AUPC Miteq Uplink Power Control Alarm

What is the normal, clear sky, input voltage level to the UPLINK POWER CONTROL SYSTEM ?

The UPC needs to be set to accept either 0 to +10 volts input or 0 to -10 volts input. Beacon voltage level goes in on J1.

There is a receiver status input also, such that if your beacon receiver becomes faulty it can tell the UPC that any signal voltage provided is invalid. This fault signal is on J9 connector. For the Receiver A status input, pins 1 and 3 refer. The input fault indication is user-configurable as either a contact closure or a contact open.

Read more: https://miteq.com/docs/29TEC.PDF

It looks like you have a good clear sky signal voltage (about 8 volts) and that the UPC input range 0 to +10 volts is set correctly.

You have got Receiver Status A set to active.

This means it will give a display (i.e. FAIL or OK) depending on the connections to pins 1,3 on connector J9. It is expecting a pair of relay contacts, either closed or open under FAIL conditions.

What do you have connected to J9 ?

If your receiver has a fault alarm on it, with relay contact closure or open, then these two wires need to go from the receiver to the Uplink Power Control connector J9.  The beacon receiver might have a power fault (e.g. be switched off) or have lost lock on the beacon signal, in which case the output voltage (0 - 10 volts) would go to zero, but this would be an INVALID dB level and MUST NOT cause the UPC to massively increase your uplink transmit power to the satellite. The receiver FAIL status tells the UPC to continue with nominal transmit level when the beacon receiver becomes faulty.

On the UPC, the options for Receiver A status are probably:
Active
Inactive

If you switch this to Inactive and the alarm goes away you have at least isolated the cause. But don't just leave it like that. You would be hiding a serious hazard!

Under advanced configuration there may be:
Receiver A Status open circuit = FAIL
Receiver A Status closed circuit = FAIL

It is important that the UPC should not spuriously increase your transmit power to the satellite when your beacon receiver is powered off, beacon receiver has failed or complete loss of beacon signal, so try and get the two wires connected up and the open/closed circuit options set right.

I can see the plug going into J9 on the AUPC.

I note the receiver is working well. Power is good. Signal is locked.  Signal level as shown on the AUPC 8.23 volts looks good. It would give you confidence if moving the antenna causes this voltage to change exactly as you expect.  Is there a calibration scale like 1 volt = 2 dB or 1 volt=3dB .. ?

You could test, using a calibrated switchable attenuator, 1, 2, 3, 5, 10, 20 dB on the beacon receiver input. The output voltage should go down by the equivalent amounts. Turn off the UPC effect while you do such a test.

Read the receiver manual to check that -61.6 dBm is a reasonable input level. You need about 20 dB linear dynamic range down from this. The input level to the beacon receiver depends on where it is connected in the L band splitter distribution system.

If any receiver fault (loss of power, loss of signal lock) occurs there should be a contact open or contact closure on a pair of wires which should come from the receiver (possibly J11?) to the AUPC (J9).


The other end of the cable to input J9 appears to be connected from Beacon Analogue output plug J11 on the receiver. Cable #30. There are two cables, the other cable is presumably the coax, carrying the analogue 0 to +10 volts.

Read the receiver manual to find out what its alarm output contacts do. The receiver contacts outputs may be connected to pins 1,2 or 4,5 or the alarm may be opposite sense, e.g. open circuit instead of closed circuit or vice versa. There may even be a configuration in the receiver so that a fault condition causes open or closed circuit on the alarm output.