Communication can take many forms, whether verbal, written, or conveyed via body language. Each of these conforms to a syntax and a set of rules that are often influenced by culture and tradition. Radio, is no different in this respect, in that it has it’s own syntax, rules, and culture.
This article is intended to cover some of the technical basics of Radio Communication, as well as some of the syntax, rules, and cultural norms, before beginning, there is one caveat, this article is written by someone from North America, who is a native English speaker, other regions and those fluent in other languages may have different syntax, rules and culture, again, this is just an introduction.
Technical Terms
Radio is inherently a technical subject, and there are a large number of terms that are rather unique to radio that make up the basic lexicon. It is important to define these first, so the rest of the article makes sense.
Band – a range of frequencies that are used for communication. Many radios are only capable of transmitting on a relatively narrow set of frequencies, and these frequencies may have common features, so they are often referred to in this way. A band will either be expressed as a frequency usually in megahertz, or in meters which refers to the wavelength.
Radio – it is important to note, a radio can be a transmitter, a receiver, or a transceiver.
Bandwidth – the range of frequencies the transmitter can transmit and the receiver can receive, this can be thought of as what range of audio can be transmitted and received, so how low and high of a pitch without distortion or clipping.
FM/AM/SSB – Frequency Modulation usually has the most bandwidth and the best audio, however it is best suited to higher frequencies. Amplitude Modulation still has good audio quality, but uses significantly less bandwidth than FM. SSB or Single Side Band is a refinement of AM which uses even less bandwidth but often allows a radio to transmit at higher power with the narrower signal. It is worth noting there are upper and lower Side Bands.
CW – “Continuous Wave” is used for what most people would recognize as Morse code. It does have wider applications using Digital Modes. Compared to FM/AM/SSB CW uses the least bandwidth and allows the transmitter to turn more electrical energy into signal than any other mode.
Digital Modes – There are two common uses of digital modes, those that use one of the above audio modes to transmit data, and systems such as DMR and P25 which use data to encapsulate voice.
Simplex – Most people are familiar with this mode of operation from cheap handheld walkie talkies, the signal is transmitted and received on the same frequency.
Repeater – A repeater is a somewhat more complex device that consists of a receiver, a transmitter and some specialized hardware that allows the machine to receive a signal on one frequency, and simultaneously transmit it on another. The difference between the transmit and receive frequency is called the Split. Repeaters are usually elevated on the tops of mountains or buildings and provide Line of Sight coverage for an area. Cross Band repeaters will have much greater spacing between the transmit and receive frequencies and are usually less complex and may be built into a single radio.
Linked System – Linked systems are groups of repeaters which will not only receive and transmit locally, but may be connected to other repeaters in other places via the internet or radio links allowing significantly wider coverage.
Line of Sight – Radio at higher frequencies tends to act more like light, you can usually see light through trees and brush, just not as well. Radio signals behave similarly.
Call Sign – An entire article could be written about the nomenclature and use of call signs. In general, the two most common types of call-signs are ITU-R in the US these are assigned by the FCC, or pseudonymous names taken by their users. In the case of ITU-R call signs they are distinct and assigned by a licensing authority, pseudonyms are chosen by their user and are sometimes duplicated.
Voice Procedure – Again, a complex topic that will only get the most cursory of introductions here. VP is a standard format for initiating and concluding a conversation over the radio, and is a common feature of Nets.
Radio Net – A net is usually associated with an event, either for practice, or to coordinate some other activity, usually an emergency response. There is typically a Net Control operator, who will take requests from Stations (operators/users) and then service that request (answer the question, provide information, elevate a request to a higher level, share information with other stations etc). It is a very valuable technique but requires practice and relies heavily on Voice Procedure.
Use Considerations
Since the terminology is out of the way, more will certainly be added, however hopefully the meaning of the words can be gleaned from inference. Rather than dividing things into the types of equipment available, starting small, and getting bigger is the organization method chosen.
Tactical Concerns – When most consider radio communications, tactical communication is usually the first thing that come up. Putting a small handheld radio on your plate carrier, backpack or LBE somewhere is always a good way to look cool, and looking cool is sometimes pushed ahead of more practical considerations.
A quick admonishment, one of the most important investments you can make to go with your radio is a pouch or a case, or some other way that will guarantee you do not lose your radio, or allow others to gather information by seeing the front panel of your radio, which often displays the frequency or the name of the Net. If you lose your radio, frequencies, codes, and other information will need to be changed and altered, sometimes this is not a big deal. Other times it is A VERY BIG DEAL. Buy a radio, buy a hand mic, buy or find a pouch that holds your radio securely, test your equipment out and make sure you don’t lose it. Also, dummy cord the radio to your LBE.
With that out of the way, more there is more important business to attend to. Small handheld radios that are useful for this purpose can have a few different attributes, CB, MURS, GMRS/FRS, Part 90, and Part 97 radios (this references the Federal Codes that gives the FCC authority over these portions of the spectrum), have different uses, CB handhelds are usually very bulky but can be very useful for if you need to interoperate with truck drivers. However, CB is power limited, AM only (sometimes SSB) and often has problems with jamming. Over-all CB is so limited unless a specific use case is needed, it should simply be avoided.
MURS is like CB, however it is significantly higher frequency starting at about 150-156mhz, it is fairly common to find commercial stores using MURS radios, occasionally their security will use it too. It is FM which greatly improves voice quality and has good propagation properties, but is power limited to 2W. It’s not uncommon to find Pirates using the MURS band, usually they have modified ham radios or Part 90 commercial radios, and may be transmitting at up to 50W. While buying a MURS dedicated radio is not really a good buying decision, there is equipment out there, and the 5 channels available to MURS radios should at least be on the list of frequencies to monitor.
GMRS/FRS, these radios are not as common as they used to be, however some variation of them is frequently encountered. GMRS/FRS is intended mostly for family use, it technically does require a license to operate in the GMRS band however there are many who do not bother with the license. GMRS specifically offers a wider FM frequency allocation and more power (up to 25W) repeaters can also be used on GMRS. Unlike MURS and CB equipment, GMRS is worth considering, even if it does come with some peculiar headaches. It has good propagation, and can be very useful in the squad role, but with a repeater can also act as both a squad and a net radio.
Part 97 radios are those classically referred to as HAM or amateur radios. Depending on a number of factors it’s fairly common to find a Part 97 radio that will transmit on 6m (50-54mhz), 2m (144-148), 1.2 (220mhz), and 70cm (430-450). These radios will often have really desirable features such as wide-band receive and may be able to receive AM as well as FM. These radios come with some very major advantages over every other radio mentioned so far, the are frequency agile (they don’t use fixed channels), are designed to talk to repeaters, have swappable antennas, etc. In the author’s experience there are two major caveats: Cost, Licensing, and Battery life.
Many ham radios have been pushed to be smaller than is practicable, and often have strange form factors. Sometimes the capabilities of the radio make up for deficiencies in other places. Looking at the features and costs is an important part of choosing a radio, this also includes the complete ecosystem of programming cables, antennas, batteries, and spare parts.
Lastly, there are Part 90 radios, these are most often referred to as commercial radios, and have a feature set that overlaps with Part 97 radios, but may be deficient in some areas. Part 90 radios are most often single band, however more of them are available with two or more bands, but costs grow significantly. Because commercial radios have so many applications
The original Baofeng UV5R was a Part 90, however it has been reclassified as a Part 97 after having the range which it can transmit limited. Further discussion of Part 90 Radios will be reserved for later in this article.
Tactical and Area Operations – while still staying in the VHF+ portion of the spectrum (>150mhz) repeaters and mobile are the next step up, usually having larger antennas, they may be purpose built and strategically located to give the widest area coverage possible. However, as was noted in the Terms section, cross band repeaters can be used tactically by being mounted in vehicles, or can be small enough to be deployed by a few people in a few minutes.
A repeater is almost always the purview of ham and commercial radios, since this work is geared towards neophytes, a conventional repeater is likely out of the reach from a technical and cost perspective of all but the most dedicated. These systems tend to be purpose built, require licensing and the consent of the coordination bodies in a region. Learning what repeaters are available in an area and how to use them is the simplest path to acquire skill needed to one day own and operate a repeater. That said, cross band repeat is well within the capability of the newbie, and is a feature built into many dual band mobile radios.
Digital Radio and Encryption – This is one of those topics everyone wants to know about, however it’s such an expansive topic, it can be difficult to find a beginning. Of the above radios we’ve talked about thus far, Part 90 is the only type in which encryption is legally allowed. However, in many cases, using a digital radio even without encryption may be a sufficient barrier to entry for many eavesdroppers. The two most common digital modes available are DMR (Digital Mobile Radio, originally a Motorola standard), and P25, which was standardized by a consortium of radio manufacturers and is the nominative standard in digital radio. DMR offers the lowest barrier to entry for encryption, unlike P25, DMR can have keys loaded from software when the memory is being programmed. This is a significant advantage as it does not require a dedicated hardware device called a KVL (Key Value Loader), however it comes at the expense of fairly easy to break encryption. For those interested, DMR most often uses 48 or 64 bit DES encryption (I’ve seen as low as 32 in some radios), in 2001, breaking 40 bit DES was possible in under 2 minutes.
