In a recent thread, there was speculation on the WiFi specs of the Apple iPad with respect to similar non-Apple tablets; but, no proof was provided.
This thread is intended to nail down the 3 key WiFi specs of the Apple iPad.
To start, I ask of all ...
Do you know where we can find the 3 key WiFi specs for the iPad?
Googling, I found this iPad teardown, which shows the hardware:
The iPad uses a "Broadcom BCM4329XKUBG 802.11n WiFi" board.
The WiFi antenna is right behind the Apple logo:
But, I didn't see the key specs listed. So, next, I'll look at the FCC teardown.
The fcc teardown report didn't contain the 3 key specs, so, and I'm having trouble downloading the FCC SAR evaluation report:
Recent thread where? Article ID please.
In the FCC type certification test results. The tx power is somewhat different for each end of the band and for different modulation nodes (b/g/n/a). There is no single value for tx power.
For USA: Model A1219 FCC ID: BCG E2381A Model A1337 FCC ID: BCG E2328A Model A1395 FCC ID: BCG A1395 Model A1396 FCC ID: BCG A1396 For the iPad 3: Wi-Fi Only FCC ID: BCG A1416 Verizon LTE FCC ID: BCG A1403 AT&T LTE FCC ID: BCG A1430 etc...
When the FCC ID web pile stops crashing, plug the FCC ID number into: and you should eventually find the xmit power. I would post some examples, but as is normal on weekends, the FCC ID site has crashed.
For the iPad 3, nominal 2.4GHz tx output is about 16dBm. For 5GHz, it's about 17dBm, except in the UNI-1 band, where it's 13.5dBm.
That's not easily measured. The best that can be done is to assume that it's the same as the sensitivity of the chipset. Most iPads use a Broadcom BCM43291HKUBC chip, which requires that you request the data sheet from Broadcom and possibly sign and NDA. Good luck: Please note that the receive sensitivity is different of each mode (b/g/n/a) and for each connection speed. Like transmit power, there is no single value for sensitivity. Sensitivity is usually measured with a BER (bit error rate tester) and a pile of test equipment. Check out the various Wi-Fi test equipment vendors for app notes.
Just to make things interesting, the usable sensitivity can be reduced by external influences, such as your hand on the antenna as in the iPhone 4. There can also be RFI generated by the processor and display drivers inside the iPad. Treat the specs as best case.
The antennas in the various iPad mutations vary in location and type with model number. For example, the iPad 1 has it behind the Apple logo, which methinks is a great location. The iPad 2 has it just to the (rear view) right of the power connector. On the iPad 3 antenna, the wi-fi antenna is glued to the speaker, which is not a great idea. It also looks kinda minimal: See steps 41 thru 43. On the iPad Air, there are two antennas glued to the inside lower back. They're the black rectangles with the coax cables in the photo:
The dual band (2.4/5GHz) antennas are possibly a PIFA (Planar Inverted F Antenna) type. I haven't torn one apart yet to see what's inside. It's difficult to determine the gain for such antennas without an NEC model. This might help Kinda looks like these numbers came from an NEC modelling program, and not from field tests.
So, what problem are you trying to solve? Lousy sensitivity perhaps: (1400 messages). It's apparently a common problem.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Probably in one of the other two newsgroups. This is the guy who added .repair to an ongoing thread, and now started this thread crossposted to three newsgroups, still include .repair.
MIchael
it's been working fine for me.
the only problem i've had was during the government shutdown when it was offline.
they could have left the server running during that time. it's not like anyone sits there and fills the requests as they come in.
...snip...
reception on all radios is reduced with one's hand on or near the antenna, which is why just about every device maker tells you how to hold it, and not to put your hand near the antenna.
it's not just apple.
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It belches similar errors almost every weekend when I try it.
I suspect that there's nobody paying attention to log files and error messages on weekends.
Correct. Except that Apple is the worst. I was referring to the wi-fi performance, which is also affected by hand contact with the antenna. However, I don't have numbers for wi-fi, just cellular: That's about 4 years old. Not much has changed. I have some guesses as to why, but I can't prove it without destroying at least two iPhones. Hint: To the best of knowledge, Apple iPhone 4 and 5 are the only devices that use an untuned monopole as an antenna. Even the iPads don't do that.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I will try these suggestions kindly supplied in the other thread:
here are some numbers, plus the fcc ids so you can look up all the gory details:
nope. they're about the same as everyone else. a little worse than some and not as bad as others.
the iphone 4 worked *better* than the 3gs it replaced, with fewer dropped calls.
most users didn't have a problem with the antenna according to a survey from changewave. in fact, very few thought it was a serious problem.
apple sold the iphone 4 for three years (and still sells it in some parts of the world). once the initial hype died down, nobody complained.
it's the same damned phone. if it really was as screwed up as some claim, there would be ongoing complaints, and there are not.
other phones have the same issue, if not more so:
many phones say 'don't hold it wrong'
Hi Jeff, I haven't seen you on a.i.w all that much lately, but, I knew you frequented s.e.r more studiously, so, I'm very glad you stopped by to help us out.
