From: Harlan Stenn Date: Fri, 7 Jan 2000 04:50:45 +0000 (-0000) Subject: ChangeLog, configure, configure.in, audio.htm, driver36.htm, driver7.htm: X-Git-Tag: NTP_4_0_98_M^0 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7c348671eac74c7a3bcb20d0e9ec760e4772887d;p=thirdparty%2Fntp.git ChangeLog, configure, configure.in, audio.htm, driver36.htm, driver7.htm: * configure.in: 4.0.98m I skipped `l' - it looks like a `1'. * html/driver7.htm: Doc update * html/driver36.htm: Ditto * html/audio.htm: Ditto bk: 387570a5wS6oYiOawa6BdykiLU8xVg --- diff --git a/ChangeLog b/ChangeLog index 3b943d0fd..3562dae8d 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,14 @@ 2000-01-06 Harlan Stenn + * configure.in: 4.0.98m + I skipped `l' - it looks like a `1'. + + * html/driver7.htm: Doc update + * html/driver36.htm: Ditto + * html/audio.htm: Ditto + + * ntpd/refclock_wwv.c: Dvae snuck another fix/change in on me. + * configure.in: 4.0.98k * ntpd/refclock_chu.c (chu_start): Call icom_init with the speed diff --git a/configure b/configure index 94b1fa7b9..8329678dd 100755 --- a/configure +++ b/configure @@ -994,7 +994,7 @@ fi PACKAGE=ntp -VERSION=4.0.98k +VERSION=4.0.98m if test "`CDPATH=: && cd $srcdir && pwd`" != "`pwd`" && test -f $srcdir/config.status; then diff --git a/configure.in b/configure.in index 8a6efea88..e9175dd19 100644 --- a/configure.in +++ b/configure.in @@ -5,7 +5,7 @@ AC_CANONICAL_SYSTEM AC_DEFINE_UNQUOTED(STR_SYSTEM, "$target") AM_CONFIG_HEADER(config.h) AC_ARG_PROGRAM -AM_INIT_AUTOMAKE(ntp, 4.0.98k) +AM_INIT_AUTOMAKE(ntp, 4.0.98m) AC_PREREQ(2.13) ac_cv_var_oncore_ok=no diff --git a/html/audio.htm b/html/audio.htm index 04029f07d..5df5570e4 100644 --- a/html/audio.htm +++ b/html/audio.htm @@ -66,7 +66,7 @@ utility program.

Shortwave Radio Drivers

The WWV/H and CHU audio drivers require an external shortwave radio -with the audio output - speaker or headphone jack - connected to either +with the radio output - speaker or headphone jack - connected to either the microphone or line-in port on the computer. There is some degree of art in setting up the radio and antenna and getting the setup to work. While the drivers are highly sophisticated and efficient in extracting @@ -85,15 +85,13 @@ generally works better if the radio is outside the near field of computers and other electromagnetic noisemakers. It can be in the elevator penthouse connected by house wiring, which can also be used to power the radio. A couple of center-tapped audio transformers will -minimize noise pickup and allow phantom power to the radio with return +minimize noise pickup and provide phantom power to the radio with return via the AC neutral wire.

The WWV/H and CHU transmitters operate on several frequencies simultaneously, so that in most parts of North America at least one frequency supports propagation to the receiver location at any given -hour. Currently, computer-tunable radios are expensive and probably not -cost effective compared to a GPS receiver. So, the radio frequency must -be fixed and chosen by compromise. +hour. While both drivers support the ICOM CI-V radio interface and can tune the radio automatically, computer-tunable radios are expensive and probably not cost effective compared to a GPS receiver. So, the radio frequency must usually be fixed and chosen by compromise.

Shortwave (3-30 MHz) radio propagation phenomena are well known to shortwave enthusiasts. The phenomena generally obey the following rules: @@ -134,20 +132,14 @@ and the best WWV frequency is probably 15 MHz.

