Patent Publication Number: US-8121490-B2

Title: Transponder unit, transponder unit control apparatus, transponder unit control method and recording medium recording transponder unit control program

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments herein relate to a transponder unit, a transponder unit control apparatus, a transponder unit control method and a recording medium recording a transponder unit control program. 
     2. Description of the Related Art 
     WDM (Wavelength Division Multiplexing) is used commonly in the optical communication network field to increase the transmission capability of an optical fiber line. A WDM system applies the characteristic that optical signals with different wavelengths do not interfere with each other. A WDM system transmits multiple optical signals with different wavelengths through a number of transponder units equal to the number of wavelengths to be multiplexed. 
     A wide variety of client data protocols has appeared in recent years for use in optical communication in the WDM system. The client data protocols mainly use transponders applicable to various data protocol rather than a transponder only applicable to a specific data protocol. For example, SONET/SDH was predominate in existing systems while transponders which are compliant with data-related data protocols such as Giga Bit Ethernet (registered trademark) (GbE) or video-related data protocols such as DV6000 have become predominate. 
     Here, in a conventional WDM system, all transponders (such as a transponder unit A, a transponder unit B and a transponder unit C in  FIG. 11 ) must define data protocols to be supported (or used). The definition is mainly performed manually (refer to ( 1 ) and ( 2 ) in  FIG. 11 ). 
     JP-A-2004-64585, for example, discloses a technology including, in SDH line terminal equipment, identifying a line type of a received frame and processing the received frame by using setting data corresponding to the identified line type. More specifically, the SDH line terminal equipment stores setting data corresponding to the line type of the SDH line. Then, upon reception of a frame, the format of the received frame is identified, and the line type is thus identified. Then, the received frame is processed based on the setting data corresponding to the identified line type. 
     SUMMARY OF THE INVENTION 
     According to an aspect of an embodiment, a transponder unit comprises: 
     a CDR (Clock Data Recovery) section that extracts clocks from an input signal, and an oscillating section that can output various frequencies to the CDR section; 
     a frequency instruction processing section that instructs the oscillating section to output an arbitrary frequency; 
     a detection processing section that determines whether the frequency output from the oscillating section and an input signal synchronize in frequency or not in response to an instruction by the frequency instruction processing section, and detects a synchronization frequency; and 
     a frame processing section control section that operates a frame processing section based on the synchronization frequency detected by the detection processing section. 
     According to still another aspect of an embodiment, a transponder unit control apparatus comprises: 
     a transponder unit having a CDR section that extracts clocks from an input signal, and an oscillating section that can output various frequencies to the CDR section, a frequency instruction processing section that instructs the oscillating section to output an arbitrary frequency, a detection processing section that determines whether the frequency output from the oscillating section and an input signal synchronize in frequency or not in response to an instruction by the frequency instruction processing section, and detects a synchronization frequency, and a frame processing section control section that operates a frame processing section based on the synchronization frequency detected by the detection processing section; and 
     a control section that controls the transponder unit. 
     According to still another aspect of an embodiment, a transponder unit control method comprises: 
     extracting clocks from an input signal; 
     outputting an arbitrary frequency; 
     determining whether the frequency and the input signal synchronize in frequency or not and detecting a synchronization frequency; and 
     processing a frame section on the synchronization frequency. 
     According to still another aspect of an embodiment, a recording medium recording a transponder unit control program causes a computer to perform: 
     causing a CDR section to extract clocks from an input signal; 
     instructing to an oscillating section output an arbitrary frequency from; 
     determining whether the frequency output from the oscillating section and the input signal synchronize in frequency or not in response to the instruction, and detecting a synchronization frequency; and 
     operating a frame processing section based on the synchronization frequency detected by the detection. 
     The above-described embodiments of the present invention are intended as examples, and all embodiments of the present invention are not limited to including the features described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram for explaining the outline and features of a transponder unit according to a first embodiment; 
         FIG. 2  is a block diagram showing a configuration of the transponder unit according to the first embodiment; 
         FIG. 3  is a diagram showing an example of compliant frequency stored in a compliant frequency storage section according to the first embodiment; 
         FIG. 4  is a diagram for describing an example of the information on frequency synchronization to be stored in the state storage section according to the first embodiment; 
         FIG. 5  is a flowchart showing processing by a scan method according to the first embodiment; 
         FIG. 6  is a block diagram showing a configuration of a transponder unit according to a second embodiment; 
         FIGS. 7A to 7C  are diagrams for explaining an example of the processing for detecting a synchronization frequency by the sampling method according to the second embodiment; 
         FIGS. 8A to 8D  are diagrams for explaining an example of the processing for detecting a synchronization frequency by a sampling method according to the second embodiment; 
         FIG. 9  is a flowchart showing processing by the sampling method according to the second embodiment; 
         FIG. 10  is a diagram showing a program for the transponder unit according to the first embodiment; and 
         FIG. 11  is a diagram for explaining problems of a transponder unit according to conventional technologies. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference may now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     Embodiments of a transponder unit, a transponder unit control apparatus, a transponder unit control method and a transponder unit control program according to the invention will be described in detail below with reference to attached drawings. The outline and features of a transponder unit according to embodiments and configurations and processing flows of the transponder unit will be sequentially described below. 
     First Embodiment 
     Outline and Features of Transponder Unit 
     First of all, the outline and features of a transponder unit according to this embodiment will be described with reference to  FIG. 1 .  FIG. 1  is a diagram showing the outline and features of a transponder unit according to this embodiment. 
     As shown in  FIG. 1 , a transponder unit according to a first embodiment includes an oscillating section that can output various frequencies (bit rates) to a CDR (Clock Data Recovery) section. The CDR section extracts clocks from an input signal and a frame processing section performs frame processing on the input signal. More specifically, the transponder unit includes an optical/electrical (O/E) converter that receives and electrically converts an optical signal from a client and an electrical/optical (E/O) converter that converts the electrically converted signal to an optical signal. The transponder unit also includes, a CDR &amp; DRV section that extracts clocks from input data, and a frame processing section. An oscillating section that inputs a set frequency to the CDR &amp; DRV section. Finally, a control chip controls functions of the transponder unit. 
