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BBC Message Formats

Format BBC-01

This format is based on string ASCII characters, and is sent once per second. It provides year, month, day, day of week, day of month, hours, minutes, and seconds.

Number of characters: 24 (including CRLF and '.')

Example message:

T:ye:mo:da:dw:ho:mi:sc

Where:

T Indicates the synchronous moment for the time setting.
ye Year (00-99)
mo Month (01-12)
da Day of month (01-31)
dw Day of week (01=Monday to 7=Sunday)
ho Hours (00-23)
mi Minutes (00-59)
sc Seconds (00-59)

Format BBC-02

This is a hexadecimal frame/message sent twice per second. The message should be sent such that the final “99” occurs at 0 msec and 500 msec.

Number of bytes: 26

Format:

START

Year

Month

Day

Hour

Min

Sec.

AA

AA

07

DA

06

16

13

59

01

Millisecond

Time Zone

Daylight

Leap-second Sign

Leap-second Month

Leap-second Zone

GPS Week

02

BA

80

00

00

00

00

00

1A

2A

GPS Second

GPS to UTC Offset

Check-sum

END

09

3A

7E

12

FE

99

99

Where:

Leap Second Sign:

  • 01=Positive
  • FF=Negative
  • 00=No leap second

Leap Second Month:

  • 00=None scheduled
  • 03=March
  • 06=June
  • 09=September
  • 0C=December

Leap Second Zone:

  • 0=Out of zone
  • 1=Within zone
  • Zone is 15 minutes before to 15 minutes after a leap second.

GPS Week:

  • Up to FFFF

GPS Second:

  • Second of week 000000 up to 093A7F (604799 decimal)

GPS to UTC offset:

  • 2’s complement binary signed integer, seconds

Checksum:

  • Sum of all bytes up to and including the checksum (sum includes the AAAA start identifier but excludes the 9999 end identifier)

Format BBC-03 PSTN

The third format is a string ASCII characters and is sent on a received character.

The message should be advanced by an appropriate number such that the stop bit of each <CR> occurs at the start of the next second. For example, at 300 baud, 8 data bits, 1 stop bit, and no parity, each byte takes 10/300 s=33 ms, so the <CR> byte should be advanced by 33 ms in order for the <CR>’s stop bit to line up with the start of the next second.

Time information is available in UTC format or UK TOD format.

‘t’ command

Input format: t<CR>

Output format:

Current Second

Second + 1

Second + 2

Second + 3

<CR>

HHMMSS<CR>

HHMMSS<CR>

HHMMSS<CR>

Number of characters: 7 (including CR)

Each HHMMSS filed refers to the time at the start of the next second. The data transmitted by VersaSync is timed so that the stop bit of each <CR> ends at the start of the next second.

‘d’ command

VersaSync transmits the date on request.

Input format: d<CR>

Output format: YYMMDD<CR>

Number of output characters: 7 (including CR)

‘s’ command

VersaSync transmits the status information on request.

Input format: s<CR>

Output Format: status

Number of output characters: 1

Where returned, values for status are:

  • G = System Good
  • D = Failure of VersaSync internal diagnostics
  • T = VersaSync does not have correct time

‘l’ command

The loopback command will cause VersaSyncto echo the next character received back to the caller. This may be used by a caller’s equipment to calculate the round trip delay across the PSTN connection in order to apply a correction to the received time data.

Input format: l<CR>

Output format: (Next character received)

‘hu’ command

The hang up command will cause VersaSync to drop the line immediately and terminate the call.

Input format: hu<CR>

Format BBC-04

This format is a string of ASCII characters and is sent once per second.

Number of characters: 18 (including CRLF)

Example message:

T:ho:mi:sc:dw:da:mo:ye:lp:cs<CR><LF>

Where:

T Indicates the synchronous moment for the time setting.
ho Hours (00-23)
mi Minutes (00-59)
sc Seconds (00-59)
dw Day of week (01=Monday to 7=Sunday)
da Day of month (01-31)
mo Month (01-12)
ye Year (00-99)
lp 0 (for 60s, no leap) or 1 (for 61s, leap)
cs Checksum. This is calculated from the start of the message, including start identifier and excluding CRLF. It is created by adding all the 1s. If the sum is even, 0 is returned. If the sum is odd, 1 is returned. This is mathematically the same as sequentially running an XOR on each bit of each byte.

Standard Serial configuration is:

  • RS-232 format
  • 9600 baud
  • 8 data bits
  • 1 stop bit
  • No parity

Format BBC-05 (NMEA RMC Message)

The NMEA Message Format RMC, (Recommended Minimum) provides fix information, speed over ground and Magnetic Variance information. Note that this RMC Message is not 100% identical to the official NMEA RMC MESSAGE (that corresponds to the 3.01 NMEA 0183 standard and is another time code format supported by VersaSync.)

The BBC RMC message (BBC-05) corresponds to Version 2 of the NMEA 0183 standard, following the description below:

Example message:

$GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A

Where:

RMC Recommended Minimum sentence C
123519 Fix taken at 12:35:19 UTC
A Status: A=active or V=Void.
4807.038,N Latitude 48 deg 07.038' N
01131.000,E Longitude 11 deg 31.000' E
22.4 Speed over the ground in knots
84.4 Track angle in degrees True
230394 Date—23rd of March 1994
003.1,W Magnetic Variation
*6A The checksum data, always begins with *