| Testing RF Performance |
| Testing RF Performance |
Last Updated: 13-Sep-2008
The first thing we need to is define RF Performance, at least in terms of what I refer to when I say it. There are actually two main traits that come together to form this aspect of a phone. The first is the phone's ability to pull in a weak signal and thus retain a connection to the network (both when idling, and when involved in a call). I call that trait RF Sensitivity.
But how can I rate the RF sensitivity of a phone relative to all others when I don't test all phones simultaneously? There is no doubt that this is the biggest problem with making such determinations, and it certainly isn't very scientific to go completely on memory. Even if my memory was perfect, signal propagation can vary from day to day thus changing the results that a phone might get in a known location. Where possible therefore, I make side-by-side comparisons using a phone with known RF characteristics. By having a point of reference it is possible to place a newly-tested phone on an absolute scale.
To judge the signal capturing ability of a phone I need a location that provides borderline signal strength that tapers off in a relatively linear fashion. Fortunately for me, shopping malls are often great for just this purpose. Malls provide an ample supply of areas where signals fade to non-existence, and they do so quite predictably as one moves further and further "in" through various halls.
While it isn't exactly a laboratory-quality environment, it does provide a way to not only reduce the signals gradually, but it also allows two phones to be compared at equal signal levels. One such hall exists in Square One in Mississauga where I can test all phones. You will hear me refer to this hall in Square One as The Hall of Shame (a name coined by someone on HowardForums).
Regardless of the slight variability of this approach, it can generally be said that one phone has greater RF sensitivity if you can walk further down the hall before the signal fades away. By extension, one can also conclude that one phone is better than another if it can connect to the network and provide faultless audio, while the other phone cannot in the same location.
Of late however, I've been finding that most quality phones have reached a sort of pinnacle in the evolution of RF sensitivity, and so I often have nothing to say about this aspect of performance other than it's excellent. While it makes for a more boring review, it's good to see that manufacturers have come to grips with this feature and that we rarely have to concern ourselves with it any longer. However, there are still poor examples of RF sensitivity out here, and so the category will remain to report on phones that do a poor job in it.
Another aspect of RF Sensitivity is the phone's reaction to being placed close to a human body. I test this ability in free space (with the phone held away from my body with the antenna pointing up), and in places on my body where the phone would commonly be carried. This type of testing sometimes reveals severe problems with RF sensitivity when the phone is put in close proximity to the body. Many of today's smaller phones beg to be carried in a shirt pocket, yet some phones suffer incredible signal losses when you do this. Perhaps the worst phones of all time for this were the old Nokia 6190 and 5190.
The second aspect of RF performance concerns the phone's ability to cope with real-life situations. It has been my experience that under normal usage some phones exhibit problems that don't come to light when testing them when stationary or at walking speeds. In the case of 2G GSM phones (pre-3G) for example, the way the model deals with handoffs can vary from mildly annoying to all-out irritating. For CDMA phones I find that some phones seem to produce far more audio anomalies while on the move than others. These sorts of things also form part of my assessment of the phone's overall RF goodness that I call Over-the-road-Performance.
However, it has been my experience that GSM 3G (UMTS) models cope so well with on-the-move anomalies that I've yet to find one that doesn't get a grade of A+ in this category. It's almost pointless rating UMTS phones for this aspect of performance, but the category will remain just in case I encounter a model that does poorly.
But is RF performance really that important, especially in light of the excellent performance demonstrate by most modern phones? In the case of RF sensitivity at any rate, the answer is no, it doesn't matter. Except for the odd phone that does poorly, you won't find much difference between one model and the next. However, real-world behavioral problems most certainly will be an issue, but as I've noted this seems to apply only to non-GSM-3G phones. You'll get better performance from a phone while on the move if it possesses better over-the-road-performance.
No matter how good you think a network's coverage is, some indoor locations will always be a challenge. The better the phone's ability to cope with weak signals, the more indoor borderline places you'll be able to use your phone. This is especially true when it comes to the phone's ability to hold on to the network while idling.
Unfortunately there is one aspect of modern cell phones I cannot test and I cannot account for. Not all phones leave the factory with a guarantee that they are working 100%. It seems that lemons among cell phones are quite common and I can never really know for sure if I'm testing a lemon or not. So, I may end up giving a phone a poor rating for RF performance while the majority of that particular model work just fine. The only thing I can do to prevent this is to be given a second phone (which supposedly does not have RF issues) to confirm that my original test model was non-representative. However, I'm usually lucky to get just one phone to test, much less two of them.
