• Get involved.
    We want your input!
    Apply for Membership and join the conversations about everything related to broadcasting.

    After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
    If you use a disposable or false email address, your registration will be rejected.

    After your membership is approved, please take a minute to tell us a little bit about yourself.
    https://www.radiodiscussions.com/forums/introduce-yourself.1088/

    Thanks in advance and have fun!
    RadioDiscussions Administrators

Satellite Question

D

DaveR

Hi All

I had an interesting issue with loss of Satellite signal here in Carrolton today. Initially I thought it was a failed LNB. After replacing the LNB I still had no signal. Then slowly, the receivers came back on line by themselves, Starting with the stronger downlink signals. The dish that is being used is not 3.8 meter or 3.2, but 2.8 meter (which I know is undersized) and the LNB is a 20 degree Prosat LNB. I have never seen weather have an effect on C-Band Reception, which was overcast and rainy this morning. This failure looked like TI, but there is no Micro wave in the area and the site has no STL equipment. Any thoughts?

Dave R
 
Awacs filter on the LNB? If not, contact Microwave Filter.

You may be far enough off the "airborne" beaten path to have escaped this until now...

We had to get one years ago. We have the Air Force using our local airport for touch & go practice with some of their larger passenger aircraft (e.g. 737's) so there is a fair amount of military traffic over us from time to time
 
You don't mention which satellite was involved, but you do mention that the signals used are possibly on different transponders on the bird, which might rule out TI or radar.

Any information on if other downlink users of the same satellite were affected?

Any possibility the satellite owner/operator had some control problems and the satellite attitude was lost and they had to readjust the system? (We had this happen on an international bird a few months back.)

If any source of interference was airborne, it doesn't seem likely that it would knock out a downlink for a long period of time, but anything could happen.
 
DaveR said:
Hi All

I had an interesting issue with loss of Satellite signal here in Carrolton today. Initially I thought it was a failed LNB. After replacing the LNB I still had no signal. Then slowly, the receivers came back on line by themselves, Starting with the stronger downlink signals. The dish that is being used is not 3.8 meter or 3.2, but 2.8 meter (which I know is undersized) and the LNB is a 20 degree Prosat LNB. I have never seen weather have an effect on C-Band Reception, which was overcast and rainy this morning. This failure looked like TI, but there is no Micro wave in the area and the site has no STL equipment. Any thoughts?

Dave R
Click to expand...

Welllll, we are pass the dates for sun-outages.......Carrolton as in Texas? Other than flights in/out of DFW, I can't see anything affecting you as described (Addison airport traffic sometimes causes a burp at ABC RN/CMN just north of the Galleria!)

MMMMMMM
 
This does not sound like an AWACS interference problem. The tell-tale of AWACS is a satellite dropout about every ten seconds, in my experience.

It's relatively rare that the satellite itself has an issue, but it happens. If one of the major birds (especially AMC-8) had a control or electrical issue, that would be a newsworthy item. Haven't heard of any such issues.

If the dish is at ground level and adjacent to other businesses/parking lots, there could be any number of interference sources. I have heard of problems caused by cars with radar detectors that parked near a radio station dish and knocked out all the sat receivers. Similar problems with old lawn mowers with noisy spark plugs. Then there is the possibility of a large vehicle (UPS truck, etc) parking in front of the dish, although that sort of problem would have made itself apparent by now.

Some years ago I was working at a station that had a big Simul-Sat dish behind the building, and the back parking lot was being repaved. They fired up a diesel-powered asphalt tamper, and it absolutely killed every SEDAT receiver in the station. I had to make them wait to finish the work until the end of the Rush Limbaugh show.
 
I would suspect the newsworthiness of a satellite outage might really depend on the customers affected.

This is the one I was thinking of:

"Sunday 21 September at approximately 07:31GMT, IS-907 experienced a pitch error during a scheduled station keeping manoeuvre, resulting in loss of earth lock. Satellite Operations sent commands to recover satellite and restore earth lock successfully. Intelsat RF and Managed Services operations confirmed C-Band customer recovery beginning at approximately at 08:50GMT, and KU Band beginning at approximately 09:00GMT."

My guess is that IS-907 was not the satellite DaveR is watching.
 
I think it is AMC-8 Aprox. 270ish Az.. WW1, Premiere, Skyview (Braves Baseball). Sat recvrs are a mixture of XDSPRO 1, Starguide III, Wegener Ipump and XDSPRO4. Carrolton GA is the location. My other sites in Carrolton had no receive issues when this site was having problems. I don't think it is an AWACS issue. The satellite receivers were down for several hours.
 
C Band is more stable, but smaller dishes that aren't set up for the 2 degree spacing can have problems.

Here is one for you. We have the newer dishes and top notch LNBs. We are next to a factory that runs fork lift trucks in the yard. If a truck got close, we'd lose signal. We are 5 or so miles from the airport. This was going on for a while. I got out the Spectrum Analyzer and bought an expensive filter. We tuned it out. Doing this lost us a few DB of EbNo, but we never lost signal again.
So, what was the real problem? The Microwave STL was mounted close to the dishes. That was causing interference and weakening the signal received (remember that satellite signal strength is just a few watts and the STL puts out 20) and the fork trucks were just the last straw. I put the STL dish on a 30 foot tower, above the fray and it all went away.
 
Status
This thread has been closed due to inactivity. You can create a new thread to discuss this topic.


Back
Top Bottom