Instruction manual

Page 24 Z-12 Real-Time Sensor Operation and Reference Manual
the Sensor can even take advantage of RTCM-compliant messages from receivers
manufactured by other companies (such as the Trimble 4000SSi™). This design
provides the versatility and performance necessary to complete any job requiring
precision solutions.
The Sensor allows you to select any of three RTCM differential modes, as listed in
Table 2.7. The first mode uses Type 1 RTCM messages and provides solution
accuracies of better than one meter. The second mode uses Type 18/19 messages and
provides centimeter and sub-centimeter accuracy. A Sensor base and a Sensor rover
can easily be configured to operate in these modes. The third mode requires Type 9
messages to be sent to the rover. An Ashtech reference station or other broadcast
source is required for this operation. You can expect sub-meter accuracy from a
Sensor configured to receive Type 9 messages.
Table 2.6: RTCM Message Types
Message
Type
Contents of Message
1 Differential GPS corrections
2 Delta differential corrections
3 Reference station parameters
6 No parameters, used as transmission fill
(null frame)
9 High-rate differential corrections
16 Special message
18 Uncorrected carrier phase
19 Uncorrected pseudo-range
Table 2.7: Differential RTCM Message Types
Mode Message Type Send Receive Description
Expected
Accuracy
1 Type 1 Yes Yes Code phase Less than 1 meter
2 Type 18/19A* Yes Yes Uncorrected carrier phase
and pseudo-range
measurements
1 cm horizontal,
2 cm vertical
Type 18/19B Yes Yes Uncorrected carrier phase
and pseudo-range
measurements
1 cm horizontal,
2 cm vertical
3 Type 9 No Yes Code phase Less than 1 meter