Do you know where we can find the 3 key WiFi specs for the iPad?

Discussion in 'Wireless Internet' started by Liam O'Connor, Mar 1, 2014.

  1. 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?
    1. WiFi radio transmit power (usually specified in milliwatts or dBm)
    2. WiFi radio sensitivity (usually specified in dBm)
    3. WiFi antenna gain (usually specified in dBi)
     
    Liam O'Connor, Mar 1, 2014
    #1
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  2. Googling, I found this iPad teardown, which shows the hardware:
    http://www.ifixit.com/Teardown/iPad+Wi-Fi+Teardown/2183

    The iPad uses a "Broadcom BCM4329XKUBG 802.11n WiFi" board.
    http://s1.guide-images.ifixit.com/igi/V6QetUKjFdDsDYga

    The WiFi antenna is right behind the Apple logo:
    http://d3nevzfk7ii3be.cloudfront.net/igi/vVWXasqYpDiLQCC3

    But, I didn't see the key specs listed.
    So, next, I'll look at the FCC teardown.
    http://www.ifixit.com/Teardown/iPad+FCC+Teardown/2197
     
    Liam O'Connor, Mar 1, 2014
    #2
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  3. Liam O'Connor, Mar 1, 2014
    #3
  4. 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:
    <http://transition.fcc.gov/oet/ea/fccid/>
    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:
    <https://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM4329>
    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.
    <http://www.cultofmac.com/156848/ipa...t-performance-yet-but-does-it-really-matter/>
    The iPad 2 has it just to the (rear view) right of the power
    connector.
    <http://cdn.imore.com/sites/imore.com/files/field/image/2012/07/iPad-2-wifi-antenna-caution-area.jpg>
    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:
    <http://www.ifixit.com/Guide/iPad+3+4G+Wi-Fi+Antenna+Replacement/8750>
    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:
    <http://d3nevzfk7ii3be.cloudfront.net/igi/j1bWSkU3hGUAmpcU.huge>

    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
    <https://discussions.apple.com/thread/4866269>
    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:
    <https://discussions.apple.com/message/17887360#17887360>
    (1400 messages). It's apparently a common problem.
     
    Jeff Liebermann, Mar 2, 2014
    #4
  5. 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
     
    Michael Black, Mar 2, 2014
    #5
  6. Liam O'Connor

    miso Guest

    The FCC specs talking, not listening. This is kind of unfortunate since they
    have all the gear there to measure both.

    You have to depend on the manufacturer for receive specifications, and Apple
    certainly isn't going to admit to their problematic hardware. And if you
    have to compute the minimum useable signal based on guessing antenna specs,
    lots of luck.

    To be fair to Apple, it is often an annoyance when a portable device works
    too well. I've had situations where my Blackberry is trying to connect to
    some wifi 500ft away when I already have a fine LTE signal.
     
    miso, Mar 2, 2014
    #6
  7. Liam O'Connor

    Guest Guest

    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.
     
    Guest, Mar 2, 2014
    #7
  8. The Following Error(s) Occurred While Retrieving The Requested Page:
    Date and time of error: Sun Mar 02 00:02:08 EST 2014
    Requester's address: 192.168.199.13
    Requester's browser type: Mozilla/5.0 (Windows NT 5.1; rv:27.0)
    Gecko/20100101 Firefox/27.0
    Called from: http://transition.fcc.gov/oet/ea/fccid/
    Parameters specified: RequestTimeout=500
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    weblogic.common.resourcepool.ResourceDisabledException: Pool
    OETDataSource is Suspended, cannot allocate resources to
    applications..
    The error occurred on line 26.
    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:
    <http://802.11junk.com/jeffl/cellular/cell-test.htm>
    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, Mar 2, 2014
    #8
  9. 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:

    <http://www.revolutionwifi.net/2012/03/ipad-3-wi-fi-specifications.html>
    <https://discussions.apple.com/thread/4866269>
     
    Liam O'Connor, Mar 2, 2014
    #9
  10. I consider it fortunate that the FCC has not elected to expand their
    attention into such areas.

    However, the IEEE specs for 802.11b/g/a include minimum receiver
    sensitivities (at different connect rates):
    <http://www.home.agilent.com/agilent...39504&id=339504&nid=-11143.0.00&lc=eng&cc=US>
    No, I'm not going to quote the IEEE specs. Reading those turns my
    brain to mush.

    "IEEE 802.11 Wireless LAN PHY Layer (RF) Operation and Measurement"
    <http://cp.literature.agilent.com/litweb/pdf/5988-5411EN.pdf>
    For receive tests, see Pg 19 thru 23. It's 12 years old but is good
    enough for everything except 802.11n and 40MHz wide channels.
    Yeah, that's about it. None of the antennas provide a spherical
    antenna pattern. They have peaks and nulls making a single number for
    field strength sensitivity useless. For example, were the FCC to
    require a minimum receive field strength sensitivity (in some kind of
    RF absorptive room and fixture), all a manufacturer has to do is
    produce an antenna with a giant peak on one direction, and they will
    probably meet the spec. Try to use that device in another direction,
    and it probably won't even come close to meeting the spec.
    Too bad we don't have control over thresholds and priorities. It
    would be nice to have some control over when the phone switches
    between LTE and Wi-Fi, and when Wi-Fi should look for a better
    connection.
     
    Jeff Liebermann, Mar 2, 2014
    #10
  11. Liam O'Connor

    Guest Guest

    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'
    <http://dontholditwrong.tumblr.com/>
     
    Guest, Mar 2, 2014
    #11
  12. 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?
     
    Liam O'Connor, Mar 2, 2014
    #12
  13. 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)
     
    Liam O'Connor, Mar 2, 2014
    #13
  14. I have the numbers from my test at:
    <http://802.11junk.com/jeffl/cellular/cell-test.htm>
    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:
    <https://www.google.com/#q=iphone+4+dropped+calls&tbs=qdr:m>
    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, Mar 2, 2014
    #14
  15. The 3dB difference in gains between the two bands is pure coincidence.
    It can be anything.
    <http://www.rapidtables.com/convert/power/dBm_to_mW.htm>
    16dBm = 40mw
    17dBm = 50mw
     
    Jeff Liebermann, Mar 2, 2014
    #15
  16. 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.
     
    Liam O'Connor, Mar 2, 2014
    #16
  17. 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:
    <https://itunes.apple.com/us/app/wifi-perf/id458836095>
    <http://wlanbook.com/wifiperf-iperf3-iperf-3-ios-iphone-ipod-touch-ipad-app/>
    Android:
    <https://play.google.com/store/apps/details?id=com.magicandroidapps.iperf>
    PC (Java front end):
    <https://code.google.com/p/xjperf/>
    OS/X
    <http://wlanbook.com/iperf3-mac-os-snow-leopard-lion-iperf/>
    Tutorial:
    <http://openmaniak.com/iperf.php>
    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, Mar 2, 2014
    #17
  18. 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, Mar 2, 2014
    #18
  19. Liam O'Connor

    Lewis Guest

    No you didn't. The iPhone 3G did not work on Verizon. Neither did the
    iPhone 3GS. Neither did the initial iPhone 4.
     
    Lewis, Mar 2, 2014
    #19
  20. Seven years ago, I did this receiver sensitivity chart for various
    wi-fi routers:
    <http://802.11junk.com/jeffl/rx-sens/receiver sensitivity.htm>
    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, Mar 2, 2014
    #20
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