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Kirn Gill (segin)
257 followers -
Geek, futurist, and rationalist.
Geek, futurist, and rationalist.

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Not that it matters a whole lot, but for strict accuracy:

GSM Timing Advance should be in multiples of 553.5m, not 550m.

3GPP TS 45.010 defines the Timing Advance distance as the round-trip distance of light for one Normal Symbol Period, which itself is defined as 48/13 microseconds.

Light travels 1107 metres in 48/13 microseconds, and the round-trip distance is half of that, at 553.5m. 

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Are there any special handling rules for femotcells?

This particular "cell" is a T-Mobile 4G LTE CellSpot device that sits on the living room entertainment center. 
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6/25/17
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LTE network 312-770 is an alias for/MVNO of network 311-480 (Verizon Wireless). I'm recording identical CIDs/sectors/EARFCNs for both network IDs via manual network selection.

Ownership of HNI 312-770 by Verizon Wireless can also be confirmed here: http://www.imsiadmin.com/ByHNIns.cfm

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Does CellMapper log Timing Advance with cell data?

LTE Timing Advance values reported by the 4.2+ CellID API are reconised and also converted to human-readable distances. (See first screenshot.)

However, GSM Timing Advance information is simply shown as an unknown attribute named "GSM_TA", and without human-readable distances (each stepping is roughly 553m)

There should be some way to manually select GSM band for ARFCNs in the range 768-1024, as it seems that BAND_INDICATOR isn't always readable when the ARFCN is. These are GSM 1900 towers, but CellMapper cannot read the BAND_INDICATOR value (probably due to RIL/CellAPI limitations), plus GSM1800 and GSM1900 use the same ARFCN ranges.

As a cheap workaround, you could assume that all GSM towers with MCCs in the range 310-316 have BAND_INDICATOR=1 (ARFCN is for GSM1900.) The same assumption holds true for Canada, as well, in case you are also collecting ARFCNs for GSM networks (when the Android device is capable of reporting it.)


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3/16/17
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yay?
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