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Show yt- - M ch CB or Land Mobile To fulfill the communications ' needs of the farmer, there are two primary alternatives: Class D Citizens Band and Land Mobile Service. The citizens band is presently growing in popularity all across the country. This growth has resulted in extremely crowded channels and high noise levels on the citizens band. Due to the number of users on each channel, there is much interference between stations which reduces the usable range of citizens band. The high noise levels on the citizens band nake prolonged monitoring of . receiver a somewhat annoying experience. Mobile units ,vill require the installatibn of vices include the Business Special Industrial Radio Service, and Class A Citizens Band; which are the most common services in which agricultural communications are licensed. The land mobile services utilize FM transmitters and receivers, which provide noise-fre- e transmission and reception. This characteristic also eliminates the need for ignition noise suppression equipment on mobile units. Users of these communications are assigned a frequency when obtaining their license. Various methods of coordination, depending upon the selected service, are used to prevent over crowding the gnition noise suppression channels. Tone activated quipment on the engines to receiver squelching (silencing) reduce noise interference. circuits are available which Class D citizens band does have allow the receiver to be absome good points. If traveling solutely quiet except when one outside the range of your base of your own units is calling. For the serious communicastation, the ability to contact another station for emergency tions user, the land mobile serassistance is better than vice provides the best alternative by offering good range probably any other communications system. and little interference. When The Land Mobile Radio Ser operating a mobile unit outside Radio Service, the coverage area of the base station, the ability to communicate with other stations is limited. medium operating ranges (typically, 15 miles for base station antennas of less than 50 feet) between transceivers. No interferrence due to skip conditions are encountered in this WHAT TYPES OF band. This band has the highest COMMUNICATIONS number of users. Mobile antenARE AVAILABLE? nas range in length from 2 to 4 feet. High availability of The farmer contemplating equipment. UHF Band provides shorter adoption of a land mobile communications system must, with operating ranges between units the help of a reputable local (typically, 12 miles for base dealer, decide upon the band of station antennas below 50 feet). frequencies in which he wishes This shorter range can be to operate - VHF Low Band (25 corrected by using taller anto 50 Megahertz), VHF High tenna towers, increased tranBand (150 to 173.4 Megahertz), smitter power and remote or UHF (450 to 512 Megahertz). repeating transmitter sites. A few general guidelines and This band requires short mobile characteristics are as follows : antennas (less than 3 feet in VHF Low Band provides the length). This band has more available frequencies than the greatest operating range between units (in excess of 15 others and few users at present. miles for base station antennas to relative recent Due of less than 50 feet). Occasional development of this band available equipment is limited long distance skip conditions can cause interferring signals. and more expensive for this Throughout the midwest, there band than the others. are a relative low number of users in this band. These HOW FAR WILL I BE frequencies require long mobile antennas typically 4 to 9 feet in ABLE TO TALK? length. Only a limited number of radio types are available for The most common question this band. for someone contemplating an VHF High Band provides FM system is, What kind of LAND-MOBIL- E Business Communications Radio Systems Section, April 13, 1978 range can I expect? This is a very difficult question to an- - ' swer. Range in any communications system depends upon antenna heights and ground terrain. The distances discussed above can provide basic guidelines, but a dealer more familiar with the geographic area can make a more exact estimate in most cases. HOW DO I GET A LICENSE? Licensing an FM land mobile is somewhat more system complex than licensing a citizens band system. The basic license fee is the same (free) for both services. Normally, VHF low band and VHF high band systems are licensed in either the Special Industrial Radio Services or the Business Radio Service for farm usage. The Special Industrial Radio Services are probably the best choice because they are limited to only a few user types: Agricultural, Heavy Construction, and Specialized activities such as agricultural chemical application, livestock breeding services, or fuel and power delivery. This limitation on qualifying users results in a lower number of radio systems on any particular frequency and therefore less chance of in- interference. An additional advantage is the requirement for frequency coordination. Frequency coordination is an activity carried on by a national organization, which studies all new system and license applications a frequency recommends which has the least chance of interference. This coordination costs an additional $15 over the license fee and is paid to the Special Industrial Radio Service Association, Inc. (SIR-SA)- .' ter-stati- The Business Radio Service does not require frequency coordination in most cases. The number of users of these are frequencies greater, however, since anyone engaged in a commercial activity can qualify. This increases the interchances for ference, which makes this service less preferable to the Special Industrial Radio Services. In the UHF band, the Special Industrial and Business Radio Services also have frequencies which are available for agricultural use. The licensing procedures are the same for the Special Industrial Radio Service, including the frequency for the Business Radio Service. This coordination is performed by the National Association of Business & Educational Radio. CONCLUSION Ive Found the Sound can assist you in selecting the best operating band and type of system you need to meet your requirements. Unfortunately, the only way you can guard against an unscrupulous dealer is to arm yourself with the basic information given here and against the various- equipments. - manufacturers A good rule-of-thu- in buying the transceivers is that nearly all new equipment is solid state. When buying antennas a good is that, when comparing antennas for operation on the same frequency, bigger is betrule-of-thu- ter. No matter what system you choose, communications can your improve certainly operating efficiency and therefore increase your profits. . |