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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
3 | .. _frontend-stat-properties: | |
4 | ||
5 | ****************************** | |
6 | Frontend statistics indicators | |
7 | ****************************** | |
8 | ||
9 | The values are returned via ``dtv_property.stat``. If the property is | |
10 | supported, ``dtv_property.stat.len`` is bigger than zero. | |
11 | ||
12 | For most delivery systems, ``dtv_property.stat.len`` will be 1 if the | |
13 | stats is supported, and the properties will return a single value for | |
14 | each parameter. | |
15 | ||
16 | It should be noted, however, that new OFDM delivery systems like ISDB | |
17 | can use different modulation types for each group of carriers. On such | |
18 | standards, up to 3 groups of statistics can be provided, and | |
19 | ``dtv_property.stat.len`` is updated to reflect the "global" metrics, | |
20 | plus one metric per each carrier group (called "layer" on ISDB). | |
21 | ||
22 | So, in order to be consistent with other delivery systems, the first | |
e8be7e97 | 23 | value at :c:type:`dtv_property.stat.dtv_stats <dtv_stats>` array refers |
5377d91f MH |
24 | to the global metric. The other elements of the array represent each |
25 | layer, starting from layer A(index 1), layer B (index 2) and so on. | |
26 | ||
27 | The number of filled elements are stored at ``dtv_property.stat.len``. | |
28 | ||
29 | Each element of the ``dtv_property.stat.dtv_stats`` array consists on | |
30 | two elements: | |
31 | ||
32 | - ``svalue`` or ``uvalue``, where ``svalue`` is for signed values of | |
33 | the measure (dB measures) and ``uvalue`` is for unsigned values | |
34 | (counters, relative scale) | |
35 | ||
36 | - ``scale`` - Scale for the value. It can be: | |
37 | ||
38 | - ``FE_SCALE_NOT_AVAILABLE`` - The parameter is supported by the | |
39 | frontend, but it was not possible to collect it (could be a | |
40 | transitory or permanent condition) | |
41 | ||
42 | - ``FE_SCALE_DECIBEL`` - parameter is a signed value, measured in | |
43 | 1/1000 dB | |
44 | ||
45 | - ``FE_SCALE_RELATIVE`` - parameter is a unsigned value, where 0 | |
46 | means 0% and 65535 means 100%. | |
47 | ||
48 | - ``FE_SCALE_COUNTER`` - parameter is a unsigned value that counts | |
49 | the occurrence of an event, like bit error, block error, or lapsed | |
50 | time. | |
51 | ||
52 | ||
53 | .. _DTV-STAT-SIGNAL-STRENGTH: | |
54 | ||
55 | DTV_STAT_SIGNAL_STRENGTH | |
56 | ======================== | |
57 | ||
58 | Indicates the signal strength level at the analog part of the tuner or | |
59 | of the demod. | |
60 | ||
61 | Possible scales for this metric are: | |
62 | ||
63 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
64 | measurement was not complete yet. | |
65 | ||
66 | - ``FE_SCALE_DECIBEL`` - signal strength is in 0.001 dBm units, power | |
67 | measured in miliwatts. This value is generally negative. | |
68 | ||
69 | - ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100% | |
70 | measurement for power (actually, 0 to 65535). | |
71 | ||
72 | ||
73 | .. _DTV-STAT-CNR: | |
74 | ||
75 | DTV_STAT_CNR | |
76 | ============ | |
77 | ||
78 | Indicates the Signal to Noise ratio for the main carrier. | |
79 | ||
80 | Possible scales for this metric are: | |
81 | ||
82 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
83 | measurement was not complete yet. | |
84 | ||
85 | - ``FE_SCALE_DECIBEL`` - Signal/Noise ratio is in 0.001 dB units. | |
86 | ||
87 | - ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100% | |
88 | measurement for Signal/Noise (actually, 0 to 65535). | |
89 | ||
90 | ||
91 | .. _DTV-STAT-PRE-ERROR-BIT-COUNT: | |
92 | ||
93 | DTV_STAT_PRE_ERROR_BIT_COUNT | |
94 | ============================ | |
95 | ||
96 | Measures the number of bit errors before the forward error correction | |
97 | (FEC) on the inner coding block (before Viterbi, LDPC or other inner | |
98 | code). | |
99 | ||
100 | This measure is taken during the same interval as | |
101 | ``DTV_STAT_PRE_TOTAL_BIT_COUNT``. | |
102 | ||
103 | In order to get the BER (Bit Error Rate) measurement, it should be | |
104 | divided by | |
105 | :ref:`DTV_STAT_PRE_TOTAL_BIT_COUNT <DTV-STAT-PRE-TOTAL-BIT-COUNT>`. | |
106 | ||
107 | This measurement is monotonically increased, as the frontend gets more | |
108 | bit count measurements. The frontend may reset it when a | |
109 | channel/transponder is tuned. | |
110 | ||
111 | Possible scales for this metric are: | |
112 | ||
113 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
114 | measurement was not complete yet. | |
115 | ||
116 | - ``FE_SCALE_COUNTER`` - Number of error bits counted before the inner | |
117 | coding. | |
118 | ||
119 | ||
120 | .. _DTV-STAT-PRE-TOTAL-BIT-COUNT: | |
121 | ||
122 | DTV_STAT_PRE_TOTAL_BIT_COUNT | |
123 | ============================ | |
124 | ||
