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Testing and Mapping a Cellular Data Network? 114

Posted by kdawson
from the circles-and-arrows-on-the-back-of-each-one dept.
bgsneeze writes "In order to resolve an ongoing issue with a vendor, I have been trying to find a way to test different 3G data devices empirically. I would like to be able to chart signal strength, latency, and bandwidth. I would also like to create a map of the coverage area. I have a test 3G card from three different providers. I would like to be able to travel with the setup to several different locations and run tests. What software or techniques would Slashdotters use to test the different devices? Are there any free or open source software packages that will do this?"
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Testing and Mapping a Cellular Data Network?

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  • 3G (Score:1, Interesting)

    TFS:

    ...I have a test 3G card from three different providers...

    Do you mean a 3G SIM for use in mobile devices?

    If you mean the USB/PC card 3G adapters for computers, I doubt you'll be able to run them on Linux without using WINE or a VM or whatever, which may interfere with latency readings. Those adapters require you to install software(ATT Connection manager in their case) that's only supported on Windows and Mac, and that software is required to "authenticate" your computer and use the network.

    Anec

    • by trapnest (1608791)
      Most of the cell modems are made by Sierra Wireless and they've been pretty good about making sure things work in linux, at least in my experience. I've got a 598 USB Sierra card from sprint and it works fine as a backup connection for my headless Arch server.
      • Even without Linux, it should be pretty trivial to whip up an app on Windows to track signal strength. I'd install the drivers and check if any new COM interfaces appear or .NET components for interacting with the software. If so, I bet finding out the current connection status would be pretty easy.

        As far as actual throughput, there's a lot of software out there for that - even on Windows. You could also use native Windows logging facilities to track network packet rates, Mbps, whatever you want to.

    • by brentrad (1013501)
      My work's Verizon USB 3G dongle installed in Windows 7 on my laptop automatically without needing a driver disc (I think it automatically downloaded an up-to-date driver from Windows Update when I plugged it in) and worked without installing the Verizon connection manager. It made a dial-up-networking connection automatically, and I entered #77 or something like that as the phone number - you can find out the parameters to enter with a quick google search. You can install the connection manager but it's n
      • by ysth (1368415)
        Gah. I read "My work's Verizon USB 3G dongle installed Windows 7 on my laptop automatically" and thought, now that's an aggressive IT department.
    • Re:3G (Score:4, Interesting)

      by phantomfive (622387) on Monday May 17, 2010 @10:43PM (#32248330) Journal

      If you mean the USB/PC card 3G adapters for computers, I doubt you'll be able to run them on Linux without using WINE or a VM or whatever, which may interfere with latency readings...........Note: too lazy to dig up hacks and testamonials from Google.

      Sigh.......this is the kind of misconception that happens when you are too lazy to use Google. Those USB/PC card 3G adapters for computers work quite well on Linux, here is one example tutorial [wordpress.com]. Try not to give advice if you are too lazy to verify it.

      • Re: (Score:3, Informative)

        by fandingo (1541045)

        Dan Williams, the guy behind Network Manager, does a lot of work to get cellular modems working in Linux. There seems to be lots working and steady process on others.
        His blog http://blogs.gnome.org/dcbw/ [gnome.org] is informative and frankly pretty hilarious in a geeky way.

        Props to Dan for doing a great job.

        • by Cato (8296)

          As well as Network Manager, I'd recommend umtsmon and wvdial for USB 3G modems - the former tracks your data usage, the latter is just a standard PPP dialler that can be put into scripts.

    • Anecdote: I had ATT 3G in the metro San Diego area around 2007. Speeds and coverage were decent enough to browse the web, but too spotty for anything hardcore.

      There's nothing wrong with that. Softcore on the bus is cool, but people always bitch at me when I'm watching hardcore.

      Protip: Use headphones and sit in the back.

    • Re: (Score:2, Interesting)

      by Neil_Brown (1568845)

      Those adapters require you to install software(ATT Connection manager in their case) that's only supported on Windows and Mac, and that software is required to "authenticate" your computer and use the network.

