Aquiring W6 from Iraq - problem with LinkStar

1. Information.

Ask your service provider what is the name of the Downlink polarisation ( Horizontal or Vertical ).
Also, the configuration text line that must be typed into the modem.

The box for the LinkStar modem normally contains a large glossy quick reference installation guide.
See here: Linkstar install glossy pdf 693k bytes

There is a more substantial installation instructions manual available from your service provider.
See here:  Linkstar install manual pdf 1909k bytes

2. Linkstar modem configuration

You need to connect PC to the modem with cross over ethernet cable and establish communications. The initial modem gateway IP address is formed using the last 3 hex pairs from the MAC address, for the latest modems. e.g. 10.0.x.x 10.1.x.x. 10.2.x.x  10.3.x.x 10.4.x.x etc. Convert hex to decimal using your PC calculator start, all prog, accessories, calculator, scientific mode. Mask=255.255.255.0

Use telnet to enter the configuration text line that needs to be typed into the modem.
e.g. savebootparms -pop 0x011e0001 -c 0x530 -pcr 0x365 -f 1554410 -s 27500000 -o 1 -t –40  
You can type pconf and check that the config parameters have gone in successfully. -f is frequency, -s is symbol rate

IMPORTANT WARNING: Always power off at mains wall switch before working on the coax cable.  Never get the cables shorted or crossed over.

3. Connect the LNB.

Connect the small LNB module to the LinkStar modem receive input.
 
4. Antenna polarisation set up

First set the nominal (i.e. named) feed receive polarisation.  Vertical means that the broad faces of the LNB rectangular waveguide are on top and underneath. Do it.  The LNB is on the end of a filter arm and the arm is probably now sticking out at one side or the other. Which side does not matter, it is still vertical polarisation.  If Horizontal is the required polarisation name, then the LNB arm will need to start off either upwards or downwards.
 
Second, apply the polarisation adjustment angle.  A positive adjustment angle (e.g. +30) requires an clockwise movement, while facing towards the satellite. Put your inclinometer sideways across the LNB or BUC, then tilt the whole feed/BUC/LNB assembly in its yoke, by the exact adjustment angle.  This page dish pointing Iraq shows a picture of your LNB side arm at the approximate adjusted polarisation angle, as viewed with you standing behind the dish and facing forwards towards the satellite in the sky.  Obviously you must know the name (and enter it using the web page radio button) of the polarisation you want.
 
5. Finding the satellite

Set the beam elevation using the elevation scale on the bracket behind the dish.  
 
Swing the dish boldly sideways around the approx compass azimuth and the RX LED will lock up on the satellite on the first sweep, unless the dish is sagging down a bit, in which case add a couple of elevation degrees.   Initially the RX LED will go to slow green flashing.  The centre of the beam is half way between the points where the LED drops out.  Adjust up/down and sideways.
 
As you tighten the antenna, keep readjusting to the peak.  Read the QPSK BER by typing tcmp at least 30 times (possibly 50 times !).  Get it down below 0.00009 if you can.  Spend at least 30 minutes peaking up.

6.  Transmit cable and site commissioning

Power off at the mains wall switch and connect up the TX cable.  RX LED will go slow flashing green, fast flashing green and solid green.  Don't interrupt this process.  Talk to the hub while they test your cross-pol isolation.  You may have to get yourself under the feed arm and reach up to rotate your feed polarisation a degree or two either way as they talk to you.  Be very patient between any movements; it takes the hub time to test for your x-pol null.  
 
Your modem will reboot and end up with new gateway IP address and subnet mask, ready for use.  Your service provider will tell you what are the operational gateway IP address and subnet mask.

Best regards, Eric.

That is a good point about not setting the initial modem transmit power too high.  

The modem output can be set from -30 dBm to -5 dBm.
A typical BUC saturates with input level of -20 dBm.
So it is not too difficult to accidentally start in saturation (and thus not get through to the hub due to distortion) or even damage the BUC.

The config value is in 0.5 dB steps, so if you input -t -20 it makes the output -10 dBm.  For safety I've amended the example in the previous post to -t -40 which means modem output = -20 dBm, so as to be safe even with the shortest transmit coax cable.  The lowest transmit level is -t -60 which means -30 dBm modem output level.

Best regards, Eric.

I one more thing..I want to let you know that the leinght of my coax cable is 70 ft and 10 in... let me know if I need to change something. My cable is kind of old and can't see the markings but maybe the lengh can tell what kind of cable is it

thanks again

Hello everyone

I would like first to thank all of you for your valuable help during the last couple of weeks.  I have succeeded to find the satellite 7 degreas higher from the required elevation and the modem is finally working properly.  

The SAT LED is stays solid green.

But I still have a couple of questions and i really appreciate your help.

After I type rep tcmp  the QPSK BER is changing on every second or third time from 0.0000129.. to 0.0000357..after 0.0000237 and in so on, But the readings are never going above 0.0003.... Why is this happenings and how can I fix this problem?

That is my question FOR NOW , and again thanks to you all and specially Eric, thanks again..