Add paragraph about restricted vocabulary benefits.
Radiotelephony procedures encompass international regulations, official procedures, technical standards, and commonly understood conventions intended to ensure efficient, reliable, and inter-operable communications via all modes of radio communications. The most well-developed and public procedures are contained in the Combined Communications Electronics Board’s Allied Communications Procedure ACP 125(G): Communications Instructions Radiotelephone Procedures[4].
These procedures consist of many different components. The three most important ones are:
Microphone technique—how to say it into a microphone
These procedures have been developed, tested under the most difficult conditions you can imagine, then revised to implement the lessons learned, many times since the early 1900s. According to ACP 125(G)[4] and the Virginia Defense Force Signal Operating Instructions[6]:
“Voice procedure is designed to provide the fastest and most accurate method of speech transmission. All messages should be pre-planned, brief and straightforward. Ideally, messages should be written down: even brief notes reduce the risk of error. Messages should be constructed clearly and logically in order not to confuse the recipient.”
Voice procedure is necessary because:
Speech on a congested voice net in battle must be clear, concise and unambiguous. To avoid interference between speech and data, it will often be expedient to assign the passage of data traffic to logistic or admin nets rather than to those directly associated with command and control.
It must be assumed that all transmissions will be intercepted by a portion of the civilian population. The use of a standard procedure will help reduce the threat of spreading rumors or creating panic among those uninvolved in an emergency response.
Some form of discipline is needed to ensure that transmissions do not overlap, if two people send traffic at the same time, the result is chaos.
I'm going to teach them in a different order, because before you talk on a two-way radio, you need to learn how to talk differently; then you need to learn how to talk into a microphone, and then you need to learn the specialized language used for radiotelephony.
You need to learn how to talk differently because two-way radios reduce the quality of human speech in such a way that it becomes harder to understand; you need to learn how to talk into a microphone because doing so incorrectly can make it nearly impossible for you to be understood; and you need to learn the specialized language that has been refined over more than 100 years to meet the needs of this specialized communications medium.
There are several main methods of communication over radio, and they should be used in this order of preference:
Procedure words
Standard (predefined) phraseology (for most things in aviation and maritime use)
Plain language dialogue (for things that can't be handled by phraseology)
Formal messages
Narrative messages
Dialogue (normal conversation)
Brevity codes, including Ten-codes, 92 code, Q code, and Z code (to be avoided at all costs), as these lists of codes are so extensive that it is unlikely that all participants have the full and correct definitions memorized. Many of them are designed exclusively for use in Morse code or teletypewriter use.
The standardized method of determining intelligibility is the articulation score, which counts the number of times a word is heard when another is spoken. The score is only relevant within each defined alphabet.
signal-to-noise ratio (background noise to operator voice)
inverse square law
Low frequencies (vowels) make up the largest power portion of the power of a speech signal, but higher frequencies (consonants) contribute the most to intelligibility.[7]
Know the identification number of your radio unit and that of the other station
Know how to identify yourself when calling
Know what channel the radio should be on
Check your radio at the beginning of each shift
If at a fixed post, know if the radio should remain in the battery charger when not in use.
Be sure there is an adequate supply of backup batteries.
Know if earphones and shoulder microphones should be used
Know how the radio should be carried.
Be certain who else has radios and may be listening to your conversation.
CAP 413:
Before transmitting check that the receiver volume is set at the optimum level and listen out on the frequency to be used to ensure that there will be no interference with a transmission from another station.
Be familiar with microphone operating techniques and do not turn your head away from it whilst talking or vary the distance between it and your mouth. Severe distortion of speech may arise from:
talking too close to the microphone;
touching the microphone with the lips; or
holding the microphone or boom (of a combined headset/microphone boom).
Use a normal conversation tone, speak clearly and distinctly.
Maintain an even rate of speech not exceeding 100 words per minute. When it is known that elements of the message will be written down by the recipients, speak at a slightly slower rate.
Maintain the speaking volume at a constant level.
A slight pause before and after numbers will assist in making them easier to understand.
Avoid using hesitation sounds such as 'er'.
Avoid excessive use of courtesies and entering into non-operational conversations.
Depress the transmit switch fully before speaking and do not release it until the message is complete. This will ensure that the entire message is transmitted. However, do not depress transmit switch until ready to speak.
Be aware that the mother tongue of the person receiving the message may not be English. Therefore, speak clearly and use standard radiotelephony (RTF) words and phrases whenever possible).
Messages should not contain more than three specific phrases, comprising a clearance, instruction or pertinent information. In cases of doubt, e.g a foreign pilot having difficulty with the English language or an inexperienced pilot unsure of the procedures, the controller should reduce the nmuber of items and if necessary these should be passed,and acknowledges, singly.
One of the most irritating and potentially dangerous situations in radiotelephony is a 'stuck' microphone button. Operators should always ensure that the button is released after a transmission and the microphone placed in an appropriate place that will ensure that it will not inadvertently be switched on.
After a call has been made, a period of at least 10 seconds should elapse before a second call is made. This should eliminate unnecessary transmissions while the receiving station is getting ready to reply to the initial call.
Radio call signs are a globally unique identifier assigned to all stations that are required to obtain a license in order to emit RF energy. The identifiers consist of from 3 to 9 letters and digits, and while the basic format of the call signs are specified by the ITU-R Radio Regulations, Article 19, Identification of stations,[9] though the details are left up to each country's radio licencing organizations.
Each country is assigned a range of prefixes, and the radiotelecommunications agencies within each country then responsible for allocating call signs, within the format defined by the RR, as they see fit. The Radio Regulations require most radio stations to regularly identify themselves by means of their official station call sign or other unique identifier.
Because official radio call signs have no inherent meaning outside of the above-described patterns, and other than individually licensed Amateur radio stations, do not serve to identify the person using the radio, they are not usually desirable as the primary means of identifying which person, department, or function is transmitting or is being contacted.
For this reason, functional designators (a.k.a. tactical call signs) are frequently used to provide such identification. Such designators are not sufficient to meet the FCC requirements that stations regularly identify the license they are operating under, typically every x number of minutes and at the end of each transmission, where x ranges from 10 to 30 minutes (longer for broadcast stations).
For the some radio services, the FCC authorizes alternate station IDs,[10] typically in situations where the alternate station ID serves the purposes of identifying the transmitting station better than the standard ITU format. These include:
Aircraft—the registration number (tail number) of the aircraft, preceded by the type (typical of general aviation aircraft); or the aircraft operator nickname assigned by the FAA, followed by the flight number (typical of scheduled airline services).
Land mobile—Name of the station licensee (typically abbreviated), location of station, name of city, or facility served, followed by additional digits following the more general ID.