     The frame processing section in the transponder unit according to the first embodiment has a processing section that is compliant with a data protocol. The frame processing section has, as shown in  FIG. 1 , a “SONET-related monitor section” that is a processing section compliant with a SONET-related data protocol, a “data-related monitor section” that is a processing section compliant with a data-related data protocol (such as a data protocol as in Gigabit Ethernet (registered trademark) and a “video-related monitor section” that is a processing section compliant with a video-related data protocol (such as a data protocol as in DV6000). These monitor sections operate based on the unique data protocols, and correspondence is established between each the data protocols and unique frequencies. 
     Then, a transponder unit as outlined above is mainly characterized in that the manual work for defining a data protocol to be used by a client can be reduced as described below. 
     That is, the transponder unit according to the first embodiment instructs the oscillating section to output an arbitrary frequency (bit rate) when a signal with unknown data protocol is input from a client. More specifically, the transponder unit instructs the oscillating section to sequentially output all frequencies (bit rates) that the oscillating section can output for the input signal. 
     Then, the transponder unit according to the first embodiment determines whether the frequencies output from the oscillating section in response to the instruction and the input signal synchronize in frequency or not and detects a synchronization frequency. The synchronization frequency is the frequency for the synchronization (refer to ( 1 ) in  FIG. 1 ). In other words, the transponder unit determines whether all frequencies sequentially output from the oscillating section in response to the instruction and the input signal synchronize (LOCK) in frequency or not and detects the frequency band for the synchronization (LOCK). Then, the transponder unit detects the center frequency in the frequency band for the synchronization (LOCK) as the synchronization frequency. 
     Then, the transponder unit according to the first embodiment operates the frame processing section based on the detected synchronization frequency. For example, as described in ( 2 ) in  FIG. 1 , the transponder unit instructs the control chip to operate the frame processing section and the CDR &amp; DRV section based on the detected frequency. As a result, the frame processing section and CDR &amp; DRV section process an input signal based on the set frequency, as described in ( 3 ) in  FIG. 1 . In particular, the frame processing section has a processing section (monitor section) that operates based on a unique data protocol (for example, the monitor section may be the SONET-related monitor section, the data-related monitor section or the video-related monitor section). The frame processing section operates the processing section (monitor section) based on the data protocol corresponding to an instructed frequency to perform frame processing. 
     Thus, as described in the main characteristic, the transponder unit according to the first embodiment can reduce the manual work for defining a data protocol to be used by a client. 
     Configuration of Transponder Unit 
     Next, with reference to  FIG. 2 , a configuration of the transponder unit shown in  FIG. 1  will be described.  FIG. 2  is a block diagram showing a configuration of the transponder unit. As shown in  FIG. 2 , a transponder unit  1  includes a client side input/output section  10 , a client side CDR &amp; DRV section  20 , a client side oscillating section  30 , a frame processing section  40 , a network side CDR &amp; DRV section  50 , a network side oscillating section  60 , a network side input/output section  70  and a control section  100 . Notably, the configuration of the transponder unit according to this embodiment will be described mainly on the points pertaining to this embodiment. The description on other configuration will be omitted or will be brief since it is the same as the one in a conventional transponder unit. 
     The client side input/output section  10  has a client side O/E section  11  that receives and electrically converts an optical signal from a client and a client side E/O section  12  that optically converts an electric signal and outputs the result to a client. 
     The client side CDR &amp; DRV section  20  has a client side CDR (Clock Data Recovery) section  21  that extracts clocks from an input signal and a DRV (drive) section  22  that performs the inverse processing. 
     The client side oscillating section  30  is an oscillating section that outputs various frequencies to the client side CDR section  21 . More specifically, the client side oscillating section  30  outputs the frequency instructed to a frequency setting section  102  by a frequency instructing section  108 , which will be described later, to the client side CDR section  21 . 
     The network side CDR &amp; DRV section  50  has the same function as that of the client side CDR &amp; DRV section  20 . The network side oscillating section  60  has the same function as that of the client side oscillating section  30 . The network side input/output section  70  has the same function as that of the client side input/output section  10 . 
     The frame processing section  40  performs frame processing on an input signal. More specifically, the frame processing section  40  performs processing of adding control information, for example, to an input signal and constructing a frame structure (which will be called frame addition processing) under the control of the frame processing control section  110 , which will be described later. Alternatively, the frame processing section  40  performs processing of removing a frame from an input signal (which will be called frame removal processing). In particular, the frame processing section  40  performs frame processing based on the settings in a speed &amp; frequency setting data section  106 , which will be described later, controlled by the frame processing control section  110  and a frame processing setting data section  107  (or by using a monitor section compliant with the data protocol corresponding to an instructed frequency, for example). 
     Then, as shown in  FIG. 2 , the frame processing section  40  has processing sections compliant with data protocols (such as a SONET-related monitor section  41 , a data-related monitor section  42  and a video-related monitor section  43 ), an OTU-OH (Optical Channel Transport Unit_Over Head) adding section  44 , an FEC (Forward Error Correction) adding section  45 , an OTU-OH removing section  46 , an FEC removing section  47 , a speed converting section  48  and a speed converting section  49 . 
     The OTU-OH adding section  44  adds an OTU-OH for performing frame addition processing. The FEC adding section  45  adds an error correction function (FEC) for performing frame addition processing. The OTU-OH removing section  46  removes an OTU-OH for performing frame removal processing. The FEC removing section  47  removes an error correction function (FEC) for performing frame removal processing. The speed converting section  48  and the speed converting section  49  perform speed conversion on a signal input to the frame processing section  40 . For example, the speed converting section  48  and the speed converting section  49  has a voltage controlled crystal oscillator (VCXO). 
     The control section  100  has an internal memory for storing a control program, a program defining a routine, for example, and necessary data. The control section  100  is a processing section that performs various routines by the programs. According to this embodiment, the control section  100  mainly includes a CPU section  101 , a frequency setting section  102 , a state monitoring section  103 , a state storage section  104 , a supported frequency storage section  105 , a speed &amp; frequency setting data section  106 , and a frame processing setting data section  107 . 
