Specifications

VP ONCORE COMMAND REFERENCE
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ALMANAC DATA INPUT MESSAGE (@@Cb)
This input data command loads an almanac into the receiver's
nonvolatile memory via the serial port. The entire almanac data message
consists of 34 unique formatted messages that correspond to the
subframe and page number of the almanac data (see GPS-ICD-200 for
format description).
The VP echoes the input almanac data subframe and page numbers of
messages received so the user can validate that each almanac slice has
been accepted. The receiver will collect an entire almanac in local
storage, then check the almanac for validity The receiver will update the
internal almanac data with the new user-supplied almanac upon
completion of the receipt of a valid almanac.
Upon completion of the receipt of a valid almanac, the VP outputs an
almanac status message (see Almanac Status.) This output verifies that
the almanac was accepted and is currently being used for satellite
visibility and DOP computations. Upon completion of the storage of the
new almanac to nonvolatile memory (EEPROM), the VP will output
another almanac status message to verify successful storage of the
almanac.
Any single input message that has an invalid subframe (i.e., not 4 or 5)
will reset the almanac collection software so that the local collection of
almanac data can begin fresh. Subframe 5 page 1 marks the beginning
message and resets the collection process. The data for subframe 5
page 1 must appear first in the string of 34 commands that make up the
total almanac input data. The order for the remaining data is not
important.
At 9600 baud, the user can insert up to about 1K of data per second into
the serial port. Consequently, the user should be aware that the 34 total
messages (of 33 bytes each) that make up the almanac data will take
longer than one second to input into the receiver. Also, the output
response message to each input is limited to 750 maximum byte
transfers per second. As a result, the VP will take several seconds to
operate on all 34 input almanac data commands.
If the VP is currently storing an almanac when the user inputs another
almanac, the VP will complete storage of the first almanac to nonvolatile
memory before accepting the new user input almanac.
109 Synergy Systems, LLC 05OCT01