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| 1 | +# 7. Dedispersion |
| 2 | + |
| 3 | +## 7.1 Introduction |
| 4 | + |
| 5 | +- Pulsars produce a narrow beam of electromagnetic |
| 6 | +radiation which rotates like a lighthouse beam, so |
| 7 | +a pulse is seen as it sweeps over a radiotelescope. |
| 8 | +The signal is spread over a wide frequency range. |
| 9 | + |
| 10 | +- If space was an empty vacuum, all the signals would |
| 11 | +travel at the same speed, but due to free electrons |
| 12 | +different frequencies travel at slightly different speeds |
| 13 | +(dispersion). |
| 14 | + |
| 15 | +## 7.2 Dedisperse |
| 16 | + |
| 17 | +This method performs dedispersion on the filterbank data. |
| 18 | + |
| 19 | +### 7.2.1 Parameters |
| 20 | + |
| 21 | +| Parameters | Description | |
| 22 | +|---|---| |
| 23 | +| Samples | Array or sequence containing the data to be plotted. | |
| 24 | +| DM | Dispersion measure (cm<sup>-3</sup> pc) | |
| 25 | + |
| 26 | +### 7.2.2 Returns |
| 27 | + |
| 28 | +| Variable | Description | |
| 29 | +|---|---| |
| 30 | +| Samples | Dedispersed samples | |
| 31 | + |
| 32 | +## 7.3 find_dm |
| 33 | + |
| 34 | +This method finds the dispersion measure. |
| 35 | + |
| 36 | +### 7.3.1 Parameters |
| 37 | + |
| 38 | +| Parameters | Description | |
| 39 | +|---|---| |
| 40 | +| Samples | 1-D array or sequence. Array or sequence containing the data to be plotted. | |
| 41 | + |
| 42 | +### 7.3.2 Returns |
| 43 | + |
| 44 | +| Variable | Description | |
| 45 | +|---|---| |
| 46 | +| dm | Dispersion measure | |
| 47 | + |
| 48 | +## 7.4 find_line |
| 49 | + |
| 50 | +This method finds a line starting from the sample index given in the parameters. This will stop if there isn't a intensity within the max_delay higher than the average_intensity. |
| 51 | + |
| 52 | +### 7.4.1 Parameters |
| 53 | + |
| 54 | +| Parameters | Description | |
| 55 | +|---|---| |
| 56 | +| Samples | 1-D array or sequence. Array or sequence containing the data to be plotted. | |
| 57 | +| start_sample_index | The start sample index | |
| 58 | +| max_delay | The max delay of the recieved signal | |
| 59 | +| average_intensity | The average intensity | |
| 60 | + |
| 61 | +### 7.4.2 Returns |
| 62 | + |
| 63 | +| Variable | Description | |
| 64 | +|---|---| |
| 65 | +| start_sample_index | The first frequency | |
| 66 | +| previous_sample_index | The higher frequency | |
| 67 | + |
| 68 | +## 7.5 find_estimation_intensity |
| 69 | + |
| 70 | +This method finds the average intensity for top x intensities. |
| 71 | +The `average_intensity` is considered a requirement for intensities to be considered a pulsar. |
| 72 | + |
| 73 | +### 7.5.1 Parameters |
| 74 | + |
| 75 | +| Parameters | Description | |
| 76 | +|---|---| |
| 77 | +| Samples | Array or sequence containing the data to be plotted. | |
| 78 | + |
| 79 | +### 7.5.2 Returns |
| 80 | + |
| 81 | +| Variable | Description | |
| 82 | +|---|---| |
| 83 | +| average_intensity | The avarage intesity | |
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