Land mobile railroad—Name of railroad, followed by the train number, engine number etc.
The United States has been assigned all call signs with the prefixes K, N, and W, as well as AAA–ALZ. Allocating call signs within these groups is the responsibility of the National Telecommunications and Information Administration (most all government stations) or the Federal Communications Commission (all other stations), and they subdivide the radio call signs into the following groups:
Ham station call signs begin with A, K, N or W, and have a single digit from 0 to 9 that separates the 1 or 2 letter prefix from the 2 or 3 letter suffix (special event stations have only three characters: the prefix, the digit, and a one-letter suffix).[11]
Maritime call signs have a much more complex structure, and are sometimes replaced with the name of the vessel or a Maritime Mobile Service Identity (MMSI) number.
Microphones are imperfect reproducers of the human voice, and will distort the human voice in ways that make it unintelligible unless a set of techniques are used to avoid the problems. The recommended techniques vary, but generally align with the following guidelines, which are extracted from the IARU Emergency Telecommunications Guide[12]
Hold the microphone close to your cheek, just off to the side of your mouth, positioned so that you talk across, and not into, the microphone. This reduces plosives (popping sounds from letters such as "P").
Speak in a normal, clear, calm voice. Talking loudly or shouting does not increase the volume of your voice at the receiving radios, but will distort the audio, because loud sounds result in over-modulation, which directly causes distortion.
Speak at a normal pace, or preferably, slower. Not leaving gaps between words causes problems with radio transmissions that are not as noticeable when one is talking face-to-face.
Pronounce words carefully, making each syllable and sound clearly distinguishable.
Adjust the microphone gain so that a normal voice 50 mm away from the microphone will produce full modulation. Setting the gain higher than that will transmit greater amounts of background noise, making your voice harder to hear, or even distorted. Noise-cancelling microphones can assist in this, but do not substitute for proper mic placement and gain settings.
If you use a headset boom microphone, be aware that lower-cost models have omni-directional elements that will pick up background noise. Models with uni-directional or noise-cancelling elements are best.
Do not use voice operated transmission (VOX) microphone circuits for emergency communication. The first syllable or so of each transmission will not actually be transmitted, while extraneous noises may also trigger transmission unintentionally.
If not operating in a vehicle, use a foot push-to-talk switch so that both of your hands are free to transmit.
Always leave a little extra time (1 second will suffice) between depressing the PTT switch and speaking. Numerous electronic circuits, including tone squelch, RF squelch and power-saving modes, need a substantial fraction of that time in order to allow your signal to be transmitted or received. This is especially true of repeaters, which might also have a “kerchunk” timer that prevents brief transmissions from keying the transmitter, and doubly true of linked repeaters, which have multiple sets of such circuits that must be activated before all stations can hear you.
One must also leave gaps between the last station that transmitted and the next station, because such gaps are necessary to let other stations break in with emergency traffic. A pause of two seconds, approximated by a count of "one, one thousand" is sufficient in many conditions.
Similarly, the U.S. military radio procedures recommend headsets with noise-cancelling microphones:
Use of Audio Equipment. In many situations, particularly in noisy or difficult conditions, the use of headsets fitted with a noise cancelling microphone is preferable to loudspeakers as a headset will aid concentration and the audibility of the incoming signal. The double-sided, noise cancelling microphone is designed to cancel out surrounding noise, for example engine noise or gunfire, allowing speech entering on one side to pass freely. The microphone should be as close to the mouth as possible.[4]
Communicating by voice over two-way radios is more difficult than talking with other people face-to-face or over the telephone. The human voice is changed dramatically by two-way radio circuits. In addition to cutting off important audio bandwidth at both the low and high ends of the human speech spectrum (reducing the bandwidth by at least half, other distortions of the voice occur in the microphone, transmitter, receiver, and speaker—and the radio signal itself is subject to fading, interruptions, and other interference. All of these make human speech more difficult to recognize. In particular, because momentary disruptions or distortions of the signal are likely to block the transmission of entire syllables.
The best way to overcome these problems is by greatly reducing the number of single-syllable words used. This is very much counter to the human nature of taking shortcuts, and so takes training, discipline, and having all operators using the same language, techniques, and procedures.[13]
Several radio operation procedures manuals, including ACP 125(G) teach the same mnemonic of Rhythm, Speed, Volume, and Pitch (RSVP):[4]
Rhythm—Use short sentences divided into sensible phrases which maintain a natural rhythm; they should not be spoken word by word. Where pauses occur, the press-to-talk should be released to minimize transmission time and permit stations to break in when necessary.
Speed—Speak slightly slower than for normal conversation. Where a message is to be written down by the recipients, or in difficult conditions, extra time should be allowed to compensate for the receiving station experiencing the worst conditions. Speed of transmission is easily adjusted by increasing or decreasing the length of pauses between phrases, as opposed to altering the gaps between words; the latter will create an unnatural, halted style of speech, which is difficult to understand.
Volume—Speak quietly when using whisper facilities, otherwise the volume should be as for normal conversation. Shouting causes distortion.
Pitch—The voice should be pitched slightly higher than for normal conversation to improve clarity.
According to the UK's Radiotelephony Manual, CAP 413, radio operators should talk at a speed of fewer than 100 words per minute.[14]
According to the Air Force MARS training, you should speak slightly slower and pronounce words more deliberately than in everyday speech, and in a conversational tone and level.[15]
Communicating over a half-duplex, shared circuit with multiple parties requires a large amount of discipline in following the established procedures and conventions, because whenever one particular radio operator is transmitting, that operator can not hear any other station on the channel being used.[16][17][18][19]
Whenever a report or a request is transmitted over a two-way radio, the operator should consider including the standard Five Ws in the transmission, so as to eliminate additional requests for information that may occur and thereby delay the request (and other communications).
