The parse driver currently supports several clocks with different
query mechanisms. In order for you to find a sample that might be
similar to a clock you might want to integrate into parse i'll sum
up the major features of the clocks (this information is distributed
in the parse/clk_*.c and xntpd/refclock_parse.c files).

---
	Meinberg: 127.127.8. 0- 3 (PZF535TCXO)
		  127.127.8. 4- 7 (PZF535OCXO)
		  127.127.8. 8-11 (DCFUA31)
		  127.127.8.28-31 (GPS166)
	Meinberg: start=<STX>, end=<ETX>, sync on start
                  pattern="\2D:  .  .  ;T: ;U:  .  .  ;    \3"
		  pattern="\2  .  .  ;  ;   :  :  ;        \3"
		  pattern="\2  .  .  ;  ;   :  :  ;    :  ;        ;   .         .       "

	Meinberg is a german manufacturer of time code receivers. Those clocks
	have a pretty common output format in the stock version. In order to
	support NTP Meinberg was so kind to produce some special versions of
	the firmware for the use with NTP. So, if you are going to use a
	Meinberg clock please ask whether there is a special Uni Erlangen
	version.

	General characteristics:
	Meinberg clocks primarily output pulse per second and a describing
	ASCII string. This string can be produced in two modes. either upon
	the reception of a question mark or every second. NTP uses the latter
	mechanism. The DCF77 variants have a pretty good relationship between
	RS232 time code and the PPS signal while the GPS receiver has no fixed
	timeing between the datagram and the pulse (you need to use PPS with
	GPS!) on DCF77 you might get away without the PPS signal.

	The preferred tty setting for Meinberg is:
		CFLAG		(B9600|CS7|PARENB|CREAD|HUPCL)
		IFLAG		(IGNBRK|IGNPAR|ISTRIP)
		OFLAG		0
		LFLAG		0

	The clock is run at datagram once per second.
	Stock dataformat is:

       <STX>D:<dd>.<mm>.<yy>;T:<w>;U:<hh>:<mm>:<ss>;<S><F><D><A><ETX>
   pos:  0  00 00 0 00 0 11 111 1 111 12 2 22 2 22 2 2  2  3  3   3
         1  23 45 6 78 9 01 234 5 678 90 1 23 4 56 7 8  9  0  1   2

    <STX>           = '\002' ASCII start of text
    <ETX>           = '\003' ASCII end of text
    <dd>,<mm>,<yy>  = day, month, year(2 digits!!)
    <w>             = day of week (sunday= 0)
    <hh>,<mm>,<ss>  = hour, minute, second
    <S>             = '#' if never synced since powerup else ' ' for DCF U/A 31
                      '#' if not PZF sychronisation available else ' ' for PZF 535
    <F>             = '*' if time comes from internal quartz else ' '
    <D>             = 'S' if daylight saving time is active else ' '
    <A>             = '!' during the hour preceeding an daylight saving time
                          start/end change

    For the university of Erlangen a special format was implemented to support
    LEAP announcement and anouncement of alternate antenna.

    Version for UNI-ERLANGEN Software is: PZFUERL V4.6 (Meinberg)

    The use of this software release (or higher) is *ABSOLUTELY*
    recommended (ask for PZFUERL version as some minor HW fixes have
    been introduced) due to the LEAP second support and UTC indication.
    The standard timecode does not indicate when the timecode is in
    UTC (by front panel configuration) thus we have no chance to find
    the correct utc offset. For the standard format do not ever use
    UTC display as this is not detectable in the time code !!!

