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Type I clocks belong to the Option 1 hierarchy based on 2048kbit/s. The maximum peak-to-peak amplitude at each frequency is taken from Table 13 of G.812. This is a translation of the MTIE mask defined in Table 9 of G.812, using the relationship between tone frequency, f, and observation interval, tauτ, of f = 1/ ptpi.tau πτ .
The lowest tone frequency specified in below is 0.0001Hz (0.1mHz). This is 30 times lower than the bandwidth of a Type I clock. It has a period of almost 2.8 hours, and hence requires a test time at least that long. While Table 13 of G.812 is extends as low as 0.000012Hz (12µHz), which has with a period of over 23 hours . However, the longest observation interval specified in the MTIE mask (Figure 3) is 10000s, equivalent to a tone frequency of 0.000032Hz (32µHz). Therefore it is sufficient to make 32µHz the lowest tone frequency in the testthe test time would be extremely long, and being so far into the pass-band it is very unlikely that either the wander tolerance or wander transfer would be any different.
The possible input signals for a Type I G.8266 clock are SyncE Option 1, 2048kHz, or 2048kbit/s (E1).
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Frequency (Hz) | Amplitude (ns) | Test Time (Cycles) | Test Time (s) | Max. Gain (dB) | Max. Output Amplitude (ns) | ||||||
1 | 750 | 300 | 300 | -50.5 | 38 | ||||||
0.32 | 750 | 96 | 300 | -40.6 | 43 | ||||||
0.01 | 750 | 30 | 300 | -10.8 | 251 | ||||||
0.043 | 750 | 13 | 302 | -23.1 | 88 | ||||||
0.032 | 1000 | 10 | 313 | -20.6 | 129 | ||||||
0.016 | 2000 | 5 | 313 | -14.7 | 404 | ||||||
0.01 | 2000 | 3 | 300 | -10.8 | 610 | ||||||
0.0032 | 2000 | 3 | 938 | -3.3 | 1403 | ||||||
0.0008 | 2000 | 12 | 12502500 | 0.2 | 2082 | ||||||
0.00032 | 5000 | 1 | 3125 | 0.2 | 5152 | ||||||
0.0001 | 5000 | 1 | 10000 | 0.2 | 5152 | 0.000032 | 5000 | 1 | 312500.2 | 5152 |
The filtering characteristic expected from the clock is shown in the following diagram. While there is no minimum gain specified, the frequency response is expected to be fairly close to the maximum. Appendix II of G.812 suggests the result should be within 2% of the mask for long observation intervals.
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Tone Frequencies for G.8266 Type II and Type III Clocks
Type II and III clocks belong to the Option 2 hierarchy based on 1544kbit/s. The maximum peak-to-peak amplitude at each frequency is taken from Table 14 of G.812. This is a translation of the MTIE mask defined in Table 10 of G.812, using the relationship between tone frequency, f, and observation interval, tauτ, of
f = 1/ 2.5tau 5τ . This is slightly different to the relationship used for the Option 1 hierarchy.
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Frequency (Hz) | Amplitude (ns) | Test Time (Cycles) | Test Time (s) | Max. Gain (dB) | Max. Output Amplitude (ns) | ||||||
4 | 300 | 1200 | 300 | -72.0 | 36 | ||||||
1.26 | 301 | 377 | 300 | -62.0 | 36 | ||||||
0.4 | 303 | 120 | 300 | -52.0 | 36 | ||||||
0.126 | 308 | 38 | 302 | -42.0 | 38 | ||||||
0.04 | 325 | 12 | 300 | -32.0 | 44 | ||||||
0.0126 | 380 | 4 | 318 | -22.0 | 66 | ||||||
0.004 | 550 | 3 | 750 | -12.3 | 169 | ||||||
0.00143 | 1000 | 3 | 2100 | -4.8 | 609 | ||||||
0.0004 | 1007 | 1 | 2500 | 0.2 | 1066 | ||||||
0.0001260001 | 10291037 | 1 | 795010000 | 0.2 | 1088 | 0.000041097 | 1 | 25000 | 0.2 | 1158 |
The The filtering characteristic expected from the clock is shown in the following diagram. While there is no minimum gain specified, the frequency response is expected to be fairly close to the maximum. Appendix II of G.812 suggests the result should be within 2% of the mask for long observation intervals.
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