19c2daa00SOllivier Robert<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 29c2daa00SOllivier Robert 39c2daa00SOllivier Robert<html> 49c2daa00SOllivier Robert 59c2daa00SOllivier Robert <head> 6ea906c41SOllivier Robert <meta http-equiv="content-type" content="text/html;charset=iso-8859-1"> 79c2daa00SOllivier Robert <meta name="generator" content="HTML Tidy, see www.w3.org"> 89c2daa00SOllivier Robert <title>Radio CHU Audio Demodulator/Decoder</title> 9ea906c41SOllivier Robert <link href="scripts/style.css" type="text/css" rel="stylesheet"> 109c2daa00SOllivier Robert </head> 119c2daa00SOllivier Robert 129c2daa00SOllivier Robert <body> 139c2daa00SOllivier Robert <h3>Radio CHU Audio Demodulator/Decoder</h3> 149c2daa00SOllivier Robert <hr> 159c2daa00SOllivier Robert <h4>Synopsis</h4> 169c2daa00SOllivier Robert Address: 127.127.7.<i>u</i><br> 179c2daa00SOllivier Robert Reference ID: <tt>CHU</tt><br> 189c2daa00SOllivier Robert Driver ID: <tt>CHU</tt><br> 199c2daa00SOllivier Robert Modem Port: <tt>/dev/chu<i>u</i></tt>; 300 baud, 8-bits, no parity<br> 209c2daa00SOllivier Robert Autotune Port: <tt>/dev/icom</tt>; 1200/9600 baud, 8-bits, no parity<br> 219c2daa00SOllivier Robert Audio Device: <tt>/dev/chu_audio</tt> and <tt>/dev/audioctl</tt> 229c2daa00SOllivier Robert <h4>Description</h4> 239c2daa00SOllivier Robert <p>This driver synchronizes the computer time using data encoded in radio transmissions from Canadian time/frequency station CHU in Ottawa, Ontario. It replaces an earlier one, built by Dennis Ferguson in 1988, which required a special line discipline to preprocessed the signal. The new driver includes more powerful algorithms implemented directly in the driver and requires no preprocessing.</p> 249c2daa00SOllivier Robert <p>CHU transmissions are made continuously on 3330 kHz, 7335 kHz and 14670 kHz in upper sideband, compatible AM mode. 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 as propagation conditions change throughout the day and night. The performance of this driver when tracking the station is ordinarily better than 1 ms in time with frequency drift less than 0.5 PPM when not tracking the station.</p> 259c2daa00SOllivier Robert <p>While there are currently no known commercial CHU receivers, a simple but effective receiver/demodulator can be constructed from an ordinary shortwave receiver and Bell 103 compatible, 300-b/s modem or modem chip, as described on the <a href="../pps.html">Pulse-per-second (PPS) Signal Interfacing</a> page. The driver can use the modem to receive the radio signal and demodulate the data or, if available, the driver can use the audio codec of the Sun workstation or another with compatible audio interface. In the latter case, the driver implements the modem using DSP routines, so the radio can be connected directly to either the microphone or line input port.</p> 269c2daa00SOllivier Robert <p>This driver incorporates several features in common with other audio drivers such as described in the <a href="driver36.html">Radio WWV/H Audio Demodulator/Decoder</a> and the <a href="driver6.html">IRIG Audio Decoder</a> pages. They include automatic gain control (AGC), selectable audio codec port and signal monitoring capabilities. For a discussion of these common features, as well as a guide to hookup, debugging and monitoring, see the <a href="../audio.html">Reference Clock Audio Drivers</a> page.</p> 279c2daa00SOllivier Robert <p>Ordinarily, the driver poll interval is set to 14 (about 4.5 h), although this can be changed with configuration commands. As long as the clock is set or verified at least once during this interval, the NTP algorithms will consider the source reachable and selectable to discipline the system clock. However, if this does not happen for eight poll intervals, the algorithms will consider the source unreachable and some other source will be chosen (if available) to discipline the system clock.