        <STX><dd>.<mm>.<yy>; <w>; <hh>:<mm>:<ss>; <U><S><F><D><A><L><R><ETX>
    pos:  0   00 0 00 0 00 11 1 11 11 1 11 2 22 22 2  2  2  2  2  3  3   3
          1   23 4 56 7 89 01 2 34 56 7 89 0 12 34 5  6  7  8  9  0  1   2
    <STX>           = '\002' ASCII start of text
    <ETX>           = '\003' ASCII end of text
    <dd>,<mm>,<yy>  = day, month, year(2 digits!!)
    <w>             = day of week (sunday= 0)
    <hh>,<mm>,<ss>  = hour, minute, second
    <U>             = 'U' UTC time display
    <S>             = '#' if never synced since powerup else ' ' for DCF U/A 31
                      '#' if not PZF sychronisation available else ' ' for PZF 535
    <F>             = '*' if time comes from internal quartz else ' '
    <D>             = 'S' if daylight saving time is active else ' '
    <A>             = '!' during the hour preceeding an daylight saving time
                          start/end change
    <L>             = 'A' LEAP second announcement
    <R>             = 'R' alternate antenna

    Meinberg GPS166 receiver

    You must get the Uni-Erlangen firmware for the GPS receiver support
    to work to full satisfaction !

        <STX><dd>.<mm>.<yy>; <w>; <hh>:<mm>:<ss>; <+/-><00:00>; <U><S><F><D><A><L><R><L>; <position...><ETX>
 *
           000000000111111111122222222223333333333444444444455555555556666666
           123456789012345678901234567890123456789012345678901234567890123456
        \x0209.07.93; 5; 08:48:26; +00:00;        ; 49.5736N  11.0280E  373m\x03
 *
    
    <STX>           = '\002' ASCII start of text
    <ETX>           = '\003' ASCII end of text
    <dd>,<mm>,<yy>  = day, month, year(2 digits!!)
    <w>             = day of week (sunday= 0)
    <hh>,<mm>,<ss>  = hour, minute, second
    <+/->,<00:00>   = offset to UTC
    <S>             = '#' if never synced since powerup else ' ' for DCF U/A 31
                      '#' if not PZF sychronisation available else ' ' for PZF 535
    <U>             = 'U' UTC time display
    <F>             = '*' if time comes from internal quartz else ' '
    <D>             = 'S' if daylight saving time is active else ' '
    <A>             = '!' during the hour preceeding an daylight saving time
                          start/end change
    <L>             = 'A' LEAP second announcement
    <R>             = 'R' alternate antenna (reminiscent of PZF535) usually ' '
    <L>		   = 'L' on 23:59:60


    For the Meinberg parse look into clock_meinberg.c

---
    RAWDCF: 127.127.8.20-23 (Conrad receiver module - delay 258ms)
	    127.127.8.24-27 (FAU receiver - delay 210ms)
	    127.127.8.40-43 (Boeder receiver - delay 258ms)
    RAWDCF: end=TIMEOUT>1.5s, sync each char (any char), generate psuedo time
            codes, fixed format

    direct DCF77 code input
    In Europe it is relatively easy/cheap the receive the german time code
    transmitter DCF77. The simplest version to process its signal is to
    feed the 100/200ms pulse of the demodulated AM signal via a level
    converter to an RS232 port at 50Baud. parse/clk_rawdcf.c holds all
    necessary decoding logic for the time code which is transmitted each
    minute for one minute. A bit of the time code is sent once a second.

	The preferred tty setting is:
		CFLAG           (B50|CS8|CREAD|CLOCAL)
		IFLAG		0
		OFLAG		0
 		LFLAG		0

	DCF77 raw time code

	From "Zur Zeit", Physikalisch-Technische Bundesanstalt (PTB), Braunschweig
	und Berlin, Maerz 1989

	Timecode transmission:
	AM:
	time marks are send every second except for the second before the
	next minute mark
	time marks consist of a reduction of transmitter power to 25%
	of the nominal level
	the falling edge is the time indication (on time)
	time marks of a 100ms duration constitute a logical 0
	time marks of a 200ms duration constitute a logical 1
	FM:
	see the spec. (basically a (non-)inverted psuedo random phase shift)

