When a ship is unable to get a connection...

We've seen an increase in difficulty of accessing the high speed data channels of Inmarsat-B (BSHD). In one recent case, a ship was unable to make a connection, with sporadic attempts, over the duration of an entire "business" day. This can be a frustrating time for a shipboard SeaNet operator, especially if there's pressure from an onboard science party or from ship's business. To ease this frustration, we offer the following suggestions.

Indications of the problem can be observed on the Nera handset if it gets to the point of "Busy with call" but hangs up shortly thereafter. To help pinpoint the problem as inability to access a BHSD channel, use the Nera unit's Clear Cause Log. This log saves the last ten call failure events and provides the events times and a failure codes. It can be accessed via the Nera handset or through the SeaNet control interface. Most failure codes are given in the Saturn Bm Marine Mk2 Technical manual, which is a part of the printed documentation set that accompanies a SeaNet system. This manual can also be seen on-line at www.seanet.int under the Operations/Documentation links.

To look at the Clear Cause Log on the handset, handset access level has to be set to Operator level (2) or higher (Function 12). The Clear Cause Log is accessed via Function 32. The keystroke sequence would be [FUNC]32[ENTER], then [MORE] to get further information about a particular event, and the up(^) and down arrows to scroll through the list of ten events.

To use the SeaNet interface to examine the Clear Cause Log, click on the Diagnostics link in the upper left frame, then on the Nera Info Queries link in the lower left frame. Check the Clear Cause Log(wneralog32) box then click Submit in the upper right. After a few moments the log will be presented in the lower right frame.

Once it's apparent that BHSD channel access is the difficulty, then there's an option of contacting the COMSAT or Station 12 land stations (LES). These companies seem to be most responsive to problem calls when they're made from the vessel that's having the problem. Checking with them can be done to to see if there's some problem with the satellite to which the Nera unit is trying to connect, or simply to learn that the HSD channel is extremely busy. Since BHSD calls are carried on different channels than voice or fax calls, these voice calls may still be made even when there's an HSD channel problem. The call to COMSAT or Station 12 won't cost any money.

To call customer support at the default LES (function 5) as defined in the Nera handset, dial 31# . To select a particular LES, prepend the LES's code, e.g., Comsat, 1*31# , and Station12, 12*31#.