The following site provides three tables listing the following information:
- Ham Radio Maritime Mobile Nets
- Ham Radio HF Emergency Net Frequencies (USB or LSB as appropriate)
- Marine Radio HF Maritime Mobile Nets (all USB)
- Repeater Operating Practices
- Two Way Radio Overview Link
Here is great information on constructing a small RF local area network using GMRS Radio Repeater and Portable Radios.
Extra Long Range GRMS Radios
When it comes to range of GMRS radios there are some pretty outrageous claims out there. Some manufacturers are actually claiming up to a 36 mile range. While this is technically possible it is not likely the range you will experience in the real world. Only by using a repeater can you get extra long range from GMRS two way radios.
GMRS stands for General Mobile Radio Service and refers to a group of frequencies in the 462 to 467 Megahertz range of the UHF end of the radio spectrum. Seven of the GMRS channels are shared with the non licensed FRS or Family Radio Service. GMRS radios require a license to operate but this is frequently ignored by users. Channels 15-22 require that you purchase an $80.00 FCC license to use. No license is required to use GMRS in Canada. GMRS is for personal, non business use. You can apply for a license at www.fcc.gov/uls.
There are 8 GMRS only channels for simplex use and 7 channels that are shared with FRS. There are additional channels reserved for use with repeaters, which give GMRS radios long range. The repeater channels are found only on more expensive radios, not those sold in discount stores.
Most 2-Way radios sold to consumers are the so called hybrid models which include 7 FRS only channels, 7 shared FRS-GMRS channels and 8 GMRS only channels. Only on the 8 GMRS channels radios are you allowed a transmit power of up to fifty watts by law. However, most handheld GMRS radios typically use 5 watts or less due to battery size. This limits the practical range of most consumer models to around 5 miles or less due to terrain and obstacles.
COTHEN is an HF ALE network that uses landlines to connect nineteen transmission sites spanning the nation in order to form one unified coverage area. Currently, the network has 19 sites, 89 remote communications consoles (RCC’s), and a TSC in Orlando, FL.
Back in 1984, the design for a U.S. Customs radio network was conceived. Code-named COTHEN, Customs Over The Horizon Enforcement Network, it combines a radio, computer, and a tactical voice privacy unit into a state-of-the-art communications system that meets the demanding requirements of tactical interdiction aircraft and boats in their fight against smuggling activities.
COTHEN’s first fixed station transmitter near Memphis, Tenn., became operational in 1985. The Blue Lightning Operations Center was the first command office and its marine vessels were the first tactical platforms to have COTHEN radios. This initial deployment proved so successful that COTHEN grew to include all U.S.Customs aircraft.
The Motorola DTR600 Digital Two-Way Radio is a limited-keypad, professional, 30-channel two-way radio for seamless and efficient on-site business communications. It enables the user to have interference-free and private communications with loud, crisp-clear audio over an area as wide as 350,000 sq ft, up to 30 floors. The portable two-way radio offers enhanced and flexible communication options like Digital One-to-One Calling and Digital One-to-Many Calling along with private reply, Call All Available, Page All Available, Direct Call and mute.
DTR600 has a full-graphic, backlit display with an intuitive navigation menu, and a prominant functional keypad to help locate all the radio features. Built-in anti-microbial housing properties prevent the growth of mold and germs, hence helping to keep the device stain and odor-resistant. The two-way radio comes in a slim, compact and rugged design that meets U.S Military 810G standards to withstand extreme shock, vibration, water, dust and temperature conditions.
For those of you that cannot justify an expensive radio, the radio above is a great choice for local communications around your home and access to our TRI-STATE EMERGENCY COMMUNICATIONS Network if you’re within 1-2 miles of one of our HUB Radios.
If you purchase a HUB Radio, (Kenwood TM-V71 above) for approx. $380.00, then you will have access into our Network with the HUB radio.
LIMARC the Long Island Mobile Amateur Radio Club, Inc., is a not-for-profit corporation, formed to encourage and foster mutual interest in amateur radio communications and provide public service. LIMARC provides such communication when required as a result of normal communication means being disrupted by natural or man made causes. LIMARC operates several radio repeater stations to enhance the quality of communication available.