There are radio-service specific voice procedures that differ slightly to greatly from these basic procedures (rephrase text or cite Voice procedure article):
Aeronautical mobile service
Voice communications procedures for international air traffic control and communications among airplanes are defined by the International Civil Aviation Organization in Annex 10—Aeronautical Telecommunications, Volume II—Communications Procedures including those with PANS status,[24][25] in Procedures for Air Navigation Services—Air Traffic Management (PANS-ATM, ICAO Doc 4444)[26], and in ICAO Doc 9432 (AN/925) Manual of Radiotelephony.[27]
Voice communications procedures for vessels operating internationally are defined by ITU-R M.1171: Radiotelephony procedures in the maritime mobile service.[28]
The voice calling procedure (sometimes referred to as "method of calling" or "communications order model") is the standardized method of establishing communications. The order of transmitting the called station's call sign, followed by the calling station's call sign, was first specified for voice communications in the International Radiotelegraph Convention of Washington, 1927[29], however it matches the order used for the radiotelegraph calling procedure that had already existed since at least 1912.[citation needed] In the United States, the radiotelegraph calling procedure is legally defined in FCC regulations Part 80.97 (47 CFR 80.97(c)), which specifies that the method of calling begins with the call sign of the station called, not more than twice, [THIS IS] and the call sign of the calling station, not more than twice".[30] This order is also specified by the ICAO for international aviation radio procedures (Annex 10 to the Convention on. International Civil Aviation: Aeronautical Telecommunications.[31]), the FAA (Aeronautical Information Manual[32]) and by the ITU-R for the Maritime Mobile Service (ITU-R M.1171),[33] and the U.S. Coast Guard (Radiotelephone Handbook[34]). The March, 1940 issue of The APCO Bulletin explains the origin of this order was found to have better results than other methods,[35]
MUST give the callsign of the station you are calling, twice (never three times)
MUST follow the callsign with the proword THIS IS
MUST give your callsign once, and once only
Communicate
SHOULD end your transmission with the proword OVER, or OUT, although this can be omitted when using a repeater that inserts a courtesy tone at the end of each transmission.
Stations needing to interrupt other communications in-progress shall use the most appropriate of the below procedure words, followed by their call sign.
All of these break-in procedure words must be followed by your call sign, because that information will help the NCS determine the relevant importance when dealing with multiple break-ins of the same precedence, and to determine the relevance when multiple calls offering a CORRECTION or INFO are received.
Priority
Proword
Signal Type
Use For
Handling
Prosign/OPSIG
1
FLASH
Message precedence
Events that are a grave threat to the nation or a region
FLASH messages are to be handled as fast as humanly possible, ahead of all other messages, with in-station handling time not to exceed 10 minutes.[36] U.S. Government use only per CFR 47. FLASH messages are handled before all three types of international priority signals, including MAYDAY.[37][37]
Z
2
MAYDAY MAYDAY MAYDAY
International priority signals
Lives or property are in danger
Immediate! All radio traffic not actively engaged in assisting the station in distress stops or moves to another frequency. This rule applies on all frequencies allocated to emergency use. On other frequencies, the rule is modified to allow FLASH precedence traffic,[38] because FLASH messages have a similar scope of immediate danger (especially when it is a military communication) and also need immediate responses.
SOSSOSSOS
3
PAN-PAN PAN-PAN PAN-PAN
Urgent situations that are not life threatening
Immediate, unless there is an ongoing Mayday issue. This is considered to be IMMEDIATE precedence traffic.[38] If the condition is medical, use PAN-PAN MEDICAL, PAN-PAN MEDICAL, PAN-PAN MEDICAL.
XXXXXXXXX
4
SÉCURITÉ SÉCURITÉ SÉCURITÉ
Important safety information
Immediate, unless there is an ongoing Mayday or Pan-pan issue. Must be sent as T T T instead of TTT in order to differentiate it from the Morse code symbol for O. This is considered to be IMMEDIATE precedence traffic.[38]
TTTTTTTTT
5
IMMEDIATE
Message precedence
Handling within 30 minutes
IMMEDIATE messages are processed, transmitted, and delivered in the order received and ahead of all messages of lower precedence. They are to be handled as quickly as possible, with in-station handling time not to exceed 30 minutes.[36]
O
6
PRIORITY
Handling within 3 hours
PRIORITY precedence messages are processed, transmitted, and delivered in the order received and ahead of all messages of ROUTINE precedence. They are to be handled as quickly as possible, with in-station handling time not to exceed 3 hours.[36]
P
7
ROUTINE
Handling by the next day
Used for all types of message traffic justifying transmission by rapid means, but not of sufficient urgency to require higher precedence. They should be handled as soon as traffic flow allows, but no later than the beginning of the next duty day.[36]
R
8
CORRECTION
Message handling
Providing a correction to another station
Use to let the Net Control Station know you have a correction for something that the NCS or another station transmitted.
EEEEEEEE
9
INFO
Providing an answer to another station
Use to let the NCS know that you have information relating to a topic or question transmitted by the NCS or another station.
Procedure words are a direct voice replacement for procedure signs (prosigns) and operating signals (Q codes), and must always be used on radiotelephone channels in their place. Prosigns/operating signals may only be used with Morse Code (as well as semaphore flags, light signals, etc.) and TTY (including all forms of landline and radio teletype, and Amateur radio digital interactive modes).
Describe relationship between procedure signals and procedure words, and difference from operating signals.
Procedure words for general use
Proword
Explanation
Prosign/ OPSIG
THIS IS
This transmission is from the station whose designator immediately follows.
DE
UNKNOWN STATION
The identity of the station with whom I am attempting to establish communication is unknown.
AA
NOTHING HEARD
To be used when no reply is received from a call station.
ZGN (military)
NIL
(civilian)
ROGER
This is a method of receipt. I have received your last transmission satisfactorily.
R
OVER
This is the end of my transmission to you and a response is necessary. Go ahead, transmit
K
WILCO
I HAVE RECEIVED YOUR SIGNAL, UNDERSTAND IT, AND WILL COMPLY. To be used only by the addressee. Since the meaning of ROGER is included in that of WILCO, the two prowords are never used together.
OUT
This is the end of my transmission to you and no answer is required or expected.
AR
closing
I am closing my station and going off-air.
CL
CQ
General call to all stations
CQ
OUT TO YOU
This is the end of my transmission to you. I am about to call (or resume a call) with other station(s).
AR
WAIT
I must pause for a few seconds
AS
WAIT – OUT
I must pause for longer than a few seconds.
ASAR
understood
I understand you must pause and I will wait.
SN
FIGURES
Numerals or numbers follow.
n/a
I SPELL
I shall spell the next word phonetically.
n/a
SPEAK SLOWER
Your transmission is too fast. Reduce speed of transmission.
QRS
WORD AFTER
The word of the message to which I have reference is that which follows…………..
WA
WORD BEFORE
The word of the message to which I have reference is that which precedes…………..
WB
ALL AFTER
The portion of the message to which I have reference is all that follows……………
AA
ALL BEFORE
The portion of the message to which I have reference is all that precedes…………..
AB
all between
BN
SAY AGAIN
Repeat all of your last transmission. Followed by identification data means “Repeat………… (portion indicated).”
IMI?
I SAY AGAIN
I am repeating transmission or portion indicated.
IMI
CORRECTION
An error has been made in this transmission. Transmission will continue with the last word correctly transmitted.
