fig1 is a schematic diagram illustrating an application environment of a system for testing a video signal generator ( hereinafter , “ the system ”) in accordance with one embodiment . the system typically includes a computer 1 , a video signal generator 2 and a standard measuring apparatus 3 . the computer 1 includes two ports : a first com port and a second com port . the video signal generator 2 includes at least one com port 20 that is connected with the first com port of the computer 1 via a first data line 5 . the standard measuring apparatus 3 includes , but not limited to , a com port 30 that is connected with the second com port of the computer 1 via a second data line 6 . the video signal generator 2 is electronically linked with the standard measuring apparatus 3 via a plurality of conducting lines 4 . in the preferred embodiment , the computer 1 is installed with a test program 10 , which can provide a graphical user interface on the computer 1 for setting test parameters . the test parameters include voltage - test parameters and frequency - test parameters . the computer 1 invokes the test program 10 that transmits the test parameters to the video signal generator 2 via the com port 20 , and performs various function tests on the video signal generator 2 . the function tests may include a voltage test and a frequency test . for example , the “ chroma 2326 ” is used to illustrate the video signal generator 2 . the “ chroma 2326 ” typically includes three channels : a red channel ( hereinafter “ r channel ”), a green channel ( hereinafter “ g channel ”), and a blue channel ( hereinafter “ b channel ”). the video signal generator 2 is connected to the r channel , the g channel , and the b channel of the standard measuring apparatus 3 correspondingly via the conducting lines 4 . if the operator wants to perform the voltage test on the video signal generator 2 , a data collector is adopted as the standard measuring apparatus 3 . if the operator wants to perform the frequency test , a cymometer is adopted as the standard measuring apparatus 3 . as known in the art , the video signal generator 2 corresponds to a standard working range . the standard working range generally includes a maximum voltage value , a minimum voltage value , a maximum frequency value , and a minimum frequency value . fig2 is a schematic diagram of software function modules of the test program 10 in fig1 . the test program 10 typically includes a detecting module 100 , a setting module 102 , a test module 104 , a value receiving module 106 , a report generating module 108 , and a calibrating module 110 . the detecting module 100 is configured for detecting whether the computer 1 has successfully connected with the standard measuring apparatus 3 , and alerting the operator of a connection error if the computer 1 is not connected with the standard measuring apparatus 3 . otherwise , if the detecting module 100 detects that the computer 1 has successfully connected with the standard measuring apparatus 3 , the computer 1 remotely controls the standard measuring apparatus 3 to receive signals via the second data line 6 . the setting module 102 is configured for setting the test parameters to test the functions of the video signal generator 2 . the test parameters include the voltage - test parameters and the frequency - test parameters . in the preferred embodiment , the data collector is adopted as the standard measuring apparatus 3 to perform the voltage test on the video signal generator 2 . the setting module 102 is configured for setting the voltage - test parameters and initializing the data collector to receive the signals output by the video signal generator 2 . the voltage - test parameters typically include an offset of a direct current of rgb ( red , green , blue ) pictures ( depicted as “ dc offset ( r , g , b )”), a synchronous level of the green picture ( depicted as “ sync level ( g )”), luminances and chromatism values of the rgb pictures . in another preferred embodiment , the cymometer is adopted as the standard measuring apparatus 3 to perform the frequency test of the video signal generator 2 . the setting module 102 is configured for setting the frequency - test parameters by selecting a test frequency stored in the video signal generator 2 , and setting a functional mode of the cymometer to a mode of a phase locked logic unit ( hereinafter “ pll unit ”). the test module 104 is configured for performing the voltage test or the frequency test based on the test parameters set by the setting module 102 . namely , the video signal generator 2 receives the test parameters from the setting module 102 , and generates signals according to the test parameters . the test module 104 controls the standard measuring apparatus 3 to receive the signals through the r channel , the g channel , and the b channel , to convert the signals into test values , and to transmit the test values to the computer 1 . the test values may be voltage values or frequencies . the value receiving module 106 is configured for receiving the test values from the test module 104 . the report generating module 108 is configured for determining whether the video signal generator 2 passes the function test by comparing the test values with the standard working range , and for generating a test report based on the test values , the test parameters , and the standard working range of the video signal generator 2 . if the video signal generator 2 does not pass the function test , the