1.25-meter band explained

The 1.25 meter band is a portion of the VHF radio spectrum allocated for amateur radio use in ITU Region 2, comprising frequencies from 222 MHz to 225 MHz in the United States (with the addition of 219–220 MHz on a limited, secondary basis) and Canada and from 220 to 225 MHz in the rest of Region 2.[1] [2] It is not available for use in ITU Region 1 (except in Somalia[3]) or ITU Region 3. The license privileges of amateur radio operators include the use of frequencies within this band, which is primarily used for local communications.

History

The 1.25 meter band has a very long and colorful history dating back to before World War II.

Pre-Cairo Conference

Some experimental amateur use in the U.S. was known to occur on the "1¼-meter band" as early as 1933, with reliable communications achieved in fall of 1934.[4]

The Cairo Conference

In 1938 the FCC gave U.S. amateurs privileges in two VHF bands: 2.5 meters (112 MHz) and 1.25 meters (224 MHz).[5] Both bands (as well as 70 centimeters) were natural harmonics of the 5 meter band. Amateur privileges in the 2.5 meter band were later reallocated to 144–148 MHz (becoming the modern-day 2 meter band), and the old frequencies were reassigned to aircraft communication during World War II. At this time, the 1.25 meter band expanded to a 5 MHz bandwidth, spanning 220–225 MHz.

The VHF/UHF explosion

Amateur use of VHF and UHF allocations exploded in the late 1960s and early 1970s as repeaters started going on the air. Repeater use sparked a huge interest in the 2 meter and 70 centimeter (420–450 MHz) bands, however this interest never fully found its way into the 1.25 meter band. Many amateurs attribute this to the fact that there was an abundance of commercial radio equipment designed for 136–174 MHz and 450–512 MHz that amateurs could easily modify for use on 2 meters and 70 centimeters. There were no commercial frequency allocations near the 1.25 meter band, and little commercial radio equipment was available. This meant that amateurs who wanted to experiment with the 1.25 meter band had to build their own equipment or purchase one of the few radios available from specialized amateur radio equipment manufacturers.

Furthermore, since the band is allocated mostly in ITU Region 2 (Somalia, in Region 1, being the only exception thus far), the major equipment manufacturers (Kenwood, Yaesu, and Icom) do not often offer transceiver models that cover the frequency range. (see Novice Licensees Get Privileges). This exacerbates the lack of usage of the 1.25 meter band, though manufacturers argue that what equipment they have produced hasn't sold well compared to other products. In recent years, Kenwood and Yaesu have both included the 1.25 meter band in some of their multi-band handheld transceivers. The Kenwood TH-F6A, the Yaesu VX-6R, VX-7R & VX-8R include coverage of the 1.25 meter band in addition to the more popular 2 meter and 70 centimeter bands. Aside from handheld transceivers, the only 1.25 meter radio equipment widely available today is offered by Alinco, another Japanese manufacturer.

Novice licensees get privileges

By the 1980s, amateur use of 2 meters and 70 centimeters was at an all-time high while activity on 1.25 meters remained stagnant. In an attempt to increase use on the band, many amateurs called for holders of Novice-class licenses (the entry-level class at that time) to be given voice privileges on the band. In 1987, the FCC modified the Novice license to allow voice privileges on portions of the 1.25 meter and 23 centimeter (1.24–1.30 GHz) bands. In response, some of the bigger amateur radio equipment manufacturers started producing equipment for 1.25 meters. However, it never sold well, and by the early 1990s, most manufacturers had stopped producing equipment for the band.

Reallocation

In the late 1980s, United Parcel Service (UPS) began lobbying the FCC to reallocate part of the 1.25 meter band to the Land Mobile Service. UPS had publicized plans to use the band to develop a narrow-bandwidth wireless voice and data network using a mode called ACSSB (amplitude-companded single sideband). UPS's main argument for the reallocation was that amateur use of the band was very sparse and that the public interest would be better served by reallocating part of the band to a service that would put it to good use.

