ERM HR C6000, Руководство пользователя

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this time passes 7 times. The extraction of the symbol rate hardly determines the golay decoding to
select the best one.
The detailed usage is detailed in Appendix A2.2.2.
6.2.3 DTMF reception
The demodulation process of DTMF analyzes the air signal frequency distribution and reverse
decodes according to the DTMF combination. Calculate the frequency response amplitude of the air
signal at 8 groups of frequencies, and select the maximum amplitude in the high frequency part and
the maximum amplitude in the low frequency part respectively. A combination of the two can
determine the DTMF code.
At the end of each set of DTMF decoding, a system interrupt will be generated, and a flag
indicating whether the DTMF detection is complete. After receiving the interrupt, the peripheral
saves the DTMF code in a buffer area, and when a certain interrupt comes and the detection end
flag information is valid, all the previously stored DTMF codes are combined into one frame
output.
Figure 6.13 DTMF Receive Block Diagram
The detailed usage is detailed in Appendix A2.2.3.
6.2.4 2-tone reception
2-tone's demodulation mechanism is similar to address matching, and the voice path can only be
turned on when 2-tone matches the receive address setting. 2-tone contains two sets of tones or a set
of long tones, so each time the match is correct, the demodulation coefficient is set to the
corresponding value of the next set of received frequency points. In addition, a timeout mechanism
is added to the module. If the frequency point cannot be matched for a long time, the previous result
is cleared and the matching process is restarted.
OMISSIS
Figure 6.14 2-tone Receiver Block Diagram
The detailed usage is detailed in Appendix A2.2.4.
6.2.5 5-tone reception
The 5-tone reception process is the same as 2-tone, and is distinguished by different register control
bits. The detailed usage is detailed in Appendix A2.2.5.