TIME

Time data

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, SPAN CPT7, SMART7, SMART2

Firmware Stream:     

This log provides several time related pieces of information including receiver clock offset and UTC time and offset. It can also be used to determine any offset in the PPS signal relative to GPS reference time.

To find any offset in the PPS signal, log the TIME log 'ontime' at the same rate as the PPS output. For example, if the PPS output is configured to output at a rate of 0.5 seconds (see the PPSCONTROL command) log the TIME log 'ontime 0.5' as follows:

log time ontime 0.5

The TIME log offset field can then be used to determine any offset in PPS output relative to GPS reference time.

GPS reference time is the receiver’s estimate of the true GPS system time. GPS reference time can be found in the header of the TIME log. The relationship between GPS reference time and true GPS system time is:
GPS system time = GPS reference time - offset

Message ID: 101

Log Type: Synch

Recommended Input:

log timea ontime 1

ASCII Example:

#TIMEA,COM1,0,86.5,FINESTEERING,1930,428348.000,02000020,9924,32768;VALID,
1.667187222e-10,9.641617960e-10,-18.00000000000,2017,1,5,22,58,50000,VALID
*2a066e78

  1. Consider the case where you used the ADJUST1PPS command to synchronize two receivers in a primary/secondary relationship to a common external clock. You can use the TIME log after the clock model status is valid to monitor the time difference between the Primary and Secondary receivers.

  2. The header of the TIME log gives you the GPS reference time (the week number since January 5th, 1980) and the seconds into that week. The TIME log outputs the UTC offset (offset of GPS system time from UTC time) and the receiver clock offset from GPS system time.

If you want the UTC time in weeks and seconds, take the week number from the header. Then take the seconds into that week, also from the header, and add the correction to the seconds using the 2 offsets. Ensure not to go negative or rollover (go over the total number of seconds, 604800, in a week). In the case of a rollover, add a week and the left over seconds become the seconds into this new week. If negative, subtract a week and the remainder from the seconds of that week become the seconds into this new week.

For example:

TIME COM1 0 73.5 FINESTEERING 1432 235661.000 02000000 9924 2616 VALID -0.000000351 0.000000214 -14.00000000106 2007 6 19 17 27 27000 VALID

From the time information above:

GPS reference time = 1432 (GPS reference week), 235661.000 (GPS seconds) from the header.

From the description in UTC offset row in the following table:

UTC time = GPS reference time - offset + UTC offset
UTC time

= week 1432, 235661.000 s – (- 0.000000351 (offset) ) - 14.00000000106 (UTC offset)
= week 1432, seconds 235647.00000034994

Field

Field type

Description

Format

Binary Bytes

Binary Offset

1

TIME header

Log header. See Messages for more information.

 

H

0

2

clock status

Clock model status (not including current measurement data), see Table: Clock Model Status

Enum

4

H

3

offset

Receiver clock offset in seconds from GPS system time. A positive offset implies that the receiver clock is ahead of GPS system time. To derive GPS system time, use the following formula:

GPS system time = GPS reference time - offset.

The GPS reference time can be obtained from the log header.

Double

8

H+4

4

offset std

Receiver clock offset standard deviation (s)

Double

8

H+12

5

utc offset

The offset of GPS system time from UTC time, computed using almanac parameters. UTC time is GPS reference time plus the current UTC offset minus the receiver clock offset:

UTC time = GPS reference time - offset + UTC offset

Double

8

H+20

6

utc year

UTC year

Ulong

4

H+28

7

utc month

UTC month (0-12)

If UTC time is unknown, the value for month is 0.

Uchar

1

H+32

8

utc day

UTC day (0-31)

If UTC time is unknown, the value for day is 0.

Uchar

1

H+33

9

utc hour

UTC hour (0-23)

Uchar

1

H+34

10

utc min

UTC minute (0-59)

Uchar

1

H+35

11

utc ms

UTC millisecond (0-60999)

Maximum of 60999 when leap second is applied.

Ulong

4

H+36

12

utc status

UTC status

0 = Invalid

1 = Valid

2 = Warning1

Enum

4

H+40

13

xxxx

32-bit CRC (ASCII and Binary only)

Ulong

4

H+44

14

[CR][LF]

Sentence terminator (ASCII only)

-

-

-

 

OM-20000167 v13

October 2019

Email comments to NovAtel_TPUBS@NovAtel.com

7.07.03 / OM7MR0703RN0000
PP7 07.07.03 / EP7PR0703RN0000
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