</p> 289c2daa00SOllivier Robert <p>The decoding algorithms process the data using maximum-likelihood techniques which exploit the considerable degree of redundancy available in each broadcast message or burst. As described below, every character is sent twice and, in the case of format A bursts, the burst is sent eight times every minute. In the case of format B bursts, which are sent once each minute, the burst is considered correct only if every character matches its repetition in the burst. In the case of format A messages, a majority decoder requires at least six repetitions for each digit in the timecode and more than half of the repetitions decode to the same digit. Every character in every burst provides an independent timestamp upon arrival with a potential total of over 60 timestamps for each minute.</p> 299c2daa00SOllivier Robert <p>A timecode in the format described below is assembled when all bursts have been received in the minute. The timecode is considered valid and the clock set when at least one valid format B burst has been decoded and the above requirements are met. The <tt>yyyy</tt> year field in the timecode indicates whether a valid format B burst has been received. Upon startup, this field is initialized at zero; when a valid format B burst is received, it is set to the current Gregorian year. The <tt>q</tt> quality character field in the timecode indicates whether a valid timecode has been determined. If any of the high order three bits of this character are set, the timecode is invalid.</p> 309c2daa00SOllivier Robert <p>Once the clock has been set for the first time, it will appear reachable and selectable to discipline the system clock, even if the broadcast signal is lost. Since the signals are almost always available during some period of the day and the NTP clock discipline algorithms are designed to work well even in this case, it is unlikely that the system clock could drift more than a few tens of milliseconds during periods of signal loss. To 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.</p> 319c2daa00SOllivier Robert <p>The last three fields in the timecode are useful in assessing the quality of the radio channel during the most recent minute bursts were received. The <tt>bcnt</tt> field shows the number of format A bursts in the range 1-8. The <tt>dist</tt> field shows the majority decoder distance, or the minimum number of sample repetitions for each digit of the timecode in the range 0-16. The <tt>tsmp</tt> field shows the number of timestamps determined in the range 0-60. For a valid timecode, <tt>bcnt</tt> must be at least 3, <tt>dist</tt> must be greater than <tt>bcnt</tt> and <tt>tsmp</tt> must be at least 20.</p> 329c2daa00SOllivier Robert <h4>Program Operation</h4> 339c2daa00SOllivier Robert <p>The program consists of four major parts: the DSP modem, maximum likelihood UART, burst assembler and majority decoder. The DSP modem demodulates Bell 103 modem answer-frequency signals; that is, frequency-shift keyed (FSK) tones of 2225 Hz (mark) and 2025 Hz (space). This is done using a 4th-order IIR filter and limiter/discriminator with 500-Hz bandpass centered on 2125 Hz and followed by a FIR raised-cosine lowpass filter optimized for the 300-b/s data rate. Alternately, the driver can be compiled to delete the modem and input 300 b/s data directly from an external modem via a serial port.</p> 349c2daa00SOllivier Robert <p>The maximum likelihood UART is implemented using a set of eight 11-stage shift registers, one for each of eight phases of the 300-b/s bit clock. At each phase a new baseband signal value from the DSP modem is shifted into the corresponding register and the maximum and minimum over all 11 samples computed. This establishes a slice level midway between the maximum and minimum over all stages. For each stage, a signal level above this level is a mark (1) and below is a space (0). A quality metric is calculated for each register with respect to the slice level and the a-priori signal consisting of a mark bit (previous stop bit), space (start) bit, eight arbitrary information bits and the first of the two mark (stop) bits.</p> 359c2daa00SOllivier Robert <p>The shift registers are processed in round-robin order as each modem value arrives until one of them shows a valid framing pattern consisting of a mark bit, space bit, eight arbitrary data bits and a mark bit. When found, the data bits from the register with the best metric is chosen as the maximum likelihood character and the UART begins to process the next character.