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Author Topic: TV reception question
The Famous Druid

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Icon 1 posted September 08, 2010 20:21      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
I have an external TV antenna, which leads to 2 antenna sockets, one in the lounge room, one in the kitchen.

The Digital TV in the lounge room is getting good reception, the kitchen socket is connected to a Digital TV dongle hooked up to a USB port on my Mac Mini.

The problem is, the Mac Mini is getting crap reception, good signal strength, crap signal quality, to the point where it refuses to recognize most of the TV channels, and those it does try to display are nearly unwatchable due to the high error rate.

Here's where it gets interesting: if I disconnect the TV in the lounge room from the antenna, the reception on the Mac Mini in the kitchen improves dramatically, I get good signal on all channels.

So, it looks like there's some kind of cross-interference going on between the TV and the tuner dongle on the Mac. Anyone got any ideas how I can fix this?

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

Posts: 10668 | From: Melbourne, Australia | Registered: Oct 2002  |  IP: Logged
CommanderShroom
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Icon 1 posted September 08, 2010 21:05      Profile for CommanderShroom     Send New Private Message       Edit/Delete Post   Reply With Quote 
I would actually hazard a guess that the splitter is going bad for the two leads.

If I am wrong, at least it's a cheap test.

Posts: 2463 | From: Utarrrrggggghhh!!!!!!!! | Registered: Mar 2003  |  IP: Logged
dragonman97

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Icon 1 posted September 08, 2010 21:38      Profile for dragonman97   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Get it all via Pirate Bay!!!!1111 [Wink]

</troll†>

Just for grins, have you tried a traditional tuner (i.e. another TV) using the same connection used by the Mini? If it works, that says bad things about the dongle; if it doesn't work, the splitter is crap.

† I do not endorse the aforementioned idea! [Smile]

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There are three things you can be sure of in life: Death, taxes, and reading about fake illnesses online...

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TheMoMan
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Icon 1 posted September 09, 2010 03:44      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
____ This is where RF gets fun. A: Cross talk from each unit. B: Too much signal
C: Too Little signal.

____ Have you tried reversing their locations?

____ Have you tried a different splitter?

____ Do you have access to an amplifier?

____ Have you tried any High/Low pass filters?

____ Are all the Coax connections good Electrically and Mechanically?

____ Also there are devices called L-Pads to intentional weaken a signal, in case the tuner is being over loaded with crap.

____ If you were paying for the signal (Cable) you could force them to do all this testing plus they have the correct test gear. Thats all I got.

____ Is this TV a Plasma?

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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5835 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
garlicguy

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Icon 1 posted September 09, 2010 08:45      Profile for garlicguy   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Based upon the information given, and the implied notion that both sockets were functioning well in the recent past, the splitter is the most suspect component contributing to the problem. But do not overlook loose connections, especially involving shielded cable ends.

Beyond that, you might wish to consider any 'leaky' device recently added to the kitchen vicinity which may be throwing "noise" in that area. Sometimes even a kitchen blender, refrigerator or other appliance utilizing a high-speed motor will actually create a conflicting frequency able to adversely affect RF signals in the immediate locale. Similarly, all electronic devices have similar disruptive capabilities under certain, um, 'ideal' circumstances.

FWIW, YMMV.

gg

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I don't know what I was thinking... it seemed like a good idea at the time.

Posts: 3752 | From: Pluto, no matter what you call it, is still my home. | Registered: Dec 2004  |  IP: Logged
TheMoMan
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Icon 1 posted September 10, 2010 03:49      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
____ TFD, Disconnect the antenna connections at both TV devices. Then with a multi meter, check with both units off. A: is there any voltage from the antenna to the device. B: now turn on the receiver and check again.

____ I am not sure how wiring is done in OZ but you may be suffering a Neutral/Ground fault. It may be as simple as plugging into a different outlet or even reversing one plug.

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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5835 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
The Famous Druid

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Icon 1 posted September 10, 2010 14:52      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
Thanks guys, I'll try some of the suggestions and report back.

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

Posts: 10668 | From: Melbourne, Australia | Registered: Oct 2002  |  IP: Logged
The Famous Druid

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Icon 1 posted September 11, 2010 04:52      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
Hmmm....

I plugged the Mac to the antenna socket in the kitchen, then went into the lounge room, turned the TV off, and plugged the antenna cable into the socket there.

Bright flash.

No doubt about it, a spark.

Not in the mood for further experimentation at the moment, electrickery is scary.

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

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MacManKrisK

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Icon 1 posted September 11, 2010 06:56      Profile for MacManKrisK     Send New Private Message       Edit/Delete Post   Reply With Quote 
You have a ground loop, probably caused by a voltage difference between the equipment (TV) in the lounge room and the equipment (Mac Mini) in the kitchen. My suspicion is that it's got something to do with the transformer (i.e. power brick) used to convert your mains power into something the Mini can use. Similarly, I used to have an iBook (G3) that would give me a shock from the latch when I would plug it into a power inverter in the car.

It's also possible that you're just getting a buildup of static charge in the line. Something like this might take care of either or both of those conditions, if you ground the grounding device, of course!

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"Buy low, sell high
get rich and you still die"


Posts: 2331 | From: Southwest Michigan, USA | Registered: Oct 2001  |  IP: Logged
TheMoMan
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Icon 1 posted September 11, 2010 07:10      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
____ That TFD, is why I wanted you to use a MULTI-METER.

____ Disconnect all devices, turn on the TV you should see a noise pattern, -->Yes, check from antenna terminal to antenna no voltage make connection.-->No take to repair shop for estimate.

____ Repeat with Mac.

____ It is possible that no Semiconductors were harmed.

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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5835 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
CommanderShroom
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Icon 1 posted September 11, 2010 10:01      Profile for CommanderShroom     Send New Private Message       Edit/Delete Post   Reply With Quote 
I think it is worth mentioning that the innards of a digital splitter is different than the old style analog splitters. So if the splitter is defective, there is a chance it is shorting out internally.

However, I do second MoMan's advice on making sure you are not getting any phantom juice out of anything.

I would also attempt to see if the spark is a result of the equipment or the cable. Is there any way to get those connected to the antenna without using your existing wiring?

Have you done any home projects recently where something along the wiring path could have been effected? Really coax is pretty simple, it is like troubleshooting anything. Eliminate suspected points and go from there.

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The Famous Druid

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Icon 1 posted September 11, 2010 16:06      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by TheMoMan:
____ That TFD, is why I wanted you to use a MULTI-METER.

I'll borrow one from work on Monday.

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

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Xanthine

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Icon 12 posted September 11, 2010 18:19      Profile for Xanthine     Send New Private Message       Edit/Delete Post   Reply With Quote 
A man without an instrument is a sad sad thing. And that's all I really have to add.

I think my husband has a little voodoo dance he does when RF gets funky on him, but he's never needed to do that around the house.

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And it's one, two, three / On the wrong side of the lee / What were you meant for? / What were you meant for?
- The Decemberists

Posts: 7670 | From: the lab | Registered: Mar 2001  |  IP: Logged
The Famous Druid

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Icon 1 posted September 12, 2010 02:09      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by Xanthine:
A man without an instrument is a sad sad thing.

Has Mrs Druid been talking to you?

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

Posts: 10668 | From: Melbourne, Australia | Registered: Oct 2002  |  IP: Logged
Xanthine

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Icon 1 posted September 12, 2010 19:18      Profile for Xanthine     Send New Private Message       Edit/Delete Post   Reply With Quote 
No. But Mr. Xanthine lost his multimeter a while back and it was terrible. I went out and bought him a new one. I can't be married to a man lacking an instrument.

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And it's one, two, three / On the wrong side of the lee / What were you meant for? / What were you meant for?
- The Decemberists

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Ugh, MightyClub
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Icon 1 posted September 13, 2010 10:41      Profile for Ugh, MightyClub     Send New Private Message       Edit/Delete Post   Reply With Quote 
Did you buy him a larger instrument with better battery life from the internet?

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Ugh!

Posts: 1739 | From: Ithaca, NY | Registered: Dec 2004  |  IP: Logged


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