Texting trouble with the LTE shield!


Next on my bucket list for things to test out with the Botletics LTE Shield was text messaging, or SMS. According to the demo, it was supposed to be really easy and straight forward, but it wasn’t.

First, I used the Hologram Dashboard to send an SMS message to the device. It “showed up” but I couldn’t read it:

—> AT+CMGF=1
<— OK
<— +CPMS: “SM”,1,10,”SM”,1,10,”SM”,1,10

Reading SMS #1
—> AT+CMGF=1
<— OK
—> AT+CSDH=1
<— OK

Then I tried sending one from the device:

Type out one-line message (140 char): testing
—> AT+CMGF=1
<— OK
<— >
> testing


And it wouldn’t send one either. I tried several variations of this for about an hour, and just wound up frustrated. Later, I took a look through prior issues, and I found another user who had the same problem. Turns out, in their situation, they originally connected to Verizon, and then couldn’t send or receive. Then they connected to AT&T, and they could send and receive. So, I took a look, and sure enough, I was connected to a Verizon network. I reset my board, and tried connecting again. This time (by no work of my own) it connected to an AT&T network, and I too could send and receive SMS messages! Check it out:

  • Sending – I received it on my phone in seconds!

Type out one-line message (140 char): testing
—> AT+CMGF=1
<— OK
<— >
> testing

  • Receiving – I sent the reply of “Cool!” from my phone.

Read #1
Reading SMS #1
—> AT+CMGF=1
<— OK
—> AT+CSDH=1
<— OK
+CMGR: “REC READ”,”+<MYPHONENUMBER>”,,”19/04/25,21:39:28+00″,145,4,0,3,”+19703769316″,145,5
—> AT+CMGF=1
<— OK
—> AT+CSDH=1
<— OK
+CMGR: “REC READ”,”+<MYPHONENUMBER>”,,”19/04/25,21:39:28+00″,145,4,0,3,”+19703769316″,145,5
***** SMS #1 (5) bytes *****

So, if you too are trying to follow the tutorial for the LTE demo using the Botletics SIM7000A shield, be sure you are hooked up to AT&T. Also, if you were hooked up to Verizon, be sure you unplug the Arduino, and the power supply/battery of the board. Otherwise, the modem might still be on!

Linux – keep it simple.

LTE shield for Arduino: Web Page Download!


First up on my list of learning about this Botletics LTE shield was how to pull data. Fortunately for me, the LTE demo sketch included a method for downloading something from the internet. It works like this:

// The code below was written by Adafruit and only works on some modules
case ‘w’: {
// read website URL
uint16_t statuscode;
int16_t length;
char url[80];
Serial.println(F(“URL to read (e.g. dweet.io/get/latest/dweet/for/sim7500test123):”));
Serial.print(F(“http://&#8221;)); readline(url, 79);
if (!fona.HTTP_GET_start(url, &statuscode, (uint16_t *)&length)) {
while (length > 0) {
while (fona.available()) {
char c = fona.read();

// Serial.write is too slow, we’ll write directly to Serial register!
#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)
loop_until_bit_is_set(UCSR0A, UDRE0); /* Wait until data register empty. */
UDR0 = c;
if (! length) break;

As the code states, it was originally written by Adafruit, and some portions of this code (the Adafruit Fona library) were updated by Timothy Woo of Botletics) and it allows you to look up a URL and download it. So, I tested Google. It downloaded it like so:


And I copied/pasted it into a text file, and saved it as html, which opened in a browser, like this:


So, that works. Granted, using this method was extremely slow. I am using a serial monitor connection over USB at a 9600 baud rate, which really took a while to catch all of the data. You could literally watch the characters being written on the screen. However, I think the modem is much faster, just my interface to it is not as quick. I’ll have to play with it some more, but it was nice to be able to download a web page at least!

Linux – keep it simple.

