Field Test Mode & SpeedTest

Discussion in 'iPhone' started by willmtaylor, Feb 7, 2017.

  1. willmtaylor Suspended

    willmtaylor

    Joined:
    Oct 31, 2009
    Location:
    A Natural State
    #1
    I have a quick question about Field Test Mode and SpeedTest results.

    I have Verizon and always have reliable speeds and good reception where I live/work/play. I never drop calls, never drop off of LTE, and regularly get speeds of 10-30 megs down and 5-10 megs up.

    That being said, I keep my iPhone 7 in Field Test Mode, as I prefer decibel values to arbitrary dots. I've read the values and have read that -40 is about ideal reception, -60 to -80 is good, and that -80 to -120 is bad with anything above that having no reception.

    However, despite having good reception and data speeds, my phone almost always reads numbers of -100 to -115. What gives?

    IMG_8334.PNG
    Worse reception with better speeds (in my basement office).

    IMG_8336.PNG
    Better reception with worse speeds (in a corner classroom).
     
  2. eyoungren macrumors P6

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
    Phoenix • 85037
    #2
    I think you're confusing CDMA strength with LTE.

    -100 is actually pretty good strength. My understanding is that even if you were standing right on top of a LTE tower -80 is near perfect and would be about the best you could get.

    Here's something that may help: http://s4gru.com/index.php?/blog/1/entry-308-rssi-vs-rsrp-a-brief-lte-signal-strength-primer/

    Note that it's Sprint, that the author is reviled by many and that it may be technical. However, despite how much hate the author has garnered over the years he's still an RF expert and a university professor who teaches RF. That's about the limit of the respect I will grant him - he knows what he's talking about when it comes to this stuff.

    Hope that helps you out a bit.
     
  3. willmtaylor thread starter Suspended

    willmtaylor

    Joined:
    Oct 31, 2009
    Location:
    A Natural State
    #3
    Thanks. I'll check that out when I get the chance.
     
  4. eyoungren macrumors P6

    eyoungren

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    #4
    No problem. It's basically just an overview so not too long a read.
     
  5. willmtaylor thread starter Suspended

    willmtaylor

    Joined:
    Oct 31, 2009
    Location:
    A Natural State
    #5
    @eyoungren , are you saying that field test decibels only show cellular reception (CDMA) and Speed Test is only showing data speeds (LTE), so it's two different units of measure?
     
  6. eyoungren, Feb 7, 2017
    Last edited: Feb 7, 2017

    eyoungren macrumors P6

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
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    #6
    No, I am saying that your understanding of signal strength may be more relevant to CDMA signal strength. The difference between RSSI and RSRP as mentioned in the article.

    You have to understand that 3G (Verizon/Sprint) is CDMA while LTE is a GSM technology. They have two different units of measure.

    It's like saying something is 3 meters tall when you meant 3 feet. Entirely different units of measure.
    --- Post Merged, Feb 7, 2017 ---
    You also want to look at your ping time. You can have weaker signal but a faster ping and thus a faster connection. Ping is determining how quickly your signal is getting back and forth. The dbm is just a measure of how strong the signal is.
     
  7. jpiszcz macrumors regular

    Joined:
    Mar 28, 2010
    #7
    Great read! Have you come across anything like this for HSPA/UMTS?
     
  8. eyoungren macrumors P6

    eyoungren

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    Aug 31, 2011
    Location:
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    #8
    No, but I haven't ever looked. I was with Sprint for 16 years so there was never any interest on my part in that area just because CDMA was all I knew about (but not in any depth).
     
  9. M. Gustave macrumors 68000

    M. Gustave

    Joined:
    Jun 6, 2015
    Location:
    Grand Budapest Hotel
    #9
    Look at your two screenshots: two different cell tower hosts. That can radically change your up/down speeds.

    The tower choice is manually configurable in the app, FYI.
     

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