User manual

ZyWAN User Manual Configuring the ZyWAN

Field Bytes Description

Flag Bits:

Bit 5: UTC TIME FLAG – This bit must be set to indicate that the

TIMETAG represents UTC time.

Bit 6: OVERFLOW FLAG – This bit is set to indicate that this

position, after being added to the store and forward cache, caused

an existing position in the store and forward cache to be deleted.

Bit 7: FIRST POSITION FLAG – This bit is set to indicate that this is

the first position to be transmitted after the device was powered on.

For all subsequent positions, this bit must be cleared.

sats 1 Number of satellites currently being tracked.

lat 4 Latitude of the position in 1/100,000 minutes. For example, the

‘North 26 Degrees 8.767840 Minutes’ is represented as (26 * 60 *

100000 + 8.767840 * 100000) = 156876784.

lon 4 Longitude of the position in 1/100,000 minutes. For example, the

‘WEST 80 Degrees 15.222400 Minutes’ is represented as - (80 * 60 *

100000 + 15.222400 * 100000) = - 481522240.

psrc 1 ASCII ‘G’(0x47) if this is a valid GPS position, otherwise ASCII

‘N’(0x4E).

speed 1 Speed in miles per hour.

head 2 Heading in degrees