Category Archives: Cell Phones

Updated Signal Check Database

Hello everyone, here’s an updated Signal Check Pro database dump covering Sprint towers.

Mostly Complete
Linn County, Johnson County

Partially Complete
Cedar County, Butler County, Muscatine County, Mercer County (IL)

Please feel free to email me with your own updates to the database, if you identify sites I’ve not yet captured, please do send me an email with the information and I will get it added to the next database update! Continue reading

RTL-SDR Based LTE Signal Analyzer

Have you ever wanted to detect what network is installed at what tower? screenshot_01Interested to see how a network upgrade or overlay is progressing?  Or, maybe you are interested in getting a better idea of the relative signal strength of multiple LTE networks, with a passive receiver?  If so, this is the blog post for you.

This post will explain how to build a custom application for the Kali Linux system which will allow you to use a RTL-SDR DVB TV tuner chipset to perform spectrum analyzer functions on LTE signals.  Using the E4000 chipset, I have decoded LTE signals in 700MHz, 800MHz, 1900MHz (PCS) and 2300MHz (AWS) frequencies. Continue reading

Cell Phone Network Analysis With the Nexus 5

The Nexus 5 may have been discontinued by Google but the phone still packs a powerful punch for those interested in analyzing the cell network they are connected to.  This blog post is the first in a series of posts explaining how to better understand the cellular network.

Screenshot_2015-04-30-13-31-46To properly review the network information, you will need to purchase the app Signal Check Pro.  The pro version contains many logging features, which will make exploring the network much easier.

Signal Check Pro, when launched, will display information such as what is displayed on the left.  Depending on the network you are connected to, you may see various different pieces of data.  In this example, I am connected to the Sprint LTE network, running on Band 25 (1900MHz)

The signal strength bar graph at the top is self explanatory, and the RSRP and RSRQ are signal strength indicators.  Each panel (or directional antenna) will have a unique GCI to identify the panel, however Sprint conventionally assigns all panels on a specific tower the same first 6 hexadecimal numbers.  For instance, in the example to the left, the Coralville water tower, all the panels will share the same beginning GCI of 08A067xx.  Each panel will have a PCI ID as well, but these may not be unique with some PCIs being repeated.  The TAC represents a regional code shared among all sites within a geographic area. Continue reading

Identification of CDMA2000, GSM, and LTE signals with SDR# and RTL SDR

So, you’re interested in seeing just what carriers are at that cell tower by your house.  Or maybe you’re interested in trying to determine the best location in your home for mobile reception.  There are many reasons why it might be useful to peek at the cellular, PCS, and AWS signals that make up our day to day communications network.  Unfortunately, the FCC does not maintain a database of all cellular and PCS transmitters and their locations.

However With the RTL-SDR, for $30 and open so

urce software, you can tune the frequency ranges for each carrier and see a graphic deception of the types of signals found.  Using this graphical depiction you can identify the type of signal (CDMA, GSM or LTE) and combined with looking up what block of frequencies it is in and who owns that block in this market, you can identify the carrier.

Continue reading