     The supported frequency storage section  105  stores the frequency supported by the oscillating section. More specifically, the supported frequency storage section  105  stores all frequencies that the client side oscillating section  30  and/or the network side oscillating section  60  can output. Describing in particular, as shown in  FIG. 3 , the supported frequency storage section  105  stores on a “OSCILLATOR SUPPORTING FREQUENCY TABLE” the “HIGHEST FREQUENCY (MHz)” describing the highest frequency that the client side oscillating section  30  and/or the network side oscillating section  60  can output and the “LOWEST FREQUENCY (MHz)” describing the lowest frequency that the client side oscillating section  30  and/or the network side oscillating section  60  can output. 
     In the example shown in  FIG. 3 , the supported frequency storage section  105  stores “2666.325” as the “HIGHEST FREQUENCY (MHz)” and “621.9866” as the “LOWEST FREQUENCY (MHz)” on the “OSCILLATOR SUPPORTING FREQUENCY TABLE”. Notably,  FIG. 3  shows an example of the supported frequencies to be stored in the supported frequency storage section according to the first embodiment. 
     The state storage section  104  stores a result of the monitoring by the state monitoring section  103 , which will be described later. More specifically, as shown in  FIG. 4 , the state storage section  104  stores a “REFERENCE FREQUENCY (MHz) IN OSCILLATING SECTION” describing the frequency output from the client side oscillating section  30  to the client side CDR section  21  and a “CDR STATE” describing a result of the monitoring by the state monitoring section  103 , which will be described later, in connection with each other. The state storage section  104  further stores a “CENTER FREQUENCY” describing the center frequency in a frequency band calculated by the detecting section  109 , which will be described later, a “DEVIATION (ppm) FROM CENTER FREQUENCY” describing the deviation (ppm) from the center frequency calculated by the detecting section  109 , which will be described later, and a “WIDTH OF FREQUENCY BAND” describing the width of the frequency band calculated by the detecting section  109 , which will be described later, in connection with each other. 
     In the example shown in  FIG. 4 , the state storage section  104  stores “2666.325” and “Un-LOCK” as the “REFERENCE FREQUENCY (MHz) IN OSCILLATING SECTION” and the “CDR STATE”, respectively, in connection with each other. The state storage section  104  stores “2666.058”, “1100.3729 and −100.035” and “±100 ppm” as the “CENTER FREQUENCY”, the “DEVIATION (ppm) FROM CENTER FREQUENCY” and the “WIDTH OF FREQUENCY BAND”, respectively, in connection with each other. Notably,  FIG. 4  shows an example of the information on frequency synchronization stored in the state storage section according to the first embodiment. 
     The speed &amp; frequency setting data section  106  defines the setting controlled by the frame processing control section  110 , which will be described later, to the speed converting section  48 , speed converting section  49  and network side oscillating section  60 . More specifically, information on the frequency to be set is input from the frame processing control section  110  to the speed &amp; frequency setting data section  106 , which then defines the setting corresponding to the input frequency to the speed converting section  48 , speed converting section  49  and network side oscillating section  60 . 
     The frame processing setting data section  107  defines the setting controlled by the frame processing control section  110 , which will be described later, to the frame processing section  40 . More specifically, information on the frequency to be set is input from the frame processing control section  110  to the frame processing setting data section  107 , which then defines the setting corresponding to the input frequency to the frame processing section  40 . For example, the frame processing setting data section  107  defines the data protocol corresponding to the input frequency and defines the monitor section (such as the SONET-related monitor section) to be used in the frame processing section  40 . 
     The frequency setting section  102  defines an arbitrary frequency instructed by the frequency instructing section  108 , which will be described later, to the client side oscillating section  30 . 
     The state monitoring section  103  monitors whether the frequency output from the client side oscillating section  30  and an input signal synchronize in frequency or not in response to an instruction by the detecting section  109 , which will be described later. More specifically, in response to an instruction by the detecting section  109 , the state monitoring section  103  determines whether all of the frequencies sequentially output from the oscillating section in response to the instruction and an input signal synchronize in frequency or not and detects the frequency band for the synchronization. In particular, the state monitoring section  103  monitors whether the frequency output from the client side oscillating section  30  and an input signal synchronize in frequency (LOCK) or not and stores the “REFERENCE FREQUENCY IN OSCILLATING SECTION” and the “CDR STATE” in the state storage section  104  in connection with each other. 
     For example, the state monitoring section  103  outputs a frequency (such as “2666.325”) from the client side oscillating section  30  in response to an instruction by the detecting section  109 , which will be described later. After that, if the frequency and the input signal do not synchronize in frequency (LOCK), the output frequency (such as “2666.325”) and “Un-LOCK” in connection are stored in the state storage section  104 . In a case where a frequency (such as “2666.057”) is output from the client side oscillating section  30  and then synchronizes with an input signal in frequency (LOCK), the output frequency (such as “2666.057”) and “LOCK” in connection are stored in the state storage section  104 . 
     The CPU  101  is a control section that controls the transponder. The CPU section  101  has the frequency instructing section  108 , the detecting section  109 , the frame processing control section  110  and a frame processing monitoring section  111 . The frequency instructing section  108  and the frequency setting section  102  correspond to the claimed “frequency instruction processing section”. The detecting section  109  and the state monitoring section  103  correspond to the claimed “detection processing section”. The frame processing control section  110 , the speed &amp; frequency setting data section  106  and the frame processing setting data section  107  correspond to the claimed “frame processing section control section”. The frame processing monitoring section  111  corresponds to the claimed “monitoring section”. 
     The frequency instructing section  108  instructs an oscillating section to output an arbitrary frequency. More specifically, the frequency instructing section  108  instructs the client side oscillating section  30  to sequentially output all frequencies that the client side oscillating section  30  can output. In particular, the frequency instructing section  108  instructs the client side oscillating section  30  to sequentially output the “HIGHEST FREQUENCY” (or the “LOWEST FREQUENCY”) through the “LOWEST FREQUENCY” (or the “HIGHEST FREQUENCY”) stored in the supported frequency storage section  105 . 
