SatSig topic:

Pointing trouble to 10E W1

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Oct 14^th, 2008 at 12:32am

I need some suggestions to help pointing my dish im in baghdad and have an hn7000 modem from ats iraq, a 2 watt antenna. my signals seems to bounce all over the place, but never above 28 or 29. After I score a 29 and power cycle the modem it will not go above 15. The freq is 1622.4mhz the used to have me at 1544.0mhz, i was able to get a signal up to 98 sometimes but connection had serious ping time issues. they changed my modem and put me on a new freq and my ping times got better and stopped having time out errors. anyways during a sand storm a couple weeks ago my connection started having serious problems, as in i would have hours of no connectivity, so i changed my coax cables and tried repositioning the dish but i cant seem to get above a 29 on my signal strength.

My dish has a 17.4 degree offset, but i dont know where im supposed to calculate that in, im assuming that its from the rear angle of the dish.

my mag az. is 227, and my elevation is 36.4. my polar is 40.6 plus a 3.5 compensation for the eutelsat brings me to 44 which is what the antenna was delivered at.

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Oct 14^th, 2008 at 3:27pm

If the new modem was working perfectly very recently (so it has a good configuration stored) and it is now not giving a signal reading above 29 then the dish pointing has probably moved to the wrong satellite.

The readings won't go above 29 till your modem is receiving the wanted carrier. Readings 0 - 29 refer to power and you can peak up on any satellite. If your configuration (frequency, symbol rate etc) is wrong you can also peak up on the wanted satelite but the peak reading will still be limited to 29.

30 - 99 means you are receiving the correct carrier.

Note that the modem tuning frequency needs to be entered in units of 100 kHz. So type in 16224, not 1622.4

Elevation angle: The bracket elevation scale shows 42 deg, but this assumes the pole is upright. It is nice to see you have tried my inclinometer, but it is uncertain what part of your dish is the reference. Normally offset angles refer to the slope of the front rim of the dish. So if you had a strip of wood from top to bottom, across the front rim then, when that wood strip is vertical the beam elevation angle would be the offset angle. In your case I recommend using the elevation scale on the bracket and trying to keep the pole vertical. Note there may be another scale on the other side that reads different.

If you are certain the modem configuration is correct I would try looking at the satellites either side of the current pointing (left a few deg and upwards, right a few deg and downwards).

If you are uncertain about the modem configuration contact your service provider for a new configuration sheet and check all the details, including no decimal point for the frequency - as explained above.

Best regards, Eric.

Oct 14^th, 2008 at 5:56pm

Thanks for the reply, just for me to carify, yes it is actually entered as 16224 100khz, i just wrote as mhz here.

as for the elevation, and which angle to read, my manual says the dish has a 17 degree offset, it also says to use the "B" side of the the dish support to read the elevation. my pole is not perfectly vertical. so i think 42 is pretty close as i think theres about 6 degrees for forward lean on the mast section. which would correlate to the measure 19 degrees of the dish plus the 17 degree off set. my problem is this, i've spent nearly 20 hours sweeping, and moving the dish, and this is the only area i get a hit. and its almost dead on with my magnetic azimuth.

one problem i noticed is that my recieve sps on my sheet is 5,000,000 sps, but in the modem configuration its listed as 20,000,000 and no matter how many times i enter the new value, it never saves. the sheet also has the 22khz tone as off, but on the config, same problem its stuck on and wont save as off.

thanks for your help, its greatly apreciated.

Oct 14^th, 2008 at 9:01pm

If you have the wrong symbol rate configured in the modem (for example 20000000 instead of 5000000) then it won't lock to the wanted carrier and you will not get a reading over 30.

The fault seems to be that you cannot get the modem to accept the new symbol rate.

Someone else had a similar problem where the frequency could never be changed. It kept going back to default. I am trying to remember the reason. Meanwhile contact your service provider for advice. The symbol rate goes in like 5000000, not 5,000,000

The 22kHz tone is probably due to the same fault.

The 22kHz tone is needed only if you have an LNB that has selectable local oscillator frequencies like 9.75 and 10.6 GHz. What LNB model number do you have ? It is most likely fixed frequency e.g. NJR2784 LO=10GHz.

Best regards, Eric.

Oct 14^th, 2008 at 10:14pm

Do you have - or can you borrow - a satellite signal test set? That is, a signal tester that can detect the presence (and relative strength) of an L-band signal on the RX cable - between the LNB and the modem?

//greg//

Oct 14^th, 2008 at 11:17pm

again thanks for the replys guys its really apreciated. as for the symbol rate, i do not enter it with commas. but i'm almost certain thats what the problem is. i spent a few more hours tonight trying to aim this thing, but with the dish angle set at 19 degrees i have huge sweet spot at 29 right at my correct azimuth so im almost certain i've found the right sat, its the only one near the correct elevation and azimuth. i just need to figure out my modem problem.

as far as test equipment i have access to a pretty wicked spectrum analyzer, but i dont have the right adapter to plug into coax Sad

Oct 14^th, 2008 at 11:31pm

The fault symptom of having unchangeable parameters on the config screen was fixed by someone who use the rf command. ( rf = reset to factory default ) before inputting all the details again from the config sheet. I can't find the details on how this rf command was done. Is it a command line command or is it in the menu lists somewhere?. Any ideas anyone ?

If you have a spectrum analyser it may not tolerate any DC voltage applied to the RF input. In such cases a DC block or splitter with DC block on one side and DC power pass on the the other side is suggested. Test with a voltmeter before connecting the analyser. Several $000 damage can be caused to professional analysers by applying DC to the RF input.

Best regards, Eric.

Oct 15^th, 2008 at 1:35am

its done by telnet into the modem, i know how to do it, but i've bricked 2 modems doing this so, im nervous on doing it again. the problem was that the modem had problems with software downloads from the sat after doing this command.

Oct 15^th, 2008 at 8:00am

In view of the risk of permanently making the modem useless I recommend you contact your service provider and get their instructions as to what to do to solve the problem of stuck parameters on the configuration screen (unable to change symbol rate or 22kHz tone state, in your case).

Best regards, Eric.