The audio drivers include extensive debugging support to help hook up the audio signals and monitor the driver operations. The documentation page for each driver describes the various messages that can be produced -either in real-time or written to the clockstats file for +either in real-time or written to the clockstats file for later analysis. Of particular help in verifying signal connections and compatibility is a provision to monitor the signal via headphones or speaker. -

Monitor Data

-

The drivers write a synthesized timecode to the clockstats -file each time the clock is set and at other times if verbose monitoring -is enabled. The format includes several fixed-length fields defining the -Gregorian time to the millisecond, together with additional variable- -length fields specific to each driver. The data include the interval -since the clock was last set, the audio gain and various state variables -and counters specific to each driver. +

The drivers write a synthesized timecode to the clockstats +file each time the clock is set or verified and at other times if verbose monitoring is enabled. The format includes several fixed-length fields defining the Gregorian time to the millisecond, together with additional variable-length fields specific to each driver. The data include the intervals since the clock was last set or verified, the audio gain and various state variables and counters specific to each driver.

Additional Information

diff --git a/html/driver36.htm b/html/driver36.htm index 5fe3e4d3a..404b4cd72 100644 --- a/html/driver36.htm +++ b/html/driver36.htm @@ -9,7 +9,7 @@ Radio WWV/H Audio Demodulator/Decoder Address: 127.127.36.u
Reference ID: WWV or WWVH
Driver ID: WWV_AUDIO -
Autotune Port: /dev/icom; 1200 baud, 8-bits, no parity +
Autotune Port: /dev/icom; 9600 baud, 8-bits, no parity
Audio Device: /dev/audio and /dev/audioctl

Description

@@ -19,8 +19,8 @@ shortwave radio transmissions from NIST time/frequency stations WWV in Ft. Collins, CO, and WWVH in Kauai, HI. Transmissions are made continuously on 2.5, 5, 10, 15 and 20 MHz. An ordinary shortwave receiver can be tuned manually to one of these frequencies or, in the -case of ICOM receivers, the receiver can be tuned automatically by this -program as propagation conditions change throughout the day and night. +case of ICOM receivers, the receiver can be tuned automatically by the +driver as propagation conditions change throughout the day and night. The performance of this driver when tracking one of the stations is ordinarily better than 1 ms in time with frequency drift less than 0.5 PPM when not tracking either station. @@ -79,7 +79,7 @@ matched filter and 8000-stage comb filter.

The phase of the 100-Hz subcarrier relative to the second sync pulse is fixed at the transmitter; however, the audio highpass filter in most radios affects the phase response at 100 Hz in unpredictable ways. The -program adjusts for each radio using two 170-ms synchronous matched +driver adjusts for each radio using two 170-ms synchronous matched filters. The I (in-phase) filter is used to demodulate the subcarrier envelope, while the Q (quadrature-phase) filter is used in a tracking loop to discipline the codec sample clock and thus the demodulator @@ -95,7 +95,7 @@ slice level establishes the length of the data pulse, which in turn establish probabilities for binary zero (P0) or binary one (P1). The values are established by linear interpolation between the pulse lengths for P0 (300 ms) and P1 (500 ms) so that the sum is equal to one. If the -program has not synchronized to the minute pulse, or if the data bit +driver has not synchronized to the minute pulse, or if the data bit amplitude, signal/noise ratio (SNR) or length are below thresholds, the bit is considered invalid and all three probabilities are set to zero. @@ -189,7 +189,7 @@ function described below. indicated time be limited only by the characteristics of the propagation medium. Conventional wisdom is that synchronization via the HF medium is good only to a millisecond under the best propagation conditions. The -performance of the NTP daemon disciplined by this driver is clearly +performance of the NTP daemon disciplined by the driver is clearly better than this, even under marginal conditions. Ordinarily, with marginal to good signals and a frequency averaging interval of 1024 s, the frequency is stabilized within 0.1 PPM and the time within 125 Program Operation -The program begins operation immediately upon startup. It first searches -for one or both of the stations WWV and WWVH and acquires minute sync. -It then acquires second sync, which can take up to several minutes, -depending on signal quality. At the same time the program accumulates -likelihood values for each of the nine digits of the clock, plus the -seven miscellaneous bits included in the WWV/H transmission format. The -minute units digit is decoded first and, when five repetitions have -compared correctly, the remaining eight digits are decoded. When five -repetitions of all nine digits have decoded correctly, which normally -takes 15 minutes with good signals and up to an hour when buried in -noise, and no alarms are raised, the clock is set (or verified) and is -selectable to discipline the system clock. +The driver begins operation immediately upon startup. It first searches +for one or both of the stations WWV and WWVH and attempts to acquire +minute sync. This may take some fits and starts, as the driver expects +to see three consecutive minutes with good signals and low jitter. If +the autotune function is active, the driver will rotate over all five +frequencies and both WWV and WWVH stations until three good minutes are +found. + +

The driver then acquires second sync, which can take up to several +minutes, depending on signal quality. At the same time the driver +accumulates likelihood values for each of the nine digits of the clock, +plus the seven miscellaneous bits included in the WWV/H transmission +format. The minute units digit is decoded first and, when five +repetitions have compared correctly, the remaining eight digits are +decoded. When five repetitions of all nine digits have decoded +correctly, which normally takes 15 minutes with good signals and up to +an hour when buried in noise, and the second sync alarm has not been +raised for two minutes, the clock is set (or verified) and is selectable +to discipline the system clock.

As long as the clock is set or verified, the system clock offsets are provided once each second to the reference clock interface, where they @@ -246,8 +253,8 @@ groomed by the median filter and trimmed-mean averaging functions. Using these functions, the system clock can in principle be disciplined to a much finer resolution than the 125-ms sample interval would suggest, although the ultimate accuracy is probably -limited by propagation delay variations due to ionspheric height -variations. +limited by propagation delay variations as the ionspheric height varies +throughout the day and night.

As long as signals are available, the clock frequency is disciplined for use during times when the signals are unavailable. The algorithm @@ -260,9 +267,9 @@ variations due to temperature fluctuations and ionospheric height variations.

It may happen as the hours progress around the clock that WWV and -WWVH signals may appear alone, together or not at all. When the program +WWVH signals may appear alone, together or not at all. When the driver is first started, the NTP reference identifier appears as NONE. -When the program has acquired one or both stations and mitigated which +When the driver has acquired one or both stations and mitigated which one is best, it sets the station identifier in the timecode as described below. In addition, the NTP reference identifier is set to the station callsign. If the propagation delays has been properly set with the @@ -286,7 +293,7 @@ protect against this most unlikely situation, if after four days with no signals, the clock is considered unset and resumes the synchronization procedure from the beginning. -

To work well, this program needs a communications receiver with good +

To work well, the driver needs a communications receiver with good audio response at 100 Hz. Most shortwave and communications receivers roll off the audio response below 250 Hz, so this can be a problem, especially with receivers using DSP technology, since DSP filters can @@ -304,9 +311,9 @@ just as well as an expensive communications receiver. response to changing radio propagation conditions throughout the day and night. The radio interface is compatible with the ICOM CI-V standard, which is a bidirectional serial bus operating at TTL levels. The bus can -be connected to a standard serial port using a level converter such as -the CT-17. The serial port speed is presently compiled in the program, -but can be changed in the icom.h header file. +be connected to a serial port using a level converter such as the CT-17. +The serial port speed is presently compiled in the program, but can be +changed in the driver source file.

