iDirect 3000 series TX Power Adjustment

Hi polpan,

Are you tring to set the TX from the hub or remote end?  Usually the initial and max TX power of the NM is set by your hub.  Thus you will only be able to drive the NM to the max set by the hub.  I take it you need to increase the TX past the maximum set in the option file?
You may be able to do this manually by opening the option file as a text documentn changing the max TX power and then reloading it on the NM.
Let me know how you get on.

Thanks,

Lukio ;.)

Don't change the modem output power setting locally.  If you have service problems ask the hub to investigate and let them make appropriate changes, if necessary.

The modem output power setting needs to be correct, neither too high nor too low.  Increasing it without the hub monitoring may interfere with the service of other people, increase the bit error rate and damage your BUC.

Best regards, Eric.

Be careful..

If the BUC has 55 dB gain and you put -20 dBm into it then output power should be +35 dBm or +5 dBW or 3.2 watts.

1 watt = +30 dBm or +0 dBW
2 watts = +33 dBm or +3 dBW
4 watts = +36 dBm or +6 dBW
8 watts = +39 dBm or +9 dBW
10 watts = +40 dBm or +10 dBW

Unless you have a very long cable, a modem level of -5 dBm is likely to overload the BUC and cause severe interference to return link services on adjacent frequencies. It will also degrade your own carrier as it will be distorted.

BUCs must be operated at or below their -1dB compression point, which is the rated power.

In other words don't try to transmit more than 2 watts with a 2 watt BUC.

Once the hub has control they should adjust for the correct level.

Ideally the hub should put the transmit into CW mode and increase the drive in 1 dB steps while measuring the output. Once the graphed line becomes non-linear and there is a 1 dB vertical gap between the projected straight line and the actual output curve, the BUC is at its 1 dB gain compression point. The drive level for the 1 dB gain compression point should be recorded for reference as a "never-to-exceed" value. ( opt file. max power )


This image shows how altering the modem tx power altered the receive level at the hub. Note that during the last three adjustments it goes non linear and at the final measurement the gain is 1 dB below what the straight line projects. This is the rated 2 watt output maximum at the -1dB compression point.

Cross pol measurement and adjustment should made if necessary. With modulation back on the Eb/No should be set to nominal, assuming clear sky conditions at the time.

It gives confidence if you then experimentally and temporarily reduce the power 4 dB (at Ku band) and check everything continues to work normally under faded conditions. This shows you have a decent rain margin.  Reducing the power by 10 dB should make it fail. If such a reduction actually improves the service be alert to the possibility that the BUC might have been operating in grossly overloaded way.

Best regards, Eric.

Quote:


i mean...raise it  at increment of -5dbm only...from -25dbm to -20bm only example.....

do i need to edit the options file in notepad then upload it again... how should i do it...

pol,

there are two power settings in your opt file. max power and initial power.

max power should only be set by the hub as described above with respects to your compression point. if thats too low then you uplink chain is starting to degrade. whether because parts or merely antennae alignment. start with a peak and pole to maximize alignment.

if your issue is that the modem's initial power is too low, such as the modem wont come back into the network until you raise power, then have the hub set your initial power higher and push down the reset. typically this should be set 2-3db above your normal operating power.

nigel