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the Sensor can even take advantage of RTCM-com pliant m essages 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.
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
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 2.7: Differential RTCM Message Types
Mode
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†
Type 9
No
Yes
Code phase
Less than 1 meter
3
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Message Type
Z-12 Real-Time Sensor Operation and Reference Manual