Each ICOM radio is assigned a unique 8-bit ID select code, usually expressed in hex format. To activate the CI-V interface, the @@ -317,35 +324,115 @@ keyword or a zero argument leaves the interface disabled. The driver will attempt to open the device /dev/icom and, if successful will activate the autotune function and tune the radio to each operating frequency in turn while attempting to acquire minute sync from either -WWV or WWVH. - -

Once acquiring minute sync, the program operates as above to acquire -second sync and set the clock. However, during the three seconds -beginning at second 58 of each minute it tunes the radio to one of the -five broadcast frequencies to measure the sync pulse and data pulse -amplitudes and SNR and update the compare counter. Each of the five -frequencies are probed in a five-minute rotation to build a database of -current propagation conditions for all signals that can be heard at the -time. At the end of each rotation, a mitigation procedure scans the -database and retunes the radio to thebest frequency and station found. - -

For the autotune function to work well, the radio should be set for a -fast AGC recovery time. This is most important while tracking a strong -signal, which is normally the case, and then probing another frequency, -which may have much weaker signals. - -

The driver is liberal in what it assumes of the configuration. If the -/dev/icom link is not present or the open fails or the CI-V bus -or radio is inoperative, the driver quietly gives up with no harm done. +WWV or WWVH. However, the driver is liberal in what it assumes of the +configuration. If the /dev/icom link is not present or the open +fails or the CI-V bus or radio is inoperative, the driver quietly gives +up with no harm done. + +

Once acquiring minute sync, the driver operates as described above to +set the clock. However, during seconds 59, 0 and 1 of each minute it +tunes the radio to one of the five broadcast frequencies to measure the +sync pulse and data pulse amplitudes and SNR and update the compare +counter. Each of the five frequencies are probed in a five-minute +rotation to build a database of current propagation conditions for all +signals that can be heard at the time. At the end of each rotation, a +mitigation procedure scans the database and retunes the radio to the +best frequency and station found. For this to work well, the radio +should be set for a fast AGC recovery time. This is most important while +tracking a strong signal, which is normally the case, and then probing +another frequency, which may have much weaker signals. + +

Reception conditions for each frequency and station are evaluated +according to a metric which considers the minute sync pulse amplitude, +SNR and jitter, as well as, the data pulse amplitude and SNR. The minute +pulse is evaluated at second 0, while the data pulses are evaluated at +seconds 59 and 1. The results are summarized in a scoreboard of three +bits + +

+ +

0x0001 +
Jitter exceeded. The difference in epoches between the last minute +sync pulse and the current one exceeds 50 ms (400 samples).
+ +
0x0002 +
Minute pulse error. For the minute sync pulse in second 0, either +the amplitude or SNR is below threshold (2000 and 20 dB, +respectively).
+ +
0x0004 +
Minute pulse error. For both of the data pulses in seocnds 59 and 1, +either the amplitude or SNR is below threshold (1000 and 10 dB, +respectively).
+ +
+ +

If none of the scoreboard bits are set, the compare counter is +increased by one to a maximum of six. If any bits are set, the counter +is decreased by one to a minimum of zero. At the end of each minute, the +frequency and station with the maximum compare count is chosen, with +ties going to the highest frequency. + +

Diagnostics

+ +

The autotune process produces diagnostic information along with the +timecode. This is very useful for evaluating the performance of the +algorithm, as well as radio propagation conditions in general. The +message is produced once each minute for each frequency in turn after +minute sync has been acquired. + +

wwv5 agc wwv wwvh + +

where agc is the audio gain for this frequency and +wwv and wwvh are two sets of fields, one each for WWV +and WWVH. Each of the two fields has the format + +

ident score comp sync/snr/jitr + +

where identencodes the station (C for WWV, +H for WWVH) and frequency (2, 5, 10, 15 and 20), score +is the scoreboard described above, comp is the compare counter, +sync is the minute sync pulse amplitude, snr the SNR +of the pulse and jitr is the sample difference between the +current epoch and the last epoch. An example is: + +