An error has been made in this transmission (or message indicated). The correct version is…… That which follows is a corrected version in answer to your request for verification"
EEEEEEEE
C C
CORRECT
Yes, affirmative, you are correct, or what you have transmitted is correct. Because AFFIRMATIVE could be confused with NEGATIVE, always use CORRECT instead of YES or AFFIRMATIVE.
C
NEGATIVE
No, or negative.
ZUG (military)
N (civilian)
WRONG
Your last transmission was incorrect. The correct version is…….
ZWF
DISREGARD THIS TRANSMISSION – OUT
This transmission is in error, disregard it. (This proword shall not be used to cancel any message that has been completely transmitted and receipted.
EEEEEEEE AR
REQUEST TIME CHECK
I am requesting an accurate time check.
QTR
TIME CHECK
I am about to confirm the exact time
TIME
The time I am transmitting is exact as at the moment I said TIME
QTR
weather report?
Weather report forllows
WX
INTERCO
International Code of Signals groups follow (spoken IN-TER-CO)
Whenever you are transmitting and uncertain of how good your radio and/or voice signal are, you should use the procedure words for Plain language radio checks. This is the modern method of signal reporting that replaced the old 1 to 5 scale reports for the two aspects of a radio signal, and as with the procedure words, are defined in ACP 125(F):
The prowords listed below are for use when initiating and answering queries concerning signal strength and readability.
Proword
Meaning
RADIO CHECK
What is my signal strength and readability?
ROGER
I have received your last transmission satisfactorily.
NOTHING HEARD
To be used when no reply is received from a called station.
In the tables below, the mappings of the QSA and QRK Morse code prosigns is interpreted because there is not a 1:1 correlation. See QSA and QRK code for the full procedure specification.
Proword
Meaning
Prosign/OPSIG
LOUD
Your signal is very strong.
QSA5
GOOD
Your signal strength is good.
QSA4
WEAK
Your signal strength is weak.
QSA3
VERY WEAK
Your signal strength is very weak.
QSA2
FADING
At times your signal strength fades to such an extent that continuous reception cannot be relied upon.
Having trouble reading you because your signal is intermittent.
QRK2
UNREADABLE
The quality of your transmission is so bad that I cannot read you.
QRK1
The reporting format is one of the signal strength prowords followed by an appropriate conjunction, with that followed by one of the readability prowords:
LOUD AND CLEAR means Excellent copy with no noise
GOOD AND READABLE means Good copy with slight noise
FAIR BUT READABLE means Fair copy, occasional fills are needed
WEAK WITH INTERFERENCE means Weak copy, frequent fills are needed because of interference from other radio signals.
WEAK AND UNREADABLE means Unable to copy, a relay is required
According to military usage, if the response would be LOUD AND CLEAR, you may also respond simply with the proword ROGER. However, because this reporting format is not currently used widely outside of military organizations, it is better to always use the full format, so that there is no doubt about the response by parties unfamiliar with minimization and other shorthand radio operating procedures.
If the need for the break-in is to pass message traffic and is not a condition covered by MAYDAY, PAN-PAN, or SÉCURITÉ, then one of the message priority precedence words of FLASH, IMMEDIATE, or PRIORITY should be used.[39]
The priority levels described below are derived from Article 44 of the ITU Radio Regulations, Chapter VIII, and were codified as early as the International Telecommunication Convention, Atlantic City, 1947 (but probably existed much earlier).
Radiotelephony communications priority
Order of priority
Simplify calling procedure
Radiotelephony signal
Radiotelegraph signal
1
Distress calls, distress messages, and distress traffic
Informal messages are basically conversational. Formal messages use the 16-line message format and are considered Record Communication, which needs to be logged and archived.
Verbatim: from acp 125H:
Informal messages are those tactical, operational, and service messages commonly sent on user operated nets, e.g. field tactical and air control. These types of traffic tend to utilise a more conversational procedure. Informal messages may contain any element of the basic message format, howver, they will normally only consist of a call, a text, and an ending, i.e. format lines 2, 3, 12, and 15. All elements used are to be in the sequence described in the basic message format, and when used, time groups sent in format line 14 would normally be time of transmission rather than time of origin.
spelling alphabets to overcome voice quality reductions inherent in radio
Rules for spelling
Spelling is necessary when difficult radio conditions prevent the reception of an obscure word, or of a word or group, which is unpronounceable. Such words or groups within the text of plain language messages may be spelt using the phonetic alphabet; they are preceded by the proword “I SPELL”. If the word is pronounceable and it is advantageous to do so, then it should be spoken before and after the spelling to help identify the word.[4]
Rules for Numbers and Figures
When radio conditions are satisfactory and confusion will not arise, numbers in the text of a message may be spoken as in normal speech. During difficult conditions, or when extra care is necessary to avoid misunderstanding, numbers are sent figure by figure preceded by the proword FIGURES. This proword warns that figures follow immediately, to help distinguish them from other similarly pronounced words.[4]
To synchronize time across all stations on a net or other activity, it is first necessary to reference a reliable time source. To support operating without an Internet connection, radio operators should practice with as many of these methods as possible. Ideally, multiple sources should be used simultaneously, because confidence in the accuracy of the time is increased when two or more different sources all agree.
For any permanent location, WWVB radio-controlled clocks or NTP-controlled clocks should be provided in the communications center, so that radio operators not using computers can view an accurate time source. Ideally this should be a model that decodes both the pulse-width modulated and the phase modulated "enhanced WWVB broadcast format" used since 2012. The only consumer-level clock currently available that decodes the phase modulated signal is the La Crosse 14" UltrAtomic Analog Wall Clock.
For any computer connected to a native Ethernet or Wi-Fi network (which does not use a cellular data network as its WAN link), NTP or SNTP should be used, with software that syncs more frequently than Windows' built-in SNTP client. This will be the easiest to configure and requires no additional hardware.
The best way to specify an NTP server is to use the NTP pool system, wherein pool.ntp.org will provide a round-robin selection of official time servers closest to you, based on ping time. This server address works worldwide, but if greater certainty is desired that the automatically chosen server is on the same continent as you, you can use the geographic narrowing, as in na.pool.ntp.org for North America, and us.pool.ntp.org for the United States. If a specific official server is desired, NIST maintains a current list.[41]
For any computer not connected to an Ethernet or Wi-Fi network, a physical GPS receiver should be used, because the hardware is ubiquitous, inexpensive, and will provide 1 millisecond accuracy when used with software that processes the 1PPS signal some GPS units provide.
