RT17 is a streaming service used
to encode and transmit real time GPS measurements. RT stands for Real
Time, and 17 refers to the record type 17 GPS measurement information
stored in Trimble DAT and T00 files. This is the basic information used
to produce GPS positions and corrections. RT17 was designed to allow
similar information to be streamed for real time applications. The
format has been expanded beyond basic measurements and now includes:
-
Phase
-
Pseudorange
-
Carrier to noise ratios
-
General tracking information, such as azimuth and elevation
-
Calculated Positions
-
Data collected from Met/Tilt sensors
Stream Control
The epoch interval is used to specify the rate at which the
measurements and/or positions are sent out the port. The output rate
varies from 0.1 second to 10 minutes. The rate selected is based on the
application. High data rates are used for highly dynamic applications,
whereas low data rates are used for long-term monitoring applications.
If the receiver has mixed use, multiple RT17 ports can be configured
with different data rates, and applications can connect to the
appropriate port.
Two checkboxes are provided to control the information that
is included in the stream.
-
Positions
When checked positions will be included in the stream at the
interval specified by the Epoch Interval control.
-
Measurements
When checked GPS measurements will be included in the stream at
the interval specified by the Epoch Interval control.
Stream Options
There are various options that modify the information included in the
RT17 stream. Each is controlled by a checkbox on the web-browser
interface. The options are:
-
Use Concise Format
When checked, some less frequently used information is omitted
from the measurement stream and the precision of some numbers is
reduced from an 8 byte double to a 4 byte float. Refer to the
documentation outlining these formats for the details of the
differences.
-
Send Raw GPS Data
When checked, raw data extracted from GPS satellites is
included in the stream.
-
Send Raw WAAS Data
When checked, raw data extracted from WAAS satellites is
included in the stream.
-
Send Ephemeris GPS Data
When checked:
- Satellite ephemeris data is sent each time a new ephemeris
issue is decoded.
- Ephemeris data for all satellites will be sent when the stream
is first started, or whenever a new TCP or UDP client for the
stream is detected.
- Ephemeris data for all tracked satellites will be re-transmitted
approximately every 5 minutes. Data from non-tracked
satellites will be sent approximately every 15 minutes.
- The Ionospheric Model data will be sent at stream startups, when
new clients are detected, and approximately every 5 minutes.
-
Send IODE Values and Cycleslip Counts
When checked, the stream includes information to assist in
determining if a new ephemeris has been decoded, together with a
count of cycle slips to assist in determining if slips have occurred
when intermediate data are missing.
-
Smooth Carrier Phase
When checked, smoothing is applied to carrier phase
measurements.
-
Smooth Code Phase
When checked, smoothing is applied to code phase measurements.
-
Use Record Type 27
When checked, GPS observables data will be formatted using
the record type 27 instead of the standard record type 17.
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