The 70 cm satellite frequency refers to the amateur radio band ranging from 420 MHz to 450 MHz, commonly used for satellite communications.
Table of Contents
Frequency Range
The 70 cm satellite frequency is a part of the 420 MHz to 450 MHz band, which is widely allocated for amateur radio service in many countries. Consequently, a band becomes an essential frequency range for amateur satellite communications through which the downlink and uplink signals can be transmitted between a ground station and a satellite. Instances, in which radio amateurs select the 70 cm band to communicate through a satellite, occur frequently because the signal at this frequency is convenient for numerous purposes. Initially, it has greater penetration through the atmosphere and is attenuated less by foliage, elucidating why it is advised for receiving purposes.
That effect could be explained simply with the shorter length of the leaves and branches of the trees. An amateur radio operator can easily install a Yagi antenna, which is about 1 meter long, on their backyard residing in a suburban area to send and receive messages to a passing amateur radio satellite in low earth orbit. This frequency is cost-effective for hobbyists and could be utilized by amateur specialists to implement more regimented and shortwave tests to be prepared for disaster recovery.
The range of this communication could be different, but it rarely exceeds several hundred kilometers. The higher bands, for instance, 23 cm, require much more forceful equipment and more funds since their signal is susceptible to interference with other physical barriers and atmospheric disturbances. That being said, the 70 cm band is the best alternative for amateur hobbyists using reasonable equipment and limited space resources on a backyard for an expensive antenna.
Usage
One of the most widely used bands for amateur radio users is the 70 cm satellite frequency band. Radio enthusiasts use this band for both terrestrial and satellite communications. For a wide range of purposes such as educational projects, emergency communications, and simply for fun, radio amateurs exchange information with amateur radio satellites using the 70 cm band. For example, the 70 cm band is widely used during the field days and various kinds of amateur radio contests, when the goal is to make as many contacts as possible with the help of the reliable communication with satellites . The setup for such occasions includes the portable radio, which is used for transmission to the Earth. The radio has such digital modes of communication as packet radio and PSK31, which allows for data transmission to be performed efficiently using the 70 cm spectrum.
One more frequent use of the 70 cm band is the balloon experiments, to which radio amateurs have to use the low cost and small-sized transmitters. The repeater systems, which are carried by the balloon class of the aircraft and reach altitude of 30 km or about 100,000 feet, transmit the telemetry to the stations on the ground. Mostly, the telemetry includes the data regarding to the position and height of the balloon and the direction and speed of the wind . The balloon experiments can use either the amplitude modulation or the frequency modulation. The latter provides the extremely high quality of the picture.
The advantages of the 70 cm band are penetration of built-up areas and the long range to the repeater station, since all other bands usually have worse characteristics. The 70 cm band is also of tremendous use in the emergency services, when other infrastructures cease functioning due to the natural disasters, such as hurricanes, eruptions, and earthquakes. In such situations, amateur radio users establish temporary networks and pass the information, necessary for the rescue operations and provision of the first aid. They use the 70 cm band as it requires less power and provides long range.
Comparing with the 1.2 GHz band, the 70 cm band is ideal due to the lesser power requirement and more reliable penetration into the built-up areas and closed spaces . This is of vital importance for emergency applications and during the mobile operations when battery-powered, rather than the commercial power, transmitters are used. The cost for equipping 70 cm station also seems to be the lowest. Transceivers for this range are sold for about $200, while the antenna can cost from $50 to $150 depending on the complexity and gain.
ITU Region Specificity
ITU regions allocate of 70 cm satellite frequency varies significantly across the ITU regions and determines how amatures throughout the world could use the band for satellite communication. On the one hand, Region 1 gives amateurs an allocation from 440 MHz to 450 MHz. Operators in this regions need to be more cautious with their equipment. They must make sure that they can operate within the confines of the law with equipment that is more accurate at setting its frequency. The equipment must also be efficient to make sure that it does not scatter its output into out-of-band frequencies, which can interrupt other services that are adjacent to these bands.
Region 2 gives their ITU amateurs a wider allocation from 420 MHz to 450 MHz. They can choose whichever frequency they can operate with, and they can experiment with different communication forms and technology. For example, they can experiment with digital data mode of communication that requires different bandwidths and signal strengths. Amateurs in Region 2 countries can also experiment with varying communication modes where signals are scattered within the neighboring band. They do not need to worry much about getting to the exact frequency of 430 MHz or 440 MHz before communicating. Region 3 is made up of Asia and Oceania, and they have a similar allocation to Region 2, the National restriction applying if any, is that Japan gives amateurs an allocation of 430 MHz to 440 MHz only.