The ideal GPS receiver should support WAAS, output the GPRMC, GPSGGA, and GPSZDA sentences, and provide a 1PPS on the DCD line feeding into the serial-to-USB chip in the device. As of January 2018[update], the only commercially available USB GPS receiver that provides a 1PPS signal are the Navisys GR-601W, GR-701W, and GR-801W, which were designed at the request[42] of Eric S. Raymond and Dave Taht in order to provide a highly accurate time signal source that is affordable, using consumer-grade hardware. Currently, the GR-701W is available for $50 on Etsy.
The most accurate and stable time on a computer is provided by tying a 1PPS GPS time source or an NTP server to an NTP client that adjusts the speed of the PC's clock. Sometimes called "training the PC clock", this training is not available with SNTP clients, only full NTP clients are able to offer clock training. Those needing this level of time accuracy on Windows should read the article Windows Serial Port GPS/PPS reference clock for NTP[43] for guidance on configuring the complex interaction of Meinberg NTP and the 1PPS GPS receiver.
All other systems should be used only for failover or when NTP and GPS sources are not available, because their accuracy is significantly worse. For example, the NIST Telephone Time-of-Day Service, which provides the WWV audio over telephone lines, has a delay of at least 30 ms (from a landline telephone), but may be more than 250 ms when used over the cellular telephone network; the WWV and WWVB radio broadcasts also suffer ionospheric propagation delays and do not have correction data embedded in their signals, as GPS/WAAS signals do, and when decoded by a software-defined radio and then run through an audio decoder, the delay is unpredictable and may be much larger than 250 ms. However, if an HF radio receiver is the only means of receiving a time signal, it will suffice. Before using these signals, you should read Recommendation ITU-R TF.768-2: Standard Frequencies and Time Signals.[44]
The NIST and USNO dial-up modem services can be used as a less-accurate backup in locations where a telephone line is available. And as a last resort, a radio operator should use the NIST or USNO dial-up telephone voice time services:
+1-303-499-7111 (for the continental United States and the Caribbean)
+1-808-335-4363 (for Hawaii and all other U.S. territories in the Pacific)
– International Electrotechnical Commission (IEC) 61162-2 is harmonized with NMEA 0813 HS
For Windows users, the recommended list of software follows:
BktTimeSync[45] is free and can be configured to use GPS, NTP, or both. However, it does not support the 1PPS signal, so will be accurate only to the nearest second or so.
winacts-32-bit.exe[46] will let you use the NIST ACTS and USNO modem time servers.
For Linux users, the recommended list of software follows:
Stations without the ability to acquire one of the above time signals should request a time check at the start of every shift, or once a day minimum. If your station is part of a net, you should ask the Net Control Station (NCS) for a time check by waiting for an appropriate pause, keying up and stating your call sign, and then using the prowords "REQUEST TIME CHECK, OVER" when the NCS calls on you. Otherwise, you may ask any station that has access to any of the above time signals for a time check.
Once requested, the sending station will state the current UTC time plus one minute, followed by a countdown as follows:
This is Net Control, TIME CHECK WUN AIT ZERO TOO ZULU (pause) WUN FIFE SECONDS…WUN ZERO SECONDS…FIFE FOWER TREE TOO WUN…TIME WUN AIT ZERO TOO ZULU…OVER
The receiving station will then use the proword "TIME" as the synch mark, indicating zero seconds. If the local time is desired instead of UTC, substitute the time zone code "JULIETT" for "ZULU".
Instead of providing time checks on an individual basis, the NCS should give advance notice of a time check by stating, for example, "TIME CHECK AT 0900 JULIETT", giving all stations sufficient time to prepare their clocks and watches for adjustment. A period of at least five minutes is suggested.
Three or more stations in communication constitute a net.[15] Nets operate either on schedule or continuously (continuous watch). Nets operating on schedule handle traffic only at definite, prearranged times and in accordance with a prearranged schedule of intercommunication. Nets operating continuously are prepared to handle traffic at any time; they maintain operators on duty at all stations in the net at all times. When practicable, messages relating to schedules will be transmitted by a means of signal communication other than radio.[49]
In this mode, no station other than the net control station can communicate with any other station, except for the transmission of urgent messages, without first obtaining the permission of the net control station.[50]
Free net
In this mode, any station may communicate with any other station in the same net without first obtaining permission from the net control station to do so.[50]
For conveying messages and information between different locations and levels of command. This is where formal messages are exchanged, so it serves the same purpose as an IARU Traffic net.[51]
Tactical Net
A Tactical Net is established whenever a requirement exists to coordinate the actions of deployed units in a mobile or portable environment. The primary purpose is to support deployed units, and it would generally be conducted from an Incident Command Post[51]
Liaison Nets
Anytime the host of the net is involved with other agencies.[51]
Contingency Nets
Communications managers at each level have the authority to initiate stand-by nets, placing radio stations within their span of control on alert to be available for developing conditions that may result in event activity.[51]
Training Net
Communication managers may establish nets for training purposes, such as to teach radio procedures to novice operators, or new skills and procedures to more advanced operators.[51]
Resource net
Used for incoming operators to receive assignments, and to be reassigned as needs changed. Can also be used to locate equipment and operators with special skills. More than one resource net may be created in large-scale events if the traffic warrants.[52]
Logistics net
A type of resource net specifically tasked with logistical needs separate from those of the communications teams.[52]
Tactical net
Handle the primary on-site emergency communication.[52]
Information net
Used to disseminate official bulletins, answer general questions, etc.[52]
A Traffic Net that handles messages among those people impacted by or in the vicinity of a disaster and their friends and family living outside the disaster zone.[52] These nets usually handle messages between concerned friends, families and persons within and outside of the disaster area where legally permitted. In Amateur radio, these nets are conducted with the National Traffic System and exchange ARRL Radiograms.
A net manager is the person who supervises the creation and operation of a net over multiple sessions. This person will specify the format, date, time, participants, and the net control script. The net manager will also choose the Net Control Station for each net, and may occasionally take on that function, especially in smaller organizations.
Nets can be described as always having a net opening and a net closing, with a roll call normally following the net opening, itself followed by regular net business, which may include announcements, official business, and message passing. Military nets will follow a very abbreviated and opaque version of the structure outlined below, but will still have the critical elements of opening, roll call, late check-ins, and closing.
A net should always operate on the same principle as the inverted pyramid used in journalism—the most important communications always come first, followed by content in ever lower levels of priority.
Net opening
Identification of the NCS
Announcement of the regular date, time, and frequency of the net
Purpose of the net
Roll call
A call for stations to check in, often times from a roster of regular stations
A call for late check-ins (stations on the roster who did not respond to the first check-in period)
A call for guest stations to check in
Net business
Optional conversion to a free net
Net closing
Each net will typically have a main purpose, which varies according to the organization conducting the net, which occurs during the net business phase. For amateur radio nets, it's typically for the purpose of allowing stations to discuss their recent operating activities (stations worked, antennas built, etc.) or to swap equipment. For Military Auxiliary Radio System and National Traffic System nets, net business will involve mainly the passing of formal messages, known as radiograms.