The LIMARC repeaters are licensed by the Federal Communications Commission and the users of said repeaters MUST comply with ALL FCC mandated rules and regulations.
IN ADDITION, beyond the minimum required by law, LIMARC has established operating procedures to optimize the use of the repeaters and to define a level of quality representative of the club.
While not all-inclusive, the following procedures establish a baseline for all repeater users to follow.
- Station Identification- All stations should identify themselves using their FCC assigned callsign upon initially transmitting on the repeater and every ten minutes thereafter. In addition, when operating in a net or “roundtable” your callsign should be announced more frequently if needed to facilitate efficient communication.
- When initially coming on the repeater, when not previously in use (verified by LISTENING for a few minutes PRIOR to transmitting), it is only necessary to announce your call. If you are trying to contact a specific station, you should announce … “K2XXX from WB2XXX”.
- If the repeater is already in use, please wait for a pause between transmissions to announce your call. ONLY USE THE TERM “BREAK” OR “BREAK BREAK” in an emergency or life- threatening situation.
- All stations using the repeater should pause after the previous station drops to minimize inadvertent “doubling” (simultaneous transmission) and to allow time for new stations to identify.
- When a new station enters the roundtable, those stations using the repeater, and the next station in rotation should acknowledge the new station AND turn it over to them. Also indicate whom they should turn it over to in order to keep the rotation intact.
- If a station announces a single or double “break” the repeater is to be given to them IMMEDIATELY for their traffic.
- Communication should be in plain language. “Q” codes and “10” codes are not required and their use should be minimized. Similarly, phonetics should be reserved for those instances when they are required (minimal signal/emergency traffic for example).
- Extraneous Tones and Identifiers – Except when required for control or identification purposes, extraneous audible content should NOT be transmitted before, during or at the completion of a transmission.
- Simplex vs. Repeater – If you are close enough to another station to hear them directly AND it is only the two of you communicating, move to a simplex frequency. It is not only courteous… IT IS REQUIRED BY THE FCC. Transmitting on the repeater OUTPUT frequency, while the repeater is operating is prohibited.
- Content – While certain topics and vocabulary are not “illegal” for commercial broadcasting, LIMARC, as the operator of the club repeaters DOES prohibit those communications which are in poor taste or a waste of the repeater facility. While the following should not be considered all-inclusive, it will establish a baseline for behavior which is NOT PERMITTED by the club on LIMARC Repeaters:
- “Off Color” comments, sexual innuendo and ANY double entendre. Remember, use of codes and ciphers is NOT permitted by FCC regulations. If it can’t be said in plain English, it probably should not be broadcast on the repeater.
- Commercial communication – you can, certainly, identify your occupation..however, if you are, for example, a car salesman, you CANNOT try to sell your wares on the repeater.
- Derogatory remarks directed at any group (ethnic, racial, religious, sexual etc).
- “Bathroom Humor” – If you wouldn’t tell the joke to your ten year old child, don’t tell it on the repeater.
- Any activity in violation of FCC rules and/or any other Federal, state or local laws or ordinances (including, but not limited to: jamming, “stepping on”, broadcasting of music, unidentified carrier etc). Note: intentionally transmitting simultaneously with another station (“stepping on”) is prohibited by FCC regulation… even if the intent is good natured kidding among friends… it is still illegal.
- Malicious Interference – When subject to interference which is clearly intentional, DO NOT RESPOND TO THE INTERFERING STATION. It not only provides encouragement, if the individual is unlicensed YOU would then be operating illegally.Make note of all pertinent information (date and time of occurrence, your location, fixed or mobile, if you can hear the interfering station on the input, was your signal heard above the interfering signal, type of equipment you are using) and contact the interference committee with the information.
Members who violate the above will be warned after the first offense. If the behavior recurs, steps will be taken, up to and including revoking the person’s membership, as provided for in the LIMARC By-Laws.
Proper and legal operating etiquette is 95% common sense. While the above limits on content are not all inclusive, they should make clear the type of communication which is NOT appropriate.
In general, if what is being said could be construed as embarrassing or hurtful by a listener, it is probably NOT permitted. Always err on the side of caution. When in doubt… DON’T.