</p> 369c2daa00SOllivier Robert <p>The burst assembler processes characters either from the maximum likelihood UART or directly from the serial port as configured. A burst begins when a character is received and is processed after a timeout interval when no characters are received. If the interval between characters is greater than two characters, but less than the timeout interval, the burst is rejected as a runt and a new burst begun. As each character is received, a timestamp is captured and saved for later processing.</p> 379c2daa00SOllivier Robert <p>A valid burst consists of ten characters in two replicated five-character blocks. A format B block contains the year and other information in ten hexadecimal digits. A format A block contains the timecode in ten decimal digits, the first of which is a framing code (6). The burst assembler must deal with cases where the first character of a format A burst is lost or is noise. This is done using the framing code to correct the phase, either one character early or one character late.</p> 389c2daa00SOllivier Robert <p>The burst distance is incremented by one for each bit in the first block that matches the corresponding bit in the second block and decremented by one otherwise. In a format B burst the second block is bit-inverted relative to the first, so a perfect burst of five 8-bit characters has distance -40. In a format A block the two blocks are identical, so a perfect burst has distance +40. Format B bursts must be perfect to be acceptable; however, format A bursts, which are further processed by the majority decoder, are acceptable if the distance is at least 28.</p> 399c2daa00SOllivier Robert <p>Each minute of transmission includes eight format A bursts containing two timecodes for each second from 31 through 39. The majority decoder uses a decoding matrix of ten rows, one for each digit position in the timecode, and 16 columns, one for each 4-bit code combination that might be decoded at that position. In order to use the character timestamps, it is necessary to reliably determine the second number of each burst. In a valid burst, the last digit of the two timecodes in the block must match and the value must be in the range 2-9 and greater than in the previous burst.</p> 409c2daa00SOllivier Robert <p>As each hex digit of a valid burst is processed, the value at the row corresponding to the digit position in the timecode and column corresponding to the code found at that position is incremented. At the end of each minute of transmission, each row of the decoding matrix encodes the number of occurrences of each code found at the corresponding position of the timecode. However, the first digit (framing code) is always 6, the ninth (second tens) is always 3 and the last (second units) changes for each burst, so are not used.</p> 419c2daa00SOllivier Robert <p>The maximum over all occurrences at each timecode digit position is the distance for that position and the corresponding code is the maximum likelihood candidate. If the distance is zero, the decoder assumes a miss; if the distance is not more than half the total number of occurrences, the decoder assumes a soft error; if two different codes with the same distance are found, the decoder assumes a hard error. In all these cases the decoder encodes a non-decimal character which will later cause a format error when the timecode is reformatted. The decoding distance is defined as the minimum distance over the first nine digits; the tenth digit varies over the seconds and is uncounted.</p> 429c2daa00SOllivier Robert <p>The result of the majority decoder is a nine-digit timecode representing the maximum likelihood candidate for the transmitted timecode in that minute. Note that the second and fraction within the minute are always zero and that the actual reference point to calculate timestamp offsets is backdated to the first second of the minute. At this point the timecode block is reformatted and the year, days, hours and minutes extracted along with other information from the format B burst, including DST state, DUT1 correction and leap warning. The reformatting operation checks the timecode for invalid code combinations that might have been left by the majority decoder and rejects the entire timecode if found.