Specifications

42 Z-Family Technical Reference Manual
Ashtech remote receivers (both Differential and RTK) operate with any base station
that generates the industry standard RTCM messages.
Base Data Latency
Both Differential and RTK operation are better the lower the latency of the Base-
Remote data link. To minimize latency set the baud rate of the radios as high as
possible, and use radios that are optimized for low latency GPS operation, such as the
Ashtech SSRadio.
Maximum acceptable base-remote data latency is controlled by $PASHS,RTC,MAX
for code differential mode and by $PASHS,CPD,MAX for RTK mode.
The latency is indicated in the “age of correction” field of the GGA message. The age
increments when the correction message is not received or if it is invalid (bad
checksum). When the age reaches max age, the differential position does not output
anymore (for more information see, "Auto Differential Mode" on page 47).
Figure 3.1: Combined Differential/RTK Base Station and Remote Operation