In 1988, over the objections of the amateur radio community, the FCC adopted the 220 MHz Allocation Order, which reallocated 220–222 MHz to private and Federal Government land mobile use while leaving 222–225 MHz exclusively for amateur use. The reallocation proceeding took so long, however, that UPS eventually pursued other means of meeting their communications needs. UPS entered into agreements with GTE, McCall, Southwestern Bell, and Pac-Tel to use cellular telephone frequencies to build a wireless data network. With the 220–222 MHz band now left unused, the FCC issued parts of the band to other private commercial interests via a lottery in hopes that it would spark development of super-narrowband technologies, which would help them gain acceptance in the marketplace.

The 1.25 meter band today

Today, the 1.25 meter band is used by many amateurs who have an interest in the VHF spectrum.

There are pockets of widespread use across the United States, mainly in New England and western states such as California and Arizona with more sporadic activity elsewhere. The number of repeaters on the 1.25 meter band has grown over the years to approximately 1,500 nationwide as of 2004.

The attention that 1.25 meters received in the late 1980s and early 1990s due to the reallocation of the bottom 2 MHz sparked a renewed interest in the amateur community. Many amateurs feared that if activity on 1.25 meters remained sparse, it would only be a matter of time until the FCC re allocated the remaining 3 MHz to another service. Today, while not as widely available as 2 meter and 70 centimeter equipment, 1.25 meter equipment is much easier to obtain than it has been in the past and there is new handheld and mobile equipment being produced by amateur radio manufacturers. It is estimated that more amateurs have 1.25 meter equipment now than at any point in the past.

Known countries with band allocation

ITU Region 1

ITU Region 2

Propagation characteristics

Enthusiasts of the 2 meter and 70 centimeter bands cite characteristics about each band that make it preferable to the other. Two meter enthusiasts cite that band's longer-distance propagation and lower susceptibility to multipath as compared to 70 centimeters, while 70 centimeter enthusiasts cite that band's better building-penetration characteristics and its lower noise floor level as compared to 2 meters.

Since the 1.25 meter band is situated between the two bands in the radio spectrum, many amateurs like to say that 1.25 meters offers the "best of both worlds". This means that 1.25 meters offers a taste of the more desirable characteristics of both the 2 meter and 70 centimeter bands.

On one hand, if one assumes that the transmitting antenna's wavelength, height above average terrain and effective radiated power is equal, a transmitted signal on 1.25 meters will usually travel equally as far as that same signal would if transmitted on 2 meters, as well as exhibiting an equally low susceptibility to multipathing. On the other hand, the wavelength of 1.25 meters is closer to that of 70 centimeters, thus it tends to have building penetration and noise floor characteristics that more resemble those of 70 centimeters.

External links

Notes and References

  1. US Amateur Radio Frequency Allocations. http://www.arrl.org/FandES/field/regulations/allocate.html accessed 12 May 2008.
  2. U.S. Code Title 47, Part 97, Section 303. http://www.arrl.org/FandES/field/regulations/news/part97/d-301.html#303 Accessed 4 June 2008
  3. Ministry of Information, Telecommunication and Culture Garowe, Puntland, Somalia. Regarding authorised amateur radio frequency bands and transmitter power output in Somalia. http://www.arrl.org/FandES/field/regulations/io/Somalia.pdf Accessed 4 June 2008.
  4. DeSoto. Clinton B. 200 Meters and Down: The Story of Amateur Radio, 2001 edition. Newington, Conn.: The Amateur Radio Relay League. p. 129.
  5. Francis Colt de Wolf. The Cairo Telecommunication Conferences. The American Journal of International Law, 32;3(July 1938):562-568.
  6. Aruba application for a visitor's license. http://www.qsl.net/aarc/P4A.PDF accessed 1 November 2008.
  7. French Amateur Radio frequency allocations http://accueil.ref-union.org/jo_031008.pdf accessed 1 November 2008.
  8. Mexico Amateur Radio frequency bands and channel allocations http://www.geocities.com/wd9ewk/docs/xe-regs-15dec1994-c.pdf (PDF is archived from 15 December 1994) accessed 1 November 2008.