</p> 439c2daa00SOllivier Robert <p>If the timecode is valid, it is passed to the reference clock interface along with the backdated timestamp offsets accumulated over the minute. A perfect set of nine bursts could generate as many as 90 timestamps, but the maximum the interface can handle is 60. These are processed by the interface using a median filter and trimmed-mean average, so the resulting system clock correction is usually much better than would otherwise be the case with radio noise, UART jitter and occasional burst errors.</p> 449c2daa00SOllivier Robert <h4>Autotune</h4> 459c2daa00SOllivier Robert <p>The driver includes provisions to automatically tune the radio in 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.</p> 469c2daa00SOllivier Robert <p>Each ICOM radio is assigned a unique 8-bit ID select code, usually expressed in hex format. To activate the CI-V interface, the <tt>mode</tt> keyword of the <tt>server</tt> configuration command specifies a nonzero select code in decimal format. A table of ID select codes for the known ICOM radios is given below. Since all ICOM select codes are less than 128, the high order bit of the code is used by the driver to specify the baud rate. If this bit is not set, the rate is 9600 bps for the newer radios; if set, the rate is 1200 bps for the older radios. A missing <tt>mode</tt> keyword or a zero argument leaves the interface disabled.</p> 479c2daa00SOllivier Robert <p>If specified, the driver will attempt to open the device <tt>/dev/icom</tt> and, if successful will tune the radio to 3.330 MHz. If after five minutes at this frequency not more than two format A bursts have been received for any minute, the driver will tune to 7.335 MHz, then to 14.670 MHz, then return to 3.330 MHz and continue in this cycle. However, the driver is liberal in what it assumes of the configuration. If the <tt>/dev/icom</tt> 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.</p> 489c2daa00SOllivier Robert <h4>Radio Broadcast Format</h4> 499c2daa00SOllivier Robert <p>The CHU time broadcast includes an audio signal compatible with the Bell 103 modem standard (mark = 2225 Hz, space = 2025 Hz). It consist of nine, ten-character bursts transmitted at 300 b/s and beginning each second from second 31 to second 39 of the minute. Each character consists of eight data bits plus one start bit and two stop bits to encode two hex digits. The burst data consist of five characters (ten hex digits) followed by a repeat of these characters. In format A, the characters are repeated in the same polarity; in format B, the characters are repeated in the opposite polarity.</p> 509c2daa00SOllivier Robert <p>Format A bursts are sent at seconds 32 through 39 of the minute in hex digits</p> 519c2daa00SOllivier Robert <p><tt>6dddhhmmss6dddhhmmss</tt></p> 529c2daa00SOllivier Robert <p>The first ten digits encode a frame marker (<tt>6</tt>) followed by the day (<tt>ddd</tt>), hour (<tt>hh</tt>), minute (<tt>mm</tt>) and second (<tt>ss</tt>). Since format A bursts are sent during the third decade of seconds the tens digit of <tt>ss</tt> is always 3. The driver uses this to determine correct burst synchronization. These digits are then repeated with the same polarity.</p> 539c2daa00SOllivier Robert <p>Format B bursts are sent at second 31 of the minute in hex digits</p> 549c2daa00SOllivier Robert <p><tt>xdyyyyttaaxdyyyyttaa</tt></p> 559c2daa00SOllivier Robert <p>The first ten digits encode a code (<tt>x</tt> described below) followed by the DUT1 (<tt>d</tt> in deciseconds), Gregorian year (<tt>yyyy</tt>), difference TAI - UTC (<tt>tt</tt>) and daylight time indicator (<tt>aa</tt>) peculiar to Canada. These digits are then repeated with inverted polarity.</p> 569c2daa00SOllivier Robert <p>The <tt>x</tt> is coded</p> 579c2daa00SOllivier Robert <dl> 589c2daa00SOllivier Robert <dt><tt>1</tt> 599c2daa00SOllivier Robert <dd>Sign of DUT (0 = +)/dd> 609c2daa00SOllivier Robert <dt><tt>2</tt> 619c2daa00SOllivier Robert <dd>Leap second warning. One second will be added. 629c2daa00SOllivier Robert <dt><tt>4</tt> 639c2daa00SOllivier Robert <dd>Leap second warning. One second will be subtracted. This is not likely to happen in our universe. 649c2daa00SOllivier Robert <dt><tt>8</tt> 659c2daa00SOllivier Robert <dd>Even parity bit for this nibble. 