Globalstar Product Management – Technical Support

The following procedure should be used to re-establish a data link if the previous connection is unexpectedly terminated, regardless of whether the call termination is caused by:

1. User’s processor de-asserts DTR_DP (DTR of the Data_Port)
2. The 2-way satellite signal is lost due to problems with sky blockage (truck parks next to your modem), antenna problems, etc.
3. Local RF interference
4. Any other reason

Monitor the DCD signal on the Data Port (DCD_DP):

1. Whenever the GSP-1720 establishes a data connection, the modem will assert DCD on the Data_Port (DCD_DP)
2. When the the data link is terminated, the modem will de-assert DCD_DP

When DCD_DP is de-asserted, the attached processor (e.g., data logger) should generally:

1. De-assert DTR_DP
2. Wait 20 seconds for a graceful closeout of the session

Once the user has de-asserted DTR_DP and the required wait period has expired, either:

1. Re-assert DTR_DP, compliant with the steps outlined in the document “GSP-1720 timing requirements” and then re-dial AT#777
2. or — Shut down the modem by disconnecting Pin_13 from ground, and allowing it to float.
   • NOTE: make sure that your script is compliant with the procedures outlined in the document “GSP-1720 timing requirements”

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Additional keywords:  1720, sdvm