Aug
17
written by:
James Burke
17 August 2008
The iPhone is a great device but like many smartphones includes a large number of radio transmitters/receivers that may interefere with other devices.
Whilst out cycling yesterday I stopped to take a brief photo looking over towards Reeth in the Yorkshire Dales with an iPhone 3G:
After taking the photo I looked down to my cycling computer (Polar CS300) and noticed that the speed continued at a steady rate, and the trip distance slowly increased, whilst I was stationary taking a photo - as can be seen in the photos below.
During the hour prior to this I had been using the iPhone as an iPod and at three times (maybe coincidentally but seemed to happen on descents when speed reached above 30mph) the player stopped for around 2-3 minutes and then started again with no intervention.
During the cycle I was wearing a Polar wireless heart rate transmitter, and the cycle was fitted with both a wireless cadence and speed sensor that transmitted data to the cycling computer.
The iPhone of course has many wireless receivers/transmitters for 3G, GSM, GPS, BlueTooth and Wifi that provide the potential for radio frequency interference in a number of different ways.
Both devices undergo FCC testing and certification but that of course offers no guarantees that no interference with other devices will occur and indeed if there is intereference the devices must accept and handle that.
The iPhone Product Information Guide states that "Nearly every electronic is subject to radio frequency interference from external sources if inadequately shielded or or designed, or otherwise not configured to be compatible. As a result, iPhone may cause interference with other devices."
Most devices are shielded from radio frequency signals but something is clearly not quite right with this combination.
Luckily this is not a situation where a medical device such as a pacemaker is involved (as referenced in this blog post) but as we carry around more wireless devices on us during everyday life and other wireless networks start to spread out around us the problem of radio frequency interference can only get worse?
For info, the FCC Compliance Statement for the iPhone is:
This device complies with part 15 of the FCC rules. Operation is subject to the following two conditions:
- this device may not cause harmful interference, and:
- this device must accept any interference received, including interference that may cause undesired operation.
Tags: