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| Rev 690 | Rev 711 | ||
|---|---|---|---|
| Line 104... | Line 104... | ||
| 104 | else // within the PPM frame |
104 | else // within the PPM frame |
| 105 | { |
105 | { |
| 106 | if(index < 10) // channel limit is 9 because of the frame length of 22.5 ms |
106 | if(index < 10) // channel limit is 9 because of the frame length of 22.5 ms |
| 107 | { |
107 | { |
| 108 | // check for valid signal length (0.8 ms < signal < 2.1984 ms) |
108 | // check for valid signal length (0.8 ms < signal < 2.1984 ms) |
| - | 109 | // signal range is from 1.0ms/3.2us = 312 to 2.0ms/3.2us = 625 |
|
| 109 | if((signal > 250) && (signal < 687)) |
110 | if((signal > 250) && (signal < 687)) |
| 110 | { |
111 | { |
| - | 112 | // shift signal to zero symmetric range -154 to 159 |
|
| 111 | signal -= 466; // offset of 1.4912 ms ??? (469 * 3.2µs = 1.5008 ms) |
113 | signal -= 466; // offset of 1.4912 ms ??? (469 * 3.2µs = 1.5008 ms) |
| 112 | // check for stable signal |
114 | // check for stable signal |
| 113 | // the deviation of the current signal level from the average must be less than 6 (aprox. 1%) |
115 | // the deviation of the current signal level from the average must be less than 6 (aprox. 1%) |
| 114 | if(abs(signal - PPM_in[index]) < 6) |
116 | if(abs(signal - PPM_in[index]) < 6) |
| 115 | { |
117 | { |
| 116 | // a good signal condition increases SenderOkay by 10 |
118 | // a good signal condition increases SenderOkay by 10 |
| 117 | // SignalOkay is decremented every 2 ms in timer0.c |
119 | // SignalOkay is decremented every 2 ms in main.c |
| 118 | // this variable is a level for the average rate of noiseless signal |
120 | // this variable is a level for the average rate of a noiseless rc signal |
| 119 | if(SenderOkay < 200) SenderOkay += 10; |
121 | if(SenderOkay < 200) SenderOkay += 10; |
| 120 | } |
122 | } |
| 121 | // calculate exponential history for signal |
123 | // calculate exponential history for signal |
| 122 | tmp = (3 * (PPM_in[index]) + signal) / 4; |
124 | tmp = (3 * (PPM_in[index]) + signal) / 4; |
| 123 | if(tmp > signal+1) tmp--; else |
125 | if(tmp > signal+1) tmp--; else |