      (Disclaimer - I work for Vodafone, albeit as a lawyer)

      I have never tried with one of the PCMIA cards, but, most Huawei modems will work fine under Linux - you might need usb-modeswitch to flip it into modem mode (as opposed to mass storage mode), but, otherwise, it should not be a problem.

      If u

    • by jimicus (737525)

      You'd better tell my employer. They think that the USB 3G units they're using for a Linux embedded device work just fine, thanks.

  • by Anonymous Coward

    Obviously this can only be used for terrorism.

    • Back in 2001/2002 I was doing drive testing for US Cellular. One day we were cruising through some random suburb of northern Illinois. My driver that day was an Iranian American. Nice guy, but not the usual bleached white skin tones folks are used to seeing in such a location. Someone called us in to the police as possible terror suspects, driving the neighborhood around with "computer equipment".

      So we got pulled over by a fleet of police. Took about 5 seconds for them to realise what we were doing and we w

  • by Anonymous Coward

    http://www.cellularmaps.com/coverage_finder.shtml

    • by bughunter (10093) <bughunter&earthlink,net> on Monday May 17, 2010 @10:09PM (#32248082) Journal

      These are simply links to the coverage maps advertised by the providers, in which service quality is frequently exaggerated, if not blatantly false.

      For example, AT&T (my provider) claims "good" coverage in two neighborhoods in my home town, Pasadena, where I know for a fact that there is no coverage, or worse, sporadic one-bar-then-no-bar coverage that drains my cellphone battery in an hour. And even worse, they show "best" coverage throughout San Marino, a town in which I can never make or receive calls on AT&T.

      • by xixax (44677)

        The data is outright modelled and cannot take into account a bunch of factors that limit the actual signal strength. I had a somewhat heated discussion with a saleperson who was convinced that their telco had actually sent someone with a meter to measure the reception at 100 metre intervals across some wild and rugged terrain. It would be funny to take some samples and quantiatively demonstrate the exaggeration in each provider's coverage maps, the tabloid media would lap up the right analysis.

        Xix.

      • by sjames (1099)

        Typical of marketing. If one person once managed to make a call, the coverage is "good". If it wasn't dropped in the middle of "hello", it's "excellent".

  • by mtmra70 (964928) on Monday May 17, 2010 @09:50PM (#32247932)

    http://www.mytruecoverage.com/ [mytruecoverage.com] is a good site to show coverage. You can install an app on your phone then manually run tests. The results usually take 12-36 hours to post to the website.

  • I assume that you are not working with a network operator? They have plenty of tools to do drives and plot out signal. Also, chip makers have these tools. I used to work for a large mobile phone chip maker and we had internal test setups that can be driven around in a car to plot signal, etc. Also, we developed a small device FPGA based device that could be tuned to various channels and recover the "sync" and "paging" channels of a CDMA system. You could do the same for UMTS, EVDO, etc. If you just wanted
    • I assume that you are not working with a network operator?

      It looks like he is trying to independently verify/disprove his cell provider's claims. They are about as likely to send a network engineer to evaluate his situation as BP is likely to send a scientist to evaluate the situation at the bottom of the Mexican Gulf.

      • I meant in a more cooperative sense. If he is working for a provider of services to say, Verizon, then he might be able to at least get access to some VZ tools. For example, back a while ago I was working with some of the FloTV people (they provide VZ and ATT mobile TV), and we did independent verification of signal and picture quality, but we had help from the network people. The other problem he would run into without assistance is figuring out where towers are. Most providers don't publicly give out ne
  • by TheOddOne (208550) on Monday May 17, 2010 @09:56PM (#32247980)

    Empirical testing with wireless CELLULAR networks can be very tricky; A few things that you will need to keep in mind is that for testing, you want to make sure your transceiver setup is perfectly reproducable; Same card, same ANTENNA, same position of antenna. When performing your testing, your signal strength will depend on several factors: Distance from the site, antenna type/gain, and specifically what sector/node on the site you happen to be on. while driving in a straight line, you may find that you approach steep nulls near the border of a cells sector boundary. Alot depends on the ability of your particular card to handle the handoff between sectors/sites.

