Archive for September, 2012

How to Switch from Bars to Numerical Signal Level on iOS without Jailbreaking

I’ve made a habit of only ever looking at signal level in numerics on iOS since the iPhone 3GS days. This has paid off a few times in the past (notably the iPhone 4 antenna situation) but in general just gives a better perspective for network conditions. I regularly post screenshots with both cellular and WiFi in numerics instead of the default bars, and on iOS this is pretty simple to make happen, at least to the cellular signal level indicator, without jailbreaking.

To do this the basic workflow is to enter FieldTest.app, then force quit the application. When FieldTest launches, it changes a .plist file for springboard which controls whether numerics are being shown for cellular signal. This is exactly the file that SBSettings tweaks if you’re toggling “Numeric GSM” and “Numeric WiFi.” I should note that these settings also stay around across iOS restores. Anyhow a lot of people have been asking on Twitter lately for some reason how to make this happen, so I thought I’d write it up.

  
Dialer for FieldTest (left), FieldTest.app (right)

Anyhow to show cellular signal without using SBSettings:

  1. Launch FieldTest.app by going into the dialer and dialing *3001#12345#*
  2. Hold down standby/lock like you’re going to turn the phone off
  3. Release standby/lock after the power off slider appears, then hold home (this is force quit on iOS – it’s impressive so few people know it)
  4. Boom, you have numerics instead of bars

This can now be tapped to switch back and forth. Launching FieldTest again and quitting will restore the file however, so every time you quit this will have to be a force quit to preserve the setting without jailbreaking or restoring an iOS backup with the plist file set how you want it.

I should also note that on LTE this number is RSRP (Reference Signal Received Power) in units of dBm. On WCDMA this is RSCP (Received Signal Code Power) in dBm, and on CDMA2000 1x/EVDO this is RSSI I believe (or EC, I haven’t ever carried a CDMA2000 iPhone for an apreciable amount of time). On WCDMA and 1x/EVDO values between -50 and -113 dBm are typical, with -50 being at cell center and -113 dBm being at cell edge. On LTE because the iDevice is showing RSRP, values between -75 and -120 dBm are typical, with RSRP showing ~20 dB lower than the analogous RSCP/WCDMA-land signal if you’re trying to compare.

Update/Note: In iOS 7 the signal bars were changed to dots, but the trick still works. Although switching into numerals by force quitting Field Test still works, sometimes it takes a few tries before it works. I’m not sure why that is, but keep force quitting or try quitting and coming back and force quitting again and eventually you’ll switch over.

AT&T 4G LTE in Tucson, AZ – Coming Before End of 2012

It has been what seems like an eternity since I wrote a bit about Verizon 4G LTE coming to Tucson, AZ. Since then, the network has been deployed and working just fine, and made it into my mental take-it-for-granted state. Since then, Cricket has lit up their own LTE network on AWS (1700/2100 MHz), and next up is AT&T who just recently announced details about their LTE deployment for a bunch of markets before the end of this calendar year. I wrote about the AT&T LTE news at a high level at AnandTech, and the announcement comes a not-so-coincidentally timed week before the next iPhone announcement in an attempt to prevent lots and lots of LTE related churn.

I’m burying the lead a bit, but before the end of 2012 AT&T will have LTE finally lit up in my part of the world. There’s a relevant press release here which is relatively light on detail – there’s no outline for what parts of town will get LTE, whether it will include surrounding areas, or any further detail. I guess we can only hope that they mean the greater metro area. I’ve asked a few of my sources for a better timeline, but can only say that before December LTE should be lit up.

I hope it goes without saying, but LTE (3GPP Long Term Evolution) is completely different from the earlier announcements AT&T made about “4G” coming to Tucson in May 2011. That was really just deployment of HSPA+ with up to 16QAM on the downlink (HSDPA 14.4) and some additional WCDMA carriers for capacity reasons. I’m pretty pleased with the state of AT&T WCDMA in town, I see around 2-3 carriers on PCS (1900 MHz) around town and what I consider very good peak speeds.

AT&T Spectrum Holdings in Pima County (As of Sept. 7 2012)

Since AT&T LTE doesn’t use the same channel bandwidth everywhere, it’s worth noting that in this particular market (Pima County), AT&T can run 10 MHz FDD-LTE on Band 17, (Lower 700 MHz B+C blocks) and 5 MHz FDD-LTE on AWS (1700/2100) when the time arises. I haven’t seen AT&T enable any LTE on AWS quite yet, this is likely coming at some future date after the rollout is closer to completion or as a way to mitigate loading in the future.