indicator light blinking constantly?

Issues relating to installation of your USB-UIRT device.

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indicator light blinking constantly?

Postby Guest » Sat Dec 13, 2003 4:21 am

I have successfully installed usb-uirt on a win2k machine. Is the indicator light supposed to blink and be on constantly or only when it receives a signal?
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Postby JimHugh » Sun Dec 14, 2003 2:21 pm

It blinks whenever it receives IR.

There are a number of sources of IR that can cause it to blink. Plasma TV and Sunlight are two big culprits.

I have a PowerMID pyramid IR-RF/RF-IR repeater. when it is powered on, I get a LOT of spurious signals. Powered off, pretty much just when a remote is pointed at it.

IIRC, there is a an option in the Girder Plugin that allows you to turn off the LED indicator.
Jim Hughes
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Postby Guest » Mon Dec 15, 2003 4:59 am

I've got a Radio Shack ir-rf repeater that came with my 15-2117. When I unplug it the light stops blinking. Thanks for the tip. I'll look around in Girder for the setting...
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Postby jrhees » Mon Dec 15, 2003 3:03 pm

Yes,

IR repeaters are common culprits, since they amplify any IR energy such that it becomes significant.

To turn off the USb-UIRT's LED, go into Girder and into the USB-UIRT Plugin dialog (as if you're going to learn a code, etc.), press the 'Configuration...' button, and go to the preferences tab.

-Jon
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I'm also getting constant flashing...

Postby Benj » Thu Jan 08, 2004 4:28 am

Here's a strange one... have you ever heard of something like this?

I was trying out a new placement of USB-UIRT to see if I can avoid purchasing external emitters. Here's the top to bottom order of components in my rack:

RCA F38310 (38" widescreen tube)
shelf
Kenwood VR-507 receiver
shelf
cable box
VCR

I tried moving the UIRT from on top of the cable box to the top of the Kenwood, because the Kenwood was missing commands some of the time. Suddenly, I started getting nearly constant flashing. (This is with it set up to only flash on receive, not transmit.)

It's night time here. I shut off all lights anyway. I ripped batteries out of all the remotes. I shut off everything in the rack except the HTPC hiding behind the TV. Still flashing! But when I covered the UIRT lens with my hand, the flashing stopped. So there's IR coming from somewhere!

One by one I actually unplugged components, figuring it was the Kenwood somehow. Nope. Finally, I unplugged the TV. Sure enough, the flashing stopped. Plugged it back in, and the flashing started back up. Here's the kicker: it's not coming from the TV's IR lens. If I take the UIRT out and point it at the TV, no flashing. But if I point it at the crack between the TV and the shelf it's on, big time flashing. It's coming out of the bottom of the TV!! And it's leaking through the shelf to the Kenwood below. One more shelf down seems "shielded" enough.

Do you have any idea why an RCA HDTV would be spewing out so much IR from its belly? In the meantime, I guess I'll invest $10 in an external emitter so I can leave the UIRT on top of the cable box... It's not the flashing that's bothersome, seeing as I can disable that. I'm worried that USB-UIRT will be wasting cycles on the constant spurious signal decoding to the point of making real signal handling unreliable.

-Benj
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Postby jrhees » Thu Jan 08, 2004 5:11 am

Benj,

A bit of trial and error testing on your part will tell you if the IR/EMI noise makes operation unreliable...

It may *not* be IR at all, but EMI (electromagnetic) noise. Televisions' High voltage supplies generate a LOT of EMI, and sensitive high-gain circuits can pick this up. I suppose its also possible that there's IR radiation coming off of the neck of the picture tube...

To find out if its IR (light) or EMI (magnetic), instead of covering the lens with your hand, tape a piece of cardboard over the lens (and take your hand away). You hand will shield both whereas the cardboard or thick paper will only stop light.

-Jon
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EMI, not IR

Postby Benj » Thu Jan 08, 2004 3:15 pm

Jon,

I did the cardboard test. Sure enough, with carboard instead of my hand obstructing the USB-UIRT lens, the flashing persists. And if I listen closely when plugging in the TV, I can hear the capacitors (or something) charging up. The flashing doesn't start until the capacitors are finished charging and some circuit clicks on. I guess all of this points to EMI noise. Interesting... It didn't make sense to me that IR would be leaking through a 3/4" plywood shelf! But EMI would.

I'll pick up a couple external emitters and a stereo -> dual mono jack, and keep my UIRT safely two 3/4" plywood shelves away. :)

Thanks again,
-Benj
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Postby jrhees » Thu Jan 08, 2004 6:59 pm

Regarding EMI, the largest effector of EMI strength is *distance*. EMI tapers off in relation to distance squared.

-Jon
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