Fldigi interface6/13/2023 ![]() Typing out a message ( and even encoding it further via a brevity matrix or One Time Pad) and sending it within a few seconds greatly mitigates the exploitative value of our message. Having a dirt-cheap data terminal is a must-have for clandestine communications. It takes a bit of patience and experimentation, but the reward is certainly worth it. There’s a learning curve to this, and don’t expect it to work exactly right off the bat. So its something to keep in mind during your own planning phase. One thing to note is that the mobile version of FLDigi is a bit different than the full version- its missing several specific modes, including CW (morse code). Throw in the cost of the mobile device if you’re buying on the cheap and you’re still under $100. ![]() ![]() But if you’re like me you’ve probably got a few extra devices and older laptops laying around, and there’s no reason not to have one set up for field commo duty. But what you can do is either build your own mobile device using a Raspberry Pi, or pick up an Android Tablet specifically marked for wifi-only. ![]() Unless you disassemble it and remove the transmitter, which might be more trouble than its worth, using it is a liability. I don’t advise using a phone for this- even if service has long since been disconnected, the phone itself will still ping the closest towers. The install is pretty straightforward, and there’s a distro of FLDigi for the Android OS. Next you’ll need a laptop or mobile device with FLDigi. The cable plugs into any audio jack found on laptops and mobile devices, and is nearly dummy-proof. The most common use for this cable, as the name suggests, is for Automatic Position Reporting System (APRS) which is useful for hams aiding in search and rescue (SAR), but obviously for our purposes we won’t be transmitting position data. What this does is send the transmitted audio from FLdigi to the radio instead of using the microphone. The next thing you’ll need is an audio interface cable, like the Baofeng APRS K-1 cable. What you’ll need is a Baofeng, Quansheng or similar type handheld with the standard kenwood two prong microphone plug. Let’s talk about how to set the system up. So if you’re following the other points of a solid communications plan, you’re going to be a hard target to catch. A long message, such as a detailed CYRIL report, can be sent in just over four seconds. ![]() Not only that, with some of the wider band modes available, its transmission time is incredibly fast. And because it gets very little use in these bands, most folks won’t know what it is if/when they hear it. FLDigi is normally thought of only for HF radio, but it has a lot of uses on VHF and UHF as well. Either a digital handheld radio, normally a DMR, D-Star or Fusion, or one of the many modes found in a free program called FLDigi. For most, one of two things will come to mind here. So that points us in the direction of digital communications. After all, exploitation is the primary goal of intelligence- how can I use what I’ve collected against an enemy? Students in my Signals Intelligence course have learned exactly how dangerous that can be, creating a massive amount of confusion in a short period of time. But most importantly, the largest drawback of using your own voice over the radio is that if a sophisticated opponent is monitoring you, they now have a voice to record and exploit. Transmitting a long message can take some serious time, is susceptible to interference and/or jamming, and also might not be understood on the other end. First and foremost, in keeping with the basic principles of clandestine radio communications for guerrilla groups, we’ve got to keep our time on the mic short and transmitting power low, and if at all possible, using a directional antenna such as my small UHF Yagi on a simple camera tripod. ![]()
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