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Thread: Identifying cell sites with CellMapper

  1. #1
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    Identifying cell sites with CellMapper

    DISCLAIMER: This is an enthusiast post - not a promotional post. I am not posting this at the request of any app developer nor am I being compensated in any way for this post.

    Many mobile enthusiasts such as myself are interested in knowing the locations of wireless tower sites and if a given provider is on a particular tower. Apps like OpenSignal that claim to show cell locations are often woefully inaccurate. In the past, it was possible to estimate or identify the location of a cell site on AT&T's coverage maps by looking at the center of the darkest orange coverage, but they have more recently removed that helpful data and now show their maps as having service in areas where one might only be able to actually have service there with an external antenna. RootMetrics also used to be helpful for identifying cell sites, but no longer as their system now shows 'green' in any area where a voice call should be reliable, which means most areas show in green. Sensorly is helpful, at least as helpful as AT&T's maps used to be, in that the darkest green or purple is the best signal area and probably near a tower. However, it requires an area to be well mapped in order to have any success at actually identifying cell locations.

    Enter CellMapper. While like Sensorly it requires an area to be well mapped -- highways plus side streets for depth, and street level driving through cities and neighborhoods to actually show true coverage patterns -- it is still possible to quickly use CellMapper to determine if a particular carrier such as AT&T is on a tower. So if you want to know if AT&T, for example, is on a given tower, fire up CellMapper, set it to record data every 1-2 seconds, and then drive/walk/bike around a tower. (The actual proximity to the tower/cell site for accuracy varies depending on the area -- in a rural area, within a mile or two might actually be sufficient. In suburban neighborhoods, a few blocks is good. In dense urban areas, block by block is good. In sports stadiums, even a distance of yards may matter.) But anyway, circle the cell site and then wait a few minutes and look at the collected data. If you have successfully identified and surrounded the cell tower, you should see 3 sectors mapped with the estimated cell site location somewhere in between. If you only get 1 or 2 sectors, keep trying -- you didn't get all the way around the tower so it is probably a site other than the one you thought.

    Now, some helpful info in identifying towers/cell sites by sector (for LTE).
    As a *general* rule, sector 1 is north/northeast facing, sector 2 is southeast/south facing, and sector 3 is southwest/west facing. Sectors 1-3 are Band 5, or 850 MHz.
    Other common ranges include:
    Sectors 15-17, Band 17, 700 MHz. (15 = north/northeast, 16 = southeast/south, 17 = southwest/west).
    Sectors 8-10, Band 2, 1900 MHz. (8 = north/northeast, ETC.)
    Sectors 22-24, Band 4, 1700/2100 MHz.

    So if you detect sectors 16 and 17 but not 15, chances are the tower is to the north of your location.
    15 and 17, the tower is probably to your east or south. 15 and 16, the tower is probably to your west. (And so on with other corresponding sector patterns; 1=8=15=22, 2=9=16=23, and 3=10=17=24.

    Cell IDs for LTE on AT&T are six digits, with the first two digits being a region code and the last four being the cell site, with the sector identified separately. For HSPA/HSPA+, the region code is not shown (though can still be identified by Location Area Code) and the first four digits are the cell site with the last digit the sector. HSPA and LTE cell site IDs do typically correspond; e.g. 242206 on LTE = 22061, 22062, and 22063 on HSPA and GSM. The first two digits of the HSPA Location Area Code correspond with the first two digits of the LTE cell eNB ID.

    Happy mapping and I hope this is helpful for those who are trying to identify where a particular cell signal. Many areas are still very sparsely mapped on CellMapper, but if more people start using it regularly that many more areas will be mapped and identified. And lastly, it is Android only - sorry, iPhone users, but Apple has restricted too much of the technical data for iPhones to be useful in cell mapping.

    Post with any questions, and again, I'm just an enthusiast and not connected in any way with development of CellMapper and have not received (and will not receive) any compensation for this post.