     For example, when a signal is input to the client side O/E section  11 , the frequency instructing section  108  loads the “HIGHEST FREQUENCY 2666.325” (or “LOWEST FREQUENCY 621.9866”) stored in the supported frequency storage section  105  (refer to  FIG. 3 ). The frequency instructing section  108  instructs the frequency setting section  102  to sequentially output from the “HIGHEST FREQUENCY” (or the “LOWEST FREQUENCY”) loaded by the client side oscillating section  30 . As a result, the frequency setting section  102  sets a frequency to the client side oscillating section  30 . Then, the frequency instructing section  108  instructs the frequency setting section  102  to slightly decrease (or increase) the frequency set to the client side oscillating section  30  if all frequencies that the client side oscillating section  30  can output are not output. As a result, the frequency setting section  102  sets the frequency to the client side oscillating section  30  according to the instruction by the frequency instructing section  108 . 
     In particular, the frequency instructing section  108  instructs the frequency setting section  102  to slightly decrease (or increase) the frequency set to the client side oscillating section  30  if the frequency synchronization (LOCK) is detected by the detecting section  109 , which will be described later. On the other hand, if the frequency synchronization (LOCK) is not detected, the frequency instructing section  108  instructs the frequency setting section  102  to largely decrease (or increase) by the amount more than the amount of decrease when the frequency synchronization (LOCK) with the frequency set to the client side oscillating section  30  is detected. As a result, the frequency setting section  102  sets the frequency to the client side oscillating section  30  according to the instruction by the frequency instructing section  108 . 
     The detecting section  109  detects the synchronization frequency, which is a frequency synchronizing between the frequency output from an oscillating section in response to the instruction and an input signal. More specifically, the detecting section  109  detects the center frequency in the synchronizing frequency band as the synchronization frequency. If multiple synchronizing frequency bands are detected, the center frequency of the widest one of the detected multiple frequency bands is detected as the synchronization frequency. 
     In particular, the detecting section  109  detects the synchronizing frequency band based on the “REFERENCE FREQUENCY IN OSCILLATING SECTION” and “CDR STATE” stored in the state storage section  104  by the state monitoring section  103 . If one synchronizing frequency band is detected, the detecting section  109  detects the “CENTER FREQUENCY” in the frequency band as the synchronization frequency. If multiple synchronizing frequency bands are detected, the detecting section  109  calculates the “DEVIATION (ppm) FROM CENTER FREQUENCY” of the synchronization frequencies. Then, the “WIDTH OF FREQUENCY BAND (LOCK WIDTH)” is calculated, and the “CENTER FREQUENCY” describing the highest value in the calculated “FREQUENCY BAND (LOCK WIDTH)” as the synchronization frequency. In other words, the synchronization frequency is detected from the widest frequency band. 
     For example, describing with reference to the example shown in  FIG. 4 , the detecting section  109  detects the synchronizing frequency band (such as the frequency band at “2666.325” through “2665.79”) from the “REFERENCE FREQUENCY IN OSCILLATING SECTION” and the “CDR STATE” stored in the state storage section  104  by the state monitoring section  103 . Then, if one synchronizing frequency band is detected, the detecting section  109  detects the “CENTER FREQUENCY” (such as “2666.058”) as the synchronization frequency in the synchronizing frequency band (such as the frequency band at “2666.325” through “2665.79”). On the other hand, if multiple synchronizing frequency bands are detected (such as the frequency band at “2666.325” through “2665.79” and the frequency band at “622.1733 through “621.9867”), the detecting section  109  calculates the “CENTER FREQUENCIES” (such as “2666.058” and “622.08”) of the frequency bands. Then, the “DEVIATION (ppm) FROM CENTER FREQUENCY” of each of them is calculated, and the “WIDTH (LOCK WIDTH) OF FREQUENCY BAND” is calculated. For example, with reference to the “CENTER FREQUENCY: 2666.058”, the “DEVIATION (ppm) FROM CENTER FREQUENCY: 100.3729 through −100.035” is calculated, and the “WIDTH OF FREQUENCY BAND (LOCK WIDTH): ±100 ppm” is calculated. For example, with reference to the “CENTER FREQUENCY: 622.08”, the “DEVIATION (ppm) FROM CENTER FREQUENCY: 149.9807 through −149.981” is calculated, and the “WIDTH OF FREQUENCY BAND (LOCK WIDTH): ±150 ppm” is calculated. After that, the “WIDTHS OF FREQUENCY BAND (LOCK WIDTHS)” (such as “±100 ppm” and “±150 ppm” are compared, and the “CENTER FREQUENCY” (such as the “CENTER FREQUENCY: 622.08”) indicating the highest value (such as “±150 ppm”) in the calculated “WIDTH OF FREQUENCY BAND (LOCK WIDTH)” is detected as the synchronization frequency. 
     The detecting section  109  assumes the case where it is determined that the frame processing section  40  has an error in the processing based on the data protocol set by the frame processing control section  110 , which will be described later, and detects multiple synchronization frequencies. More specifically, in the processing of detecting synchronization frequencies, synchronization frequency candidates are also detected, which have higher possibilities of being the synchronization frequency. Then, if it is determined that the frame processing section  40  has an error, the detecting section  109  detects the synchronization frequency candidates as the multiple detected synchronization frequencies. 
     For example, describing with reference to the example shown in  FIG. 4 , the detecting section  109  loads and compares the “WIDTHS OF FREQUENCY BAND (LOCK WIDTHS)”, “±100 ppm” and “±150 ppm”, which are stored in connection with the “CENTER FREQUENCY” when the detecting section  109  detects the “CENTER FREQUENCIES” “2666.058” and “622.08”. Then, the detecting section  109  detects the “622.08” as the synchronization frequency and also detects “2666.058” as the synchronization frequency candidate. Then, the frame processing control section  110 , which will be described later, operates the frame processing section  40  based on the detected synchronization frequency “622.08”. After that, in a case where the frame processing monitoring section  111  monitors that the processing in the frame processing section  40  has an error, the detecting section  109  immediately detects the synchronization frequency candidate (such as “2666.058”) as the synchronization frequency. 