669c2daa00SOllivier Robert </dl> 679c2daa00SOllivier Robert <p>By design, the last stop bit of the last character in the burst coincides with 0.5 second. Since characters have 11 bits and are transmitted at 300 b/s, the last stop bit of the first character coincides with 0.5 - 10 * 11/300 = 0.133 second. Depending on the UART, character interrupts can vary somewhere between the beginning of bit 9 and end of bit 11. These eccentricities can be corrected along with the radio propagation delay using the <tt>fudge time1</tt> variable.</p> 689c2daa00SOllivier Robert <h4>Debugging Aids</h4> 699c2daa00SOllivier Robert <p>The most convenient way to track the program status is using the <tt>ntpq</tt> program and the <tt>clockvar</tt> 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 trace feature (<tt>-d</tt> on the <tt>ntpd</tt> command line)is enabled, the program produces detailed status messages as it operates. If the <tt>fudge flag 4</tt> is set, these messages are written to the <tt>clockstats</tt> file. All messages produced by this driver have the prefix <tt>chu</tt> for convenient filtering with the Unix <tt>grep</tt> command.</p> 709c2daa00SOllivier Robert <p>With debugging enabled the driver produces messages in the following formats:</p> 719c2daa00SOllivier Robert <p>A format <tt>chuA</tt> message is produced for each format A burst received in seconds 32 through 39 of the minute:</p> 729c2daa00SOllivier Robert <p><tt>chuA n b s code</tt></p> 739c2daa00SOllivier Robert <p>where <tt>n</tt> is the number of characters in the burst (0-11), <tt>b</tt> the burst distance (0-40), <tt>s</tt> the synchronization distance (0-40) and <tt>code</tt> the burst characters as received. Note that the hex digits in each character are reversed and the last ten digits inverted, so the burst</p> 749c2daa00SOllivier Robert <p><tt>11 40 1091891300ef6e76ecff</tt></p> 759c2daa00SOllivier Robert <p>is interpreted as containing 11 characters with burst distance 40. The nibble-swapped timecode shows DUT1 +0.1 second, year 1998 and TAI -UTC 31 seconds.</p> 769c2daa00SOllivier Robert <p>A format <tt>chuB</tt> message is produced for each format B burst received in second 31 of the minute:</p> 779c2daa00SOllivier Robert <p><tt>chuB n b f s m code</tt></p> 789c2daa00SOllivier Robert <p>where <tt>n</tt> is the number of characters in the burst (0-11), <tt>b</tt> the burst distance (0-40), <tt>f</tt> the field alignment (-1, 0, 1), <tt>s</tt>the synchronization distance (0-16), <tt>m</tt>the burst number (2-9) and <tt>code</tt> the burst characters as received. Note that the hex digits in each character are reversed, so the burst</p> 799c2daa00SOllivier Robert <p><tt>10 38 0 16 9 06851292930685129293</tt></p> 809c2daa00SOllivier Robert <p>is interpreted as containing 11 characters with burst distance 38, field alignment 0, synchronization distance 16 and burst number 9. The nibble-swapped timecode shows day 58, hour 21, minute 29 and second 39.</p> 819c2daa00SOllivier Robert <p>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 messages. Interpretation of these messages requires knowledge of the CI-V protocol, which is beyond the scope of this document.</p> 829c2daa00SOllivier Robert <h4>Monitor Data</h4> 839c2daa00SOllivier Robert When enabled by the <tt>filegen</tt> facility, every received timecode is written to the <tt>clockstats</tt> file in the following format: 849c2daa00SOllivier Robert <pre> 859c2daa00SOllivier Robert sq yy ddd hh:mm:ss.fff ld dut lset agc rfrq bcnt dist tsmp 869c2daa00SOllivier Robert 879c2daa00SOllivier Robert s sync indicator 889c2daa00SOllivier Robert q quality character 899c2daa00SOllivier Robert yyyy Gregorian year 909c2daa00SOllivier Robert ddd day of year 919c2daa00SOllivier Robert hh hour of day 929c2daa00SOllivier Robert mm minute of hour 939c2daa00SOllivier Robert ss second of minute 949c2daa00SOllivier Robert fff millisecond of second 959c2daa00SOllivier Robert l leap second warning 969c2daa00SOllivier Robert d DST state 979c2daa00SOllivier Robert dut DUT sign and magnitude in deciseconds 989c2daa00SOllivier Robert lset minutes since last set 999c2daa00SOllivier Robert agc audio gain (0-255) 1009c2daa00SOllivier Robert rfrq radio frequency 1019c2daa00SOllivier Robert bcnt burst count 1029c2daa00SOllivier Robert dist decoding distance 1039c2daa00SOllivier Robert tsmp timestamps captured 1049c2daa00SOllivier Robert</pre> 1059c2daa00SOllivier Robert The fields beginning with <tt>year</tt> and extending through <tt>dut</tt> are decoded from the received data and are in fixed-length format. The <tt>agc</tt> and <tt>lset</tt> fields, as well as the following driver-dependent fields, are in variable-length format. 