All we want to do is nail down the iPad WiFi specs.
There is speculation that they are substandard (as compared to similar non-Apple equipment); but let's leave that speculation out of the factual data for now, and just figure out what it is.
I have a question about what those numbers in the quote are for.
If the transmit "output" is 16dBm at 2.4GHz and 17dBm at 5GHz, I presume you mean sans an antenna because I don't see the customary 3dB difference between the two numbers (which would be entirely antenna related).
If so, the radio transmit power is roughly 40mW at 2.4GHz. And, at 5GHz, it's roughly 50Mw.
Are my assumptions above about nominal transmit power correct?
Hi Jeff,
In a word, yes.
I recently obtained an iPad for the first time in my life, and I was shocked (and appalled) over what appears to be lousy receiver sensitivy (as compared to non-Apple devices in my very handsat the very same time and place).
I mentioned that in a recent a.m.i thread, where others refuted my ad hoc observations. A few people said their reception is just fine, and that I might have a bad unit.
Since I have anecdotal information that some/most/all Apple devices are weak in radio reception and/or antenna gain, I was asked to provide the details, which I didn't have.
So, the goal is merely to compare your typical iPad with your typical non-Apple simimlar device for the three nominal specs of:
a. Antenna gain (we can pick a single frequency for simplicity) b. Radio sensitivity (again, we can pick a single frequency) c. Radio transmit power (at any one frequency should be good enough)
I have the numbers from my test at: What do you have?
Try your phone, whatever it might be. Post the signal strength in
-dbm for holding it normally, holding it with 2 fingers, and holding it in a death grip covering the antenna.
I used an iPhone 3G for about 2 years on Verizon. No dropped calls. However, my friends with similar phones on AT&T were constantly dropping calls. Oddly, when the problems with the iPhone 4 appeared my friend's iPhone 3G's magically stopped dropping calls. AT&T said they didn't change anything. What happened is that the disconnect time was extended, so that the system could tolerate extended deep fades as produced by the antenna grip problem.
Sigh. If you just bought an iPhone and someone asked if you're having "serious" problems what would you say? I'm in the computer repair biz and find Apple users rarely admit they have problems unless they are totally desperate. Instead of asking if they had "serious" problems, I wonder how the survey would look if they asked "Have you learned to tolerate the antenna grip problems"?
Sure. The rubber bumpers sorta work.
I see. If there are no complaints, there is no problem. Time for an old anecdote. Once upon a time, I helped a friend who owned a company that sold light pens for the PC. Included with each pen were the usual instructions, drivers, and documentation. After shipping about
2000 light pens, someone casually mentioned that the demo software crashed. I checked and sure enough, it crashes every time. My guess is at least 800 users had installed the card, ran the install software, ran the demo, watched it crash, and said absolutely nothing. It never ceases to amaze me how much poor quality, bad software, junk hardware, miserable design, etc the GUM (great unwashed masses) has learned to tolerate.Oh, yes. Nobody complains. Here's Google search for "iphone 4 dropped calls" with the date limited to the past month: Seems to be quite a few complaints. Instead of nobody complaining, perhaps the problem is that nobody is listening to the constant complaints?
I find it interesting that you picked two videos that measure signal strength in "bars". Both phones have pages that show signal strength in -dBm. All I want to know is how many dB does the signal level drop when the phone is badly gripped.
Yep. That's part of the wholesale repudiation of responsibility and litigation avoidance document included with every product these days.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
The 3dB difference in gains between the two bands is pure coincidence. It can be anything.
16dBm = 40mw
17dBm = 50mw-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
OK. Maybe I'm mistaken.
In "my" experience, when I buy, say, an 18 inch dish reflector for a WiFi radio, there always seems to be a 3dB gain in the 5GHz specifications as compared to the 2.4GHz specifications for the same power setting of the radio.
I had thought that 3dB doubling of power was due to the inherent physics behind doubling the frequency from 2.4 to 5 GHz.
Which iPad? Model number or FCC ID number please. I don't like working in the dark.
I don't think you're going to have much luck with converting specifications to performance expectations. It's much easier to avoid most of the math and just do a comparison with a known working device.
I suggest you install iPerf/Jperf on your iPad and on a desktop (any OS). For IOS: Android: PC (Java front end): OS/X Tutorial: Scroll to near the bottom for what Jperf looks like.