    Download link from Google Play: https://play.google.com/store/apps/d...net.cellmapper
    Last edited by joelwnelson; 12-23-2014 at 07:05 PM.

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    I use it in combination with Sensorly as I do prefer their maps visually and speed wise. But then the cell mapper shows more data. Wish they would show the LTE GCI in hex as that's what most other things use.

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    I have covered many in SoCal
    AT&T... your world, throttled.

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    Quote Originally Posted by digiblur View Post
    I use it in combination with Sensorly as I do prefer their maps visually and speed wise. But then the cell mapper shows more data. Wish they would show the LTE GCI in hex as that's what most other things use.
    I'll get in contact with Ivan and see what I can do to get that added.

    I've mapped extensively around Erie, PA, and have mapped quite a bit from Chicago, IL all the way up into Upstate NY, Philadelphia, PA, Washington, DC, West Virginia, Ohio, and parts of Indiana. I previously traveled a LOT for work being a contractor, but I've got a 9-5 in Chicago now.

    If anyone else has any suggestions for CellMapper, let me know, and I'll pass them along to the developer.

    Sent from my Nexus 6 using Tapatalk

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    Sigh... One of the few pitfalls of being an iPhone user 😒

    I guess I'll have to wait for the day to get a Android phone to use in tandem.

    Too much trouble at present, but I'll benefit from the info you guys are putting out there via you Android devices... so thanks!!!




    Thank You John Legere!!!
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    Great find. I'll put forth the mapping for Staten Island/NYC, which is rather short on info.

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    Quote Originally Posted by unforgiven512 View Post
    I'll get in contact with Ivan and see what I can do to get that added.

    I've mapped extensively around Erie, PA, and have mapped quite a bit from Chicago, IL all the way up into Upstate NY, Philadelphia, PA, Washington, DC, West Virginia, Ohio, and parts of Indiana. I previously traveled a LOT for work being a contractor, but I've got a 9-5 in Chicago now.

    If anyone else has any suggestions for CellMapper, let me know, and I'll pass them along to the developer.

    Sent from my Nexus 6 using Tapatalk
    Another thing that might help the dev is AT&T will sometimes use the same site ID but incremented by 4000. Look at several I mapped around Baton Rouge, LA. For example 181035 and 185035 are the same site just either a different band or sector. Not sure why they do that at times. But it messes up the cellmapper triangulation formula.

    Been mapping a good bit with it though as I have mapped just about all of my major roads on Sensorly already. It does a pretty decent job at pin pointing the sites once you circle the site and it has enough data to figure it out.

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    Quote Originally Posted by digiblur View Post
    Another thing that might help the dev is AT&T will sometimes use the same site ID but incremented by 4000. Look at several I mapped around Baton Rouge, LA. For example 181035 and 185035 are the same site just either a different band or sector. Not sure why they do that at times. But it messes up the cellmapper triangulation formula.
    Interesting! I have never seen that on LTE before, but have seen that with HSPA sites though off by 3000 (e.g. 22061, 52061). Although now that I think about it, I have seen some small cells with IDs 200 apart. E.g. 240510 and 240710 which seem to be the same site but band 17 vs band 4.

    Is that sector always off by 4000 from the rest of the site or does it vary from time to time? If that one sector is consistently off, I wonder if it has to do with the hex cell ID programmed at the base -- if an engineer set it wrong.

    I've mapped a lot of LTE between St. Louis, MO and Lincoln, NE since installing the app this spring. Plus some in Boulder, Colorado as well in the spring. I typically run Sensorly and CellMapper concurrently as well as Rootmetrics in the background when travelling.

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    Quote Originally Posted by joelwnelson View Post
    Interesting! I have never seen that on LTE before, but have seen that with HSPA sites though off by 3000 (e.g. 22061, 52061). Although now that I think about it, I have seen some small cells with IDs 200 apart. E.g. 240510 and 240710 which seem to be the same site but band 17 vs band 4.

    Is that sector always off by 4000 from the rest of the site or does it vary from time to time? If that one sector is consistently off, I wonder if it has to do with the hex cell ID programmed at the base -- if an engineer set it wrong.

    I've mapped a lot of LTE between St. Louis, MO and Lincoln, NE since installing the app this spring. Plus some in Boulder, Colorado as well in the spring. I typically run Sensorly and CellMapper concurrently as well as Rootmetrics in the background when travelling.
    The site has a 2nd ID for the 4th and 5th HSPA channels. They must get confused at times and use it for some LTE sectors. They did it all the time during the first band 4 overlay here but they have fixed some of them when they added the band 2 overlay but then some of them they switched the band 17 ID as well. No rhyme or reason.

    I've been seeing some weird sector numbers that don't fit any of my band range identifications but I haven't been able to snag a debug screen in time since I notice the odd GCI later in the day in my logs.

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    Quote Originally Posted by unforgiven512 View Post
    I'll get in contact with Ivan and see what I can do to get that added.

    I've mapped extensively around Erie, PA, and have mapped quite a bit from Chicago, IL all the way up into Upstate NY, Philadelphia, PA, Washington, DC, West Virginia, Ohio, and parts of Indiana. I previously traveled a LOT for work being a contractor, but I've got a 9-5 in Chicago now.

    If anyone else has any suggestions for CellMapper, let me know, and I'll pass them along to the developer.

    Sent from my Nexus 6 using Tapatalk
    Here's another idea. Let us filter the map by LTE band.

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    Quote Originally Posted by digiblur View Post
    Another thing that might help the dev is AT&T will sometimes use the same site ID but incremented by 4000. Look at several I mapped around Baton Rouge, LA. For example 181035 and 185035 are the same site just either a different band or sector. Not sure why they do that at times. But it messes up the cellmapper triangulation formula.

    Been mapping a good bit with it though as I have mapped just about all of my major roads on Sensorly already. It does a pretty decent job at pin pointing the sites once you circle the site and it has enough data to figure it out.
    I've seen that extensively here in Chicagoland, but not a constant offset. If cellid= 210398, it'll be 219398. If it's 211888, it'll be 219888. It follows the same pattern -- typically a different band or sector. No real pattern. I've noticed them getting reset to the "main" GCI with the band 2 overlay that's ongoing here. I've been chatting with Ivan about a "related sites" concept, that would alleviate this issue.

    Quote Originally Posted by joelwnelson View Post
    Interesting! I have never seen that on LTE before, but have seen that with HSPA sites though off by 3000 (e.g. 22061, 52061). Although now that I think about it, I have seen some small cells with IDs 200 apart. E.g. 240510 and 240710 which seem to be the same site but band 17 vs band 4.

    Is that sector always off by 4000 from the rest of the site or does it vary from time to time? If that one sector is consistently off, I wonder if it has to do with the hex cell ID programmed at the base -- if an engineer set it wrong.

    I've mapped a lot of LTE between St. Louis, MO and Lincoln, NE since installing the app this spring. Plus some in Boulder, Colorado as well in the spring. I typically run Sensorly and CellMapper concurrently as well as Rootmetrics in the background when travelling.
    I haven't really paid much attention to UMTS here in Chicagoland, but the small cells that AT&T deployed along the local rail lines use LTE GCI xx3yyy, with decimal sectors 42 (band 17) and 49 (band 4). Haven't seen band 2 on one, yet. The urban cells (DAS?) seem to be xx4yyy.

    Quote Originally Posted by digiblur View Post
    The site has a 2nd ID for the 4th and 5th HSPA channels. They must get confused at times and use it for some LTE sectors. They did it all the time during the first band 4 overlay here but they have fixed some of them when they added the band 2 overlay but then some of them they switched the band 17 ID as well. No rhyme or reason.