Net opening
Specify mode of net
Remind stations of standard break-in procedure words?
Remind stations of priority rules?
Roll call
abbreviated call sign usage
Types of calls
Single call (call to one station)
Multiple call (call to two or more specific stations, by listing each call sign)
collective calls (group calls)
a collective call is a call to the entire net (Net call sign)
a limited collective call is to a subset of the net
collective call sign
individual call sign
call sign allocation plan
Exempt call (collective call where one or more stations are not required to answer)
Operational status of roadway transportation network, especially pre-defined emergency supply routes critical for response and recovery efforts.
Rail Network (including bridges)
Operational status of railway transportation network
Navigable Waterways
Operational status of navigable waterway transportation network.
Air Transportation Infrastructure
Operational status and capabilities of airports and airspace.
Area Command Locations
Location and activation status of area command (often overlaps with state emergency operation centers)
Staging Areas
Location, status, and type of staging areas, which are used to temporarily store resources required for emergency response and recovery
Points of Distribution (PODS)
Location, type, and operation status of PODs for distribution of food, water, and other bulk comodities
Joint Reception, Staging, Onward Movement and Integration (JROSI) Sites
Location, status, and points of contact for JRSOI sites, established by the State branch of the National Guard to coordinate emergency response efforts
Injuries and Fatalities
Confirmed number of injuries and fatalities
Shelters
Location and operational status of sheltering facilities
Communications
Operational status of landline, cellular, and internet access
Hospitals
Operational status of hospitals, including beds available, supply status, etc.
Example from FM 24-19 (starting at page 5-4):
NET THIS IS NCS THIS IS A DIRECTED NET.
OF WHAT PRECEDENCE AND FOR WHOM ARE YOUR MESSAGES OVER.
U.S. Army Field Manual ACP 125(G) has the most complete set of procedure words used in radio nets:[4]
Proword
Explanation
Prosign/ OPSIG
NET NOW
All stations are to net their radios on the unmodulated carrier wave which I am about to transmit.
ZRC2
THIS IS A DIRECTED NET
From now until further notice this net is directed.
ZKB
THIS IS A FREE NET
From now until further notice this net is free.
ZUG ZKB
BRAODCAST YOUR NET
Link the two nets under your control for automatic rebroadcast
STOP BROADCASTING
Cut the automatic link between the two nets that are being rebroadcast and revert to normal working.
REBROADCAST YOUR NET
Commence automatic rebroadcasting of your other net onto this frequency
STOP REBROADCASTING
Cease rebroadcasting your other net onto this frequency
QRT
ASSUME CONTROL
You will assume control of this net until further notice
ZKD
I AM ASSUMING CONTROL
I am assuming control of this net until further notice
ZKA
REPORTING INTO THE NET
Calling station is joining an established net or returning after having been closed down.
REPORT STRENGTH AND READABILITY
Report to me how you are receiving all other stations on the net
ANSWER AFTER
The station called is to answer after call sign……..when answering transmissions.
ZGO
USE ABBREVIATED CALL SIGNS
Call signs are to be abbreviated until further notice.
USE FULL CALL SIGNS
Call signs are to be sent in full until further notice.
USE ABBREVIATED PROCEDURE
As conditions are normal, all stations are to use abbreviated procedure until further notice.
USE FULL PROCEDURE
As conditions are not normal, all stations are to use full procedure until further notice.
SILENCE (Repeated three or more times)
Cease transmissions on this net immediately. Silence will be maintained until lifted. (Transmissions must be authenticated by use of a self authenticated system, codeword, etc.)
HMHMHM
SILENCE LIFTED
Silence is lifted. (Transmissions must be authenticated by means of self authentication system, codeword, etc.)
ZUG HMHMHM
CLOSE DOWN
Stations are to close down when indicated. Acknowledgments are required
Coordinated Universal Time Modern world-wide standard date/time format that sorts in chronological oder (ITU-R TF.460-4)
The U.S. Military's Date-time group must not be used except where required in radiograms because it has an order that is confusing to those not trained in the use of the 16-line message format.
Sending and receiving messages over voice radio circuits is a task that requires adherence to well-established and long-tested procedures in order to deliver the messages quickly, accurately, and reliably. Such messages are called Radiograms.
Both of these message handling procedures are detailed and complex enough to justify them being considered a separate branch of radiotelephony procedures. For the transmission of 16-line radiograms by voice, the current procedures are contained in ACP-125: Communications Instructions, RadioTelephone Procedures.[4]
Messages are handled (received, transmitted, and delivered) by a Message center, the operations of which have variously been defined in:
FM 24-5 (message center procedures)
FM 24-17 Tactical Communications Center Operations
TM 11-450 (training specifications for signal specialists)
TM 11-454 The Radio Operator
TM 11-490-2 Army Communications Facilities Telecommunications Center Operating Procedures
AR 105-31 Message Preparation
MOS 72E Combat Telecommunicatios Center Operator
Method of sending:(FM 24-5)
Receipt or R method, in which both the transmitting and receiving stations normally may use their transmitters in order to effect delivery of messages, and in which the transmitting station usually requires and obtains a receipt for each message thus transmitted. This is the normal method.
Broadcast or F (Fox) method in which several stations are addressed, but are not permitted to receipt to the transmitting station for the messages thus received. (is this "DO NOT ANSWER"?)
Intercept or I method in which, by prearrangement, messages intended for a silent station are exchanged between two regularly operating stations.
Executive (IX) method, which is used for messages which require the execute sign to indicate the instant of execution.
A 16-line message appears like this when recorded on a typewriter or computer text file:
CALLED_STATION THIS IS CALLING_STATION MESSAGE NUMBER 051
ROUTINE TIME 221855Z APR 2015
FROM ORIGINATION PLAIN LANGUAGE ADDRESS
TO ADDRESSEE RI AND PLAD INFORMATION ADDRESSEE 2 RI AND PLAD
GROUP NO COUNT
BREAK
UNCLASSIFIED THIS IS A TEST MESSAGE
BREAK
OVER
The format is composed of the following format lines, and in addition to the structure of each line, there are well-defined procedures for conducting voice message handling nets in order to transmit these radiograms efficiently.