Amature satellite operators should know the region of the world they operate in and the frequency allocation to operate effectively. For example, an amateur radio that operates in Germany must ensure that the equipment works only between 430 MHz to 440 MHz. An amateur from Brazil can have the equipment specifically calibrated to operate at any frequency in the 20 MHz wide band.The issue of frequency allocation increases the cost of operation for the amateur because an equipment that can operate with a specific frequency must be narrowly tuned, and they will most likely need a frequency filter to make sure that the out-of-band issue is managed. Tunable equipment is therefore encouraged for those who are operating close to the bands edge. A tunable equipment can increase costs by 20-30%. Individuals in Region 2 need not worry about getting a tunable equipment.
Popular Satellites
The 70 cm frequency band is used by a number of amateur satellites, which makes it a very useful and popular band of frequencies. These satellites provide opportunities for people interested in radio to communicate and experiment with relatively simple tools. Some of the most well-known satellites include the OSCAR series, CubeSats, and the more recent Es’hail-2, which operates from 26-27.75 GHz Hopping uplink and 10489.660 GHz Hopping downlink. AMATEUR SATELLITES ON 70 CENTIMETER . For instance, AO-91, or Fox-1B, and the following are part of the satellite series of Orbiting Satellite Carrying Amateur Radio, or OSCAR.
These satellites utilize transponders to relay signals between amateurs. For the AO-91 alternative, this process uses the UHF uplink frequency of 435.250 MHz and the downlink of 145.960 MHz. Many OSCAR satellites rely on the 70 cm band, offering a simple tool to communicate across the globe. The distance covered for some examples of CubeSat, such as the FUNcube listed below, is more than 4,000 km miles UKube-1.
FUNcube-1 is a CubeSat operated and deployed after it is built by amateur amateurs at their workplace, with the help of AMSAT-UK TT&C FUNcube The FUNcube-1 downlink can be used to obtain both a signal for communication and an educational data signal, which can be learned in radios of various complexities. The relatively simple tool of communication, accessible by even schools, entails a cost of the simple signal receiver.
Amore up-to-date amateur satellite or the OSCAR series is the QO-100 provided for free access to transmission by both ECC in the RSGB, and in Qatar. The satellite utilizes a 2.4 GHz uplink and a 10.45 GHz downlink with the help of transponders in a higher frequency and is geostationary to provide accessibility at all times. The other part of the satellite is a narrow band transponder that converts 70 centimeter frequencies of the uplink to the 2.4 GHz downlink on the QO-100. It also covers a narrow band region and reduces the interest of satellite in the net. The order must therefore spend at least three times range of hardware from $300 and a UFS space and $1000 for the QO-100 using a Yagi antenna.
License Requirements
In order to operate on the 70 cm satellite frequency, one must follow specific licensing regulations. These ensure that a limited resource is being used correctly and can be managed. Every country will set their own requirements based on the ITU’s broader recommendations for amateur radio, and the common elements include an examination. This examination will generally cover both the technical knowledge required to operate a radio safely and effectively, as well as the operations and legal side of radio.
In the United States, this is established under the Federal Communications Commission , which states that operators must have a license of at least Technician class to be able to transmit on the 70 cm band. This license is established by passing a 35-question multiple-choice examination covering radio theory, regulations and operating practices. Although there may be additional costs, the examination fee is generally no more than $15, which makes it a very accessible one.
The United Kingdom requires operators to pass a Foundation exam. This examination includes a practical assessment of the student’s ability to operate as well as theoretical exam; a similar Foundation examination is likely available in the U.S., but is frequently waived. This licensing is designed to ensure that amateurs are not only theoretically knowledgeable sufficiently to operate a radio, but also that they have practical experience. The cost of the U.K.’s examination is in the vicinity of £27.50, a somewhat higher cost despite slightly lower requirements.
In regions such as Europe or Asia, the requirements can be quite different. In Germany, for example, although a successful completion of an examination is required, the amount of technical ability tested is significantly higher than that for the U.S. examination. This is consistent with the German attitude of ensuring that operators have a full understanding of the equipment they use; more advanced operations also require additional levels of qualification.
The amateur radio operator must renew their license every period; in the United States, the process must be re-qualified every ten years, in the UK the license must be requalified every five years with no exam. This measure ensures that the operator with little practice is not using outdated understanding.
In terms of cost of set-up once licensed, this can be relatively minimal. An entry-level will be in the region of $100 to $200, and is sufficient for basic satellite communication. An appropriate antenna will be under $100, although there will be additional costs of up to $2000 for tower and beam antennas for other types of communication. Only those seeking to take part in Earth-Moon-Earth communications, one of the most technically demanding forms, may need to acquire the more expensive antennas and power amplifiers – which can bring the overall cost of their set-up to over $1000.
