My computer kills my cell phone reception

phuschnickens

My computer tower jams my cell phone signal. I'm on verizon in metro detroit and get GREAT service everywhere... except near my computer. It is about the most annoying thing imaginable. This has happened at my home since I moved in. I always suspected that it was my computer b/c I started to notice that I could guarantee to lose all cell signal if I was within two feet of the tower. Most of the time even being within 5 ft makes my signal drop. At first I thought it could be just be a 10 ft dead zone based simply on location. But... I had to bring my computer to work for something yesterday and the same happens here. My coworker who is on sprint's network tested his phone and the exact same thing happens. Neither of us have ever had a problem in 15 x 15 sqft office.

Please what can i do? My case is an antec p182. I think when i moved to the case might've been when the problem started.

P.S. no wireless card in my computer, no bluetooth

thanks in advance

phu

lordbean

Evidently, your tower is generating a decent EM field to be cutting off cell phone reception. This honestly doesn't really surprise me... my cell phone gets very low signal when it's sitting beside my tower, and it's a Cooler Master HAF 932.

Basically, any piece of electronics generates an electromagnetic field. The more power flowing through the gadget, the more EM interference it generates. Computers (in particular gaming computers) are fairly heavy-draw devices compared to other consumer electronics that might be in your usual work and/or leisure area, and so are the most likely source of cell phone service disruption through EM interference in this scenario.

phuschnickens

I was wrong... it's not the enclosure.. b/c it doesn't happen when turned off. Your explanation sounds sensible... anything I might be able to do about it? I'm not into gaming but i'm definitely a computer hobbyist and love the performance so... kryptonite shield? or even swapping something out??? but not the power supply, motherboard or processor?

lordbean

As for what you can do about it, I don't really know... I usually just leave my cell phone somewhere in my room that isn't near my computer, because for one, my speakers seem to pick up the cell phone's communications with the radio tower, which produces an irritating spurt of morse-code-sounding noise. There may be some way to shield the computer to contain the EM field, but I've never looked into it, and so I really don't know where to look.

Thrax

@Lordbean: You have a GSM phone which operates on a frequency that causes unshielded solid state amplifiers in the audio chain to act as an RF detector. What you're hearing are the bursts of power required to transmit the TDMA signal-- the tower communication.

Phus' problem bewilders me, however, as CDMA -- Verizon/Sprint -- usually does not suffer RFI. This is why CDMA is often considered to be a superior network, and why Verizon is more reliable.

ardichoke

You could try building a small faraday cage to put around your tower. It's totally not practical but is probably the only way to "fix" the problem.

lordbean

mmm, interesting reading.

Seems like what we're looking for is something that produces a significant amount of interference in the 800-900MHz radio band. Detailed specs of the PC may help...

Hawk

This may help.... Most mobo's have something very similar to this in the bios.
You can try it to see what effect it has on both the pc system and the cell phone.

Spread Spectrum
Options : Enabled, Disabled, 0.25%, 0.5%, Smart Clock
When the motherboard's clock generator pulses, the extreme values (spikes) of the
pulses creates EMI (Electromagnetic Interference). The Spead Spectrum function
reduces the EMI generated by modulating the pulses so that the spikes of the pulses
are reduced to flatter curves. It does so by varying the frequency so that it doesn't
use any particular frequency for more than a moment. This reduces interference
problems with other electronics in the area.
However, while enabling Spread Spectrum decreases EMI, system stability and
performance may be slightly compromised. This may be especially true with timing-
critical devices like clock-sensitive SCSI devices.
Some BIOSes offer a Smart Clock option. Instead of modulating the frequency of the
pulses over time, Smart Clock turns off the AGP, PCI and SDRAM clock signals when
not in use. Thus, EMI can be reduced without compromising system stability. As a
bonus, using Smart Clock can also help reduce power consumption.
If you do not have any EMI problem, leave the setting at Disabled for optimal
system stability and performance. But if you are plagued by EMI, use the Smart
Clock setting if possible and settle for Enabled or one of the two other values if
Smart Clock is not available. The percentage values denote the amount of jitter
(variation) that the BIOS performs on the clock frequency. So, a lower value
(0.25%) is comparatively better for system stability while a higher value (0.5%) is
better for EMI reduction.

danball1976

Thrax wrote:

@Lordbean: You have a GSM phone which operates on a frequency that causes unshielded solid state amplifiers in the audio chain to act as an RF detector. What you're hearing are the bursts of power required to transmit the TDMA signal-- the tower communication.

Phus' problem bewilders me, however, as CDMA -- Verizon/Sprint -- usually does not suffer RFI. This is why CDMA is often considered to be a superior network, and why Verizon is more reliable.

I've always wondered what that sounds was until someone on Second Life mention or said "I hear someone's cell phone" and then described what was going on. Also, I have noticed that moving my phone away from the laptop (using the phone as a modem - Samsung Rant - Sprint), it does get a better signal/connection speed.

I also hear that occasionally on the morning radio show from one of the guy's phone in the studio, and even heard it on TV (news, Beck or Hannity)

Hawk

Also I forgot to mention that most hard drives have a Spread Spectrum Clocking enable/disable setting through the Jumper on the back. [SSC Mode]
They vary from different drive manufacturers.
So, You would have to refer to your manuals.

danball1976

Hawk wrote:

Also I forgot to mention that most hard drives have a Spread Spectrum Clocking enable/disable setting through the Jumper on the back. [SSC Mode]
They vary from different drive manufacturers.
So, You would have to refer to your manuals.

Really? I've never seen that on any hard drive. Is that what the extra one or two pair of connectors are for?

Thrax

The extra pair of pins are usually the "park jumpers," where you park a jumper you don't need.