By contrast, P25 radios usually have a dedicated module inside them that handles all the cryptographic processes. However, this board usually costs $1-200 as of this writing, the radio it goes in to may cost another $300-6000 (yes, thousand) depending on features, capabilities etc. Additionally, in order to load new cryptographic keys into the radio a KVL, or some rather advanced infrastructure must be set up. Even architecting such a system usually requires a dedicated team of full time individuals.
A final note on DMR, DMR does have one very large advantage in the ham radio context, in that there are very large networks that connect very wide areas and will pass DMR traffic between multiple repeaters provided users are all tied to the same talk group. This gives DMR a very significant advantage at the cost of a lot of complexity. Also, DMR radios are not particularly expensive, and units like the MD-380 and 390 are in the sub-$150 range. It’s worth noting, that DMR radios are capable of talking to conventional radios as well.
Wide Area Communications – At frequencies lower than are really useful for anything above there is the HF spectrum. This is usually best thought of as 30mhz and lower (~10m). While the 10m band shares some properties of both the VHF and the HF band, it tends not to be used in that way very often.
Most wide area communications are going to happen on HF, in either AM or SSB, maybe CW if someone is really dedicated, however any of these transmission modes can be used fairly easily with digital programs like fldigi which is a program that will use any HF radio’s audio input to transmit in a number of digital modes, using an AFSK input. Any of these digital modes, would allow a user to communicate with another station by typing a message into a keyboard, and “sending” over the radio. If combined with the proper hardware, this will key (tell the radio to transmit) the radio, and then send some warbling over the air where it can be received and decoded by another computer, attached to a radio. In many cases, if one-way communication is acceptable an RTL-SDR dongle can be used as a receive only radio, and can be a listening station capable of receiving, storing, or decoding the messages which can then be forwarded in some other way.
FLDIGI is a more than just a single program, but something of a suite of programs that provide a significant amount of service and capability. Even without access to an HF radio, FLDIGI can be used to send digital messages much faster over VHF and UHF links by selecting a higher baud rate. Also, since FLDIGI operates as an audio program, experimentation can be done simply using the built in speakers and microphones in most laptop computers. Give it a try!
Just Listening – That old saying “you were born with one mouth, but two ears” has a lot of merit and is actually a peculiar skill when it comes to radio. Being able to scan the airwaves, determine what a signal is, receive it, decode it, and determine what it means may be a remarkably valuable skill in the future, and it’s one that can be undertaken with the bare minimum of hardware.
Several years ago someone determined that a particular brand of USB receiver dongles that was intended to receive European digital TV contained a set of chips that also made them very capable receivers when combined with the right software. Much time has passed, and there are now very good, nearly professional products available for very bargain basement prices. A DTV-B dongle can still be purchased for a few dollars, however RTL-SDR now makes very professional dongles that are optimized for receiving and analyzing signals, when combined either with SDR-Sharp (PC, Mac, Linux) or SDR-Touch (Android).
Just listening allows the reception of satellite imagery from NOAA and METEOR weather satellites, as well as the ability to monitor a number of frequencies from the haunting sounds of Numbers Stations, to the Communist rhetoric of Radio Havana, Christian Broadcasts towards South America, and International News from ABC (Australia), NHK, and others which still broadcast in the short-wave band.
Conclusions and Next Steps
While great care was taken not to present this topic in the deep exquisite detail that might give the reader the perception that this is less of a skill-set and more an eldritch horror that sprung from the minds of Marconi and Tesla, that was entirely unintentional. It is a complex topic that deserves complex answers, but with all things, doing is a more practical means than reading.
The first step, would be to get some variety of Baofeng (this is now the generic term) from either Aliexpress, or Banggood, yes, it is available from Amazon, however there seems to be stricter control, and the transmit frequencies are clipped to either GMRS or the Ham bands. The unclipped versions (Part 90) will typically have a transmit range of 117-174mhz and 400-520mhz. (400-480 is also common), a programming cable (look for one with the CH340 chipset, it usually says), a hand mic, and maybe an antenna upgrade, and a larger battery. Download ChiRP, learn to program the radio, look at the Band Plans. Without a license, stick to using MURS and GMRS/FRS, buy two radios and try them out with the help of a friend.
After building up some familiarity and skill, consider getting an amateur radio license. The additional license greatly opens up new opportunities to learn how to use repeaters, and consider buying a mobile radio with cross band repeat. It’s only a matter of time before the skills to use DMR radios is within reach, and higher.
The most important aspect of radio, is to acquire these skills now. Don’t buy all the gear, stick it in a closet, and then wait for the day you really need it to pull it out and start reading the manual.