      Your latency measurements will also vary according to the individual usage of the sector/site that you are currently on, and additionally vary with time and also variable bandwidth allocation to the sites from the main switch.

    There are quite a few test sets and software suited that are commercially available and are tailored for this use, and are used heavily by the mobile data/cellular industry in their drive testing and coverage verification methodologies.

    Good luck to you on your testing.

    --ToO

    • Re: (Score:3, Informative)

      by adolf (21054)

      Please mod parent up: He's completely correct, and his simple methodology is a good example of best practices.

      However, there are more impromptu ways to accomplish similar feats:

      One obvious possibility is the test mode built into many (perhaps all) cell phone handsets. These will typically display a number of different datapoints, such as signal strength and error rate. If the asker is troubleshooting only troubleshooting GSM or CDMA (so that switching carriers does not necessarily entail switching radios

  • One idea (Score:3, Funny)

    by TubeSteak (669689) on Monday May 17, 2010 @09:57PM (#32247994) Journal

    What software or techniques would Slashdotters use to test the different devices? Are there any free or open source software packages that will do this?

    I would suggest the "grad student technique".
    Find a nearby university and convince a professor to lend some (under)grad students to your cause.
    It helps if you have friends that can refer you to professors/students who'd be interested in the challenge.

    P.S. The only thing better than the "grad student technique" is the "summer intern technique"

  • Many cellphones have test/debug modes that will give you all kinds of data regarding signal quality and strength. Can't say for bandwidth / latency though. You could check some of the phone hacking forums for a debug mode / debug drivers for your card(s), and see what kind of data you could get to.
  • There's plenty of network monitoring tools around.

    Signal strenght might be harder if the manufacturer of the device doesn't give easy access to that data (many cellphones can be switched into diagnostic mode; or some smartphone OSes have diagnostic software available). Maybe you can find some electrosensitive person?

  • There is the Placelab.org [placelab.org] project, but their mailing list has died down over the years.
  • by zill (1690130) on Monday May 17, 2010 @10:16PM (#32248132)
    Can you ping me yet?







    How about now?
  • by deathcow (455995) * on Monday May 17, 2010 @10:16PM (#32248138)

    At least, this is what I see working with SNMP data coming off dumps from the cellular base transceiver stations attached to our towers.

    Every 15 minutes, every GSM handset measures the perceived strength of the tower signal it is using, this is reported to the tower, and we record them all. Also every 15 minutes, the strength of the handset signal, from the perspective of the tower is sampled and recorded.

    These readings go into buckets, for example if a reading showed a -78 dbm signal, it goes in the -78dbm bucket. Before long, a histogram can be generated with the datain the buckets, and we can see typical distribution for receive performance - for both handsets and the tower. Different towers have very different "signatures" in this data.

    You may go around sampling receive performance, (which would be interesting) but I don't think you'll be able to map how well the cellular system is receiving from you.

    • Re: (Score:3, Informative)

      by kent_eh (543303)

      You may go around sampling receive performance, (which would be interesting) but I don't think you'll be able to map how well the cellular system is receiving from you.

      Which is most often the limiting factor.

      The base station is transmitting at 50-100 watts ERP, but your handset (modem) is transmitting at less than a watt.
      Sure the base station has pretty efficient recieve antennas, possibly with tower mounted pre-amps, but if it can't see your signal, it can't do much with it.
      And a signal path needs to work in both directions to be able to do something useful with it.

  • Most providers use modelled data to estimate signal strength as it's too expensive to actually measure every point within their coverage. You might be able to obtain and use modelled coverage (which is mostly based on putting virtual towers into a digital terrain model) and undertake some validation. This would provide a meaure of the optimism usually present in modelled coverage. Actual coverage is usually going to be less due to buildings, weather, trees and other rubbish you rarely see in a DTM. Validati

  • After what happened to wardriving be sure you legally have your butt covered. Especially if you prove the network sucks >.>

  • by Stenchwarrior (1335051) on Monday May 17, 2010 @10:28PM (#32248218)

    I wouldn't worry about charting the signal strength for 3G. You can be in a densely populated area showing five bars of 3G and your speed and latency can still be dog shit depending on how many people are hitting the tower, similar to your cable modem. It might be worth it to record whether or not you have 3G just to help map out your general coverage, but that doesn't mean you'll have great speed. Although, you can find something like that here [cellularmaps.com].

    As for speed I like to use a util called iperf [ucf.edu] for measuring speed from one device to another across a network. You may have to open ports on your firewall or setup a VPN, which will add unwanted overhead, but you will get a good idea of which carriers have the best speeds. You can also run the simple tests using other websites like here [speedtest.net] or here [pingtest.net].

    • Re: (Score:3, Insightful)

      by kent_eh (543303)

      I wouldn't worry about charting the signal strength for 3G. You can be in a densely populated area showing five bars of 3G and your speed and latency can still be dog shit depending on how many people are hitting the tower, similar to your cable modem. It might be worth it to record whether or not you have 3G just to help map out your general coverage, but that doesn't mean you'll have great speed.

      Also, if your 3G network is based on CDMA (WCDMA, HSPA, HSDPA) then signal-to-noise ratio is as important as raw signal strength. SNR in both the downlink (what you receive from the base station) path - which you might be able to measure, and the uplink (what the base station receives from you) -which you have no way of measuring directly.
      And while you might be able to control the signal level somewhat, you have very little control over the noise part of the equation.

      • by wowbagger (69688)

        "Also, if your 3G network is based on CDMA (WCDMA, HSPA, HSDPA) then signal-to-noise ratio is as important as raw signal strength."

        Actually, this is true for ALL communications, bar none - S/N is what matters. You could have a signal that is barely 6 dB above what your receiver can detect and have a good S/N ratio, or have a signal that is so large it is driving the receiver into compression, thus distorting the signal and driving the S/N ratio down into the weeds. Shannon's Law.

        However, reporting signal le

  • cdrouter (Score:4, Informative)

    by mveloso (325617) on Monday May 17, 2010 @10:35PM (#32248256)

    Industry standard?

    http://www.qacafe.com/cdrouter [qacafe.com]

  • I've done similar things using Linux. Basically, when you hook up the 3G card, it presents itself as an old-school modem (although it's over USB). You can then use a program such as wvDial or Minicom to send AT commands (if you want to do a connect, you need to find out the number to dial. You can find this on your carrier's website).

    A lot of wireless modems have AT commands for signal strength and other info, you can do a Google search for documentation about AT commands for your specific modem. A war
  • If you're on Linux you can use gpsd for interacting with your GPS. If you're on Windows using the new Location API in Win7 would be nice, but, more realistically, you'll be listening on the serial port your GPS uses and parsing NMEA packets. No worries, this isn't that hard to do. After a either a certain interval or time or distance traveled, send a few pings to a server and download a reference file. Dump your data into a CSV or use OGR to make a shapefile, KML, PostGIS layer, whatever.

    • Of course the network testing I've mentioned only works for one provider/device at a time, unless you do some kind of funky network configuration. I also doesn't measure signal strength,
  • Sensorly on Android (Score:2, Interesting)

    by mykro76 (1137341)
    http://www.sensorly.com/ [sensorly.com] Run it on your phone manually (or have it triggered intermittently). The 3G, EDGE and wifi coverage that your phone detects is uploaded to the central server and within a minute your phone receive the updated maps. You can only contribute to the maps for your phone's carrier, but you can view the maps for all carriers.
  • I'm a bit rusty, but since your network is probably TCP/IP, can't you do this with standard TCP/IP tools?

