Given all the recent attention the iPhone4 antenna reception problems, I thought it would be interesting to start a poll to see what everyones average signal losses are when holding your phone normally.
Since signal "bars" are arbitrary and have no scientific meaning, to participate in this poll, please look at your RSSI which is displayed in -dBm. To see that in your BlackBerry hold down the ALT key and press the key sequence NMLL at the same time. Your bars will be gone and RSSI displayed instead.
Lay the phone on a table, look at the RSSI. Pick it up, look at the RSSI after a few seconds. Do it in different rooms, different locations, and try to get a feeling of what is "normal". Then come back and post your results here.
Oh, it's also important that you know that you are on the same cell. If you drop alot of dB's, you phone may switch over to another cell and then you'll be looking at the RSSI of a different cell and the test is not valid.
You can use the app I made (download OTA at cellumap.com/ota or download off-line at Cellumap Cellular Coverage Maps) that displays the GSM/UMTS cell ID (CID) or the CDMA Base Station ID (BID). Make sure the BID or CID doesn't change.
I'm a Radio Network Engineer and have been making GSM/UMTS RF link budgets since the late 1990's. On average, the typical "body loss" should be in the 3-6dB range (read example here). As the book also says, in some "worst case" situations, the loss can be 10dB or more. But that is not "usual". If you pick up your phone all the time and lose every time more than 5-10dB, then I'd say something looks wrong.
Mine is always around -70 dBm to -75 dBm at my house. Holding it does not make a difference whether I hold it in my left hand, right hand, both hands. I always touch the sides when I hold it in my left hand while talking on the phone.
The only signal issues are due to AT&T, not my 9000. For instance, I was in a dead zone yesterday. I got SOS without even holding the device at all.
I went to the extremes with this test. I took off my case, put the phone against my body and covered the entire phone with my hands except for a little sliver so I could see the signal and still -80dB + all 5 bars showing on the regular indicator.
If Thanks for the replies so far. If you are in good coverage, say better than -80, your hand may not be enough to induce a loss. In weak signal areas, say less than -90 it should be more noticeable (note: you should lose the network at around -110). But as long as you aren't seeing a major signal drop just by touching it, i think everythings fine and normal.
-89 all over the place but then my house is 150 yards from a cell tower in a countrified setting. From my back garden I have full view of the tower.
It made no difference on my 9700 whether I held it or left it on the table.
Jobs is right. All cell phones suffer some signal loss. This is simply the physics of the device and of the transmission technology. It would seem however that there is a difference between the carefully designed BlackBerrys that seem affected to a minimal degrees and the incompetent fools in the Apple styling department who have precipitated a catastrophic failure in their flagship device.
Oh, for those of you on UMTS, another reason you won't see your signal moving around that much is due to the fact that UMTS uses a "rake receiver" to combine signals and keep them a bit stronger and steadier than GSM. Also GSM is narrowband (200KHz) TDMA and UMTS is wideband (5MHz) spread-spectrum. If you look at your GSM signal in comparison, you'll see it jump around more than UMTS.
Here's an explanation about RAKE receivers (UMTS uses CDMA):
MULTIPATH AND RAKE RECEIVERS
One of the main advantages of CDMA systems is the capability of using signals that arrive in the receivers with different time delays. This phenomenon is called multipath. FDMA and TDMA, which are narrow band systems, cannot discriminate between the multipath arrivals, and resort to equalization to mitigate the negative effects of multipath. Due to its wide bandwidth and rake receivers, CDMA uses the multipath signals and combines them to make an even stronger signal at the receivers. CDMA subscriber units use rake receivers. This is essentially a set of several receivers. One of the receivers (fingers) constantly searches for different multipaths and feeds the information to the other three fingers. Each finger then demodulates the signal corresponding to a strong multipath. The results are then combined together to make the signal stronger.
It's really hard to get an accurate measurement in my house. My signal seems to vary anywhere between -83 and -102 dBm no matter where I am or how I am holding. That said, sitting in the living room chair near the sliding glass door it was hovering between -83 and -87 mostly. In a few cases my signal actually seemed to increase when I gripped the phone, but generally speaking there really didn't seem to be much effect either way...I'd say no more than a 3 dBm change.
BTW, I like the app you made and have a question. Would you ever be interested in making a simple app that uses the GPS to display travel speed in very large print that is legible while driving? That's all I want, just current speed. I have found a few apps that give that information and the print is so small I can hardly read it while holding the phone up to my face, much less when the phone is holstered in the dash mount!
