à Satellite Modem Audio Interference à

[Kadosh]

After getting hooked up to a broadband satellite provider, I immediately noticed a pulsing sound coming through my home stereo speakers. Generally speaking, while the connection is idle, 1 pulse per second, more if I am surfing. These consistent pulse sounds coincide with the send and receive lights on the satellite modem. I have my home stereo system hooked up to my computers, by way of 1/8-inch mini jack.
1. If I unplug the 1/8-inch mini jack at the back of the computer, sound stops.
2. If I unplug the Cat cable from the satellite modem, no change, pulsing continues.
After trying several things, I am at a loss.
It is either coming through the AC line, or possibly from the DC cord connected to the satellite modem.
Thoughts, ideas, remedies,
Best Regards,
Brian

 

[VEBill]

The latest broadband by satellite systems (such as Wildblue) are two-way, Ka-band. The transmitter at the dish feed point is about 3 watts peak. Hopefully the installation is such that you don't have to worry about direct RF interference from the dish installation. If the dish is just on the other side of the wall, then perhaps that is something to worry about.

You mentioned that the noise coincides with the send and receive lights on the satellite modem. Do you mean that you get noise on either light? In other words, do you get noise when the receive light is on? If so, then it is probably data noise as opposed to RF.

You could try the following in whatever order is easiest:

Add some ferrite chokes to the cables coming to and going from the modem. Especially power line if not already equipped.

Try new audio cables with better shielding. Reroute these cables away from noise sources.

Rearrange the AC power so that the modem doesn't share a power strip with the rest of the gear.

Complain to the installer.

Call their tech support.

 

[MacGyverS2000]

Ground loop, most likely... are all of the components (PC, stereo, modem) connected to the same circuit (i.e., the same breaker in the box)?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

PC speakers and audio just aren't that robust. My cell phone interferes with my PC speaker output

TTFN

FAQ731-376

 

[Kadosh]

After more careful evaluation, it appears the pulsing coincides only with the send light as it blinks.

Even when the connection is idle, the modem is constantly pinging the satellite every second, resembling the rhythm of a heart beat. When actively surfing it gets worse based on the amount of activity.

With any luck, the following may better help identify the culprit.

This pulsing affects both computers systems.

The dish is on the roof, some 25-feet or more away from all equipment.

Currently all the equipment is on the same circuit.

Thanks for the ideas, I will try them and hopefully something will work.

Best Regards,

Brian

 

[Comcokid]

I agree with previous postings - ground loop or isolation issue. Stereo amplifiers use a linear supply (with a big stepdown transformer) so they can achieve maximum AC line isolation. However, PCs use a switching powersupply for lower weight and higher efficiency. I would guess that your satellite modem is using a switching supply as well. Switching supplies do not have good AC line isolation.

I suggest you try an audio isolator on your 1/8" mini jack. A quick google shows that Radio Shack has such a device for around $17 - part number 270-054.

disclamer - I didn't check the details of this RS part for the particulars of your application.

 

[Kadosh]

Update: Problem solved!

In this particular case, I can personally vouch for the Radio Shack part number 270-054, (i.e., Ground Loop Isolator) it worked perfectly.

The problem is completely gone; in fact, I often got a pop through my speakers when I turned off my florescent desktop lamp, not anymore.

This device even cured my Low level hum; I could not be more pleased.

Thank you all for your help, tracking down these types of problems can be daunting and very time consuming, not to mention expensive and frustrating, as any trial an error approach can be.

Thanks again!

Best Regards,

Brian

 

[itsmoked]

We appreciate your feedback greatly.
Thanks!

Happy tunes..

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com