wwv5 111 C20 0100 6 8348/30.0/-3 H20 0203 0 22/-12.4/8846 + +

Here the radio is tuned to 20 MHz and the AGC is currently 111 at +that frequency. The message contains a report for WWV (C20) and +WWVH (H20). The WWV report scoreboard is 0100 and the compare +count is 6, which suggests very good reception conditions, and the +minute sync amplitude and SNR are well above thresholds (2000 and 20 dB, +respectively). Probably the most sensitive indicator of reception +quality is the jitter, -3 samples, which is well below threshold (50 ms +or 400 samples). While the message shows solid reception conditions from +WWV, this is not the case for WWVH. Both the minute sync amplitude and +SNR are below thresholds and the jitter is above threshold. + +

A sequence of five messages, one for each minute, might appear as +follows: + +

agc 95 sync  C2 0107 0 164/7.2/8100  H2 0207 0 80/-5.5/7754
+agc 99 sync  C5 0104 0 3995/21.8/395  H5 0207 0 27/-9.3/18826
+agc 239 sync C10 0105 0 9994/30.0/2663 H10 0207 0 54/-16.1/-529
+agc 155 sync C15 0103 3 3300/17.8/-1962 H15 0203 0 236/17.0/4873
+agc 111 sync C20 0100 6 8348/30.0/-3 H20 0203 0 22/-12.4/8846
+ +

Clearly, the only frequencies that are available are 15 MHz and 20 +MHz and propagation may be failing for 15 MHz. However, minute sync +pulses are being heard on 5 and 10 MHz, even though the data pulses are +not. This is typical of late afternoon when the maximum usable frequency +(MUF) is falling and the ionospheric loss at the lower frequencies is +decreasing.

Debugging Aids

-

The most convenient way to track the program status is using the +

The most convenient way to track the driver status is using the ntpq program and the clockvar command. This displays the last determined timecode and related status and error counters, even -when the program is not discipline the system clock. If the debugging +when the driver is not discipline the system clock. If the debugging trace feature (-d on the ntpd command line)is enabled, -the program produces detailed status messages as it operates. If the +the driver produces detailed status messages as it operates. If the fudge flag 4 is set, these messages are written to the clockstats file. All messages produced by this driver have the prefix chu for convenient filtering with the Unix grep @@ -354,12 +441,13 @@ command.

In the following descriptions the units of amplitude, phase, probability and likelihood are normalized to the range 0-6000 for convenience. In addition, the signal/noise ratio (SNR) and likelihood -ratio are measured in decibels and the status and alarm words are in +ratio are measured in decibels and the words with bit fields are in hex. Most messages begin with a leader in the following format:

wwvn ss stat sigl +

where wwvn is the message code, ss the second of -minute, stat the program status word and sigl the +minute, stat the driver status word and sigl the second sync pulse amplitude. A full explanation of the status bits is contained in the driver source listing; however, the following are the most useful for debugging. @@ -388,30 +476,54 @@ clock.

With debugging enabled the driver produces messages in the following formats: -

Format wwv3 messages are produced while the decoder is -working on the unit digit of the minute. They show the results of -decoding each bit of the transmitted timecode. +

Format wwv8 messages are produced once per minute by the WWV +and WWVH station processes before minute sync has been acquired. They +show the progress of identifying and tracking the minute pulse of each +station. + +

wwv8 call comp ampl snr epoch jitr offs + +

where call is the station callsign, comp the +compare counter, ampl the pulse amplitude, snr the +SNR, epoch the sample number of the minute pulse in the minute, +jitr the change since the last epoch and offs +the minute pulse offset relative to the second pulse. An example is: + +

wwv8 WWV 2 9247 30.0 18843 -1 1 +
wwv8 WWVH 0 134 -2.9 19016 193 174 + +

Here the driver has not yet acquired minute sync, WWV has been heard +for at least two minutes, and WWVH is in the noise. The WWV minute pulse +amplitude and SNR are well above the threshold (2000 and 6 dB, +respectively) and the minute epoch has been determined -1 sample +relative to the last one and 1 sample relative to the second +sync pulse. The compare counter has incrmented to two; when it gets to +three, minute sync has been acquired. + +