Format Line
Voice Radiogram (ACP-125)
1
line 1 is not used in voice radiograms
2
CALLED_STATION THIS IS CALLING_STATION MESSAGE NUMBER 051
4
line 4 is not used in voice radiograms
5
ROUTINE TIME 221855Z APR 2015
6
FROM ORIGINATION PLAIN LANGUAGE ADDRESS
7
TO TO ADDRESSEE RI AND PLAD
8
INFO INFORMATION ADDRESSEE 1 RI AND PLAD
INFORMATION ADDRESSEE 2 RI AND PLAD
9
10
11
12
13
BREAK
14
line 14 is not used in voice radiograms
15
line 15 is not used in voice radiograms
16
OVER
Legibility of handwriting (Military block printing)edit
Military block letter printing diagram from ACP 125(F)
When writing anything on paper related to communications, you should use the specific hand lettering form known as military block printing. This form originated during or before World War II, but is still published in U.S. Government publications in the 21st Century.
These letter forms must be used on all message forms and station logs, to ensure that all radio operators can easily read all record communications. Even if you think all the other radio operators you work with can read your handwriting, these forms must be used so that anyone inside or outside the organization can read the communications records during After-Action Reviews.
There are a large number of emergency frequencies, spread across different bands and radio services. The most important ones that should be monitored during a disaster include:
156.800 MHz is the international radiotelephone distress, urgency, safety, call and reply frequency for ship, public and private coast stations. G3E emission.
If equipped with Digital selective calling, initiate a DSC distress call on 2187.5 kHz on MF, or channel 70 (156.525 MHz) on VHF
Tune to the non-DSC emergency frequency on the same band you sent the DSC call on: 2182 kHz on MF, and channel 16 (156.800 MHz) on VHF to wait for acknowledgement of the call.[58]
HF DSC channel 6215 kHz is monitored by U.S. Coast Guard coast stations 24x7[59]
HF DSC channel 8291 kHz is monitored by U.S. Coast Guard coast stations 24x7[59]
8364 kHz— International CW/MCW lifeboat,life raft, and survival craft[60]
Aeronautical service
121.5 MHz GARD frequency for old-style distress radiobeacons, but all U.S. civilian pilots are required by the FAA to monitor this frequency whenever it is possible to do so..
243.0 MHz for NATO military aircraft emergencies
406 MHz to 406.1 MHz is used by the Cospas-Sarsat international satellite-based search and rescue (SAR) distress alert detection and information distribution system
123.1 MHz: Aeronautical Auxiliary Frequency (International voice for coordinated SAR operations).
Amateur radio
For North America, the 2 m simplex frequency of 146.520 MHz is the one channel most frequently used for emergencies
Grid of 16 different pictograms describing audible and visual distress signals.
Radio operators must be able to recognize the several voice and Morse code emergency alert signals detailed below (radiotelegraph alarm, radiotelphone alarm, ELT beacons, EAS alerts, and the radiotelephone navigation warning signal, but being able to recognize all of the officially defined non-radio distress signals provides the operator with the ability to quickly relay the distress to emergency services. Because many of these signals are obscure to those not fully trained in aircraft, boating, and wilderness rescue signals, and even if a dozen other people spot one, the radio operator might be the only one that realizes it's a sign of someone needing immediate rescue.
Used on broadcast radio and television, and cable television.
The attention signal (the combination of 853 Hz and 960 Hz sine waves attention signal, which lasts between eight and 25 seconds, followed by the SAME header SAME header, which is a 1200Hz wide with a 260Hz AFSK shift.
The proword MAYDAY is the official worldwide voice signal that indicates distress, but radio operators should also be aware that the following signals, designed to activate automated alerting equipment, may also be heard. One should expect the radiotelegraph alarm signal and radiotelephone alarm signals to be followed by a Morse code SOS or voice MAYDAY call and message.
radiotelegraph alarm signal
The international radiotelegraph alarm signal consists of a series of twelve dashes sent in one minute, the duration of each dash being four seconds and the duration of the interval between consecutive dashes one second.
radiotelephone alarm signalThis is the International Radiotelephone Alarm Signal, defined by ITU-R Rec. 219-1 Recommendation 219-1, 47 CFR 80.317, and other national Radio Regulations. It consists of two substantially sinusoidal audio frequency tones transmitted alternately. One tone must have a frequency of 2200 Hertz and the other a frequency of 1300 Hertz, the duration of each tone being 250 milliseconds.
This is the International Radiotelephone Alarm Signal, defined by ITU-R Rec. 219-1 Recommendation 219-1[62] (and incorporated into Article 39 of the Radio Regulations), 47 CFR 80.317[63], and other national Radio Regulations. It consists of two substantially sinusoidal audio frequency tones transmitted alternately. One tone must have a frequency of 2200 Hertz and the other a frequency of 1300 Hertz, the duration of each tone being 250 milliseconds.
Designated for use on 2182 kHz, emission code J3E, but can also used on VHF channel 16 in Canada, but not in the U.S.[64]
Radiotelephone navigation warning signal. In the United States, the SÉCURITÉ signal may be preceded by a single 2200 Hz tone transmitted twice per second, which is used to announce a storm or similar warning.[64]
Simplify this section after further edits to main article.
Various emergency radio beacons exist that radio operators should be familiar with. With regards to those intended for, or which might be used at sea, one should read the U.S. Coast Guard report: AIS SART Vs Radar SART Trials[65] for a good understanding of the range these devices can be detected from when searching from an aircraft.
When activated, 406 MHz units transmit a 5-watt, 0.5 second long digital burst every 50 seconds. All of these beacons also produce a swept alarm tone AM signal (A3X and/or N0N emissions) ranging between 1600 Hz and 300 Hz, with 2-4 sweeps per second, but it sweeps down for ELTs, up for PLBs, and either down or up for EPIRBs.[66][67]
It may be that whether EPIRBs sweep up or down depends on whether a particular unit is designed to be a vessel (up) or personal (down) device.
Generally registered to a specific vessel (MMSI number?)
IMO and ICAO require an auxiliary 121.5 MHz at another frequency (T.001 does not)
When activated, 406 MHz units transmit a 5-watt, 0.5 second long digital burst every 50 seconds.
