the CTM transceiver module  100  being part of a receiver for receiving signals. As shown in the sub-diagram (B) of  FIG. 1B , the SRC module  103  converts the transmission signal TS carried in the sampling rate SR 2  to generate a CTM receiver signal CTMRS carried in the sampling rate SR 1  to the CTM module  101 . The CTM module  101  processes the CTM receiver signal CTMRS carried in the sampling rate SR 1  to generate a processed signal PS carried in the sampling rate SR 1 . The SRC module  102  converts the processed signal PS carried in the sampling rate SR 1  to generate an output signal OS carried in the sampling rate SR 3 . It should be noted that the sampling rates SR 2  and SR 3  are decided by a negotiation module (not shown in  FIG. 1B ) negotiating with a base station before the communication starts, and the sampling rates SR 2  and SR 3  are usually the same. Nowadays, signals to be transmitted maybe carried in either 8 KHz, 16 KHz, 32 KHz, or 48 KHz; therefore, the present disclosure can enable the signals which have been processed by the CTM module  101  to be transmitted in a higher sampling rate, which improves the communication quality and experience for users. 
         [0020]      FIG. 2  is a diagram illustrating a CTM communication progress according to an implementation of the present disclosure. As shown in  FIG. 2 , the uplink is a path for the CTM transceiver module  200 _ 1  being part of a transmitter to transmit signals and the downlink is a path for the CTM transceiver module  200 _ 2  being part of a receiver to receive signals. Both CTM transceiver modules  200 _ 1  and  200 _ 2  may be implemented using the CTM transceiver module  100  shown in  FIG. 1 . Text phones can operate in three modes: the full mode, the Voice Carry Over (VCO) mode, and the Hearing Carry Over (HCO) mode. In the full mode, both the user A and the user B shown in  FIG. 2  are allowed to transmit text signals via text telephones  201  and  204 . In this case, the user A transmits a text signal (i.e. the input signal IS) by typing on the text telephone  201 . The CTM transceiver module  200 _ 1  processes the input signal IS to generate a transmission signal TS to a backend speech encoder  202 . The transmission signal TS is then transmitted to the receiver end through a base station (i.e. the downlink shown in  FIG. 2 ). Through a speech decoder  203  at the receiver end, the transmission signal TS is sent to the CTM transceiver module  200 _ 2  for further processing. The CTM transceiver module  200 _ 2  generates an output signal OS according to the transmission signal TS. In this case, the output signal OS is the text signal and will be shown on the text telephone  204  for the user B. If the user B wants to communicate with the user A in a text signal, it will follow the same process described above, and the text signal will be shown on the text telephone  201  for the user A. It should be noted that sampling rates of the input signal IS, the output signal OS and the transmission signal TS are predetermined by negotiating with the base station before the communication is started, and might be higher than the working frequency of the conventional CTM. Therefore, the quality of the communication will be improved greatly due to the proposed sampling rate conversion. 
         [0021]      FIG. 3  is a diagram illustrating the VCO mode and the HCO mode of the text phone according to an implementation of the present disclosure. As shown in the sub-diagram (a) of  FIG. 3 , in the VCO mode, a user A uses a microphone MIC of the text telephone  201  to transmit a speech signal SS and a user B receives the speech signal SS via a speaker SP of the text telephone  204 . As shown in the sub-diagram (B) of  FIG. 3 , in the HCO mode, a user A transmits a text signal TXS via the text telephone  201  which will be shown on the text telephone  204  for a user B for communicating. The communication process of both the VCO mode and the HCO mode are identical to the above-mentioned communication process of the full mode; a detailed description is thus omitted here for brevity. 
         [0022]      FIG. 4  is a flowchart illustrating an operating flow of a CTM transceiver module according to an implementation of the present disclosure, wherein steps  301  to  304  are operated by one CTM transceiver module (e.g.  200 _ 1 ) being part of a CTM transmitter and steps  305  to  308  are operated by another CTM transceiver module (e.g.  200 _ 2 ) being part of a CTM receiver. The flow is described as follows. 
         [0023]    Step  301 : Convert an input signal to generate a converted signal. (In this step, the input signal is carried in a third sampling rate which is different from a first sampling rate having a frequency in which only the CTM can work (e.g. 8 KHz), and the converted signal is carried in the first sampling rate. The input signal maybe a speech signal or a text signal.) 
         [0024]    Step  302 : Process the converted signal to generate a CTM transmitter signal. 
         [0025]    Step  303 : Convert the CTM transmitter signal to generate a transmission signal. 
         [0026]    Step  304 : Output the transmission signal to a CTM receiver through a base station. 
         [0027]    The transmission signal is carried in a second sampling rate which is different from the first sampling rate. Due to the second sampling rate usually being higher than the first sampling rate, the transmission signal is thus transmitted with a better quality. The second sampling rate and the third sampling rate are determined by negotiating with the base station before the communication is started. 
         [0028]    Step  305 : Receive the transmission signal from the CTM transmitter. 
         [0029]    Step  306 : Convert the transmission signal to generate a CTM receiver signal.
       (In this step, the CTM receiver signal is carried in the first sampling rate for being processed in the CTM module  101 .)       
 
         [0031]    Step  307 : Process the CTM receiver signal to generate a processed signal. 
         [0032]    Step  308 : Convert the processed signal to generate an output signal. 
         [0033]    In Step  308 , the output signal is carried in the third sampling rate. Likewise, the second sampling rate and the third sampling rate in the receiver end are determined by negotiating with the base station before the communication is started. In this way, even if the CTM can only process signals carried in a specific sampling rate, e.g. 8 KHz, the proposed disclosure can still deal with input signals carried in an arbitrary frequency, which improves the communication quality. 
         [0034]    The CTM transceiver module  100 / 200 _ 1 / 200 _ 2  of the present disclosure may be implemented as a program code and can be stored in a non-transitory machine readable medium of an electronic device such as a smart phone, a tablet or a laptop. The implementation of  FIG. 2  can be implemented by coupling the electronic device with a text telephone (e.g. the text telephones  201  and  204 ) to transmit a speech signal or a text signal having improved quality.  FIG. 5  is a diagram illustrating an electronic device  400  according to an implementation of the present disclosure. As shown in  FIG. 5 , the electronic device  400  comprises a processor  401  and a non-transitory machine readable medium  402 , wherein the non-transitory machine readable medium  402  stores a program code PROG. The non-transitory machine readable medium  402  maybe a volatile memory or a non-volatile memory. In this implementation, the electronic device  400  is coupled to a text telephone to perform a CTM signal transmission/reception. The flow described in the implementation of  FIG. 4  will be executed if the program code PROG stored in the non-transitory machine readable medium  402  is loaded and executed by the processor  401 . The person skilled in the art should understand the implementation readily after reading the above paragraphs; a detailed description is thus omitted here for brevity. 
         [0035]    Briefly summarized, the present disclosure discloses a method for CTM operation, wherein a sampling rate of a signal to be transmitted is adjusted. Even if the conventional CTM can only process a signal with specific sampling rate, e.g. 8 KHz, the disclosure can still deal with input signals carried in an arbitrary frequency, which improves the quality and experience for users. 
         [0036]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the disclosure. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.