Interference on RF 22

[kittyhas1000legs]

I noticed lately that I'm having trouble with WGBY 57.1 (RF 22) out of Springfield, MA. I thought it was an antenna alignment issue, but after peakingthe signal with the SDR it seems to be interference. If I'm standing right behind the antenna the channel comes in fine, but once I enter my apartment the signal drops to zero on my TV and Windows Media Center. If I stand in certain spots by the entertainment center, I can get a signal, so it seems something is interfering with that channel (518-524MHz). Turning off different devices doesn't really seem to help. Is there some way I could possibly block the RF noise between the entertainment center and antenna without looking like a nutball to my apartment complex? Perhaps something to attach to the back of the antenna reflector (DB8)?

 

[FaT Air]

Try 'sniff' around with the SDR? Might be a neighbor is the source. "apartment " No chance of moving the antenna away from the interference source??
Other than that, about the only thing I can think of is metal screening. Maybe attached to the backside of the DB8 reflector? But may require a foot or more of 'spacing', only experimentation would provide the answer. Would maybe even make it larger than the existing reflector by 6 inches each way.

 

[kittyhas1000legs]

It seems the biggest source of interference (from MY apt) is the pc that I use as the dvr. I turned it off and the channel came in on the tv at 40ish rather than 0-2. Some experimentation/voodoo is needed.

 

[mike123abc]

It seems the biggest source of interference (from MY apt) is the pc that I use as the dvr. I turned it off and the channel came in on the tv at 40ish rather than 0-2. Some experimentation/voodoo is needed.

Is it a metal case and it is closed and grounded? If it is a plastic case, try taping foil over the sides and see if it improves, have the foil touch the back frame to ground it.

 

[FaT Air]

I 'sorta' have a similar symptom. If I run windows (Vista) on the laptop too close to a remote extender receiver, the remotes don't work. Run Linux, Mint or Ubuntu, on same computer at the same location, using the same WIFI, the remote extender works just fine. Go Figure???
Also have a TV that will overload a remote extender TX unit for about 3 minutes after initial turn on.
Both of my problems are easily 'worked around'. Good luck with yours. But some grounded shielding should help.

 

[kittyhas1000legs]

Moving a couple things around on the balcony seems to have helped (a little). I moved the antenna a few feet to the left which didn't do much, then moved the yet-to-be-used 1M dish that's waiting for a cleaning and painting. The dish seems to be blocking some of the interference, making the channel (usually) watchable. I may move the PC next, though that'll involve messing with my bird's nest of wires. I'll swap which side of the TV stand it's on with the subwoofer, moving it another 4-5 feet from the antenna. Hopefully I can convince my fiancee to move to another building in our complex, giving us LOS for 125W so I won't have to fight to get PBS Create and World (maybe aim the antenna south for New Haven stations?)

I'm not sure about using foil as shielding, as it'd mess with what little airflow my PC gets. Right now the CPU's at 53C without even doing much of anything.

 

[mike123abc]

Is your case plastic or metal? You do not have to cover up air holes, you probably only need a small section of the case to block the interference.

 

[kittyhas1000legs]

Metal case, I think steel. Now that I think about it, the interference may have started when I got the new video card.

 

[mike123abc]

You mentioned that having the satellite dish in the proper position could block the interference or at least cut it down. Is there some other metal object you could put in between the computer and the antenna? A metal trash can or something?

 

[kittyhas1000legs]

WHAT HATH SCIENCE WROUGHT?

It may be ugly, but here's my fix:

1: Set up the 1M dish on its NPRM and aim it north.
2: I took our last wire coat hanger and turned it into a bow-tie antenna.
3: Tried putting the bow-tie at the dish's focal point, watching SDRSharp to see how it improved (if at all)
4: Eventually, putting it nowhere near the focal point for the LNB worked.
5: Use a couple hooks and some skinny rope to hold it in the right spot, plus half a water bottle to push it out a bit. Getting a constant 35-40 on the TV (Heck yeah, Curious George!)

Of course, pictures!

First, the antenna:



Next, a few screenshots from SDRSharp. (1) is at the focal point (no amplifier), (2) is at the focal point with amp, (3) is the final position. (4) is the DB8 that I've been using for a while. Apparently the little bit of noise is enough to kill the signal.



Hopefully after all this I can convince Steph that we should move to that other building with LOS for 125W...

EDIT: It looks like the directional antenna made me lose iON/HSN/QVC and MyTV (oh well), but now BOTH Springfield stations are booming. No problem whatsoever with that tradeoff.

 

[mike123abc]

All you need now is some duct tape and bailing wire to make it official! At least you got your signal...

MacGyver would be proud!

 

[FaT Air]

Dish is operating as a reflector approx 1/4 wave behind the active element. Should have great F/B ratio. Think the frequency is too low to use the actual focal point.
Duct tape is Red Green's domain. MacGyver usually just blew stuff up.