Alarm signal can sweep upwards or downwards
This is the International Radiotelephone Alarm Signal, defined by ITU-R Rec. 219-1 Recommendation 219-1, 47 CFR 80.317, and other national Radio Regulations. It consists of two substantially sinusoidal audio frequency tones transmitted alternately. One tone must have a frequency of 2200 Hertz and the other a frequency of 1300 Hertz, the duration of each tone being 250 milliseconds.obsolete Class C EPIRBs operated on VHF channels 15 and 16. "They transmit a short burst [of chirps] on VHF-FM channel 16 (156.8 MHz) and a longer homing signal on channel 15 (156.75 MHz). Their usefulness depends upon a coast station or another vessel guarding channel 16 and recognizing the brief, recurring tone as an EPIRB"[71]
Transmits the international radiotelephony alarm for 1.5 seconds on channel 16, and then for 24 hours on channel 15 (with occasional periods of silence), after which it must shut itself off.[72]
The radiotelephony locator beacon sound made by PLBs and some EPIRBs.PLB (hand-held personal portable units; Average cost is $300[69])
PLB alerts are passed to State and Local rescue agencies[68]
Alarm signal sweeps upward
Must be registered to a specific person (with NOAA in the U.S.)
PLB equipment is required to include 406 MHz plus a homing frequency on 121.5 MHz[73]
A dedicated, hand-held AIS transmitter that transmits four beacons each second, two on AIS1 and two on AIS2, to increase the chances that the beacons are transmitted at the top of a wave and on a channel that a rescue-capable vessel is monitoring.
These require a commercial subscription, but offer features not found on the other systems, and may be more suitable for some users than PLBs, but because the communicate only via private satellite systems not part of the COSPAS-SARSAT netwrok and do not have 121.500 MHz or 406 MHz locator beacons, they do not provide any radio signal that can be used for boots-on-the-ground direction finding.
As of 2017, only devices marketed as SEND devices will meet the standards and interface to the Search and Rescue systems.[74]
The use of MAYDAY is defined by, and governed by, ITU Radio Regulations, Article 32, sections 32.8 through 32.64. In particular, Article 32.9 § 7 describes the situations in which the signal is to be used:
"The transmission of a distress alert or a distress call indicates that a mobile unit or person is threatened by grave and imminent danger and requires immediate assistance."[75]
Both ITU-R Radio Regulation Number 32.13C and 32.13D[75] and CFR 47 80.314[76] give the following order of the information that should be transmitted in the distress message, which several sources suggest memorizing with the mnemonic MIPNANOO[77]:
Distress message required information
Letter
Item
M
MAYDAY MAYDAY MAYDAY
I
Identification: THIS IS (vessel name, callsign, and MMSI)
P
your Position
N
the Nature of the distress
A
the kind of Assistance required
N
Number of people on board
O
any Other useful information (you should include your intended actions)
Once a MAYDAY call has been made, the station in distress or the station initiating the call (or their designee) can impose emergency radio silence upon the frequency, to remain in-effect until cancelled by one of the participating parties.[citation needed]
International procedures for imposing and cancelling emergency silence
ITU-R
ICAO
ACP 125(G)
ACP 135
Initiating silence
SEELONCE MAYDAY
STOP TRANSMITTING - MAYDAY
SILENCE SILENCE SILENCE
SEELONCE MAYDAY (for vessel in distress) or
SEELONCE DISTRESS (for a station acting on behalf of the vessel in distress)
Restricted working
HELLO ALL STATIONS
THIS IS (call sign)
PRU-DONCE
OUT
Ending silence
MAYDAY
ALL STATIONS
THIS IS (name of station or vessel three times, callsign, time)
MMSI (followed by name and call sign of mobile station which was in distress)
SEELONCE FEENEE
OUT
MAYDAY
HELLO ALL STATIONS
THIS IS (aircraft identification)
time
DISTRESS TRAFFIC ENDED
SILENCE LIFTED
MAYDAY
HELLO ALL STATIONS
THIS IS (name of station or vessel three times, callsign, time)
MMSI (followed by name and call sign of mobile station which was in distress)
SEELONCE FEENEE
OUT
Radio room clock, showing the 500 kHz silence periods (red wedges), the 2182 kHz silence periods (green wedges), and alternating red and white bars around the circumference to aid manual transmission of the 4-second SOLAS signal.
Up until the procedure was replaced by the Global Maritime Distress and Safety System (August 1, 2013 in the U.S.), maritime radio stations were required to observe radio silence on 500 kHz (radiotelegraph) for the three minutes between 15 and 18 minutes past the top of each hour, and for the three minutes between 45 and 48 minutes past the top of the hour; and were also required to observe radio silence on 2182 kHz (upper-sideband radiotelephony) for the first three minutes of each hour (H+00 to H+03) and for the three minutes following the bottom of the hour (H+30 to H+33).
In the United States, this is still a legal requirement for 2182 kHz, according to 47 CFR 80.304 - Watch requirement during silence periods.[78]
If there exists an urgent situation that is urgent but not life threatening, then you should use the urgency signal, which is defined thusly:
"The urgency call format and the urgency signal indicate that the calling station has a very urgent message to transmit concerning the safety of a mobile unit or a person."—ITU-R Radio Regulations Article 33.1 § 5[75]
The PAN-PAN signal is based on the French word for breakdown, and keeping that in mind will help guide you in when it's appropriate to use.
When medical assistance is required for a condition that is not life-threatening, the proword MEDICAL should be used in conjunction with the distress signal PAN-PAN, and you should also use the phrase "medical transport". This is especially important, because the term is defined in the 1949 Geneva Conventions and Additional Protocols[79] and will legally entitle those engaged in the rescue operation to protection from wartime hostilities.
For any safety situation that you wish to alert other stations to, especially concerning navigation or weather, the safety signal SÉCURITÉ shall be used:
"The safety call format or the safety signal indicates that the calling station has an important navigational or meteorological warning to transmit."—ITU-R Radio Regulation Article 33.34 § 18[75]
Although most two-way radio stations are no longer legally required to keep records of all radio transmissions, there are situations in which logging operations and retaining their records is either advisable or required by law.
All formal messages should be kept for a period of two years. (based on broadcaster requirement in §73.1820)
Record communications and logs involving communications incident to a disaster (including search and rescue operations) or regarding an FCC investigation must be retained until authorized for destruction by the FCC.
If the log relates to a complaint of which the licensee has received notice, relevant records must be maintained (even if there are not normally a requirement to keep such logs) until the matter has been fully resolved or the applicable statute of limitations has run.
Consists of four parts, the list of operators on duty, the communications status log, the Operating log, and the Message logs. Combined with the file of transmitted and received messages, the station log forms a complete record of events and operating conditions which occur during a radio day at a station.
The operating log records the times, channels (identified with frequency designators), and the message and subject of messages sent or received. Technical notations about the station may also be included, such as changes of radio, antennas, backup power availability, etc.
Combine best elements of Master Station Log, DD 1753[80] and CAP FORM 110[81]
It should include:
opening and closing of stations
causes of delays in traffic
Frequency adjustments and changes
Unusual occurrences such as procedure violations, circuit/equipment problems, backlogs, personnel shortages, etc.