1069c2daa00SOllivier Robert <dl> 1079c2daa00SOllivier Robert <dt><tt>s</tt> 1089c2daa00SOllivier Robert <dd>The sync indicator is initially <tt>?</tt> before the clock is set, but turns to space when the clock is correctly set. 1099c2daa00SOllivier Robert <dt><tt>q</tt> 1109c2daa00SOllivier Robert <dd>The quality character is a four-bit hexadecimal code showing which alarms have been raised during the most recent minute. Each bit is associated with a specific alarm condition according to the following: 1119c2daa00SOllivier Robert <dl> 1129c2daa00SOllivier Robert <dt><tt>8</tt> 1139c2daa00SOllivier Robert <dd>Decoder alarm. A majority of repetitions for at least one digit of the timecode fails to agree. 1149c2daa00SOllivier Robert <dt><tt>4</tt> 1159c2daa00SOllivier Robert <dd>Timestamp alarm. Fewer than 20 timestamps have been determined. 1169c2daa00SOllivier Robert <dt><tt>2</tt> 1179c2daa00SOllivier Robert <dd>Format alarm. The majority timecode contains invalid bit combinations. 1189c2daa00SOllivier Robert <dt><tt>1</tt> 1199c2daa00SOllivier Robert <dd>Frame alarm. A framing or format error occurred on at least one burst during the minute. 1209c2daa00SOllivier Robert </dl> 1219c2daa00SOllivier Robert <p>It is important to note that one or more of the above alarms does not necessarily indicate a clock error, but only that the decoder has detected a condition that may in future result in an error.</p> 1229c2daa00SOllivier Robert <dt><tt>yyyy ddd hh:mm:ss.fff</tt> 1239c2daa00SOllivier Robert <dd>The timecode format itself is self explanatory. Note that the Gregorian year is decoded directly from the transmitted timecode. 1249c2daa00SOllivier Robert <dt><tt>l</tt> 1259c2daa00SOllivier Robert <dd>The leap second warning is normally space, but changes to <tt>L</tt> if a leap second is to occur at the end of the month of June or December. 1269c2daa00SOllivier Robert <dt><tt>d</tt> 1279c2daa00SOllivier Robert <dd>The DST code for Canada encodes the state for all provinces. 1289c2daa00SOllivier Robert <dt><tt>dut</tt> 1299c2daa00SOllivier Robert <dd>The DUT sign and magnitude shows the current UT1 offset relative to the displayed UTC time, in deciseconds. 1309c2daa00SOllivier Robert <dt><tt>lset</tt> 1319c2daa00SOllivier Robert <dd>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 is number of minutes since the time was last verified relative to the broadcast signal. 1329c2daa00SOllivier Robert <dt><tt>agc</tt> 1339c2daa00SOllivier Robert <dd>The audio gain shows the current codec gain setting in the range 0 to 255. Ordinarily, the receiver audio gain control or IRIG level control should be set for a value midway in this range. 1349c2daa00SOllivier Robert <dt><tt>rfrq</tt> 1359c2daa00SOllivier Robert <dd>The current radio frequency, if the CI-V interface is active, or 'X' if not. 1369c2daa00SOllivier Robert <dt><tt>bcnt</tt> 1379c2daa00SOllivier Robert <dd>The number of format A bursts received during the most recent minute bursts were received. 1389c2daa00SOllivier Robert <dt><tt>dist</tt> 1399c2daa00SOllivier Robert <dd>The minimum decoding distance determined during the most recent minute bursts were received. 1409c2daa00SOllivier Robert <dt><tt>tsmp</tt> 1419c2daa00SOllivier Robert <dd>The number of timestamps determined during the most recent minute bursts were received. 1429c2daa00SOllivier Robert </dl> 1439c2daa00SOllivier Robert <h4>Modes</h4> 1449c2daa00SOllivier Robert <p>The <tt>mode</tt> keyword of the <tt>server</tt> configuration command specifies the ICOM ID select code. A missing or zero argument disables the CI-V interface. Following are the ID select codes for the known radios.