     The frame processing control section  110  operates the frame processing section based on the detected synchronization frequency. More specifically, the frame processing control section  110  operates the frame processing section  40  based on the synchronization frequency detected by the detecting section  109 . For example, when the detecting section  109  detects a synchronization frequency (such as “622.08”), the frame processing control section  110  controls the settings in the speed &amp; frequency setting data section  106  and the frame processing setting data section  107  so as to perform frame processing based on the detected synchronization frequency. As a result, the speed &amp; frequency setting data section  106  defines the speed converting section  48 , speed converting section  49  and network side oscillating section  60  (that is, sets the frequency to be output from the network side oscillating section  60 ) under the control of the frame processing control section  110 . The frame processing setting data section  107  defines the frame processing section  40  under the control of the frame processing control section  110 . For example, the frame processing setting data section  107  defines the data protocol corresponding to the input frequency. The frame processing setting data section  107  defines the monitor section (such as the SONET-related monitor section) to be used in the frame processing section  40 . 
     The frame processing control section  110  operates the frame processing section based on the next synchronization frequency candidate (such as “2666.058”) in a case where the frame processing monitoring section  111 , which will be described later, monitors an error. On the other hand, if no subsequent synchronization frequency candidates exist, the processing ends. 
     The frame processing monitoring section  111  monitors whether the processing by the frame processing section has an error or not after the frame processing section starts operating. More specifically, after the frame processing section  40  starts operating under the control of the frame processing control section  110 , the frame processing monitoring section  111  monitors whether the processing by the frame processing section has an error or not. For example, the synchronization frequency “622.08” is input from the frame processing control section  110  to the speed &amp; frequency setting data section  106  and the frame processing setting data section  107 . Then, the frame processing monitoring section  111  monitors whether the processing in the frame processing section  40  has an error or not after the frame processing based on the setting corresponding to the synchronization frequency “622.08” is started in the frame processing section  40 . 
     Processing by Transponder Unit 
     Next, with reference to  FIG. 5 , processing by the transponder unit will be described.  FIG. 5  is a flowchart showing processing by a scan method according to the first embodiment. 
     As shown in  FIG. 5 , if a signal is input to the client side O/E section (Yes in operation S 101 ), the frequency instructing section  108  loads the “HIGHEST FREQUENCY” (or “LOWEST FREQUENCY”) stored in the supported frequency storage section  105  (operation S 102 ). Then, the frequency is set to the oscillating section (operation S 103 ). In other words, the frequency instructing section  108  instructs the frequency setting section  102  such that the frequency setting section  102  can define the client side oscillating section  30  to sequentially output from the “HIGHEST FREQUENCY” (or “LOWEST FREQUENCY”) loaded from the supported frequency storage section  105 . Then, the client side oscillating section  30  outputs the set frequency (operation S 104 ). 
     Then, the state monitoring section  103  determines whether the input signal synchronizes with the frequency or not (operation S 105 ). Here, if the input signal synchronizes with the frequency (LOCK) (Yes in operation S 105 ), the state monitoring section  103  stores the output frequency (such as “2666.057”) in connection with “LOCK” in the state storage section  104  (operation S 106 ). On the other hand, if the input signal does not synchronize with the frequency (Un-LOCK) (No in operation S 105 ), the state monitoring section  103  stores the output frequency (such as “2666.325”) in connection with “Un-Lock” in the state storage section  104  (operation S 107 ). 
     Then, the frequency instructing section  108  determines whether all of the frequencies that the client side oscillating section  30  can output have been examined or not (operation S 108 ). Here, if all of the frequencies have not been examined (No in operation S 108 ), that is, all of the frequencies have not been output from the client side oscillating section  30  in response to the instruction by the frequency instructing section  108 , the frequency instructing section  108  instructs the frequency setting section  102  to slightly decrease (or increase) the frequency set to the client side oscillating section  30  (operation S 109 ). Then, the detecting section  109  examines the reset frequencies (operations S 103  to S 107 ). 
     Then, if all of the frequencies that the client side oscillating section  30  can output have been output in response to the instruction by the frequency instructing section  108 , and one synchronizing frequency band is detected (Yes in operation S 108  and Yes in operation S 110 ), the detecting section  109  detects the “CENTER FREQUENCY” in the frequency band as the synchronization frequency (operation S 111 ). 
     On the other hand, if all of the frequencies that the client side oscillating section  30  can output have been output in response to the instruction by the frequency instructing section  108  and multiple synchronizing frequency bands are detected (Yes in operation S 108  and No in operation S 110 ), the detecting section  109  calculates the widths of the frequency bands (operation S 112 ). That is, the “DEVIATION (ppm) FROM CENTER FREQUENCY” of each of the synchronizing frequencies is calculated, and the “WIDTH OF FREQUENCY BAND (LOCK WIDTH)” is calculated. Then, the detecting section  109  detects the synchronization frequency from the widest frequency band (operation S 113 ). That is, the “CENTER FREQUENCY” indicating the highest value among the calculated “WIDTHS OF FREQUENCY BANDS (LOCK WIDTHS)” is detected as the synchronization frequency. Then, the detecting section  109  detects the synchronization frequency and detects a synchronization frequency candidate (operation S 114 ). 
     Then, the frame processing control section  110  operates the frame processing section based on the detected synchronization frequency (operation S 115 ). Then, the frame processing monitoring section  111  monitors whether the frame processing section  40  has an error or not (operation S 116 ). Here, if an error in the frame processing section is monitored and there is a synchronization frequency candidate (Yes in operation S 116  and Yes in operation S 117 ), that is, if the frame processing monitoring section  111 , which will be described later, monitors that the processing in the frame processing section  40  has an error and the detecting section  109  has detected a synchronization frequency candidate, the detecting section  109  detects the synchronization frequency candidate (such as “2666.058”) as the synchronization frequency (operation S 118 ). 
     Then, if the frame processing section does not have an error (No in operation S 116 ) or if the frame processing section has an error but no synchronization frequency candidate exists (Yes in operation S 116  but No in operation S 117 ), the processing ends. 
     Effects of First Embodiment 
     As described above, according to the first embodiment, the transponder unit instructs an oscillating section to output an arbitrary frequency. Then, whether the frequency output from the oscillating section in response to the instruction and an input signal synchronize in frequency or not is determined, and the synchronization frequency is detected. Then, the frame processing section is operated based on the detected synchronization frequency. Thus, the transponder unit can detect the synchronizing frequency from an input signal and control the operation by the frame processing section. Therefore, the manual work for defining a data protocol to be used in the client can be reduced. 