A repeater will extend the distance you can talk with the same amount of power. A repeater can do this because it usually has a higher antenna and more RF power output. Simplex is simply from your radio/antenna to another radio/antenna directly. When talking on a repeater you can check the input frequency for the repeater to hear (if you can) the station you are talking with on the repeater. You may not be able to hear the other station if he is too distant, and/or running low power, and/or has a low antenna. More on the input frequency in the next section. It is a good idea as you operate on a repeater to learn where you start to have a hard time being heard by others. Sometimes this may be called “reaching the end of your string” or other lingo.
The repeater shift on 2M is 600 kHz. The repeater shift on 440 MHz (70 CM) is 5 MHz. On 2M, depending where you are in the 2M sub-bands for repeaters (there are 3 repeater sub-bands), the offset will be 600 kHz lower or higher that the repeater output frequency. PROVIDE DRAWING OF REPEATER SUB-BANDS. That means that if you hear a repeater on for example 147.200, the input frequency (or offset, or repeater shift frequency) will be on 147.800. (In this particular example, the repeater shift is a positive offset.) Your radio should be set up in this case for a positive offset being that your transmit is higher than the repeater frequency. In this example, your radio transmits on 147.800 to the repeater (as does everyone else with their radios), which is listening on this frequency, it simultaneously retransmits your signal out on 147.200 to someone who is listening there. (If you get down to the nitty-gritty technical side, there is a small latency of time for the signal to pass thru the various stages of the electronics. If you were to quickly check a station on the input and output of the repeater, or simultaneously, you could notice a small delay.) They would do the same as your radio to reply to you…that is, they would transmit on 147.800 to the repeater. If the 2M frequency for the repeater is between 145.200 MHz and 145.500 MHz, or ###.### and ###.### MHz, you would use a negative offset. If the 2M frequency for the repeater is between 146.610 and 147.395, you would use a positive offset. (Some hams may ask you to check their signal on the “reverse”, this is the same as the input frequency.) If you are able to hear a station on the input, you are within simplex range, and do not need a repeater.
Many current 2M radios have a menu option that will automatically determine the appropriate offset when you program a repeater frequency into a memory channel.
Depending on various other factors, these being: possible expected usage of the repeater by mobiles during commute time, a scheduled net time approaching, or that particular repeater’s etiquette, amongst other reasons, you might want to think about moving your conversation to another simplex frequency so as not to monopolize the repeater. This might be the case if you are talking from your home to another ham in his home. It’s not always wrong, or by any means illegal, it might be thoughtful. There may be times that you feel contrary to this if you wish to speak with anyone else, including a mobile station who might need the repeater to communicate with you if he is outside of repeater range. Just keep it in the back of your head.
Many current production V/UHF radios have a function that will allow you to scan for PL tones. If you were in an area that you did not know the PL tone to access a repeater, you might possibly be able to find the proper tone. You would do this by scanning for a tone IF you were able to hear a station on the INPUT frequency of the repeater. If you were to scan and find a tone on the output of the repeater it may be different than the tone of the input to allow you access to the repeater. Remember some repeaters output a tone to help users with other functions such as cross-banding. So, if you wish to find the PL tone to enable you access to the repeater, and it is being used, check the input to see if you can hear one or more stations. (You may not be able to hear any of the stations on the input.) Then once you can hear a station on the input, start your tone scan. The way many of my Icom radios do this, is to press [FUNC], then [T-SCAN] on the microphone control. There will be a signal showing on the S-meter, but no audio, until it finds the proper tone. The PL tones will scan (somewhat slowly) while there is a signal present, then stop once it finds the tone, and at that time you will hear audio. You now know what PL tone to use for accessing the repeater. There are other ways to determine the PL tones for repeaters. One common way is to purchase the Repeater Directory from ARRL. The ARRL also has software that you can map a route and it will tell you in order of your trip which repeaters, and all the necessary info, that you might be able to access along the way. There are also online sources such as the website: http://www.artscipub.com There are also individual states’ repeater coordination councils that may also provide listings of coordinated repeaters. Here in Michigan we have the Michigan Area Repeater Coordination Council, their website can be found @: http://www.miarc.com.