</p> 1459c2daa00SOllivier Robert <table width="100%" cols="6"> 1469c2daa00SOllivier Robert <tr> 1479c2daa00SOllivier Robert <td>Radio</td> 1489c2daa00SOllivier Robert <td>Hex</td> 1499c2daa00SOllivier Robert <td>Decimal</td> 1509c2daa00SOllivier Robert <td>Radio</td> 1519c2daa00SOllivier Robert <td>Hex</td> 1529c2daa00SOllivier Robert <td>Decimal</td> 1539c2daa00SOllivier Robert </tr> 1549c2daa00SOllivier Robert <tr> 1559c2daa00SOllivier Robert <td>IC725</td> 1569c2daa00SOllivier Robert <td>0x28</td> 1579c2daa00SOllivier Robert <td>40</td> 1589c2daa00SOllivier Robert <td>IC781</td> 1599c2daa00SOllivier Robert <td>0x26</td> 1609c2daa00SOllivier Robert <td>38</td> 1619c2daa00SOllivier Robert </tr> 1629c2daa00SOllivier Robert <tr> 1639c2daa00SOllivier Robert <td>IC726</td> 1649c2daa00SOllivier Robert <td>0x30</td> 1659c2daa00SOllivier Robert <td>48</td> 1669c2daa00SOllivier Robert <td>R7000</td> 1679c2daa00SOllivier Robert <td>0x08</td> 1689c2daa00SOllivier Robert <td>8</td> 1699c2daa00SOllivier Robert </tr> 1709c2daa00SOllivier Robert <tr> 1719c2daa00SOllivier Robert <td>IC735</td> 1729c2daa00SOllivier Robert <td>0x04</td> 1739c2daa00SOllivier Robert <td>4</td> 1749c2daa00SOllivier Robert <td>R71</td> 1759c2daa00SOllivier Robert <td>0x1A</td> 1769c2daa00SOllivier Robert <td>26</td> 1779c2daa00SOllivier Robert </tr> 1789c2daa00SOllivier Robert <tr> 1799c2daa00SOllivier Robert <td>IC751</td> 1809c2daa00SOllivier Robert <td>0x1c</td> 1819c2daa00SOllivier Robert <td>28</td> 1829c2daa00SOllivier Robert <td>R7100</td> 1839c2daa00SOllivier Robert <td>0x34</td> 1849c2daa00SOllivier Robert <td>52</td> 1859c2daa00SOllivier Robert </tr> 1869c2daa00SOllivier Robert <tr> 1879c2daa00SOllivier Robert <td>IC761</td> 1889c2daa00SOllivier Robert <td>0x1e</td> 1899c2daa00SOllivier Robert <td>30</td> 1909c2daa00SOllivier Robert <td>R72</td> 1919c2daa00SOllivier Robert <td>0x32</td> 1929c2daa00SOllivier Robert <td>50</td> 1939c2daa00SOllivier Robert </tr> 1949c2daa00SOllivier Robert <tr> 1959c2daa00SOllivier Robert <td>IC765</td> 1969c2daa00SOllivier Robert <td>0x2c</td> 1979c2daa00SOllivier Robert <td>44</td> 1989c2daa00SOllivier Robert <td>R8500</td> 1999c2daa00SOllivier Robert <td>0x4a</td> 2009c2daa00SOllivier Robert <td>74</td> 2019c2daa00SOllivier Robert </tr> 2029c2daa00SOllivier Robert <tr> 2039c2daa00SOllivier Robert <td>IC775</td> 2049c2daa00SOllivier Robert <td>0x46</td> 2059c2daa00SOllivier Robert <td>68</td> 2069c2daa00SOllivier Robert <td>R9000</td> 2079c2daa00SOllivier Robert <td>0x2a</td> 2089c2daa00SOllivier Robert <td>42</td> 2099c2daa00SOllivier Robert </tr> 2109c2daa00SOllivier Robert </table> 2119c2daa00SOllivier Robert <h4>Fudge Factors</h4> 2129c2daa00SOllivier Robert <dl> 2139c2daa00SOllivier Robert <dt><tt>time1 <i>time</i></tt> 2149c2daa00SOllivier Robert <dd>Specifies the propagation delay for CHU (45:18N 75:45N), in seconds and fraction, with default 0.0. 2159c2daa00SOllivier Robert <dt><tt>time2 <i>time</i></tt> 2169c2daa00SOllivier Robert <dd>Not used by this driver. 2179c2daa00SOllivier Robert <dt><tt>stratum <i>number</i></tt> 2189c2daa00SOllivier Robert <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. 2199c2daa00SOllivier Robert <dt><tt>refid <i>string</i></tt> 2209c2daa00SOllivier Robert <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>CHU</tt>. 2219c2daa00SOllivier Robert <dt><tt>flag1 0 | 1</tt> 2229c2daa00SOllivier Robert <dd>Not used by this driver. 2239c2daa00SOllivier Robert <dt><tt>flag2 0 | 1</tt> 2249c2daa00SOllivier Robert <dd>When the audio driver is compiled, this flag selects the audio input port, where 0 is the mike port (default) and 1 is the line-in port. It does not seem useful to select the compact disc player port. 2259c2daa00SOllivier Robert <dt><tt>flag3 0 | 1</tt> 2269c2daa00SOllivier Robert <dd>When the audio driver is compiled, this flag enables audio monitoring of the input signal. For this purpose, the speaker volume must be set before the driver is started. 2279c2daa00SOllivier Robert <dt><tt>flag4 0 | 1</tt> 2289c2daa00SOllivier Robert <dd>Enable verbose <tt>clockstats</tt> recording if set. 2299c2daa00SOllivier Robert </dl> 2309c2daa00SOllivier Robert <hr> 231ea906c41SOllivier Robert <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 2329c2daa00SOllivier Robert </body> 2339c2daa00SOllivier Robert 2349c2daa00SOllivier Robert</html>