Superposed signal sampling apparatus and sampling method

1. A superposed signal sampling apparatus, configured to extract a direct current signal from a superposed signal, wherein the apparatus comprise a processor configured to:

receive a superposed signal;

determine whether the received superposed signal is within a preset threshold range of a direct current signal; wherein if the received superposed signal is within the threshold range, the signal extracting module will extract a previously received signal as a direct current signal to be output; and if the received superposed signal is beyond the threshold range, the signal extracting module will extract a currently received signal as a direct current signal to be output;

integrate the direct current signal extracted by the signal extracting module, and then output the direct current signal; and

perform filtering processing on the superposed signal received by the signal receiving module.

2. The superposed signal sampling apparatus according to claim 1 , wherein the processor comprises a window filter.

3. The superposed signal sampling apparatus according to claim 1 , wherein the superposed signal is a HART protocol signal.

4. The superposed signal sampling apparatus according to claim 3 , wherein the processor is further configured to determine whether the received HART protocol signal is performing HART communication; wherein if the HART protocol signal is not performing HART communication, the processor will extract the currently received signal as a direct current signal to be output; and if the HART protocol signal is performing HART communication, the processor will continue to perform determining of the foregoing threshold range.

5. The superposed signal sampling apparatus according to claim 2 , wherein the superposed signal is a HART protocol signal.

6. A superposed signal sampling method, used to extract a direct current signal from a superposed signal, wherein the method comprises:

(a) receiving a superposed signal;

(b) determining whether the received superposed signal is within a preset threshold range of a direct current signal; if the received superposed signal is within the threshold range, performing step (c); otherwise, performing step (d);

(c) extracting a previously received signal as a direct current signal to be output;

(d) extracting a currently received signal as a direct current signal to be output;

(e) integrating the direct current signal extracted in step (c) or (d), and then outputting the direct current signal, and returning to step (a),

wherein, prior to step (b) filtering processing on the received superposed signal is performed.

7. The superposed signal sampling method according to claim 6 , wherein the filtering processing is a window filtering processing.

8. The superposed signal sampling method according to claim 6 , wherein the superposed signal is a HART protocol signal.

9. The superposed signal sampling method according to claim 8 , before step (b), further comprising the following step: determining whether the received HART protocol signal is performing HART communication; if the received HART protocol signal is performing HART communication, performing step (b); otherwise, performing step (d).

10. The superposed signal sampling method according to claim 7 , wherein the superposed signal is a HART protocol signal.