Trial run of SIM 7000A LTE and GPS shield for Arduino

I wanted to start playing around with cellular devices and using them with the Arduino. So, I bought a Botletics SIM7000 LTE CAT-M1 NB-IoT Cellular + GPS + Antenna Shield Kit for Arduino (SIM7000A)  that works in my locale. There are different modules, SIM7000 A,C,E, etc. that work in different places, so I picked up this one which works with AT&T as well as Verizon LTE bands in my area.

So far, I’m just getting started, and I haven’t done much yet. You can head over to the wiki to see the available open source software and examples are available. I love Open Source Hardware (OSHW)! It is really nice buying a piece of equipment and seeing all of the available diagrams, schematics, software, etc., all laid out for you to use.

In any event, I’m just getting started with this, and so far all I’ve done is register my new Hologram.io sim card, and set it up with an LTE demo sketch. Essentially, the demo sketch allows you to connect over USB with the Arduino serial monitor and use a text based menu interface to play around with the modem, without having to know all of the AT commands.

Here’s a screenshot of my Hologram dashboard:


Of course there is more information on the upper parts of the page, but I felt it was probably wise not to include my IEMI and other information on this shot. The dashboard is really intuitive. As for Hologram.io itself, so far so good. When I signed up they sent me a free card in the mail, as well as gave me 1 MB of free data a month to play with. Sending text messages to the device is free, but sending a text from the device costs 19 cents each. Overall, the monthly charge is $1.50/month to keep the card active. I think it is 40 cents for each additional MB of data I use.

The price seems a bit much for each SMS sent, but it is nice to allow me to play with this without having to get a $30+/month sim card for another carrier. I was going to try some of my other sims in it from my other phones, but you do need a phone sim that specifically does CAT-M1, which supposedly not all do.

One item of note is that the modem will not work without a battery while plugged into the Arduino. It turns out that the Arduino can’t supply enough juice during some operations that cause it to pull a little extra juice. These spikes are sporadic, and while the battery is plugged in, the battery is charged by the board, so my battery level keeps going up while plugged in.

The interesting thing about the battery is that I couldn’t get any place to ship me a battery in the mail to Alaska. Fortunately, I have several dead Android phones laying around and I pulled a 3.7v, 1400mAH battery out of one and was able to solder the wires to the terminals and hook it up that way. Check out the pictures if you want to see my handy work.

I’ll let you know as I try out a few of the features what I can come up with. I’m hoping to build some sort of rudimentary texting/web phone, and grow in some lower level cellular/gps knowledge. As always, you can follow along with my sketches on my GitLab!

Linux – keep it simple.

Mini to Nano: Cutting a Sim Card

The other day, a friend asked me about what phone I recommend that they get. They had some unique needs, and I recommended a phone for them. One thing that I didn’t consider was that the new phone used a nano sim card slot, and their old phone used a micro sim card slot.

Fortunately, this wasn’t really a problem for me, as I have cut down sim cards before. It always causes the person I’m helping to raise an eyebrow, though, and sometimes it can be difficult to get them to accept that it is okay for them to hand over the sim card to me and my scissors. I think that they were particularly doubtful, since their new phone came with specific instructions and warnings against cutting down a card to fit.

However, with a little calm reassurance, I convinced them to let me cut down their sim card. I used this template:



WARNING: cutting your sim card could cause it to never work again, and at the least, it will not be the bigger size that it was before, and certainly can’t go back into the phone it came out of. Do this at your own risk!

One thing that card cutters often forget is the thickness of the card. On the above pdf file, they mention this as a foot note:

The difference in thickness between NanoSIMs and previous SIM cards (90µm) corresponds to the thickness of a human hair and should therefore not make any difference in practice. Nevertheless you may slightly grind the plastic side of your SIM card. Never grind the chip side!

I typically just sand the back plastic side for a few seconds with a 200 grit sand paper, and I have always had a good fit. So, if you are willing to accept the risks, and run into a similar problem, then this might be a good option for you, too.

Linux – keep it simple.

Bluetooth Breakdown: Sending gatttool commands from my Ubuntu Touch Phone!

Here I am, typing commands from my phone and controlling a Bluetooth Feather!

Of course, the moment of truth! The goal of this whole Bluetooth breakdown project was to figure out how to make my home made auto start work on my Ubuntu Touch phone. Well, here it is, working!

Although the interface could use a face lift.

Last we looked at this, we saw that we could write custom scripts to send the commands from the desktop computer to the BLE auto start, or use interactive mode of gatttool and do the work there. Now we can actually do the same from the terminal of the cell phone.

While this technically counts. We now need a snazzy program that just works with clicky buttons and that sort of thing. So, I suppose that will be the next phase of this project! Stay tuned for adventure!

Linux – keep it simple.

FreedomPop in Alaska? Does it really work for free?

Okay, so this might sound like some kind of gimicky advertisement, but it’s not. I work on custom ROMs for various cell phones, and it is becoming a bit difficult to keep swapping my sim card around to test them all out. The prospect of paying money for a second sim card that I will barely use any minutes/data/texts on is not on my agenda, but I’d be willing to use a free sim card for sure!

As you probably heard, FreedomPop is offering “100% free service”. So I thought I’d put that to the test with a phone that is not my daily driver. I checked their website, and supposedly, they have service anywhere AT&T does, which includes Alaska. I picked up one of their sim cards and here is what my experiences were.


Activation was really simple and straight forward. Note that I picked up the sim card from a third party, so it was not activated yet. I guess if you order straight from FreedomPop, they will activate it as soon as you call, then send it to you. I didn’t want to do that because I was concerned about “extra” charges and setup. See, most of their deals start you signed up for more, then you have to downgrade to free. Usually there is a time period before you get charged where you can downgrade. I was concerned, because their website uses free shipping, which takes up to 14 days to Alaska, which coincides with when you get charged for non-free services. So I picked up the sim card from a third party and activated it myself.

After unwrapping, there were instructions to call or go online to activate. I HIGHLY RECOMMEND GOING ONLINE so you don’t get confused or bamboozled. During the online activation, it will ask you numerous times which plan you want. You have to constantly check each page and make sure you click the “Basic” free plan.

You will need to provide a credit card and $11. One dollar is the activation fee. The other ten go into a “top up fund”. This top up fund is in case you run out of time, then you can automatically use the money in your top up fund to purchase more data/texts/minutes/etc. When I was done, I had a truly free account.

However, when it came time to pick my phone number, there were no Alaska numbers available, so I had to pick a number from Seattle instead. Not having a local number makes it difficult for land line callers, but really doesn’t matter for cell phone callers.

I will say, though, after inserting the sim card, it picked up service right away, and loaded the APN information for me. So, it does actually work in Alaska.

The catch

Okay, so there is always a catch. Like any other business, they want your money. In this case, they are not lying, though. You don’t have to pay anything month to month, provided that you don’t go over your minutes/texts/data. But in the activation, they took $10 for the “top up fund” that will automatically buy more when you run out. So if you are very careful, the plan is free.

But I was still concerned. I’m throwing this card into other phones, or flashing custom ROM after custom ROM, and so setting the data limit on one ROM or phone was not going to keep me safe. I wanted to make sure that I would not endure any future charges.

I looked around online, and found that you can go to the web site for your account, and turn off the top up feature. However, when you do that, you have to (by way of accept or cancel button) accept the “Safety Feature”. The safety feature costs about $7 per month. Here’s the catch:

If you turn off top up, and accept the safety feature. Then you can immediately go to your billing section and opt out of the safety feature. You still lose the $7, and you have $10 of credit in your account that you will probably never get back. But, once you do that, your account is not only free month to month, but you also will not go over your limit, supposedly, you will just run out of minutes/texts/data for the month, and have no usage until the next billing cycle.


Here you can see my completely free month to month bill after paying $18 in fees.

The app

One other downside to this setup is the app. Don’t get me wrong, the app seems to work great. What I mean by downside is that you need to use the app to send a text, or calls. I did test it out, and you can dial from the normal dial app on your phone, but it will then switch once you call to this app. Also, sending and receiving texts are done through the app.

Don’t get me wrong, the app seems to work great. I have had zero issues with the app. But here are a few downsides for me and my phone testing work:

  1. The app comes from the Google Play Store. So you have to have a Google Play Store account to use their app. I did try getting the app “elsewhere” and several that I tried would flash, but didn’t “work” (it would endlessly try to connect to my account) until I tried it on a phone with Google Play Store and services installed.
  2. With the need for Google Play Store, it makes it difficult for phone testing, because I need to flash Gapps as well.
  3. With the app for VOIP phone calls and texts, I don’t get to test the actual phone and text app of phones that I am working on, which, since I’m working on them, I need to test them.
  4. Since you have to use their app, you can’t use the many million other cool texting/calling apps on your Android phone. E.g., ones with cool features that you might like.

Data, Minutes, and Text Usage

One question that begs to be asked is how far does this get you? In my testing thus far, I’ve found that if I use the WiFi at home and at work, I do not lose any data. However, visiting one web page without the WiFi on used up 20 mb of data. That’s right, one web page, with one view of it cost me 10% of my monthly allotment. With rates like that, a 30 minute “binge” of internet while outside of WiFi range will probably bring you to a halt for the month.

As for minutes, I don’t spend that much time talking on the phone usually.  Yesterday, on my regular cell phone with unlimited talking provided, I spent a total of 9 minutes on the phone between two calls. The day before I was only on the phone for 2 minutes. So for me, the minutes might actually work. If we take 10 minutes as an average per day, though, and multiply that by 30 days in the billing cycle, then you end up on the phone for 300 minutes, which means the last week of your plan you wouldn’t be able to talk to anyone.

Texting is another matter entirely. It’s only 9 AM, and I’ve already sent/received 24 text messages. Granted, I get up at 4 AM, so that is 5 hours. Some are work related, others are not. Either way, by the end of the day, I will likely have 75 text messages. This gives me six and a half days of texting. That just will not do for a daily driver. At least not for me.

So is it free? So far, yes. Is it great for the average user? Well, if you are always near WiFi, don’t talk to much on the phone, and only send texts every now and again, then I suppose so. But there are alternatives to stretch this out further…..

Stretching It Out With Alternatives

I can think of several ways one might stretch out the use of this FreedomPop service while keeping it free:

Use the WiFi of your local work and home, and pair it with free apps for chat or messaging services.

In theory, if you use something like Jabber, XMPP, or similar apps, like TOX, you could “text” people via instant message, which will not cost you anything as long as you stay on the WiFi. In some of these apps, there are options to video chat with someone, which is a lot like making a phone call. Some of these apps even allow VOIP phone calls themselves. However, these features may or may not cost money for their services. I’m sure you can find a few free ones though.

Use more than one FreedomPop sim card

Another option is using more than one FreedomPop sim card. With multiple cards, you may be able to swap between them, but this makes it very difficult to receive a call, as no one knows which one you are using. I haven’t tried it, but it seems logical, though not practical.

One of the phones I am working on has two sim card slots, but since you use the app to control usage, I’m not sure you could put both into one phone and actually make it work.

Another Resource

After I got started with this, I found a website devoted to getting the most free out of your FreedomPop account, you can find it at FreedomPop For Dummies.

We will have to see how well it works out over time. It’s not quite what I need, but it is great for just checking that the radio interface layer of the phones that I’m testing do work, and I can do a quick data test to make sure the internet works as well while working on my cell phones.

Linux – keep it simple.

Video Tutorial on How to Compile Android and Modify Kernels


For those interested, I have just posted a video tutorial series on XDA for building Android Oreo, Nougat, Marshmallow, and Lollipop on 5 different phones, the emulator, and 5 different ROMs. Also included are custom kernel editing, adding apps, changing source code, backgrounds, and more. Here’s what I posted:

From XDA: https://forum.xda-developers.com/android/general/guide-how-to-build-custom-roms-kernel-t3814251


Praise God! Finally a video tutorial of how to build Android and modify kernels!

I have created a video tutorial and guide for how to compile Android, from Lollipop through Marshmallow, Nougat, and Oreo. The video series covers several different phones, the emulator, kernel and rom editing, app source code editing, and much more!

Who is this video series for?
Well, this video tutorial is a step by step guide built primarily for the beginner. This is written for those who already know how to flash TWRP, CWM, or the like, and who have installed a custom rom before. This is designed to help those who are ready to move up from flashing and installing other peoples custom rom to actually start making their own custom roms. I recommend that a beginner watch the entire series in numerical/alphabetical order (the videos are marked).

That said, I believe that an intermediate developer may find a useful trick here and there, and they should just skip ahead to videos of interest. Perhaps kernel development, or something along those lines.

An advanced rom/kernel developer will probably far exceed my feeble abilities, and will not likely find much useful information here. Perhaps if you are an advanced developer, you would consider continuing the tutorial or making an advanced video series! (See further posts for recommendations on contributing videos.)

Why did you put this together?
Well, after building roms for several different devices, I started receiving requests from users who wanted to start building their own roms, but didn’t know how. I didn’t have enough time to answer everyones questions, so I wrote a few guides, pointed others to guides that were available, but there are some things that you just need to see to understand. Hence, the video tutorial. I just hope that someone finds it useful.

This course was written in order! While Lollipop and Marshmallow are old by today’s standards, there is still good learning value in building them, and there are topics covered there that really make them worth watching.

What’s in the videos?
During the series, we will be building for the emulator, as well as 5 different phones of various brands, and 5 different roms. I hope that this will give the viewer a good idea of how to build for their own specific phone as they see the differences and similarities across the phones and custom roms.

+ Ubuntu installation
+ Java installations
+ Using Git, GitHub, GitKraken, and the command line
+ Fastboot and ADB
+ Heimdall/Odin
+ QFIL, QPST, SALT, and other tools
+ AOSP, SlimRoms, PACrom, AOKP, AOSCP
+ Lollipop, Marshmallow, Nougat, Oreo
+ Errors
+ Overclocking CPU/GPU
+ Adding Governors and I/O Schedulers
+ Sound modifications
+ Changing app colors, text, and icons
+ Adding prebuilt apps
+ Adding source code
+ Converting device from one rom to another

**** This is an UNOFFICIAL TUTORIAL. Use at your own risk! ****
Download links:
Ogg Vorbis Video GitLab:
Clicking on a video in GitLab will allow you to watch it online.

Ogg Vorbis Video Downloads:
This download is rather large due to the multiple videos.

MP4 Video GitLab:
Clicking on a video in GitLab will allow you to watch it online.

MP4 Video Downloads:
This download is rather large due to the multiple videos.

I also have several written guides available on XDA, here are a few:

Building ROMs for the Galaxy Note Edge: [url]https://forum.xda-developers.com/note-edge/general/guide-build-aosp-roms-kernels-note-edge-t3488840[/url]
Building ROMs for the Galaxy S4: [url]https://forum.xda-developers.com/galaxy-s4-tmobile/general/guide-step-step-instructions-building-t3402637[/url]


Be sure to check out the videos or the XDA thread! I hope that these will help some of the aspiring Android developers out there!

Linux – keep it simple.

Finding apps for a ZTE Z432 dumb phone!

My wife and I recently picked up a dumb phone for things like hunting/camping/fishing. You can get them pretty cheap, and the battery life is fantastic compared to most smart phones. Besides, if you loose it, you’re only out a few bucks.

While a dumb phone is, well, dumb, we were hoping to spruce it up with a few apps for some entertainment value. Especially if you use it while traveling, like taking a plane or boat to some remote spot.

After some web searching, all I could come up with was that AT&T, who sells the ZTE Z432 phone, said that this phone did not support any apps. I recalled the yester-years spent using apps on dumb phones, and I knew this just couldn’t be true. So, if this is your plight, and you also failed to find the answer through a web search, then here you go:


I want to be clear that I am in no way endorsing “Dertz”, and I can’t say that all of their apps are safe. In fact, this may be a sure fire way to nuke your dumb phone. However, I did download and install this one:


and it worked great! How can you go wrong with Scrabble Remix?

The easiest way to install them, is to open the link in the phone browser. Once there, scroll down to the download button, and click it. A pop up will ask you if you really want to download that jar file, and if you say yes, a progress bar will appear. Once downloaded, it will be in your folders.

Find the app you downloaded in your folders, and click on it. It will pop up an install question, and if you say yes, it will ask where to install the app, in either Applications, or Games. In my case, I chose Games. After a minute or so, the app was installed and a pop up asked me if I wanted to open it. Scrabble Remix – game on!

I also experimented with the Bluetooth, which works well. Just download the app you want on a smartphone, or in my case, a Bluetooth capable computer, pair with your Z432, and send the file over that way, if you want to save yourself from painful dumb phone browser experience, or save bandwidth.

For the record, we can just insert our normal sim card from our smart phone into the dumb phone, and it works, however, we did need a sim card holder, because our smart phones use micro sims, and the dumb phone used standard sim cards, but they make a little micro to standard holder that your sim card can pop in and out of. If you need one, stop by just about any cell phone dealer, they should have one.

Linux – keep it simple.

CompTIA Mobility+ certificate to be retired on December 15th.

One of the many things that my work requires is various IT certificates. In particular, they require Network+ for the job I am currently filling, and A+, Security+, and Linux+, for various other simulators at my work. So, I make an effort to keep my certifications current, and to have as many as possible, in the event that a position opens up to which I want to apply.

Now, there are a lot of certificates out there, and while I’m not intending to talk about them all here, I would mention that there are other great programs out there, other than CompTIA. For instance, I do hold an LPIC certification, as well as a SLES, and a LFCS. Two of the great things about CompTIA, however, is the fact that they are an industry standard, and that they have a pyramid hierarchy, which allows you to make current and hold numerous “lower” tier certifications by only taking the top level test.

It was a surprise to me to learn that they are retiring the Mobility+ certificate before the close of this year. Here is their take on why they should retire this certificate:

CompTIA Mobility+ certification will officially retire on December 15, 2017. The main reason for this retirement is that the job role for Mobility+ continues to merge into the Network Administrator role, and much of the Mobility+ content is covered in CompTIA A+, Network+ and Security+.

What surprised me, though, was that this is the only certification from CompTIA, and one of the few certifications in general, that covered cellular data and infrastructure.

Sure, A+ does cover a lot of hardware, but it doesn’t seem to cover cellular towers, WiMAX, or even Satellite components, which are a part of Mobility+. Here in Alaska, with many wild and untamed areas of the state, various forms of wireless communications are utilized to get internet connectivity into remote locations.

Granted, Network+ does cover the majority of TCP/IP protocol stack, but cellular devices typically use odd protocols to control the transmission and reception of the TCP/IP data. The radio portions of Mobility+ helped differentiate between the various types of frequency shifting, hopping, and cells that are an integral part of the mobile world.

Of course, Security+ covers most aspects of authentication, authorization, and accounting, but in a more general sense. While it does cover wireless access, it only focuses on the typical 2.4 and 5 MHz bands and associated equipment, not covering the special needs of cellular devices. When it comes to MDM (Mobile Device Management), Security+ treats it as a footnote in section 4, in which all of section 4 is covered by less than 15% of the test. In Mobility+, however, Mobile Device Management alone is 28% of the exam!

It would seem to me that any cellular or satellite internet provider would make Mobility+ a mandatory requirement. Places like Verizon, T-Mobile, or AT&T would all be encouraging their technical employees to certify in this field in order to maintain their network.

What does that mean? I certainly think that the Mobility+ certificate is one worth keeping, but apparently CompTIA believes otherwise. Since it does not make logical sense to me, I can only believe that either too few people are taking the test to make it worthy of updating, or CompTIA is not earning enough revenue from Mobility+ sales to warrant it’s continued operation.

It could be that cellular technologies will be rolled into A+, Net+ and Sec+, negating the need for Mobility+, but I just renewed my Network+ and Linux+ certifications, and didn’t see any cellular references on the exam. They say that CompTIA certifications are led by the industry, and not the other way around. In a world that is becoming increasingly more mobile, I just can’t see getting rid of Mobility+.

Linux – keep it simple.

Does a mobile cell phone booster really work?

As may be evident by the name of the blog, as well as my username, I live in Alaska. Alaska is a really big state. Alaska also has relatively poor cell phone coverage, in my opinion. Often when driving around, I will loose signal, drop calls, or even have no connectivity, which can be a real problem if there were to be an emergency.

So, I decided to do something about it. I decided to buy a “mobile booster”. Of course, I was really concerned about gimmicky devices that actually wouldn’t help me, and I wanted to make sure that I was buying something worth having, without paying an arm and a leg for it. So, here is what I bought (no paybacks for me if you click on it, just a link showing what I bought) :

Car Mobile Booster 850/1900mhz Cellular Signal Repeater Cell Phone Amplifier For Truck,RV
by Protone Led
Link: https://www.amazon.com/gp/product/B06XCBQ87T/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Why did I choose this one? Well, there are many types out there, particularly of interest is what bands it supports. This model doesn’t help with LTE bands, but it does help with the 3g bands that are in use in my area. I figure that I need this to make phone calls or send texts, not to surf the web. Aside from that, it had good reviews and seemed to me that people who actually owned it thought that it helped their signal.

Of course, I wouldn’t be writing this post if I didn’t give it a good test, of which I did two.

The first test I tried to use it at my home, where there was already fair signal, to see if it would “boost” it up to great signal. I couldn’t tell the difference with the thing on or off. I decided that I needed a better test.

For my second test, I took the unit to my work. At my work is a steel enclosed room, like a Faraday cage, in which I receive almost no cellular signal. As you can see from the screen shots, while in that room, I have -118 dbm of signal. With the booster off, I tried a speed test, but it would not receive a return. I then tried a phone call, which told me I had no available network. Great! Perfect for my test.

Then I set up the booster by placing the receiving antenna outside of the room, with the cord pinched in the door weatherstripping to the inside. I hooked up the unit and broadcasting antenna inside, but didn’t plug it in. I tried several more tests to make sure that the antenna itself was not somehow a “conduit” from which my phone would receive signal. Nothing, still no usable signal.

Then I plugged the unit in.

Immediately my signal strength maxed, and SatStat showed -89 dbm of signal! I then proceeded to make a phone call: success! I was able to connect and talk to the weather station via phone. Great! I decided to get more information by running a speed test. I was able to pull 0.46 Mbps downloads, and 0.02 Mbps uploads. Latency was also pretty high, as the ping took 248 ms to complete the trip. However, compared to 0 connectivity before, I thought that was a bit of an improvement.

I also did several tests based on proximity of my cell phone to the inside repeater antenna. It didn’t seem to matter. I could walk around anywhere in the small room and still have signal. Signal would degrade a bit, however, when I put my cell phone into some of the server racks (that seems reasonable to me, though).

So, overall impression: it really does work! However, it seems best suited for a “near nothing” situation, rather than to boost signal to a decent connection. I guess now I’ll have to try it out on the road.

Linux – keep it simple.