    I've been seeing some weird sector numbers that don't fit any of my band range identifications but I haven't been able to snag a debug screen in time since I notice the odd GCI later in the day in my logs.
    You saw my list of sector IDs, right? Have you seen anything that doesn't fall in those ranges?
    • 1-2-3 | 01-02-03 | band 5
    • 8-9-10 | 08-09-0a | band 2
    • 15-16-17 | 0f-10-11| band 17
    • 22-23-24 | 16-17-18 | band 4
    • 42 | 2a | band 17 outdoor small cell
    • 49 | 31 | band 4 outdoor small cell
    • 100-101-102 | 64-65-66 | band 17 urban cell (DAS?)
    • 107-108-109 | 6b-6c-6d | band 4 urban cell (DAS?)
    • 132-133-134 | 84-85-86 | band 17 small cell (indoor/underground)
    • 139-140-141 | 8b-8c-8d | band 4 small cell (indoor/underground)


    I've recently spotted a sector 43 and 50. Imagining these are also outdoor small cells on band 17/band 4, have to return to confirm.

    Quote Originally Posted by digiblur View Post
    Here's another idea. Let us filter the map by LTE band.
    That's another concept we've been talking about. One thing that currently has us confused is T-Mobile's inconsistency with band 12. Some sites are using 4-5-6, others are using 21-22-23. This is a big issue, because T-Mobile has many 4 sector sites out there, that are using 1-2-3-4 on AWS, so it's hard to distinguish. 21-22-23 makes sense, as band 2 is 11-12-13 =/

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    Quote Originally Posted by unforgiven512 View Post
    You saw my list of sector IDs, right? Have you seen anything that doesn't fall in those ranges?
    • 1-2-3 | 01-02-03 | band 5
    • 8-9-10 | 08-09-0a | band 2
    • 15-16-17 | 0f-10-11| band 17
    • 22-23-24 | 16-17-18 | band 4
    • 42 | 2a | band 17 outdoor small cell
    • 49 | 31 | band 4 outdoor small cell
    • 100-101-102 | 64-65-66 | band 17 urban cell (DAS?)
    • 107-108-109 | 6b-6c-6d | band 4 urban cell (DAS?)
    • 132-133-134 | 84-85-86 | band 17 small cell (indoor/underground)
    • 139-140-141 | 8b-8c-8d | band 4 small cell (indoor/underground)
    Yes, I've seen your list before. The mystery cells I've logged are:

    02C4AD8E - Possibly the LSU Stadium DAS. That's 142 in decimal which falls in after your band 4 small cell range.
    0CCD2ED8 - 216 decimal. Unknown but I did notice and band 4 DAS in New Orleans starts with 0CC.
    0CCD1857 - 87 decimal. Also unknown

    I can confirm that 64,65,66 HEX range for Band 17 urban DAS as that's what they use in the French Quarter on these little stealth poles on the side walks.

    Maybe the dev can do the band filter on the carriers that seem to be following specific patterns for now?

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    I got sectors 124, 125 and 126 in Busch Stadium in St. Louis, MO this past summer -- sites 240702 and 240703. As with the numbering at Faurot Field in Columbia, MO, there seem to be two ID sets -- 2407xx and 2405xx. The 2405xx is Band 17 and uses 132,133,134 sector IDs, but whereas in Columbia the 2407xx is Band 4 using sectors 107, 108, 109 in St. Louis it is different. I assume it is band 2 or 5, but I have otherwise only ever seen Band 17 in use in St. Louis.

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    Quote Originally Posted by Wide_opeN View Post
    Sigh... One of the few pitfalls of being an iPhone user 

    I guess I'll have to wait for the day to get a Android phone to use in tandem.

    Too much trouble at present, but I'll benefit from the info you guys are putting out there via you Android devices... so thanks!!!




    Thank You John Legere!!!
    You drive expensive cars, surely you can afford an Android phone for testing

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