     Further, according to the first embodiment, the transponder unit instructs an oscillating section to sequentially output all frequencies that the oscillating section can output. Then, whether each of all of the frequencies sequentially output from the oscillating section in response to the instruction synchronizes with an input signal or not is determined, and the synchronizing frequency band is detected. Since the transponder unit detects the center frequency in the synchronizing frequency band as the synchronization frequency, the synchronizing frequency can be detected by examining all of the supported frequencies, and the operation by the frame processing section can be controlled. Then, the manual work for defining a data protocol to be used in the client can be reduced. 
     According to the first embodiment, the transponder unit detects the center frequency in the widest frequency band among multiple detected frequency bands as the synchronization frequency if multiple synchronizing frequency bands are detected. Therefore, the frequency with the highest possibility of synchronizing most accurately among them can be detected even if multiple frequencies which synchronize with an input signal are detected. 
     According to the first embodiment, the transponder unit monitors whether the processing by the frame processing section has an error or not after the frame processing section starts operating and detects the synchronization frequency again if the occurrence of an error is determined. Then, the frame processing section is operated based on the synchronization frequency detected again. Therefore, an accurate synchronization frequency can be detected again even if an improper synchronization frequency is detected, and the operation can be controlled securely based on an input signal. 
     According to the first embodiment, the transponder unit also detects a synchronization frequency candidate, which is a frequency with a higher possibility of being a synchronization frequency, in detecting the synchronization frequency. Then, if the occurrence of an error is determined, the synchronization frequency candidate is detected as the synchronization frequency detected again. Therefore, quick processing can be implemented by defining other synchronization frequency candidate and controlling the operation even if an improper synchronization frequency is detected. 
     Second Embodiment 
     Having described the first embodiment where a synchronization frequency is detected by examining the synchronization with all of supported frequencies, embodiments are not limited thereto. A synchronization frequency may be detected by sampling an input signal. A case where a synchronization frequency is detected by sampling an input signal will be described as a second embodiment. The identical points to those of the transponder unit according to the first embodiment will be described briefly. 
     Configuration of Transponder Unit According to Second Embodiment 
     First of all, with reference to  FIG. 6 , a configuration of a transponder unit according to a second embodiment will be described.  FIG. 6  is a block diagram showing a configuration of the transponder unit according to the second embodiment. As shown in  FIG. 6 , a transponder unit  1  includes a client side input/output section  10 , a client side CDR &amp; DRV section  20 , a client side oscillating section  30 , a frame processing section  40 , a network side CDR &amp; DRV section  50 , a network side oscillating section  60 , a network side input/output section  70 , a sampling oscillating section  80  that outputs a sampling frequency to be used for sampling by a detecting section  109   b , which will be described later, and a control section  100 . 
     The same reference numerals are given to the same operations as those of the first embodiment, the description of which will be omitted herein. The sampling oscillating section  80 , a frequency instructing section  108   b , a detecting section  109   b , a sampling section  112  and a frequency calculating section  113  will be only described. 
     The sampling oscillating section  80  outputs a sampling frequency, which is a frequency set for sampling, to the sampling section  112  in response to the instruction by the frequency instructing section  108   b , which will be described later. 
     This embodiment describes a case where the sampling oscillating section  80  is provided separately from the client side oscillating section  30  and/or the network side oscillating section  60 . However, this embodiment is not limited to the case, in the alternative, the sampling oscillating section  80  may be provided unitedly with the client side oscillating section  30  and/or the network side oscillating section  60  and may output a sampling frequency to the sampling section  112 . 
     The sampling section  112  samples an input signal by using the sampling frequency in response to the instruction by the frequency instructing section  108   b , which will be described later. For example, as described in  FIG. 7A , the sampling frequency is used to obtain the sampling result including “0” and “1” (such as “0, 0, 1, 1, 1, 1, 1, 1 . . . in  FIG. 7A ) from the signal electrically converted by the client side O/E section  11  in response to the instruction by the frequency instructing section  108   b , which will be described later. 
     The frequency calculating section  113  identifies points of change from the sampling result in response to the instruction by the frequency instructing section  108   b , which will be described later. After that, the frequency calculating section  113  calculates the point-of-change cycle frequency, which is a point-of-change cycle, from the value of the sampling frequency and the points of change. 
     For example, as described in  FIG. 7B  the frequency calculating section  113  identifies the points of change where “0” is changed to “1” (or “1” to “0”) based on the sampling result (such as “0, 0, 1, 1, 1, 1, 1, 1 . . . ” in  FIG. 7A ) including “0” and “1” in response to the instruction by the frequency instructing section  108   b , which will be described later. The sampling result is detected in the sampling section  112  (refer to the arrow in  FIG. 7B ). After that, as described in  FIG. 7C , the point-of-change cycle frequency is calculated (such as 2 GHz/16=0.125 GHz=125 MHz) from the sampling result (such as “0, 0, 1, 1, 1, 1, 1, 1 . . . ”), the sampling frequency (such as 2 GHz) and the points of change (such as a cycle of 16). 
     The frequency instructing section  108   b  samples an input signal by using the sampling frequency, identifies the points of change from the sampling result, and calculates the point-of-change cycle frequency, which is a cycle of points of change, from the value of the sampling frequency and the points of change. Then, the frequency instructing section  108   b  further instructs the oscillating section to output the calculated point-of-change cycle frequency. 
     For example, when a signal is input to the client side O/E section, the frequency instructing section  108   b  inputs the input signal to the sampling section  112 . Then, the sampling oscillating section  80  instructs the sampling section  112  to output a sampling frequency. As a result, the sampling oscillating section  80  outputs the sampling frequency to the sampling section  112 . 
     Then, the frequency instructing section  108   b  instructs the sampling section  112  to sample the input signal. As a result, the sampling section  112  samples the input signal (refer to  FIG. 7A ). Then, the frequency instructing section  108   b  instructs the frequency calculating section  113  to identify points of change from the obtained sampling result and calculate the point-of-change cycle frequency. As a result, the frequency calculating section  113  identifies the points of change from the obtained sampling result. 