Format wwv3 messages are produced after minute sync has been +acquired and until the seconds unit digit is determined. They show the +results of decoding each bit of the transmitted timecode.

wwv3 ss stat sigl ampl phas snr prob like +

where ss, stat and sigl are as above, ampl is the subcarrier amplitude, phas the subcarrier phase, snr the subcarrier SNR, prob the bit probability and like the bit likelihood. An example is: -

wwv3 28 0323 4122 4286 0 24.8 -5545 -1735 +

wwv3 28 0123 4122 4286 0 24.8 -5545 -1735 -

Here the program has acquired minute and second sync, but has not yet -set the clock. However, it has just decoded bit 28 of the minute. The -results show the second sync pulse amplitude well over the threshold -(500), subcarrier amplitude well above the threshold (1000), good -subcarrier tracking phase and SNR well above the threshold (10 dB). The -bit is almost certainly a zero and the likelihood of a zero in this -second is very high. +

Here the driver has acquired minute and second sync, but has not yet +determined the seconds unit digit. However, it has just decoded bit 28 +of the minute. The results show the second sync pulse amplitude well +over the threshold (500), subcarrier amplitude well above the threshold +(1000), good subcarrier tracking phase and SNR well above the threshold +(10 dB). The bit is almost certainly a zero and the likelihood of a zero +in this second is very high.

Format wwv4 messages are produced for each of the nine BCD -timecode digits. They show the results of decoding each digit of the -transmitted timecode. - +timecode digits until the clock has been set or verified. They show the +results of decoding each digit of the transmitted timecode.

wwv4 ss stat sigl radx ckdig mldig diff cnt like snr

where ss, stat and sigl are as above, @@ -421,16 +533,17 @@ current clock digit, mldig the maximum likelihood digit, cnt the compare counter, like the digit likelihood and snr the likelihood ratio. An example is: -

wwv4 8 030f 5772 10 9 9 0 6 4615 6.1 -

Here the program has acquired minute and second sync and set the -clock. It just decoded the digit preceding second 8 of the minute. The -digit radix is 10, the current clock and maximum likelihood digits are -both 9, the likelihood is well above the threshold (1000) and the -likelihood ratio well above threshold (3.0 dB). Short of a hugely -unlikely probability conspiracy, the clock digit is most certainly a 9. +

wwv4 8 010f 5772 10 9 9 0 6 4615 6.1 + +

Here the driver has previousl set or verified the clock. It has just +decoded the digit preceding second 8 of the minute. The digit radix is +10, the current clock and maximum likelihood digits are both 9, the +likelihood is well above the threshold (1000) and the likelihood +function well above threshold (3.0 dB). Short of a hugely unlikely +probability conspiracy, the clock digit is most certainly a 9.

Format wwv2 messages are produced at each master oscillator -frequency update, which starts at 4 s, but eventually climbs to 1024 s. +frequency update, which starts at 8 s, but eventually climbs to 1024 s. They show the progress of the algorithm as it refines the frequency measurement to a precision of 0.1 PPM. @@ -445,38 +558,10 @@ current frequency (PPM). An example is:

wwv2 22 030f 5795 256 256 4 0 0.0 66.7 -

Here the program has acquired minute and second sync and set the +

Here the driver has acquired minute and second sync and set the clock. The averaging interval has increased to 256 s on the way to 1024 -s, has stayed at that interval for 4 times, has measured no change in -frequency and the current frequency is 66.7 PPM. - -