	Encoding:
	Second	Contents
	0  - 10	AM: free, FM: 0
	11 - 14	free
	15		R     - alternate antenna
	16		A1    - expect zone change (1 hour before)
	17 - 18	Z1,Z2 - time zone
		 0  0 illegal
		 0  1 MEZ  (MET)
		 1  0 MESZ (MED, MET DST)
		 1  1 illegal
	19		A2    - expect leap insertion/deletion (1 hour before)
	20		S     - start of time code (1)
	21 - 24	M1    - BCD (lsb first) Minutes
	25 - 27	M10   - BCD (lsb first) 10 Minutes
	28		P1    - Minute Parity (even)
	29 - 32	H1    - BCD (lsb first) Hours
	33 - 34      H10   - BCD (lsb first) 10 Hours
	35		P2    - Hour Parity (even)
	36 - 39	D1    - BCD (lsb first) Days
	40 - 41	D10   - BCD (lsb first) 10 Days
	42 - 44	DW    - BCD (lsb first) day of week (1: Monday -> 7: Sunday)
	45 - 49	MO    - BCD (lsb first) Month
	50           MO0   - 10 Months
	51 - 53	Y1    - BCD (lsb first) Years
	54 - 57	Y10   - BCD (lsb first) 10 Years
	58 		P3    - Date Parity (even)
	59		      - usually missing (minute indication), except for leap insertion

---
	Schmid clock: 127.127.8.16-19
	Schmid clock: needs poll, binary input, end='\xFC', sync start

	The Schmid clock is a DCF77 receiver that sends a binary
	time code at the reception of a flag byte. The contents
	if the flag byte determined the time code format. The
	binary time code is delimited by the byte 0xFC.

	TTY setup is:
		CFLAG		(B1200|CS8|CREAD|CLOCAL)
		IFLAG		0
		OFLAG		0
 		LFLAG		0

	The command to Schmid's DCF77 clock is a single byte; each bit
	allows the user to select some part of the time string, as follows (the
	output for the lsb is sent first).
	
	Bit 0:	time in MEZ, 4 bytes *binary, not BCD*; hh.mm.ss.tenths
	Bit 1:	date 3 bytes *binary, not BCD: dd.mm.yy
	Bit 2:	week day, 1 byte (unused here)
	Bit 3:	time zone, 1 byte, 0=MET, 1=MEST. (unused here)
	Bit 4:	clock status, 1 byte,	0=time invalid,
					1=time from crystal backup,
					3=time from DCF77
	Bit 5:	transmitter status, 1 byte,
					bit 0: backup antenna
					bit 1: time zone change within 1h
					bit 3,2: TZ 01=MEST, 10=MET
					bit 4: leap second will be
						added within one hour
					bits 5-7: Zero
	Bit 6:	time in backup mode, units of 5 minutes (unused here)


---
	Trimble SV6: 127.127.8.32-35
	Trimble SV6: needs poll, ascii timecode, start='>', end='<',
                     query='>QTM<', eol='<'

        Trimble SV6 is a GPS receiver with PPS output. It needs to be polled.
	It also need a special tty mode setup (EOL='<').

	TTY setup is:
		CFLAG            (B4800|CS8|CREAD)
		IFLAG            (BRKINT|IGNPAR|ISTRIP|ICRNL|IXON)
		OFLAG            (OPOST|ONLCR)
		LFLAG            (ICANON|ECHOK)

	Special flags are:
		PARSE_F_PPSPPS	    - use CIOGETEV for PPS time stamping
		PARSE_F_PPSONSECOND - the time code is not related to
				      the PPS pulse (so use the time code
				      only for the second epoch)

	Timecode
	0000000000111111111122222222223333333	/ char
	0123456789012345678901234567890123456	\ posn
	>RTMhhmmssdddDDMMYYYYoodnnvrrrrr;*xx<	Actual
	----33445566600112222BB7__-_____--99-	Parse
	>RTM                      1     ;*  <",	Check

---
	ELV DCF7000: 127.127.8.12-15 
	ELV DCF7000: end='\r', pattern="  -  -  -  -  -  -  -  \r"

	The ELV DCF7000 is a cheap DCF77 receiver sending each second
	a time code (though not very precise!) delimited by '`r'

	Timecode
	  YY-MM-DD-HH-MM-SS-FF\r

		FF&0x1	- DST
		FF&0x2	- DST switch warning
		FF&0x4  - unsynchronised