     Then, the frequency calculating section  113  calculates the point-of-change cycle frequency from the obtained sampling result, the sampling frequency (such as 2 GHz) and points of change (such as a cycle of 16). In other words, the frequency calculating section  113  calculates a frequency with a higher possibility of being a point-of-change cycle frequency from the sampling result, the sampling frequency and the points of change. The frequency calculating section  113  further calculates, as the point-of-change cycle frequency the frequency closest to the frequency information stored in the supported frequency storage section  105 . 
     Then, the frequency instructing section  108   b  instructs the frequency setting section  102  to output the calculated point-of-change cycle frequency from the client side oscillating section  30 . The frequency instructing section  108   b  assumes a case where outputting a harmonic of the point-of-change cycle frequency calculated by the detecting section  109   b , which will be described later, from the client side oscillating section  30  is instructed and calculates the harmonic as a synchronization frequency candidate from the calculated point-of-change cycle frequency. 
     With reference to  FIGS. 8A to 8D , for example, the calculation of a harmonic by the frequency instructing section  108   b  will be described. The frequency instructing section  108   b  is instructed to calculate a harmonic by the detecting section  109   b , which will be described later. The frequency instructing section  108   b , as shown in  FIG. 8A , determines that the point of change cycle frequency (such as 125 MHz) calculated from the sampling result (such as “0, 0, 1, 1, 1, 1, 1, 1 . . . ”), the sampling frequency (such as 2 GHz) and the points of change (such as a cycle of 16) is a bit rate of a low frequency. In other words, as shown in  FIGS. 8A to 8D , the frequency instructing section  108   b  determines that it is not the cycle of an input signal (which is a cycle that “1” and “0” change alternately). 
     As a result, as shown in  FIGS. 8C and 8D , the frequency instructing section  108   b  determines that the calculated point-of-change cycle frequency is a frequency exhibiting the cycle of a series of multiple “1” or “0” and calculates a harmonic as a synchronization frequency candidate. In other words, in the example shown in  FIG. 8C , for example, the frequency instructing section  108   b  determines the frequency having a series of two “1” and two “0” and calculates 250 MHz, which is twice as high as 125 MHz. In the example shown in  FIG. 8D , the frequency instructing section  108   b  determines the frequency having a series of three “1” and “0” and calculates 375 MHz, which is triple as high as 125 MHz. 
     The frequency instructing section  108   b  instructs the frequency setting section  102  to output the calculated harmonic from the client side oscillating section  30  in response to the instruction to output the harmonic of the point-of-change cycle frequency calculated by the detecting section  109 , which will be described later, from the client side oscillating section  30 . 
     The detecting section  109   b  determines whether the point-of-change cycle frequency output from the oscillating section in response to the instruction and an input signal synchronize in frequency or not. If so as a result of the determination, the point-of-change cycle frequency is detected as the synchronization frequency. If not, on the other hand, the detecting section  109   b  causes the frequency instructing section  108   b  to set the harmonic of the point-of-change cycle frequency to the oscillating section and determines whether the harmonic and an input signal synchronize in frequency or not again. 
     More specifically, the detecting section  109   b  determines whether the point-of-change cycle frequency (such as 125 MHz) output by the client side oscillating section  30  and an input signal synchronize in frequency or not. Then, if so, the detecting section  109   b  detects the point-of-change cycle frequency (such as 125 MHz) as the synchronization frequency. If not, on the other hand, the detecting section  109   b  causes the frequency instructing section  108   b  to calculate a harmonic of the point-of-change cycle frequency (such as 250 MHz), causes the client side oscillating section  30  to output the harmonic and performs the determination again. 
     Processing By Sampling Method According To Second Embodiment 
     Next, with reference to  FIG. 9 , the processing by the sampling method according to the second embodiment will be described.  FIG. 9  is a flowchart showing processing by the sampling method according to the second embodiment. 
     The frequency instructing section  108   b  inputs the input signal to the sampling section  112  (operation S 202 ) in response to a signal input to the client side OIL/E section  11  (Yes in operation S 201 ). Then, the frequency instructing section  108   b  samples the input signal (operation S 203 ). In other words, the frequency instructing section  108   b  instructs the sampling oscillating section  80  to output a sampling frequency to the sampling section  112  and instructs the sampling section  112  to sample the input signal (refer to ( 1 ) in  FIG. 7A ). 
     Then, the frequency instructing section  108   b  identifies the points of change (operation S 204 ). In other words, the frequency instructing section  108  instructs the frequency calculating section  113  to identify the points of change from the obtained sampling result. Then, the frequency instructing section  108   b  calculates the point-of-change cycle frequency (operation S 205 ). In other words, the frequency instructing section  108   b  instructs the frequency instructing section  108   b  to calculate the point-of-change cycle frequency from the obtained sampling frequency (such as 2 GHz) and the point of change (such as a cycle of 16). Then, the frequency instructing section  108   b  detects the synchronization frequency and also detects a synchronization frequency candidate (operation S 206 ). Then, the frequency instructing section  10   b  instructs the frequency setting section  102  to define the client side oscillating section  30  to output the detected point-of-change cycle frequency (operation S 207 ). Then, the client side oscillating section  30  outputs the set frequency (operation S 208 ). 
     Then, the detecting section  109   b  determines whether the set frequency can be the synchronization frequency or not (operation S 209 ). Here, if so (Yes in operation S 209 ), the detecting section  109   b  detects the point-of-change cycle frequency (such as 125 MHz) as the synchronization frequency (operation S 211 ). If not, on the other hand (No in operation S 209 ), the detecting section  109   b  sets a harmonic (operation S 210 ) and causes to output the set frequency and determines the synchronization in frequency (operation S 208  to S 209 ). In other words, the detecting section  109   b  causes the frequency instructing section  108   b  to calculate a harmonic of the point-of-change cycle frequency and causes to output the frequency from the client side oscillating section  30  and performs the determination again. 
     Then, the frame processing control section  110  performs frame processing based on the detected synchronization frequency and exits the processing (operation S 212  to the end). 