Format wwv8 messages are produced once per minute by the WWV -and WWVH station processes. They show the progress of identifying and -tracking the minute pulse of each station. - -

wwv2 ss stat sigl call state ampl snr epoch jitr offs - -

where ss, stat and sigl are as above, -call is the station callsign, state the compare -counter, ampl the pulse amplitude, snr the SNR, -epoch the sample number of the minute pulse in the minute, -jitr the change since the last pulse and offs the -minute pulse offset relative to the second pulse. An example is: - -

wwv8 58 030f 5835 WWV 5 9247 30.0 18843 -1 1 -
wwv8 58 030f 5835 WWVH 0 134 -2.9 19016 193 174 - -

Here the program has acquired minute and second sync and set the -clock. WWV has been heard for at least several minutes, but not WWVH. -The WWV minute pulse amplitude and SNR are well above the threshold -(1000 and 6 dB, respectively) and the minute epoch has been determined - -1 sample relative to the last one and 1 sample relative to the second -sync pulse. - -

Format wwv5 messages are produced once per minute by the WWV -and WWVH autotune station processes which precess over the five channels -or frequencies available. These messages are described in the Autotune -section. +s, has stayed at that interval for 4 averaging intervals, has measured +no change in frequency and the current frequency is 66.7 PPM.

If the CI-V interface for ICOM radios is active, a debug level greater than 1 will produce a trace of the CI-V command and response @@ -503,7 +588,7 @@ is written to the clockstats file in the following format: dut DUT sign and magnitude lset minutes since last set agc audio gain - stn station identifier and frequency + ident station identifier and frequency comp minute sync compare counter errs bit error counter freq frequency offset @@ -571,9 +656,10 @@ effect, respectively.

dut
The DUT sign and magnitude shows the current UT1 offset relative to the displayed UTC time, in deciseconds.
+
lset
Before the clock is set, the interval since last set is the number -of minutes since the program was started; after the clock is set, this +of minutes since the driver was started; after the clock is set, this is number of minutes since the time was last verified relative to the broadcast signal.
@@ -582,7 +668,7 @@ broadcast signal. to 255. Ordinarily, the receiver audio gain control or IRIG level control should be set for a value midway in this range. -
stn +
ident
The station identifier shows the station, C for WWV or H for WWVH, and frequency being tracked. If neither station is heard on any frequency, the station identifier shows X.
@@ -591,6 +677,7 @@ heard on any frequency, the station identifier shows X.
The minute sync compare counter is useful to determine the quality of the minute sync signal and can range from 0 (no signal) to 5 (best).
+
errs
The bit error counter is useful to determine the quality of the data signal received in the most recent minute. It is normal to drop a couple @@ -607,11 +694,24 @@ local temperature fluctuations and propagation conditions.
avgt
The averaging time is the interval between frequency updates in powers of two to a maximum of 1024 s. Attainment of the maximum -indicates the program is operating at the best possible resolution in +indicates the driver is operating at the best possible resolution in time and frequency.
+

An example timecode is: + +

0 2000 006 22:36:00.000 S +3 1 115 C20 6 5 66.4 1024 + +

Here the clock has been set and no alarms are raised. The year, day +and time are displayed along with no leap warning, standard time and DUT ++0.3 s. The clock was set on the last minute, the AGC is safely in the +middle ot the range 0-255, and the receiver is tracking WWV on 20 MHz. +Excellent reeiving conditions prevail, as indicated by the compare count +6 and 5 bit errors during the last minute. The current frequency is 66.4 +PPM and the averaging interval is 1024 s, indicating the maximum +precision available. +

Modes

The mode keyword of the server configuration diff --git a/html/driver7.htm b/html/driver7.htm index 2a64d8fde..599507238 100644 --- a/html/driver7.htm +++ b/html/driver7.htm @@ -10,7 +10,7 @@ Address: 127.127.7.u
Reference ID: CHU
Driver ID: CHU
Modem Port: /dev/chuu; 300 baud, 8-bits, no parity -
Autotune Port: /dev/icom; 1200 baud, 8-bits, no parity +
Autotune Port: /dev/icom; 9600 baud, 8-bits, no parity
Audio Device: /dev/audio and /dev/audioctl

Description