    The only thing that could be a problem is measuring "signal strength". However, but a lot of mobile chipsets work under Linux. Even tools running under Windows, there may be access to this information (netstumbler)

    For latency, you could just use ping:

    $ ping -c 5 broadbandreports.com
    PING broadbandreports.com: (209.123.109.175): 56 data bytes
    64 bytes from 209.123.109.175: icmp_seq=0 ttl=46 time=248 ms
    64 b

  • You can use Gnuplot to chart data such as signal strength or error rates by location. For example, if you time sync GPS data and your statistics you can emit surface and contour maps [sourceforge.net] (such as the second glass.dat example near the bottom).
  • by GNUALMAFUERTE (697061) <almafuerteNO@SPAMgmail.com> on Monday May 17, 2010 @11:26PM (#32248586)

    In the end, the project was cancelled before we got a chance to get to test 3G coverage. But we did get to think about it. Our customer was a fleet of cargo ships, going through a fixed path on the Rio de la Plata (River Plate). Basically, we were going to install our CCTV system in there, and have it push images and other information to our servers whenever it had signal. We wanted to know approximately in what areas of the river we would have signal. We were going to base our system on the Vodafone mobile connect driver. It's a set of Python scripts. Of course, it communicates with the modem using simple AT commands. It's released under the GPL. It is capable of measuring signal, sending and receiving text messages, and other nice stuff (like, well, actually dialing and calling PPP to stablish the connection). We had it working with several Huawei devices, but I know it works with other brands too.

    Our idea was to modify this scripts so that they would try to maintain a connection, auto-dial every time it disconnected, and log the signal at certain intervals to a MySQL DB. We were also going to run download tests all the time automatically. Since there was no chance we would go on the ships with the devices (the ships were cargo ships that transported and extracted sand, and there weren't very comfortable, not to mention their average trip was at least ~72 hs.), so we wanted to do all of this automatically. The devices would also inform their IP to a web service every time their IP changed, so we could SSH in the machine running this tests in case we needed to change something.

    We were going to add a GPS to this system, that would also log its position at certain intervals, so that we could then generate a color-coded signal map.

    I hope this helps. It's really fairly simple. I would be happy to provide you with source code, but we didn't get that far into the project as to produce actual source code, since the customer changed his mind due to budget restrictions real early. Feel free to contact me if you have other questions {almafuerte (at) gmail (dot) com}

  • by DrCompE (1813808) on Monday May 17, 2010 @11:29PM (#32248610)
    http://www.cs.wisc.edu/~suman/pubs/citywide.pdf [wisc.edu]
    ABSTRACT
    We describe our experiences in building a city-wide infrastructure for wide-area wireless experimentation. Our infrastructure has two components — (i) a vehicular testbed consisting of wireless nodes, each equipped with both cellular (EV-DO) and WiFi interfaces, and mounted on city buses plying in Madison, Wisconsin, and (ii) a software platform to utilize these testbed nodes to continuously monitor and characterize performance of large scale wireless networks, such as city-wide mesh networks, unplanned deployments of WiFi hotspots, and cellular networks. Beyond our initial eorts in building and deploying this infrastructure, we have also utilized it to gain some initial understanding of the diversity of user experience in large-scale wireless networks, especially under various mobility scenarios. Since our vehicle-mounted testbed nodes have fairly deterministic mobility patterns, they provide us with much needed performance data on parameters such as RF coverage and available bandwidth, as well as quantify the impact of mobility on performance. We use our initial measurements from this testbed to showcase its ability to provide an ecient, low-cost, and robust method to monitor our target wireless networks. These initial measurements also highlight the challenges we face as we continue to expand this infrastructure. We discuss what these challenges are and how we intend to address them.
  • one possible solution:

    Download the android SDK; write an app; run it in the emulator that comes with the SDK.
    I'm not sure how much work it'd be to tie your 3G card(s) into the emulator (that comes with the SDK), but it's possible.
    Linux would be my first choice, but the SDK also runs on windows or mac os.

    Bonus for getting a useful app included in the app store.

  • While the goal is an admirable one, there are just too many variables to even begin to consider really doing this.

    First off, you aren't working with a stable environment. There are changes being made to the cellular infrastructure all the time. Changes to settings in the towers, changes to the tower equipment and addition of new towers. You will not be informed about any of this making your information out of date almost immediately.

    Next there is the problem that most throughput problems are going to be

  • by Anonymous Coward

    ...or "Spirent UTS"

    I used to do this kind of programming all the time for Qualcomm and Kyocera Wireless. Cell phones have a User Terminal Diagnostic Monitor running on them constantly that can be used to get almost all data in realtime out of the phone through it's data port. There are a couple of areas of memory that are write only for things like passwords, but you have access to pretty much everything else.

  • by lordlod (458156) on Tuesday May 18, 2010 @12:43AM (#32249056)
    Signal quality numbers are about as meaningful as CPU numbers.

    A bigger number on the same device probably means you have a better signal. A 'two' on one device could be equivalent to a 'five' on another or a 'one' on a third. There is no standard that is used across the industry, or even across all devices from a given manufacturer.

    When a device manufacturer gets customer reviews that say "I only get one bar with your phone but two from company X" the device manufacturer can either try and explain repeatedly that their one bar is better than X's two bars and that unlike X you can still make phone calls on our device on one bar. Or they can just double the number of bars reported on the next model so they don't look worse than X.

    Which do you think they do?

    To do a real test you need to use a constant antenna and location, attenuating the signal gradually until each device stops functioning. The amount of attenuation it can take is a crude indicator of the quality of the radio.

  • There are three sets of tests you need to run at each location, or along each drive route. That means three runs along the same route, or three cards. All can be scripted in dos or Linux. From simplest to most complex they are:

    1) Ping Test. A simple ping to the nearest visible IP address, usually the GGSN, will give you the round trip time for a session in progress. You are looking for the variability. A simple ping -t command for a few minutes and plot the results in excel. You can vary the packet

  • I was a 3G data engineer for Sprint PCS during the launch of 2.5G and 3G data. There are a few problems with the type of testing it sounds like you want to do.

    First, I would suggest reading the specs from the IEEE on CDMA 2000, aka 3G. CDMA2000 allows the ability to allocate and de-allocate bandwidth on demand and based upon quality of service configurations. At night, with no one on the cell tower, you're going to get the full pipe for data. You'll see bursts up in speed but then several things can happen. First, voice takes priority. So at midnight in this scenario, I pick up my phone and make a voice call and I take priority. You're pipe just got smaller. The next variable is overall tower usage. Cellular towers shrink and expand RF power with regards to usage. As more users get on, the cell tower will reduce it's footprint. So even if hardly anyone is on the phone, but there are a ton of subsribers on a cell, it can drop it's power. So your bandwidth and RF are variables which change by the second.

    So if you're just doing a "Hey lets just see what we see," type of test, then expect a huge array of data with not too many descernable results. If you're looking for data to be compared with something else (carrier vs carrier, region vs region), then it also won't be terribly useful. As a geek, it'll be cool to know you can set the test up, but as a quantitative analysis tool it won't be repeatable or statistically useful. You also can't really compare it to desktop loading times either. The images you "download" via a wireless carrier are not the same. Go to Yahoo and download the GIF for their logo using an aircard or wireless carrier device. Now, download the same with a desktop PC over a wired (or other non-wireless carrier method). Not the same file size, huh? :)

    Just as an aside, I used to test it using Stick Figure Death Theater ( www.SFDT.com [sfdt.com] ) since you can start a really long download and watch the stats. Also, it was entertaining to watch at the same time.

  • Try the application CellMapper from the Android market. It creates maps of user-submitted cell signal strength. Some of the areas you are interested in may be covered already, and any new data you submit will help to benefit the community as a whole.

  • Do it yourself (Score:1, Informative)

    by Anonymous Coward

    I found it extermely easy to write a program myself for my windows mobile handset. It took me about an hour to write a program which a) collects network information (available techniques such as GPRS, EDGE or HSDPA) and signal strength along with tcp ping statistics (for some reason some Finnish wireless base stations block icmp ping) and b) gps data (time, speed, location). This gave me a possibility to gather quite interesting data about both coverages and the effect of speed as I ran the mapping program

  • Shameless self-promotion ahead...
    This is more a suggestion to help with mapping received signal strength (RSSI), rather than data network latency and bandwidth (you can argue that those data network metrics rely heavily upon your RSSI!):
    Grab an old Nokia, use gammu [gammu.org] to enable Network Monitor mode [wikipedia.org], fire up a GPS and display the combined information streams on a map. I did exactly that as an experiment [spench.net] using a Nokia 3310 and a Navman GPS receiver. Interesting to then correlate the signal peaks to the actual [spench.net]
  • Go for the pros... (Score:1, Informative)

    by Anonymous Coward

    Warning: shameless plug dead ahead...

    Look at http://www.p3-group.com/communications/en/home.html, it's their core business and they just opened an office in the US.

  • If your end users will need to run 24 hours a day you will need to test 24 hours a day.

    We have number of little (Linux of course) boxes using 3G USB modems here in Sweden, and have discovered that Telia does all sorts of maintenance at night and at weekends.

    Furthermore the latency (as measured by ping) varies quite a bit depending on time of day, i.e. when the local farmers are downloading their porn.

    Another thing we've come across is that the versions of the USB modems changes with great frequency! Which o

  • This is my job! (Score:2, Informative)

    by simonpage (459386)

    There are plenty of expensive software solutions for this that are used at a professional level (ROMES, NEMO TEMS etc).
    If you are after a free solution, the AT commands of most units Huewai, Option etc will give you network information,
    For example: Signal as RSSi. (look under 3GPP TS 27.007) AT+CSQ? gives a number 0 (-113dBm or Less) to 31 (-51dBm or greater)

    Failing that a lot of the dashboards have open APIs (in the UK Vodafones dashboard gives you access to lots of information)
    Most of the Samsung mobiles

    • by TheSync (5291)

      I want to comment on Received Signal Strength, Eb/N0, Es/N0, SNR, etc.

      A commercial data receiver is NOT a professional test system. I did a lot of testing on satellite receivers, and what I know is that the SNR numbers you get from commercial receivers represent the ability of that receiver (antenna, front end, demodulator) to receive the signal under your current noise floor and interference situation. The SNR numbers you get may be correlated with actual SNR, but it is not exact.

      For example, if you appl

      • by simonpage (459386)

        Good reply,
        You're correct about a modem being non-professional equipment, there are some excellent PN Scanner/Decoders used in these system - Rohde & Schwarz TSMW, TSMU, TMSL, however a modem is representative of a customers experience.
        SNR is not really used as Ec/No (Chip energy over noise) is more useful. The scanners mentioned supply a CINR figure - Carrier Interference Noise Ratio.

        General testing is carried out with a user device modem/mobile and a Scanner as this is not controlled by network comm

  • "In order to resolve an ongoing issue with a vendor..." Good luck with that. Doing the testing itself is very technically interesting and worth discussion. Trying to resolve an issue with a vendor by "proving" they have a certain level of service is a different matter entirely. That type of approach to resolving business disputes just isn't the right approach. It's a good example of trying to resolve business/legal issues with proving something in technology, and that is very difficult.
  • I have used SMSlib for a similar purpose. It is an open source Java library for sending and receiving SMS with a wireless modem. I used it as a framework to communicate with the modem and extract its signal quality measurements. The basic algorithm is: -- Force the modem into 3G mode (that's what I'm interested in) -- Loop every minute: -- Read and record RSSI, BER, SNR You can read about the details on: http://knol.google.com/k/novak-petrovic/modem-based-3g-signal-analysis/1j9pv1wo3nq4h/20# [google.com] There a

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