     Effects of Second Embodiment 
     As described above, according to the second embodiment, the transponder unit samples an input signal by using a sampling frequency, identifies points of change from the sampling result, calculates the point-of-change cycle frequency from the value of the sampling frequency and the points of change, instructs an oscillating section to output the point-of-change cycle frequency, determines whether the point-of-change cycle frequency output from the oscillating section in response to the instruction and an input signal synchronize in frequency or not and, if so, detects the point-of-change cycle frequency as the synchronization frequency. If not, on the other hand, a harmonic of the point-of-change cycle frequency is set to the oscillating section through frequency instructing means, and whether the frequency synchronizes with an input signal or not is determined again. Therefore, the transponder unit can securely detect the frequency in synchronization with an input signal and can control operations. The transponder unit further can detect the synchronizing frequency accurately independent of the state of data (such as a series of multiple “1”) at the sampled frequency. The transponder unit further can reduce the manual work for defining the data protocol to be used in a client. 
     Third Embodiment 
     Having described the transponder units according to the first and second embodiments above, embodiments may be implemented in various different forms excluding the embodiments above. A transponder unit according to a third embodiment in a different form will be described below. 
     Having described the first and second embodiments in which the processing section corresponding to each data protocol can operate at all times, embodiments are not limited thereto. After the setting relating to an input signal is performed, unnecessary processing sections may be terminated. 
     More specifically, a transponder unit may terminate a processing section, which is not necessary for the processing based on a synchronization frequency, in a case where a frame processing section is operated based on the synchronization frequency. For example, describing with reference to the example shown in  FIG. 2 , in a case where an input signal is SONET-related data and in a case where the frame processing section  40  is controlled by the frame processing control section  110  based on the setting corresponding to the SONET-related data, the data-related monitor section  42  and video-related monitor section  43  are terminated, which are unnecessary processing sections for the processing based on SONET-related data. 
     In this way, the transponder unit terminates an unnecessary processing section for the processing based on a synchronization frequency in a case where a frame processing section is operated based on the synchronization frequency. Therefore, the energy consumption by the transponder unit can be reduced, which can implement the processing with a higher energy efficiency. 
     Having described the first embodiment in a case where the transponder unit detects a synchronization frequency and also detects a synchronization frequency candidate, embodiments are not limited thereto. If the occurrence of an error is determined, a synchronization frequency may be detected again from the beginning. Having described the case where the occurrence of an error is monitored by the frame processing monitoring section  111  and processing ends if no synchronization frequency candidate is detected, embodiments are not limited thereto. A synchronization frequency may be detected again from the beginning. 
     The processing routines, control routines, specific names, information including data and parameters (such as  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 6 ,  FIG. 7 ,  FIG. 8 ,  FIG. 9  and  FIG. 10 ) may be changed arbitrarily unless otherwise noted. 
     The components of the shown apparatus are functionally conceptual and do not always have to be physically configured as shown. In other words, the specific forms of the distribution/unity of apparatus are not limited to those shown in the figures. All or a part of the shown components may be physically distributed or united functionally or physically in arbitrary units according to the various loads and state of use (for example, in  FIG. 2 , the frequency setting section  102  and the frequency instructing section  108  may be united, the state monitoring section  103  and the detecting section  109  may be united, the speed &amp; frequency setting data section  106 , the frame processing setting data section  107  and the frame processing control section  110  may be united, and the transponder unit  1  and the control section  100  may be separated). All or any part of the processing functions to be performed in the apparatus may be implemented by a CPU and programs to be analyzed and executed by the CPU or may be implemented as hardware based on Wired Logic. 
     Program for Transponder Unit 
     Having described the case where the processing is implemented by a hardware logic according to the first embodiment, embodiments are not limited thereto. The processing may be implemented by executing a prepared program in a computer. With reference to  FIG. 10 , an example of a computer that executes a transponder unit control program having the same functions as those of the transponder unit according to the first embodiment will be described.  FIG. 10  is a diagram showing a program for the transponder unit according to the first embodiment. 
     As shown in  FIG. 10 , a transponder unit includes a client side E/O section  3001 , a client side O/E section  3002 , a client side CDR &amp; DRV section  3003 , a frame processing section  3004 , a network side E/O section  3005 , a network side O/E section  3006 , a network side CDR &amp; DRV section  3007 , a CPU  3110 , a ROM  3111 , an HDD  3112  and a RAM  3113 , which are connected via a bus  3008 . 
     The ROM  3111  stores control programs that function the same as those of the frequency instructing section  108 , the detecting section  109 , the frame processing control section  110 , and the frame processing monitoring section  111  according to the first embodiment. In other words, as shown in  FIG. 10 , the ROM  3111  prestores a frequency instruction program  3111   a , a detection program  3111   b , a frame processing control program  3111   c  and a frame processing monitoring program  3111   d . Notably, these programs  3111   a  to  3111   d  may be united or separated as required, like the components of the transponder unit shown in  FIG. 2 . 
     The CPU  3110  loads and executes the programs  3111   a  to  311   d  from the ROM  3111  so that the programs  3111   a  to  3111   d  can function as a frequency instruction process  3110   a , a detection process  3110   b , a frame processing control process  3110   c  and a frame processing monitoring process  3110   d , as shown in  FIG. 10 . The processes  3110   a  to  3110   d  correspond to the frequency instructing section  108 , the detecting section  109 , the frame processing control section  110  and the frame processing monitoring section  111 , respectively, shown in  FIG. 2 . 
     The CPU  3110  further executes a transponder control program based on synchronization frequency data  3113   a  and supported frequency data  3113   b  stored in the RAM  3113 . 
     It should be noted that the programs  3111   a  to  3111   d  according to this embodiment are not always required to store in the ROM from the beginning. For example, the programs may be stored in a “portable physical medium” such as a memory card, a flexible disk, a CD-ROM, an MO disk, a DVD, a magnetooptical disk and an IC card to be inserted to the transponder unit, a “fixed physical medium” such as an HDD internally or externally provided to the transponder unit or “other computer (or server)” connecting to the transponder unit over a public line, the Internet, a LAN or WAN, for example. Then, the transponder unit may load and execute the programs from the medium. 
     Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.