Communications: Bringing People Together – Part 3, by Tunnel Rabbit

(Continued from Part 2. This concludes the article.)

Without suitable commo, an extended and layered defense is less possible, or less effective. Lacking the ability to coordinate with a small community diminishes the ability to perform job number one: security. While Ham radio is a good thing when we need to talk far and wide, it is commo with our neighbors will be more important to us. At the very least, buy a Slim Jim (not a j-pole) from KB9VBR, or any omnidirectional antenna that is tuned for GMRS, or 464.500 Mhz. With that, you can for sure talk to neighbors up to a mile away on a Baofeng UV-5R as a sort of base station for the neighborhood. By ordering a Slim Jim from a small shop, we can specify a center frequency of 464.500, for GMRS. Use only FRS/GMRS channels 1-7, and 15-22 to talk on this antenna. GMRS/FRS radios are almost ubiquitous. I would also buy a box full of the least expensive GMRS/FRS to hand out, such as these: Cobra FRS/GMRS 16-Mile CX112 2 Way Radio Long Range Walkie Talkie.

Brevity Codes

Because GMRS handheld transceivers are literally everywhere, COMSEC (Communication Security) could be a real problem. Undisciplined traffic should be kept on the FRS channels 8 thru 14 because the ERP (read: actual power out) is limited to no more than 1/2 watt. The use of scramblers is illegal on GMRS, but there are older models of Midland Extra Talk, models that begin with the MXT designation in the model numbers that came with a scramble feature. After a decade, the FCC finally discovered what Midland offered, and ordered this feature to be withdrawn. It was illegal. The early MXT handheld models also transmitted with 3.5 watts, which is over the legal limit. A low power transmission that is also scrambled adds a layer of security and improves COMSEC within a community that does not otherwise have the ability. However, these older Midland transceivers were and are popular with hunters and are still out there. The use of brevity codes would be wise addition to your Signal Operating Instructions (SOI).

I refer to the excellent article by ShepherdFarmerGeek as a good source on this topic.

We can use simple encryption as recommended for most of our radio traffic, or we can use sophisticated digital encryption for sensitive traffic, yet no encryption, except a One Time Pad (OTM), is actually secure. We can buy a One Time Pad generator from Ready Made Resources, but many of us can only afford a manual version. Regardless, most persons will not be up to the challenge of using complicated codes, and sophisticated equipment, even if they could afford it. Therefore a brevity code that is not only easy to use is the best choice, and is also adequate security for a low-power community radio net.

The Old 10 Code

The recommendations made by ShepherdFarmerGeek are practical. A simple brevity code would be adequate for most occasions. Prior to encryption technology, brevity codes were successfully used. A classic example of a brevity code is the old ’10’ code used by CBers back in the 1970s and this continued to be used by police and sheriff’s departments for decades thereafter. It is effective yet simple enough to use. For example, if we heard this over the air: “10-21 for a 13 prior to 19”, few if any these days would have any idea of what was said. The ’10’ code is no longer in use, and mostly forgotten, but it works. And I remember it! Keeping a brevity code simple is where it is at. Keep the transmission business-like, to the point, and as short as possible, and listeners will not be able to glean much. 5 seconds or less, then say ‘break’, pause for a second, and then continue.

Inexpensive and simple to operate radios that most have, that are not digital and offer no encryption are for the most part plenty good enough if used properly. And most importantly useful, because like common mags and ammo, these common radios are common. Radios with scramblers and digital encryption would be helpful, yet with complex technology, we could also have a false sense of security, and could fail to use other necessary security improving practices. We could become lazy and undisciplined believing our expensive encrypted transmissions make us totally secure. And we might talk longer and more often than we should, far and wide using high power, and we could be DFed. A motivated listener could, at the least, establish a pattern of life without understanding the content. The military calls this Traffic Analysis.

Using the lowest power setting that makes communication possible is essential. Transmitting no longer than 3-5 seconds at a time to defeat scanners, should also be a rule in your SOI. We can also use the dual montior feature found on Baofengs to talk using two different frequencies (split frequency), so that scanners will likely hear only one side of the conversation. There can be thousand of different split or dual-frequency combination across many radio services. Better yet, if they cannot hear me, then the odds of them breaking the code are lower. A directional antenna, with a high front to back ratio, makes this much more likely. A good 2-meter breakdown portable version from Elk Antennas can be purchased from Ready Made Resources. Unfortunately, it is available only for 2 Meters.

Check with Arrow Antenna for a breakdown yagi for GMRS that would be compact enough to carry. A Moxon for GMRS is tiny in comparison. A good yagi for the MURS band can be purchased on eBay, and a yagi for GMRS and MURS can be custom ordered through Arrow Antennas: 2 meter yagis144-148 MHz 2 Meter Amateur Ham Radio Yagi Base Antenna Diamond A144S10.

NVIS and Short Skip Propagation

I would also use Near-Vertical Incidence Skywave (NVIS) propagation for HF when possible. There will likely be several HF sets found in a community. Keeping the NVIS dipole closer to the ground attenuates the signal, and lowers the noise level. A dipole for 160 meters installed at the fence post level can be good enough for local stations, or we can use the ground wave only. FCC satellites reportedly can not handle 160 meters well, because of the very long wavelength. The ground wave can travel 25 miles if unobstructed. Use mountains, and bodies of water to attenuate a ground wave. Use time of day, the rise and setting of the sun to attenuate the skywave or short skip signal to the east or west.

For NVIS, 40 and 80 meters is used, primarily for practical reasons. Few will use 160 meters. Most will not have HF, and fewer will use Short Skip, or NVIS propagation, fewer still will use 160 meters, and even fewer still will use the lowest power possible. As there are 280,000 possible frequencies on HF, good luck trying to listening in. Perhaps only the ground wave can be used locally during daylight hours. That could be advantageous. A valley could contain most of the ground wave signal.

We should learn about NVIS propagation for the simple fact that when the repeaters go down, lost over time, lost to an EMP, or declared illegal, this could keep nearby regions, or a mountainous community connected. Sadly, no one in my part of the country is interested, and that is because UHF/VHF is not only common, it is more convenient, and more reliable, yet the range is short without repeaters. Crossband repeater mobile transceivers could be used, and there are inexpensive low-power commercial and DIY repeaters that could be assembled quickly and easily. However, if the threat conditions are bad enough, NVIS (Short Skip) propagation could be necessary. At least understand how this works. Setting up a simple dipole for NVIS is very inexpensive and easy.

Some articles on NVIS, that might be of interest:


To reiterate and close, low-tech style of ‘secure’ radio uses techniques that have been proven to be effective in modern battlefields. High-level encryption combined with frequency hopping and low power in the 900 Mhz band would be wonderful, yet not useful for a community. We should consider that the ability to make our own antennas opens up new opportunities of many kinds. Antennas can be considered, by a serious radio guy, to be like golf clubs. If I am playing against Tiger Woods, I’d better have a full set in my bag. Even if I cannot do much more, at least antennas are my ‘bag’, and there are lots of antennas in my bag.

Of course, I do not disclose all of what I could do, yet do recommend adding at least one directional antenna to your gear. Also consider that any layer of low level of security is beneficial, and security via obscurity, that is, using off the beaten path frequencies, propagation techniques, and unusual modes for a frequency, such as SSB on MURS, adds additional layers of low tech security via obscurity. And, if I am hard to hear, then they are less likely to understand what I am saying. Low power is the way to roll, and low power through directional antennas are a killer combination. I cannot make a radio, but I can make specialized antennas in quantity, and there is my advantage.

If we use high gain directional antennas with a narrow footprint between two stations, and use the lowest power setting possible, it is more difficult to intercept, even if we are using a common frequency such as GMRS or in the 2 Meter band. If we can operate on a quiet part of the 70 cm band, or on MURS, providing another layer of obscurity. For those looking for convenience, purchasing a license from the FCC for our own frequency so that high power transceivers can be used by a small community, would be easier than attempting to get everyone on board with a Tech license. For rural areas, simply get a GMRS license, and others without the GMRS license can join you on low power transceivers. Or we could do both!

This is serious business. If any of my recommendations are in error, I would invite correction. We can learn better, together. Without a small community to support individual families, the odds of survival are much lower. For those who are ready for more sophisticated techniques, I refer you to

List of Links

If new to the topic, here are some low-cost GMRS and MURS Transceivers to Consider:

High Power, Lower Cost, GMRS Mobile Transceivers

Radioddity DB25-G GMRS Mobile Radio 25W Two Way Radio Long Range Quad Watch

Midland Authorized Reseller MXT400 MicroMobile 15 Channels 40W Two way Radio

Low Cost, 5 watt, repeater capable, Preprogammed GMRS Handhelds

Baofeng UV-9G 5W GMRS Radio IP67 Waterproof Repeater Capable NOAA V/UHF Scanner

(Note: This has a detachable antenna and can be attached to an external antenna.
BAOFENG UV-5X GMRS Radio Repeater Capable Long Range Two-Way Radio NOAA 2Pack

Low Cost, GMRS/FRS, Low Power Handhelds

(4) COBRA 22 Ch FRS/GMRS Walkie Talkie 2-Way Radios with One Y split cable (A3)

Low Cost, Preprogammed MURS Handheld Transceivers

MURS Radio Retevis RB38V Walkie Talkie Long Range NOAA Outdoor 1500mAh

Retevis RT27V MURS VHF Walkie Talkie Long Range Two Way Radio 1100mAh USB Charge

Low Cost, low power repeaters using handheld transceivers

I would consider these, not for long-term use as the duty cycle of the Baofeng is very short, especially if the power setting was on high. for longer-term use, only if the Baofeng was set on low power, and the transceivers shielded and antennas separated by at least 6 feet, or directional antennas used, and it was set up as a cross band repeater, say from MURS to GMRS. I would use this kind of thing for special occasions only such as to reach a particular station, and not as a repeater for a community.

Surecom SR-629 2in1 Duplex Cross Band Radio Repeater Controller with Radio Cable

Two Way Relay Box K Port Repeater For Baofeng UV-5R BF-88S Kenwood Walkie Talkie

Lowest cost cross band repeater in a 10 watt handheld

TYT TH-UV8000D Cross band Reapeater Amateur Radio 10W Dual band Ham RadioLow Cost Mobile Transceiver, 40/50 watts, with Cross Band Repeat
Note: This could serve a small community on low power.

AnyTone Dual Band Transceiver VHF UHF AT-5888UV Two Way and Amateur Radio

Use this antenna dual band J-pole, MURS/GMRS to use the cross-band repeat of the Anytone AT5888uv. Arrow Antenna. Open Stub J-Poles.

Moxon Antennas are available at Sal Electronics.