Scott, Two comments: 1) As Tony mentioned, the phone itself may be suspect. iPhones like any phone may suffer from self-interference since there is not an enforceable requirement to test TIS/TRP or in-band noise at the port in the absolute worst-case system noise configuration for each channel in each band covered. Ideally, the phone itself should not suffer from self-jamming, as considerably engineering time and per-unit money is spent to prevent issues. In recent years, however, several interference issues related to smartphones have come up as it is tough to impossible to cover every usage scenario.
2) The interference problem that Tim brings up happens quite often, as wireless phone link technologies are highly sensitive to noise at the antenna port. The coupling path is not always conducted as on the phone side the dock interface should be and often is matched and filtered very well and compartmentalized shielding in the phone inhibits cross-coupling. However, the interfering noise could easily be near-field coupled or radiated from the docking connector, the dock itself, etc. For wireless phone technologies, the level at the antenna port at which noise can interfere with the OTA link is several of orders of magnitude lower than the level tested to in a regulatory EMI test. If the base station comes in strong the tolerable noise level can also be high, but that is often not the case. Most manufacturers of phones and accessories require some functional testing with the OTA link active, but those tests are usually not well defined and not comprehensive. Spherical OTA link testing in an anechoic chamber is time-consuming and expensive, and usually not done for multiple usage scenarios. From a design perspective it is tough to prevent and mitigate issues. For example, wired interface clock and data harmonics (such as USB) can often be detected in-band on an antenna port. Other sources often found include residual harmonics from DC-DC or AC-DC switchers and micro-controller CPU clock harmonics. Even casually "sniffing" the connector or probing the interface with a scope does not necessarily show alarming levels of spurious noise as the in-band harmonic content is invisible in the test setup noise floor. Specialized test setups are required with very low noise amps to work these issues, and issues are often tough to chase down. Just my $0.02. Best regards, -Robert E.Robert Bonsen Sr. Engineering Consultant Orion Scientific Haynes, Tim (SELEX GALILEO, UK) wrote: > Scott, > > You might also like to consider the conducted emissions from the "dock" > into the "phone" on the interface. I have come across a problem where a > digital interface to a radio transceiver directly interfered with the > receiver when connected. These "emissions" did not show in a radiated > emission test and since the "dock" directly connected to the back of the > transceiver, no conducted emission tests were (could?) be done. > > If the receive frequency or something close, or even the I.F. frequency > is injected from the dock into the phone then it may reduce the > effective sensitivity and hence block all but the strongest of > base-stations. > > I hope I have explained this adequately. > > Regards > Tim > > ************************ > > Tim Haynes A1N10 > > Electromagnetic Engineering Specialist > > SELEX Sensors and Airborne Systems > > 300 Capability Green > > Luton LU1 3PG > > ( Tel : +44 (0)1582 886239 > > 7 Fax : +44 (0)1582 795863 > > ) Mob : +44 (0)7703 559 310 > > * E-mail : [email protected] > > P Please consider the environment before printing this email. > > > > There are 10 types of people in the world-those who understand binary > and those who don't. J. Paxman > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Scott > Douglas > Sent: 02 September 2009 07:13 > To: 'EMC PSTC' > Subject: iPhone Radiation Pattern > > *** WARNING *** > > This message has originated outside your organisation, > either from an external partner or the Global Internet. > Keep this in mind if you answer this message. > > > Can anyone tell me where I can find out the antenna location, > orientation, and radiation pattern for an iPhone? Thinking about docking > > things and why one dock interferes with phone communications and why > another does not interfere. First look suggests something getting in the > > way of the antenna pattern. > > Thus the question - where is the antenna and what direction is the > radiation pattern? And if one version phone is different from another, > please tell me as many as you can. > > Thanks in advance for your help. > > Regards, > Scott Douglas > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. To post a message to the list, send your > e-mail to <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > Graphics (in well-used formats), large files, etc. can be posted to that > URL. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> > > SELEX Sensors and Airborne Systems Limited > Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS14 3EL > A company registered in England & Wales. Company no. 02426132 > ******************************************************************** > This email and any attachments are confidential to the intended > recipient and may also be privileged. If you are not the intended > recipient please delete it from your system and notify the sender. > You should not copy it or use it for any purpose nor disclose or > distribute its contents to any other person. > ******************************************************************** > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > Graphics (in well-used formats), large files, etc. can be posted to that URL. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> > > > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
