Paradise P300 specifications Disable the Upper Temperature Limit

8Disable the Upper Temperature Limit

The specified upper internal temperature limit of the modem is 60C. Within three degrees of this the unit will raise a Unit Warning (& deferred alarm relay) “Warning: Int' temp 57C, Tx CARRIER WILL MUTE outside operating range 0-60C”. Above an internal temperature of 60C the carrier mutes and a Unit Fault is raised (& Prompt Unit alarm relay), “Unit Fault: Tx carrier muted, unit temp 61C outside operating range 0-60C”. Setting Fault Mode to 8 disables both the carrier muting and the Unit Fault / Prompt alarm above 60C, however the warning/deferred alarm above 57C is still activated. Modem operation outside the specified internal temperature range is not guaranteed, and so this option should not be used on satellite.

9Internal Test Mode (Disable Differential Encoder and Decoder)

10Extended 1 for 1 for Antenna Diversity, Initially On Ships (Software >=V2.05)

The normal 1 for 1 redundancy system will cope well with each modem in the 1 for 1 pair being connected to a different antenna (eg at opposite ends of a ship on stabilised platforms). The modems will automatically switch traffic to whichever one remains operational. Should one of the antennas loose its line of sight to the satellite it will cause the on-line modem receive to fail and the modems 1 for 1 partner to come on line, conveniently also switching the Tx to the other antenna. However one specific customer wished to integrate a `block` signal from the Antenna Control Unit (ACU) into the 1 for 1 system, to guarantee the Tx on either antenna would be muted when the corresponding ACU indicated `block` (ie when the antenna movement limits set on the ACU indicated the antenna was starting to point at the ship itself, or more importantly the crew !).

The solution is to link the `block` signal from the antenna directly to the modems external Tx Inhibit signal on pin 7 of the alarms connector (grounded when blocked, also connect a ground on pin 15) AND to set Fault Mode to 10. With the connection made but without the Fault Mode set to 10 the Tx to either antenna will be muted when the corresponding ACU `block` signal is active. It will not however immediately switch the traffic over to the other modem in the 1 for 1 pair (ie not switch the traffic to the other antenna, as the external Tx inhibit is not considered a fault by the 1 for 1 logic). Without Fault Mode set to 10 then it would be possible for the ACU to indicate `block`, muting the Tx carrier (because the antenna has just passed the ACU movement limit where the beam is approaching the ship) and for the Rx carrier to remain OK until the receive signal is fully obstructed by the ship. If this happens there will be a break in transmission from the ship until the receive totally fails, finally causing a Rx fault which will make the modems 1 for 1 partner take over, switching both Tx and Rx to the other antenna.

When Fault Mode is set to 10, the External Tx Inhibit is additionally considered as a fault by the 1 for 1 logic (although it has no effect on the normal LCD display of modem faults). Now, apart from the ACU `block` signal immediately muting the Tx carrier, the 1 for 1 modem pair will also change over to the standby modem causing the traffic to be immediately routed to the other antenna (provided the standby modem has no faults and the ACU of the other antenna is not itself indicating `block` causing the standby modem External Tx Inhibit to be active). Only when the ACU indicates `not blocked` can the traffic switch back to the first antenna. Should both ACU's indicate `block` then Tx from both antenna will be muted, with the last one to indicate `not blocked` remaining on-line (as far as the 1 for 1 is concerned) providing receive data. Full traffic will switch back to the first modem which has no faults, ie where the modem has a good receive signal and the ACU indicates `not blocked`. When both ACU's indicate `not blocked` (ie most of the time) the normal modem 1 for 1 redundancy operates.

This might take a few reads to fully understand, but it is an elegant solution to the problem requiring nothing other than a data `Y` cable, a standard 1 for 1 cable and a two wire link (ground & `blocked`) from each ACU to the corresponding modem !

A word of advice on installation. DO NOT put the modems at opposite end of the ship and run the 1 for 1 and data `Y` cables along the entire ships length. Instead co-locate the modems, keep the 1 for 1 cable and data `Y` cable short, and run the modem IF along the length of the ship. If the

P300H P300 Series Modem Installation and Operating Handbook Page 203