Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: RIM Blackberry RFIs the FT817  (Read 814 times)
SCUBA
Member

Posts: 74




Ignore
« on: March 20, 2007, 05:04:32 PM »

Hi,
I have to use a blackberry cellphone in my job.  When the BB passes data to/from the cell phone tower, really nasty RFI is spewed into any nearby audio circuit.  The audible sound is an obnoxious mosquito buzzing sound.  The buzzing overrides all FT817 audio unless I turn the BB off or move it more than 20 ft away from the FT817.

It isn't just the FT817, it's most anything with an audio circuit - car radios, table radios, stereos, you name it.  

A blackberry expert told me today that the new models still cause the RFI and that the manufacturer (RIM of Canada) has absolutely no intention of fixing the problem.  

The issue is being discusses at the Blackberry forums website
http://www.blackberryforums.com/hardware-accessories/7813-7290-making-nearby-speakers-buzz.html
In posting this here, it isn't my intent to cause redundancy, since the issue is being worked (but not resolved) on the other website.  Because it does interfere with amateur radio, I raise the issue here.

Why isn't the FCC nailing these guys.  Any FCC staff members reading this?
Logged
KF7CG
Member

Posts: 875




Ignore
« Reply #1 on: March 21, 2007, 05:54:05 AM »

Add to the list of occassional polluters. Motorola V220, V3xx, LG? cellphones.

I do not believe that this is a problem of their making. It is a problem of the same nature as amateur HF signals getting into stereos. Part 15 type stuff. When a 1 watt transmitter goes key-down near any audio stuff that doesn't have sufficient sheilding, Presto, interference.

I have seen the problem with telephone handsets too. Just happened to have the landline in one hand and the cell in the other.

What does your VHF handi-talkie do to your FT817 when you transmit with it?

Not to say it isn't a problem, but a reminder to look for other possible reasons.

KF7CG
Logged
KAISERSOUSE
Member

Posts: 327


WWW

Ignore
« Reply #2 on: March 27, 2007, 09:49:41 AM »

Every cell phone I've owned has done this. They've all been nokias and I hear the "duh duh duh...duh duh duh...duh duh duh" whenever it changes networks/towers/whatever.

I've always found it kind of amusing. Sometimes it does it RIGHT before it start ringing. I never carry my phone with me, always in teh car. Gives me time to turn the music down before I answer heh heh.
Logged
SCUBA
Member

Posts: 74




Ignore
« Reply #3 on: March 27, 2007, 06:37:44 PM »

Hi KAISERSOUSE, appreciate your reply.  I have a Samsung cell phone that does not spew out RFI, so, perhaps that proves that there are prevention measures that the Blackberry developers failed to consider.  

I've seen the blackberry jam out PC computer audio, and  PA systems where the PA amp and speakers were at least 20 feet away.  

And this problem goes on and on and on with no FCC intervention.  Is the blackberry manufacturer above the law?  It would sure seem so. If I were to spew out RFI, get warned, and continue as a habitual violator, then I'll have to endure the consequences.  


73,
Jack
Logged
KF7CG
Member

Posts: 875




Ignore
« Reply #4 on: March 28, 2007, 05:54:52 AM »

This is interesting because it points out the two-edged sword nature of RFI. My Icom IC32 causes interference to my home stereos and TVs when on high power. It causes interference to the stereo on all but the lowest power setting and then sometimes then. It is clean, but its power is enough to cause fundamental overload in the devices interferred with.

The cure for fundamental overload is to reduce the strength of the fundamental (desired transmitter output) at the device being interferred with. To test the Blackberry it should be sheilded from rig being interferred with and a small sensing loop used as an antenna to reduce the output strength of the cellphone transmitter at the antenna input, then interference should be checked for.

That these devices are hitting purely audio (pa systems) units is almost a sure signal that the problem is that they transmit with enough power to overload the device in question.

I had a different but related problem where my Ham signal got into the neighbors stereo and his landline phone. Not the fault of my station (clean, adequately grounded, not interferring with home electronics), but when I transmitted especially on 80 meters interference every time.

Check the FT817 with a handy-talky at low power on 440 MHz and observe results. If you have interference it could be the interferred with device.

Try the ARRL web site for RFI resolution ideas, you might find an answer there or not.

KF7CG
Logged
KF7CG
Member

Posts: 875




Ignore
« Reply #5 on: March 28, 2007, 09:54:52 AM »

I forgot to add that the transmitting power of a cell-phone is determined by the receiving cell. It sends a power up or power down signal to the phone to attempt to maintain a compromise between cell phone battery life and connection reliability.

The identification and power negotiation bursts are probably what your are hearing when you heare something and they tend to be at higher power than normal communications. If you have a fairly high path loss to the cell tower you will have a higher possibility of interference due to higher output powers.

With your Samsung phone it may transmit on a frequency that doesn't cause as much overload, and it may also be hitting a tower that doesn't require as high a signal level.

KF7CG
Logged
SCUBA
Member

Posts: 74




Ignore
« Reply #6 on: March 28, 2007, 04:38:26 PM »

Hi KF7CG,
Thanks much for the detailed info.  

FWIW, I've heard the Blackberry referred to as a Crackberry
- the user becomes addicted to his work email.

Personally, I would never own one for myself; I use the one I use because my employer requires it.  

Thanks again,
73/Jack
Logged
K7SU
Member

Posts: 53


WWW

Ignore
« Reply #7 on: April 07, 2007, 07:54:51 AM »

I also use a Blackberry and have calouses on each of my thumbs to prove it!   HI

I have also noticed the audio interference but it's usually when my BB is sitting very close to the rigs. If I move it away a few feet it doesn't seem to bother anything.  

I use it for my business email.  My employer does not require it and I pay for it myself but I find it's extremely handy and well worth it to have it around.  An email from work is much less intrusive than the cell phone which I AM required to carry.

I have not found the RFI it causes to be all that objectionable but as described above, it is simply a sign of the times.

73 and Thumbs Up everyone... :>)

Kelly
www.K7SU.4t.com
Logged
N9NRA
Member

Posts: 7




Ignore
« Reply #8 on: April 18, 2007, 04:23:57 PM »

Something else here, as i also had this problem before i switched phones.  The RFI might also be a result of the fact that some of those units mentioned (i think someone mentioned Nokia phones) use the GSM standard for signalling.  I had noticed this, and more-or-less just lived with it.  Hope this helps.  73 DE N9NRA
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!