H220 Integrator Guide
Appendix A- FAQ
Page A6
External Corrections
My H220 system does not appear to be using DGPS or RTK corrections from an external
correction source. What could be the problem?
This could be due to several factors. To isolate the issue:
Make sure DGPS corrections are RTCM v2.3 protocol.
Make sure RTK corrections are either ROX, RTCM v3, CMR, or CMR+ protocol.
Verify the baud rates used by the H220 match that of the external correction source.
The external correction should be using an 8-data bit, no parity, 1 stop
bit (8-N-1) serial port configuration.
Inspect the cable connection to ensure there is no damage.
Check the pin-out information for the cables to ensure the transmit line of
the external correction source is connected to the receive line of the
H220’s serial port and that the signal grounds are connected.
Make sure the H220 has been set to receive external corrections
by issuing the $JDIFF command. Refer to the
Hemisphere GNSS
Technical Reference Guide.
Installation
How will the antenna selection and mounting affect H220 performance?
For best results:
Select a multipath-resistant antenna
Ensure the antenna tracks all the available signals for the receiver
Mount the antenna with the best possible view of the sky in a location with the lowest
possible multi-path
Using a magnetic mount for the antenna will not affect performance
I could not install my antennas at the same height. How do I calibrate for the height
offset?
You may enter a non-level bias calculation that adjusts the pitch/roll output to calibrate the
measurement if the antenna array is not installed on a horizontal plane.
To calibrate the pitch/roll reading, send the following command:
$JATT,PBIAS,x<CR><LF>
where x is a bias (in degrees) that will be added to the pitch/roll measurement. The acceptable
pitch bias range is -15.0º to 15.0º (default is 0.0º).
To determine the current pitch compensation angle, send the following command:
$JATT,PBIAS<CR><LF>
The pitch/roll bias is added after the negation of the pitch/roll measurement (if so invoked with
the
$JATT,NEGTILT
command).
