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Re: Field Test mode is back in iOS 4.1

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Field Test mode is back in iOS 4.1

Sort of- iOS 4 removed access to the somewhat useful 'field test' mode for the iPhone. iOS 4.1 restores it, but only the signal-strengh meter portion, which is good enough to do things like test for signal issues with the mcell without using the ever-vague metric of 'bars'. 

 

To access it, dial *3001#12345#* and 'call'.

 

Your 'bars' will change to a dB meter... hitting the 'home' button gets you out and resets the signal strength to bars. 

 

Strictly speaking, a signal/noise meter would be more useful, due to the nature of the signals we're talking about here, but heck, dB are better than nothing. 

 

Enjoy...

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Message 1 of 10
Mentor

Re: Field Test mode is back in iOS 4.1

FYI, the signal that is displayed and is used to calculate the "bars" is based on the formula of:

Adjusted Signal Level = Received Signal - (EC/N0)

 

EC/N0 is not strictly a measurement of SNR, but rather measures anything that is not signal useful to your handset, ie: data transmitted by other cell phones is not "noise", but is counted in EC/N0, as well as noise from your microwave oven.

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Guru

Re: Field Test mode is back in iOS 4.1

Is there a field test mode that shows you what band the iPhone is operating on?  I'd be curious to know if one of both our MicroCells  are on 850 or 1900 MHz.

Message 3 of 10
Mentor

Re: Field Test mode is back in iOS 4.1

 


@jefe wrote:

Is there a field test mode that shows you what band the iPhone is operating on?  I'd be curious to know if one of both our MicroCells  are on 850 or 1900 MHz.


 

If you are using an iPhone with 3.x, the fieldtest will show your UARFCN (channel number).

If you are using an iPhone with 4.x, you can jailbreak your phone and either copy the fieldtest app and configuration plists from a 3.x device to the 4.x device, or install the "Signal" application from the Cydia store to get this information.

 

You can compare the UARFCN to the list here:

http://en.wikipedia.org/wiki/UMTS_frequency_bands

 

My device in Miami Beach, FL is on the 850Mhz band, specifically on channel 4457 downlink, and 4232 uplink, which is one channel below the highest channel numbers for both the uplink and the downlink (I assume they are leaving the last channel available as a unused separation to minimize interference, and they are keeping this far away from their macrocell channels which are much lower in the 850Mhz band).

Message 4 of 10
Guru

Re: Field Test mode is back in iOS 4.1


@winterfl wrote:

 


@jefe wrote:

Is there a field test mode that shows you what band the iPhone is operating on?  I'd be curious to know if one of both our MicroCells  are on 850 or 1900 MHz.


 

If you are using an iPhone with 3.x, the fieldtest will show your UARFCN (channel number).

If you are using an iPhone with 4.x, you can jailbreak your phone and either copy the fieldtest app and configuration plists from a 3.x device to the 4.x device, or install the "Signal" application from the Cydia store to get this information.

 

You can compare the UARFCN to the list here:

http://en.wikipedia.org/wiki/UMTS_frequency_bands

 

My device in Miami Beach, FL is on the 850Mhz band, specifically on channel 4457 downlink, and 4232 uplink, which is one channel below the highest channel numbers for both the uplink and the downlink (I assume they are leaving the last channel available as a unused separation to minimize interference, and they are keeping this far away from their macrocell channels which are much lower in the 850Mhz band).


The only iPhone I have access to is my wife's 3GS.  I installed iOS 4.1 on it for her yesterday but there's no way I'd ever jailbreak it for several reasons.

 

I looked for the Signal app, including on the Cydia store, and couldn't find it.   I found some references to it but not the app itself.  Will it function on a non-jailbroken 3GS running iOS 4.1?  If so, where can I get it and what's involved installing it?

 

I'm familar with the UMTS bands.  I'd like to know if mine, like yours on on 850 or if I'm on 1900. 

 

Thanks for the info.

Message 5 of 10
Mentor

Re: Field Test mode is back in iOS 4.1

If you have Cydia, it should be really easy to find.  It's not in the Apple App Store, and never will be, as it violates Apple's App Store rules.

Message 6 of 10
Guru

Re: Field Test mode is back in iOS 4.1

Apparently the Cydia apps are specifically for jailbroken phones.  I'm not jailbreaking so I guess I'll still be looking for a way to find out what band my MicroCells are using.

 

Thanks again.

Message 7 of 10
Teacher

Re: Field Test mode is back in iOS 4.1

i'm pretty sure i read that iphones are restricted to using 900mhz only.

Message 8 of 10
Mentor

Re: Field Test mode is back in iOS 4.1

 


@umkcdds wrote:

i'm pretty sure i read that iphones are restricted to using 900mhz only.


I have no idea where you read that, but the phone is Quad band GSM 850/900/1800/1900 and Pentaband UMTS (not sure of all the bands off the top of my head, but I think it's 800/850/900/1900/2100)

 

Message 9 of 10
Guru

Re: Field Test mode is back in iOS 4.1


@umkcdds wrote:

i'm pretty sure i read that iphones are restricted to using 900mhz only.


Well, in the US, 900 MHz isn't even a cell phone band. 902-928 MHz is, in fact, an Amateur (at least on a co-secondary basis) and part 15 band. You may be thinking 800 MHz, but as someone else already said, the iPhone can function on multiple bands.

 

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