iDirect 3000 Modem Installation

What nominal polarisation (horizontal or vertical) has your hub told you to set for receiving ?

Has your modem been preconfigured or are you expected to configure it yourself using an options file ?

Best regards, Eric.

This page will tell you the pointing angles: Dish pointing southern Africa, for example:


Polarisation:
Step 1: Start with the LNB sticking out sideways for true vertical polarisation.  The broad faces of the LNB rectangular waveguide, which define the polarisation,  will be on top and underneath.
Step 2: While facing towards the satellite, turn the feed/LNB/BUC assembly -53 deg anticlockwise.

Best regards, Eric.

The NJR2784HH LNB is a DRO type LNB with a local oscillator frequency of 10 GHz and low stability +/- 900 kHz.  It is suitable for 10.95-11.7 GHz satellite signals with large bandwidth and large bit rate and QPSK modulation.

Similar DRO LNBs
( Ref https://mc.njr.co.jp/eng/products/vsat/ku-lnb.html )
2754H with 11.3 GHz LO, 12.25-12.75 GHz
2744H with 10.75 GHz LO, 11.7-12.2 GHz

You need to choose an LNB which matches your satellite downlink carrier frequency and produces an L band output that in within the tuning range of the modem, e.g. 950-1450 MHz, 950-1700 MHz, 950-1950 MHz, 950-2050 MHz.

The choice of LNB will vary from one satellite to another and also on some satellites with many transponders you may need to use LNBs with different local oscillator frequencies.  

You need to set the iDirect options file to sweep at least +/- 900kHz to find the carrier, for the low stability NJR LNB above.

LNBs with dual local oscillators are available with the alternative LO frequencies selected by 22 kHz tone on or off. e.g. Invacom SPV30SM  LO=9.75 GHz or 10.6 GHz.

For narrow bandwidth SCPC carriers and those with advanced 8PSK and 16QAM modulation methods, Phase Lock Loop (PLL) type LNBs are recommended.  These have much higher frequency stability and lower phase noise. Their reference is typically an internal crystal oscillator.  External reference versions exist which need a 10 MHz reference from the modem.  This can give the highest stability and accuracy as the modem may be temperature stabilised indoors or the reference derived from atomic GPS clock, for example.

Read more about how an LNB works.

Best regards, Eric.

For an explanation of the options file I suggest you contact your iDirect hub and ask about any parameter that concerns you.

I have no experience with iDirect and can only read the options file and guess what the various parameters are about.  Many are obvious, but you need expert help to determine exact meaning and purpose.  The values are software settings that help the modem to work and duplicate what is stored in the hub database. The hub normally sends you a complete option file to load with a new modem.

Regarding putting an options file here, I would read through your options file first and overwrite all passwords and IP address with xxxxxxxxxx.  If you wish your location to be private reduce the accuracy of your lat long also.  Rather than post a new options file why not refer to an existing one like forum thread: iDirect options file

Don't make any changes to your options file in the actual modem without approval of your hub !

We might be able to answer a few specific questions but please don't ask for a paragraph on each item.

Best regards, Eric.

Hi all,

After getting a lock onto the satellite and iSite reading between 12 and 13 i have a few questions. I know we now have to mount the BUC:

1. What is the recommended signal strength reading?
2. What is the next step to have the VSAT commissioned?

Thanks,

Francis.