Setup a fairly fast PC or Mac desktop to act as the iPerf/Jperf server. Test it with the iPad to see if you can get reasonable TCP graphs. (don't bother with UDP for now). Play with it until it seems reliable.
Now for the real test. Dive into the settings for your wireless router and set it for 802.11g only (or b/g only) and a fixed speed of
54Mbits/sec. No 802.11n, no turbo, and no other speed enhancements. It is critical that speed is locked to 54Mbits/sec so don't skip that setting.If your iPad comes with a case or keyboard, please remove them for the test. Turn off Bluetooth as it might slow things down.
Start Jperf and start walking away from the wireless router. The speed should be fairly constant up to about 25ft, where the graph will likely drop rather quickly. Measure the distance. Now, do the same thing with other IOS devices, Android devices, and laptops. The idea is to use the signal strength and thruput while the iPad is sending or receiving data.
Note that I haven't done this for a while and am not sure exactly what will happen. I'll try it with my shiny new Galaxy Tab 3 7.0" tomorrow or sometime next week.
The distances will be approximate, but it should give you a clue as to the relative ranges of the various devices. You might see strange results if you do it indoors, but if you put the wireless router in a window or doorway, and do it outside, you will probably see more stable numbers.
There are plenty of other things that can also be tested with iPerf/Jperf but that can come later.
This test won't tell you if the iPad is meeting its own specifications, but will tell you if it's inferior to other devices or has a serious range problem.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Ok, let's grind the numbers for a dish. The gain of a dish is:
G = Pi^2 * Diameter^2 * aperture_efficiency / wavelength^2
If you multiply the wavelength by 2.4/5.7 the 5.7GHz gain will increase by 1/0.42^2 = 5.7 times. Converting to dB, that is a gain increase of 7.5 dB.
This assumes that the feed illumination angle and efficiency remain the same for both 2.4 and 5.7Ghz. That's a tolerable assumption for a dish. However, it's not for a dual band PIFA antenna, which in this case according to the specs seems to have about 4.2dB more gain at
5.7GHz than at 2.4GHz.-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
No you didn't. The iPhone 3G did not work on Verizon. Neither did the iPhone 3GS. Neither did the initial iPhone 4.
-- In the 60's, people took acid to make the world appear weird. Now the world is weird and people take Prozac to make it appear normal.
Seven years ago, I did this receiver sensitivity chart for various wi-fi routers: All of the numbers came from the data sheets which amazingly matched the chip manufacturers numbers almost exactly. That's not going to help you get the iPad sensitivity, but I thought it might be of some interest.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
i have many phones here, from flip to candybar to iphone to android, and they all drop in signal strength depending on where i hold it.
no you didn't.
the iphone 3g is gsm only. there is no cdma.
the iphone was an at&t exclusive until the iphone 4 cdma in early 2011.
at&t had a lot of issues, especially in the bay area. there were a lot of dropped calls well before the iphone 4, as well as shitty data speeds. they were overloaded, big time. they didn't expect the iphone to be as successful as it was.
in fact, at&t was the #1 complaint from iphone users early on.
what proof do you have that's what they did, when they said they didn't do anything?
and at the end of the day, the user doesn't care *why* a call didn't drop, only that it didn't.
depends if i'm having serious problems or not.
changewave is in the business of surveys. they ask a statistically valid sample. the majority (by a lot) didn't have a problem.
in fact, they did ask about that, and not that many said it was serious. i need to find the actual survey though for specifics.
those help but not required. that was mostly to get the whiners to stop whining.
note that after the free bumper offer ended, there weren't very many additional complaints.
pretty much.
if it isn't affecting anyone, then how is it even a problem?
interesting story, but i don't know what that has to do with anything.
apple has likely sold at least 100 million iphone 4 over the past 3+ years (they don't give specific model breakdowns).
they sold 51 million iphones last quarter *alone*.
the reality is that most users did not find it to be a problem. at all.
however, the number is never going to be zero. if you touch the antenna, the signal strength will drop, just like any phone.
people like to complain.
i picked a couple of videos that show the effect of 'holding it wrong'.
or it's part of actual effects.
i have a flip phone where the instructions say how to hold it, and if i hold it the way it says not to, the signal strength drops.
Wow. That's six times the power, not just doubling.
I officially will give up on my prior assumption that the power gain at 5GHz was twice that at 2.4 GHz.
It's actually 5.62 times the power!
Thanks for explaining.
The important takeaway is that the iPad antenna has
4.2dB more gain at 5.7GHz than at 2.4GHz (which means the iPad transmits 2.6 times as much power at 5.7GHz as it does at 2.4GHz).Note: My conversion of dB to power factor are from here:
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