Comtec MBT-4000 Installation And Operation Manual Download

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MBT-4000 Multi-Band Transceiver System

Revision 6

Redundancy Configuration / Operation

MN/MBT4000.IOM

Redundancy Configuration / Operation

C–7

MN/MBT4000.IOM

C.4

External Fault Monitoring

Each MBT-4000 base includes two logic inputs, one per AUX COMM connector, that may be
connected to contact closure fault indications of external equipment (usually an SSPA or LNA).
Thus, external equipment failure may participate in overall fault indication and redundant
switchover operation according to the following rules:

1. An open connection (or 2.7 V min) indicates a fault condition exists.

2. A closed connection (or 0.7 V max) indicates no fault condition exists.

3. Maximum voltage range on fault logic inputs is –12V to +12V.

4. The fault inputs correspond to a slot, the fault input of AUX COM 2 corresponds to the

BxC installed as UNIT 2. The fault input of AUX COM 1 corresponds to the BxC
installed as UNIT 1.

5. To enable fault input checking the EFI=nm command is usedwnput parameter ‘n’ can

equal 1for AUX COM 1 input, or 2 for AUX COMM 2 input. The mode parameter ‘m’
can equal 0 for disabled, or 1 for enabled. Each input must be enabled individually.

C.5

LNA Power Supply Current Monitoring

The  MBT-4000  base  and  BDC-4000  are  capable  of  supplying  power  to  external  LNAs.  The
MBT-4000 base  supplies the power from a pin  in the AUX COMM  connectors; the BDC-4000
supplies the power over the center conductor of the coaxial cable. These power supplies feature
current  monitoring with  programmable failure limits. Overcurrent and  undercurrent  failures can
participate in overall fault indication and redundant switchover criteria.

The following commands and rules configure operation of this feature:

1. The power supplies are +12.6V with a 350 mA current limit.

2. No more than two of the four possible supplies should be enabled simultaneously.

3. An individual supply is enabled by issuing the ‘LCS=sm’ command as follows:

‘s’ is the source. Valid values are 1 or 2 where: 1=AUX COMM 1 supply and
2=AUX COMM 2 supply. The BDC-4000 only has a single current source, so ‘s’
must be set to 1 on a BDC-4000.

b. ‘m’ is the mode. Valid values are 0=OFF or 1=ON.

4. In case of excessive current (more than 350 mA), the supply will be disabled and a fault

will be posted. The ‘LCS=sm’ command must be sent again to re-enable the supply.

5. To enable programmable current monitoring, the following steps are taken:

The desired output is enabled as outlined above.

b. The nominal current is calibrated using the CLC=s command, where ‘s’ is the source

as described previously.

The programmable current window is specified using the LCW=sxx command.
Where ‘s’ is the source as described previously and ‘xx’ is the allowable percentage
of variance from nominal (set by the CLC command). Acceptable values for ‘xx’ are
20 to 50 in increments of 1%. In addition, a value of ‘99’ for ‘xx’ disables the alarm
function.