PFAT: Translate Settings and Uses

The P.F.A.T.™ control system provides several innovative ways to control the messages present in every data stream.  The PFAT features are available in the Pro, Basic, editions of SNIP. Lite copies of SNIP share the same code base, but many of these innovative features are disabled in the freely available Lite edition.

Using the PFAT Translate Dialog Control

The PFAT Translate control is used to modify and translate the selected RTCM3 message types found in any Base Station data stream.  Unlike the other PFAT controls, there are several translate commands that can be invoked for various needs.  And many more are still in development.  Each has its own dialog, making the translate controls easily the most complex interface found in SNIP.  But this complexity enables a number of powerful features unique to SNIP and not found in other Casters.  The results of the translation process are forwarded on to any NTRIP Clients or to other users in SNIP (such as a PUSH_Out stream) in the normal way.  All the messages are still parsed and may be used in various navigation and monitoring services.  Whenever any PFAT Translate action is active, the right-click menu for the stream shows a check mark.  Selecting the menu item displays the Add dialog box.  The message stream must be Parsed in order to Filter the messages.  A master on/off switch for all translation steps is provided in this dialog as well.

The individual controls of the master Translate dialog are described in further detail here (link to be provided at release).  The basic user interaction is to select one of the translate steps, then complete the setting in the presented dialog for that step.  Multiple translate steps may be selected.  [An example would be to offset the Base Station ECEF position, and to downgrade 1004 message types to be 1002 message types for an L1-only user community.]   It is possible to create steps which conflict with each other, therefore some user forethought is presumed.  Like all PFAT settings, the values selected are preserved and used each time the stream (or SNIP) is started.  Hovering the mouse above a translation step will provide (in the tool-tip) a further description of its usage.

The Master Translate Dialog

The Master Translate Dialog is show below.  The translation steps that are disabled on your copy of SNIP are shown as grayed out (these are still in development).    By clicking on the Setup button for a given step, the settings dialog for that step can be brought up.

Current Translations Supported

At this time the following translation steps are shipped with all Basic and Pro models of SNIP  (and also with Evaluation models).

ECEF Adjustment

The ECEF Adjustment translation is used to adjust the ECEF position of the Base Station in the RTCM3 messages.  If the reported position from the data stream is incorrect, or in another reference frame, this translation is used to align it to the preferred datum.

See this article for further details, and this article for an example of use.

Last Observation Flag

The Last Observation Flag translation is used to adjust a flag present in the RTCM3 messages used to indicate that the last set of observations at a given common time has been sent to the user.  By convention, GPS observations are always sent first, followed by GLO observations, followed by other GNSS types.  When a given message observation type has been filtered out with other PFAT methods, it is required that the new ‘last observation’ now convey this flag.  [Failure to do this leaves the rover device hanging and waiting for the final message for the common epoch time which never arrives.]   At this time the Last Observation Flag translation operates on RTCM3 message types 1001~1004 (GPS) and 1009~1012 (GLONASS).

See this article for further details.

L1/L2 Translation to L1 Only Messages

The Remove L2 Content  translation is used remove L2 code and carrier content from RTCM3 Legacy message types 1003~1004 (GPS) and 1001~1012 (GLONASS) to produce (smaller) 1002 and 1010 messages.   This has value to network operators whose rover communities (NTRIP Clients) are made up of L1-only devices by allowing them to provide a wider set of Base Station streams without sending larger message payloads than required.

See this article for further details.

Legacy to MSM Message Conversion

The Legacy to MSM Message Conversion translation is used to create newer MSM style messages from Legacy RTCM3 message types 1001~1004 (GPS) and 1009~1012 (GLONASS).  However, it  will not add additional measurement information (more precision or Doppler data) which is not present in the original message.  This has value to network operators operating with older pre-MSM Base Stations and whose rover communities (NTRIP Clients) are made up of devices that use MSM messages, rather than more established classic messages.

See this article for further details.

MSM to Legacy Message Conversion

The MSM to Legacy Message Conversion translation is the inverse of the Legacy to MSM Message Conversion translation.  It is used to create RTCM3 Legacy message types 1002~1004 (GPS) and 1010~1012 (GLONASS) from MSM messages (types MSM4, 5, 6, and 7).  Message content is truncated when required, and some data elements (Doppler) are not supported in the classical messages.  This has value to network operators whose rover communities (NTRIP Clients) are made up of older devices that cannot use MSM messages, but only the more established Legacy messages.

See this article for further details.

See Also

  • PFAT Filter; used for Filtering message types from a data stream
  • PFAT Add; used for Adding message types to a data stream

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