125 | Measures the amount of bits received before the inner code block, during | |
126 | the same period as | |
127 | :ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>` | |
128 | measurement was taken. | |
129 | ||
130 | It should be noted that this measurement can be smaller than the total | |
131 | amount of bits on the transport stream, as the frontend may need to | |
132 | manually restart the measurement, losing some data between each | |
133 | measurement interval. | |
134 | ||
135 | This measurement is monotonically increased, as the frontend gets more | |
136 | bit count measurements. The frontend may reset it when a | |
137 | channel/transponder is tuned. | |
138 | ||
139 | Possible scales for this metric are: | |
140 | ||
141 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
142 | measurement was not complete yet. | |
143 | ||
144 | - ``FE_SCALE_COUNTER`` - Number of bits counted while measuring | |
145 | :ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>`. | |
146 | ||
147 | ||
148 | .. _DTV-STAT-POST-ERROR-BIT-COUNT: | |
149 | ||
150 | DTV_STAT_POST_ERROR_BIT_COUNT | |
151 | ============================= | |
152 | ||
153 | Measures the number of bit errors after the forward error correction | |
154 | (FEC) done by inner code block (after Viterbi, LDPC or other inner | |
155 | code). | |
156 | ||
157 | This measure is taken during the same interval as | |
158 | ``DTV_STAT_POST_TOTAL_BIT_COUNT``. | |
159 | ||
160 | In order to get the BER (Bit Error Rate) measurement, it should be | |
161 | divided by | |
162 | :ref:`DTV_STAT_POST_TOTAL_BIT_COUNT <DTV-STAT-POST-TOTAL-BIT-COUNT>`. | |
163 | ||
164 | This measurement is monotonically increased, as the frontend gets more | |
165 | bit count measurements. The frontend may reset it when a | |
166 | channel/transponder is tuned. | |
167 | ||
168 | Possible scales for this metric are: | |
169 | ||
170 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
171 | measurement was not complete yet. | |
172 | ||
173 | - ``FE_SCALE_COUNTER`` - Number of error bits counted after the inner | |
174 | coding. | |
175 | ||
176 | ||
177 | .. _DTV-STAT-POST-TOTAL-BIT-COUNT: | |
178 | ||
179 | DTV_STAT_POST_TOTAL_BIT_COUNT | |
180 | ============================= | |
181 | ||
182 | Measures the amount of bits received after the inner coding, during the | |
183 | same period as | |
184 | :ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>` | |
185 | measurement was taken. | |
186 | ||
187 | It should be noted that this measurement can be smaller than the total | |
188 | amount of bits on the transport stream, as the frontend may need to | |
189 | manually restart the measurement, losing some data between each | |
190 | measurement interval. | |
191 | ||
192 | This measurement is monotonically increased, as the frontend gets more | |
193 | bit count measurements. The frontend may reset it when a | |
194 | channel/transponder is tuned. | |
195 | ||
196 | Possible scales for this metric are: | |
197 | ||
198 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
199 | measurement was not complete yet. | |
200 | ||
201 | - ``FE_SCALE_COUNTER`` - Number of bits counted while measuring | |
202 | :ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>`. | |
203 | ||
204 | ||
205 | .. _DTV-STAT-ERROR-BLOCK-COUNT: | |
206 | ||
207 | DTV_STAT_ERROR_BLOCK_COUNT | |
208 | ========================== | |
209 | ||
210 | Measures the number of block errors after the outer forward error | |
211 | correction coding (after Reed-Solomon or other outer code). | |
212 | ||
213 | This measurement is monotonically increased, as the frontend gets more | |
214 | bit count measurements. The frontend may reset it when a | |
215 | channel/transponder is tuned. | |
216 | ||
217 | Possible scales for this metric are: | |
218 | ||
219 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
220 | measurement was not complete yet. | |
221 | ||
222 | - ``FE_SCALE_COUNTER`` - Number of error blocks counted after the outer | |
223 | coding. | |
224 | ||
225 | ||
226 | .. _DTV-STAT-TOTAL-BLOCK-COUNT: | |
227 | ||
228 | DTV-STAT_TOTAL_BLOCK_COUNT | |
229 | ========================== | |
230 | ||
231 | Measures the total number of blocks received during the same period as | |
232 | :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` | |
233 | measurement was taken. | |
234 | ||
235 | It can be used to calculate the PER indicator, by dividing | |
236 | :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` by | |
7347081e | 237 | :ref:`DTV-STAT-TOTAL-BLOCK-COUNT`. |
5377d91f MH |
238 | |
239 | Possible scales for this metric are: | |
240 | ||
241 | - ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the | |
242 | measurement was not complete yet. | |
243 | ||
244 | - ``FE_SCALE_COUNTER`` - Number of blocks counted while measuring | |
245 | :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>`. |