Lines Matching +full:system +full:- +full:clock +full:- +full:frequency
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
4 <meta http-equiv="content-type" content="text/html;charset=iso-8859-1">
13 <!-- #BeginDate format:En2m -->15-Nov-2012 06:42<!-- #EndDate -->
20 Autotune Port: <tt>/dev/icom</tt>; 1200/9600 baud, 8-bits, no parity<br>
23 …frequency stations <a href="http://www.bldrdoc.gov/timefreq/stations/wwv.html">WWV</a> in Ft. Coll…
24 …-law companding to demodulate the data. This is the same standard as used by the telephone industr…
25 …o-hop propagation delay varies from 9.3 ms in sunlight to 9.0 ms in moonlight. When not tracking t…
26 …r, the mean offset with a 2.4-GHz P4 running FreeBSD 6.1 is generally within 0.1 ms short-term wit…
27 …his page. Note that additional checks are done elsewhere in the reference clock interface routines…
28 …okup, debugging and monitoring, see the <a href="../audio.html">Reference Clock Audio Drivers</a> …
30 …-kHz μ-law companded codec samples using maximum-likelihood techniques which exploit the consid…
31 …clock for WWV transmissions. Electrical Engineering Report 97-8-1, University of Delaware, August …
32 … program, the clock discipline is modelled as a Markov process, with probabilistic state transitio…
34 …-Hz pulses and 100-Hz subcarrier are first separated using a 600-Hz bandpass filter centered on 11…
35 …-Hz subcarrier relative to the second pulse is fixed at the transmitter; however, the audio stage …
36 …-width discriminator. The discriminator samples the I channel at 15 ms (<i>n</i>), 200 ms (<i>s</…
37 …-static miscellaneous bits, such as DST indicator, leap second warning and DUT1 correction. In thi…
38 <h4>Maximum-Likelihood Decoder</h4>
39 …ssociated with the maximum over all averaged values then becomes the maximum-likelihood candidate …
40 …-likelihood digit, likelihood vector and other related data. The maximum-likelihood digit for each…
41 …-likelihood digit. If a digit likelihood exceeds the decision level and compares with previous dig…
42 <h4>Master Clock Discipline</h4>
43 …clock is derived from the audio codec clock. Its frequency is disciplined by a frequency-lock loop…
44 …frequency averaging interval is 8 seconds, in order to compensate for intrinsic codec clock freque…
45 …clock, which is independent of the epoch. However, the data decoding functions are driven by the e…
46 … is considered valid only if the 5-ms signal amplitude and SNR are above thresholds. In addit…
48 …clock frequency is stable and accurately determined, since in many applications the shortwave radi…
49 …ry scrap of signal information, but has to be careful to avoid making pseudo-sense of noise alone.…
55 <p>The figure was constructed using a 2.4-GHz P4 running FreeBSD 6.1. For these measurements the co…
56 …the receiver at Newark, DE, varies over 9.0-9.3 ms. In addition, the receiver contributes 4.7 ms a…
58 … frequencies and both WWV and WWVH stations until finding a station and frequency with acceptable …
59 …he second synch has been acquired, the clock is set (or verified) and is selectable to discipline …
60 …clock is set, it continues to provide correct timecodes as long as the signal metric is above thre…
61 …clock that WWV and WWVH signals may appear alone, together or not at all. When the driver has miti…
62 …frequency is acceptable. A consequence of this design is that, once the clock is set, the time and…
63 …system clock been set correctly it will continue to read correctly even during the holdover interv…
65 …-V standard, which is a bidirectional serial bus operating at TTL levels. The bus can be connected…
66 …frequency in turn while attempting to acquire minute synch from either WWV or WWVH. However, the d…
67 …clock. However, during seconds 59, 0 and 1 of each minute it tunes the radio to one of the five br…
68 …gation procedure selects the frequency and station with the highest valid metric, ties going first…
71 …ht (0100-1300 UTC) and the higher frequencies when the path is in sunlight (1300-0100 UTC). Note t…
73 …ters, even when the driver is not disciplining the system clock. If the debugging trace feature (<…
74 …onditions in general. The message is produced once each minute for each frequency in turn after mi…
78 …on (<tt>WV</tt> for WWV, <tt>WH</tt> for WWVH) and frequency (2, 5, 10, 15 or 20), <tt>score</tt> …
79 <pre><tt>wwv5 000d 111 5753 3967/20.1 3523/10.2 WV20 bdeff 100 8348/30.0 WH20 0000 1 22/-12.4</tt><…
85 …re decoded from the received data and are in fixed-length format. The remaining fields are in vari…
88 …<dd>The synch indicator is initially <tt>?</tt> before the clock is set, but turns to space when a…
90 …<dd>The quality character is a four-bit hexadecimal code showing which alarms have been raised. Ea…
99 …<dd>Compare alarm. A maximum-likelihood digit failed to agree with the current associated clock di…
101 …note that one or more of the above alarms does not necessarily indicate a clock error, but only th…
103 …<dd>The timecode format itself is self explanatory. Since the driver latches the on-time epoch dir…
111 …<dd>Before the clock is set, the interval since last set is the number of minutes since the driver…
115 …tt>WH<i>f</i></tt> for WWVH, and frequency <i><tt>f</tt></i> being tracked. If neither station is …
119 …that point the metric drops below threshold and the decoder switches to a different frequency.</dd>
121 …<dd>The frequency offset is the current estimate of the codec frequency offset to within 0.1 PPM. …
123 …frequency updates in powers of two to a maximum of 1024 s. Attainment of the maximum indicates the…
127 …clock has been set and no alarms are raised. The year, day and time are displayed along with no le…
141 …<dd>Specifies the microphone port if set to zero or the line-in port if set to one. It does not se…