1CH (GNSS Lost Signal Notification)¶
When the terminal detects the “GNSS signal lost”, it will use this message to notify the backend server.
The frame format of a report that only carries 1CH record is as follows:
For example (Total 77 bytes):
2B 00 00 4D 00 01 23 45 67 89 01 23 45 00 00 00 1B 00 00 36 64 F9 AA F6 00 00 1C 00 52 16 09 F9 20 A8 E1 FF 2D C0 96 5F 17 9D A0 01 7D 0A 00 25 00 01 B3 0C 59 13 03 03 02 24 11 00 37 03 05 30 45 01 02 03 06 28 18 00 9A 01 23 76 24
Parts |
Fields |
Length (Byte) |
Range/Format |
Default |
|
|---|---|---|---|---|---|
Head |
18 or 20 |
||||
Reserved |
1 or 1+N |
||||
Records |
Record Length |
1 or 2 |
00H-7FH or 8080H-FFFFH |
||
Generated Time |
4 |
||||
Record Count Number |
2 |
0000H-FFFFH |
|||
Record ID |
1 |
1CH |
1CH |
||
Event Code |
1 |
00H, 01H |
|||
Data of Record |
Data ID |
1 or 2 |
00H-7FH or 8080H-FFFFH |
||
Data Length |
1 or 2 |
00H-7FH or 8080H-FFFFH |
|||
Data Content |
N |
||||
… |
|||||
… |
|||||
Tail |
4 |
||||
The definitions of parts ‘Head’, ‘Reserved’, and ‘Tail’ are here.
Event Code
00H - The terminal detects “GNSS signal lost”.
01H - The terminal detects “GNSS signal recovery”.
Data of Record
It consists of one or more Data ID units.
By default, this record contains only the data IDs listed below, which can be changed by the AT@QRC command described below.
Configuration¶
The parameters related to the generation and transmission of 1CH record are controlled by the following QRC command:
Example:
AT@QRC=gv500cna,1C,,,1,82|89,10,012F$
+ACK:QRC,123456789012345,8203,3,0,1C,012F,20210407101530,1234$
AT@QRC?gv500cna,1C,0C37$
+QRY:QRC,123456789012345,8203,3,0,1,1,1C,,,1,82|89,10,0C37,20210407101530,1234$
Parts |
Fields |
Length (Byte) |
Range/Format |
Default |
|---|---|---|---|---|
Head |
Header |
3 |
AT@ |
AT@ |
Command Word |
3 |
QRC |
QRC |
|
Leading Symbol |
1 |
= |
= |
|
Password |
8-16 |
gv500cna |
||
Body |
Record ID |
2 |
1C |
1C |
Reserved |
0 |
|||
Mode |
<=2 |
0, 1 |
0 |
|
Action |
1 |
0-2 |
||
Data IDs |
N |
ID1|ID2|ID3… |
||
GNSS Lost Time |
<=2 |
5 - 30 (minutes) |
10 |
|
Tail |
Sequence Number |
4 |
0000-FFFF (‘0’-‘9’, ‘A’-‘F’) |
|
Tail |
1 |
$ |
$ |
Record ID
Which record to configure. Always “1C” here.
Mode
0 - Disable. The terminal no longer generates and sends the 1CH record.
1 - Enable Report. The terminal generates and sends the 1CH record. If the location information needs to be included, the terminal directly uses the currently existing location information (even if the location information has expired).
Action
Empty - No change the data IDs in the terminal. If this field is empty, the ‘Data IDs’ field will be ignored.
0 - Append the data IDs carried in the ‘Data IDs’ field to the terminal.
1 - Replace the data IDs in the terminal with the data IDs carried by the ‘Data IDs’ field.
2 - Clear the data IDs carried in the ‘Data IDs’ field from the terminal.
Note: In particular, it always will be 1 when reading this field.
Data IDs
The data IDs contained in the 1CH record. The characters ‘|’ are used to connect each data ID.
For example, “2|88” means Data 2 (Device Name) and Data 88 (SIM Card).
GNSS Lost Time
Specify a time to monitor the GNSS signal.
If there is no GNSS signal or no successful GNSS fix for consecutive time (specified by the ‘GNSS Lost Time’ parameter), the terminal will send this message to indicate “GNSS signal lost”. When the GNSS signal is recovered or a successful fix is obtained again, the terminal will send this message to indicate the “GNSS signal recovery”.
Note: If the terminal is rebooted, it will not report this message to indicate “GNSS signal recovery” even if it has reported this message to indicate “GNSS signal lost” before reboot.