Trimble Outdoors SK8 - Manual (Page 118)

A-54 Lassen-SK8 Embedded GPS Module
Trimble Standard Interface Protocol
A.17.50 Command Packet 0x70
Trimble OEM receivers have a number of filters. Command 0x70 provides control for
these filters. It returns Report 0x70. There are three filters associated with 0x70:
• Position-Velocity (PV) Filter
• Static Filter
• Altitude Filter
The Position-Velocity (PV) Filter is the main filter and is used to “soften” the effect of
constellation switches on position fixes. The filter has no effect on velocity output and
there is no lag due to vehicle dynamics. There may be a small increase in accuracy
however.
A feature of the PV filter is the “static filter” which engages when the receiver is moving
very slowly. This feature improves accuracy in the urban environment. The PV filter
should be turned off for the following applications:
• Slow-moving environments such as walking or drifting with the current
• When rooftop testing of receivers for moving applications
The altitude filter is a simple averaging filter with a time constant of a few seconds. It
should be left on in marine and land applications.
To query for the current settings, Command 0x70 is sent with no databytes. To input new
settings, Command 0x70 is sent with four data bytes, as shown in Table A-59. Also see
A.3 for information on saving the settings to non-volatile memory.
A.17.51 Report 0x70
This report is sent as a response to Command 0x70 as either a query or a set. It contains
four bytes, as shown in Table A-59.
Table A-59. Command and Report Packet 0x70 Field Descriptions
Byte/Item Item Type Bit Number
0 PV Filter BYTE 0 - Off
1 - On
1 Static Filter BYTE 0 - Off
1 - On
2 Altitude Filter BYTE 0 - Off
1 - On
3 Reserved BYTE