calibrating module 110 is configured for calibrating the test values according to the standard working range , sending the calibrated voltage values to the video signal generator 2 in order to calibrate the video signal generator 2 , and obtaining a calibrated result . the report generating module 108 is further configured for updating the test report according to the calibrated result . fig3 is a schematic diagram illustrating a partial test report of the voltage test . in the preferred embodiment , the type of the test report is not limited to the type of the partial test report of fig3 . fig4 is a flowchart of a preferred method for testing a video signal generator in accordance with another embodiment . the present embodiment gives an example for describing a method of a voltage test . before testing the video signal generator 2 , the operator connects the computer 1 with the video signal generator 2 and the standard measuring apparatus 3 as described above in fig1 . in the preferred embodiment , the standard measuring apparatus 3 is the data collector . the computer 1 invokes the test program 10 for remotely controlling the video signal generator 2 via the first data line 5 , and controlling the data collector via the second data line 6 so as to perform the voltage test on the video signal generator 2 . in step s 400 , the detecting module 100 detects whether the computer 1 has successfully connected with the data collector , and alerting the operator of the connection error if the computer 1 is not connected with the data collector . otherwise , if the detecting module 100 detects the computer 1 has successfully connected with the data collector , in step s 402 , the setting module 102 sets the voltage - test parameters , and initializes the data collector for receiving the signals output by the video signal generator 2 . the voltage - test parameters typically include the dc offset ( r , g , b ), the sync level ( g ), the luminances and the chromatism values of the rgb pictures . in step s 404 , the test module 104 performs the voltage test based on the test parameters . namely , the video signal generator 2 receives the test parameters from the setting module 102 of the computer 1 , and generates the signals according to the test parameters . in step s 406 , the test module 104 controls the data collector to receive the signals through the r channel , the g channel , and the b channel , to convert the signals to test values , and to transmit the test values to the computer 1 . the value receiving module 106 receives the test values from the data collector . in the step s 406 , the test values are voltage values . in step s 408 , the report generating module 108 determines whether the video signal generator 2 passes the voltage test by comparing the voltage values with the standard working range . if the video signal generator 2 passes the voltage test , namely the voltage values are within the standard working range , in step s 410 , the report generating module 108 generates the test report based on the voltage values , the voltage - test parameters and the standard working range of the video signal generator 2 . otherwise , if the voltage values are not within the standard working range , namely the video signal generator 2 does not pass the voltage test , in step s 412 , the calibrating module 110 calibrates the test values according to the standard working range , sends the calibrated voltage values to the video signal generator 2 in order to calibrate the video signal generator 2 , and obtains a calibrated result . in step s 414 , the report generating module 108 updates the test report according to the calibrated result . that is , after the video signal generator 2 receives the calibrated voltage values , if the test values are also not within the standard working range , the video signal generator 2 does not pass the function test . that is , the calibrated result is that the video signal generator 2 is an ineligible signal generator . otherwise , after the video signal generator 2 receives the calibrated voltage values , if the test values are within the standard working range , the calibrated result is that the video signal generator 2 is an eligible signal generator . when the operator wants to perform the frequency - test , the cymometer is adopted as the standard measuring apparatus 3 . the method for testing the frequency of the cymometer is similar to the method for testing the voltage of the data collector , excepting for the step s 402 and step s 406 of fig4 . that is , in step s 402 , the setting module 102 sets the frequency - test parameters by selecting a test frequency stored in the video signal generator 2 , and sets the functional mode of the cymometer as the mode of the pll unit . for example , the video signal generator 2 has multiple frequencies , for example , 125 mhz , 137 . 5 mhz , 150 mhz , and 162 . 5 mhz , to be selected by the setting module 102 . in step s 406 , the test values are frequencies . it should be emphasized that the above - described embodiments of the present invention , particularly , any “ preferred ” embodiments , are merely possible examples of implementations , merely set forth for a clear understanding of the principles of the invention . many variations and modifications may be made to the above - described embodiment ( s ) of the invention without departing substantially from the spirit and principles of the invention . all such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims .