Tactical Technology for TEOTWAWKI – Part 4, by J.M.

(Continued from Part 3.)

There’s an App for That

The ability to run thousands of different apps is where the power of a mobile device really comes into play. It allows you to have access applications, files, sensors and other things in the palm of your hand. One of the most obvious app uses for mobile devices in field operations is maps – you can use them to figure out where you are, plan you need to go, note your findings, etc. I’ve standardized on mapping apps that utilize Open Street Maps (OSM) data files and support GPX files for exchanging tracks and other information. My primary mapping app is OsmAnd+, along with the contour line plugin; it’s not as detailed as USGS topographic maps, but the terrain in my area of operations (AO) is only moderately hilly so I don’t really need that level of detail. I make sure to download offline maps for every area I could conceivably end up operating in, and they don’t take all that much space. OsmAnd+ also allows you to create markers on your maps, which can be exported via GPX files to other systems to share, and there are plugins that allow you to take pictures/videos/notes and associate them with map locations as well as do freehand drawing on maps.

Yes, I realize that GPS may not be available, but you can still use the apps just like you would a paper map and compass, without the problem of constantly marking up your paper maps. In addition to the OSM map apps I also have PDF copies of USGS topo maps files for my AO stored on my SD card, and high-resolution satellite map screen captures I got by connecting my laptop to a friend’s 4K TV using the laptop’s HDMI port.

Taking notes is another thing I do frequently in the field, and using my mobile device allows me to stretch out the stash of paper notebooks in my preps. You’re not going to write the next ‘War and Peace’ on a mobile device, but for quick short notes it works well. I use an app called Joplin Notes, which allows me to synchronize with a Joplin Notes server running on my home base network when I return home, supports insertion of pictures and other files (like recordings) into notes, has full end-to-end encryption and allows you to create simple checkbox lists (for my to-do items). It’s not as powerful as something like Microsoft OneNote, but there’s no cloud required and I have full control over all of my information. Note-taking in field operations can be a useful way to keep track of discoveries, create reminders, follow checklists and get a leg up on after-action reports (if you’re into such things).

An audio recording app is another useful tool for field operations. You can record quick spoken notes, interviews, capture ideas, etc. One feature you should look for is the ability to save your recordings to an SD card – the one I use is called Voice Recorder (original name, I know), and is one of the highest-rated apps on Google Play. Another possible application for a voice recorder is to record intercepted radio communications you encounter while you’re out in the field. You can just hold your mobile device’s microphone up to your radio’s speaker and record, or [if the impedance matches] you could connect the audio out from your radio to the microphone jack on your mobile device using a microphone-compatible cable. Note that this is a good solution for recording radio traffic for short periods of time – I’d recommend no more than an hour or two, since most of the recording apps don’t support voice activation, and it’ll quickly consume the battery on your mobile device. If you want the ability to do voice-activated recording of radio traffic for long periods of time I’d recommend getting a small dedicated voice recorder that supports line-in so you can directly connect it to your portable radio/scanner with the afore-mentioned cable and let it collect recordings for hours and hours.

The ability to read and potentially edit various documents and files you’ve created is another useful function a mobile device can provide. You can have access to copies of intel summaries, communications protocols, operations plans, scrounging lists and lots of other documents, along with the ability to modify them as necessary. For all of my document production I’ve standardized on using LibreOffice at home – it’s a free and open-source Microsoft Office replacement that supports documents, spreadsheets, diagrams, databases, etc., and there’s an app for reading and editing LibreOffice documents on Android devices.

I strongly recommend that you password-protect any documents you create that contain sensitive information, and both the desktop and mobile versions of LibreOffice support password-protected documents. You can create a simple password scheme that plays off of the name of each file so you don’t have to memorize lots of passwords, and it doesn’t have to be too strong since you’re probably not going to be connecting to any hacker-infested Internet.

If you don’t want to switch from Microsoft Office there are apps available for working with those documents on Android devices, but be aware that there are limitations on what you can do on a mobile device if you don’t connect to a Microsoft Office 365 account when using them. If you don’t want the ability to edit any content when you’re in the field you can always just save all of your documents as PDF files and copy them to your device – there are dozens of PDF readers available for Android; just make sure you get one that supports opening password-protected PDF files.

You can also view a lot of content like eBooks that can be purchased or downloaded for free from various websites. In some cases there are apps that provide the same information as eBooks, but tend to provide better interactions. Here are some examples:

  • Medical references – While everyone on your team should be trained in basic first aid and trauma handling, you may not have a fully-trained doctor that can recognize and treat everything you may possibly encounter. There are some great medical eBooks available, and apps that cover things like First Aid and Medical Diagnosis. It’s not going to make you a doctor, but having the right information could make the difference between life and death.
  • User manuals – You can bring copies of the user manuals for all the devices you have with you. There’s no substitute for learning how everything works beforehand, but sometimes you can’t always remember what every possible button combination does.
  • Ballistics information – There are a lot of free ballistics tables available on the internet, and tools like Ballistics Buddy can potentially improve your long-range shooting.
  • Foraging – I seem to have a mental block when it comes to recognizing plants, so I always have a copy of a foraging eBook with pictures on my device.
  • Language dictionaries – In case you need to communicate with someone that doesn’t speak your language (like North Korean invaders 8-)).
  • Animal tracking – Given how much the range and behavior of animals has changed during just the Wuhan virus debacle, there’s a good chance you may be seeing new kinds of wildlife in your AO after a major long-term event. Books like Mammal Tracks & Sign and tools like iTrack Wildlife, bird and snake guides, etc. will allow you to locate and identify various species.

Somewhat related to animal tracking is something that may sound frivolous, but which I’ve found very useful on at least one occasion – the ability to generate animal sounds. I have a small amplified speaker that plugs into the audio jack on my phone, and one time when a bunch of loud millennials were about to set up camp a few hundred feet from me in the backwoods I cranked up some bear sounds and started moving around to make noise in the underbrush. Needless to say they quickly left to find another camping spot.

You can also get apps the generate wolf, coyote, and other animal sounds that you could use for communicating, hunting, distracting, luring game, or scaring people away from your position. If you want to be able to maintain some separation from the sounds you could use a small Bluetooth speaker, which would allow you to remain 30’-40’ feet away.

Most phones also come with a number of built-in apps that can be useful in field situations:

  • Clock – A nice complement to a watch.
  • Alarms – You can set alarms for things like comm check-in times, medication schedules, guard watch rotations, etc.
  • Calendar – Useful for scheduling things on multi-day trips like planned meetings, return-to-base dates, etc. I use an app called DAVx⁵, which allows me to synch events with a DaviCal server running on the on a Raspberry Pi on my home network.
  • Calculator – Not sure what you might need to calculate when in the field, but you never know.
  • Flashlight – Most mobile devices allow you to use the camera flash as a flashlight.
  • Compass – Some mobile devices have a built-in compass that may provide a good backup. Note that there are two types of compasses on mobile devices – a magnetometer-based compass, which works on magnetic fields like a traditional compass, and a GPS-based one, which only works when you’re moving and GPS is available.

A critical point regarding apps on your mobile device – make sure you use apps that support offline operations. This means that all of the data the app needs to run is stored locally on your device, so you don’t need Internet connectivity for it to work. One example is the mapping app I mentioned earlier, which allows you to download all of the maps you need. After installing any apps put your device into airplane mode and test out all of its functions to make sure it’ll work with no Internet connection. You should also do a long-term test of 2-3 weeks with your device in airplane mode, as some apps require that you log into your account on a regular basis or the app won’t work.

Equipment-specific control and interface apps are something else you may need to install. Many of the devices I’ll be covering later in this article have their own manufacturer’s interface or control app, and you’ll typically need to install it at least initially to set the device up, which sometimes requires creating an account (and providing an email address). If you want to minimize the amount of spam generated by creating email-based login accounts for each device vendor, I recommend creating a separate free e-mail account and using it exclusively for setting up your tactical field mobile device. After you get all of your devices set up and working you could delete the new email account, or just set it up to automatically delete all incoming e-mail. You’re also going to need an email account to get access to Google Play, which is where you’ll go to install all of these apps I mentioned.

If you’ll be storing your mobile device(s) in an EMP box as part of your preps, you should plan on taking them out every month or so, charging them up and connecting them to the Internet via WiFi to install any operating system or app updates as well as copying over any new content to their microSD cards. You should also make sure you spend some time using each of your apps and devices so you’ll be comfortable with them when you need them in the field.

(To be continued tomorrow, in Part 5.)


  1. Good advice, thanks.
    My add would be to get an inexpensive tablet without cellular connectivity as backup. With the cellular companies able to push updates and/or remote wipe devices I want to make sure my tools are actually _my_ tools.

  2. N. O. – Agree 100%. I included links to a couple of inexpensive tablets in part 3, and you can find refurbished tablets pretty inexpensively on places like Amazon and Newegg.

  3. I’ve found the Surface 3 (not the pro) is really useful. Runs all my ham gear with no problem. Cheap enough on Ebay that you can buy two (search for microsoft surface 3 -pro -go -rt). And charges using a usb micro cord, so you don’t have to worry about finding a high power laptop charger that runs on 12V.

  4. The Chinese and Russians will destroy some of our GPS and communications satellites and this will render cellphones and similar devices useless. This is where good old analog maps and compass will come in handy.

  5. Hi John

    Good tip about using a digital voice recorder and it’s VOX function. Any recorder with VOX would work. I use one of these in three ways.

    1. When doing a radio survey without help. The VOX turns on the recorder and records the time and location it hears from the receiver located at the base station, as I transmit from a outlining location that needs sampling.

    2. When I cannot listen to the many scanners running, the VOX operates the recorder when traffic is heard on any one scanner. During play back, hours of time are compressed into minutes.

    3. Listening to shortwave programs, the digital recorder can record the entire day. In the evening, everyone can get together and hear the program.

    Any of these techniques can be used SHTF as one might not have time to sit a radio shack or radio room and monitor traffic for hours on end. A recorder of any kind can make efficient use of time. It could be considered a force multiplier, allowing the radio guy to be in two places at the same time.

    About GPS.

    The first time I attempted to use one out in the field, the batteries died.
    I believe modern GPS units have an ID’s and are traceable. I have old untraceable units, but I would only use one if I was uncertain about a bearing and needed verification. Basic map and compass is not hard to learn, especially if we are familiar with the area, and do not need the highest level of skill needed to call in air strikes. Using GPS as a back up, I believe is sensible, and if I had artillery, to locate a cashe or drop, I might take a single reading to pin point a location. The rest of the time, I’ll use map and compass until I get lost. I am also concerned that the GPS system available to civilians could get turned off.

    As the topic came up, I checked and found that the Magnet Declination in my area has change by almost 2 degrees since I last checked years ago. Magnet North has been moving rapidly in recent years.

    1. One tip for any newbie readers, from my years of shortwave DXing: Whenever you are dealing with headphones, speakers, and recorders, it is always important to have the impedance match. Test your equipment thoroughly, well in advance of dire need. And remember that it is the cords and connectors on those auxiliary items that get the most wear and tear, so buy spares. And don’t forget: a mini-plug to 1/4-inch adapter can be a lifesaver.

  6. Be careful out there! When playing animal sounds in the woods it turns out animals really do live in the woods! We once wanted to play a joke on some friends camping in the woods at night with a coyote caller and little did we know a pack was near us and started howling back really close by.

  7. I like TacticalNavigation app for marking points and using symbols. Nothing replaces maps and compass but this enhances it and I can share with others I’m not near.

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