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NSS7  with Idirect Netmodem II plus

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Ex Member
Ex Member

Jun 16th, 2006 at 8:56am  
Hi all,

I'm currently installing C-band 1.8m channel master with Idirect netmodem II Plus. Well I have achieved a perfect pointing  to NSS7 on my receiver with Tp freq 3931 and symbol rate 25000. my signal strenght 85% and signal quality 64% so this is very perfect. but i still have problem with getting rx lock on the netmodem and my service provider still insists that the option file they provided is correct. i reasoned that incorrect option file could course  this as it is not my first time to hook up to NSS7 C-band with netmodem II plus. Any reasonable advice is welcome.


Jeleel Alade
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Reply #1 - Jun 18th, 2006 at 11:11pm  
Is your wanted iDirect carrier on the same downlink receive polarisation as the carrier you have detected at 3931 MHz ?

If not, note how the OMT is presently attached to the polariser.  The OMT is the joint where the 4 and 6 GHz rectangular waveguides merge into a circular waveguide.  To change polarisation you will need to unbolt the OMT from the polariser, rotate 90 deg and reattach in order to receive the opposite circular polarisation.  The two attachment positions will be +/- 45 deg either way from the line of pins inside.   If you align the OMT waveguides the same as the pins the polariser have no polarising effect and you will be operating linear polarisation, which I doubt what you want.  If you are receiving circular polarision with a linear feed you will get severe interference if there are carriers on the opposite polarisation and just 3 dB loss everywhere else.  This could be your problem.

This page may also help:

Note you need to input your lat/long and satellite location and elevation angle.  It says this is critical (in red).  It is possible that the software blocks transmission unless you have done this.

If you solve the problem please tell us for future reference.    Thanks, eric@satsig.net
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Reply #2 - Jun 20th, 2006 at 6:02pm  
hello jetlee,

you did not specify the dish feed type (linear/circular). but i guess you are using a circular dish. if yes, what type of dish is it ? (andrew/prodelin) .when you have pointed the dish with the signal quality you mentioned, did you try to change the polarisation to see if the signal disappears or improves. try that and also check the option file parameters such as pid/symbol rate with your provider.
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