A Spectrum Abandon but Not Forgotten: The History
“220 represents the last spectrum opportunity that exists today,” he said. “It’s the last frontier.” Gene Clothier, President Incom RCR Wireless News May 1998
What’s happened since 1998?
In summary nothing… The radio manufacturing community stopped supporting the manufacture of 220 SMR radios. The mature cell phone industry began to replace radio networks like 220 SMR making it no longer feasible for radio manufacturers to justify the added expense of supporting the 220 SMR radio which utilizes companding technology to achieve low bandwidth communication for both voice and data applications. Today the 220 SMR band is one of the last pieces of spectrum that has not been advanced by industry in over 10 years.
A brief history on 220 SMR Technology
The 220Mhz SMR band is different from other bands in that it supports a 5Khz bandwidth allocation for each channel. While all other bands work with 6.25Khz, 8.5Khz, 12Khz or other higher bandwidth allocations. The 220 SMR is the only one restricted to 5Khz. This was purposefully done by the FCC in an effort to promote narrow band communications networks and challenge industry to service larger groups of simultaneous users. While the FCC’s decision to limit the SMR bands to 5Khz did drive some major advancement in radio, it also made the manufacture of such radios difficult because they used parts not present in other radios. This advancement could not keep up with the speed and adoption rate of the cell phone and cellular data markets. Lower adoption rates and limited market spaces prohibited the growth of the market while parts on radios in service went obsolete. In the summer of 1998 manufacturing for the radios halted and so did the spectrum’s growth.
What exactly is the 220 SMR Spectrum?
220 SMR stands for 220 Megahertz (Mhz) Special Mobile Radio (SMR). The system can be trunked via digital or analog means to allow the servicing of several users over a given band or “spectrum”. The 220 SMR radio is an Amplitude-companded Single-sideband or ACSB radio. Amplitude companding allows 5Khz voice to be transmitted clearly and was the real discriminator between this radio spectrum and others in that it allowed voice communication over a smaller band of 5Khz. Single side band operation meant that the operator and the customer benefit from low power yet very robust signal. Finally operation in the 220Mhz spectrum allowed for clear transmissions in difficult to service terrain with heavy foliage or differences in terrain altitude. The 220 SMR band starts consists of spectrum from 220Mhz though 222Mhz. The band uses 220-221Mhz base station frequencies paired with frequencies exactly 1Mhz higher taken from the 221-222Mhz band for control stations.
What was the 220 SMR radio used for?
During its heyday 220 SMR was used for a wide variety of dispatch radio applications. Businesses and governments relied on the band for servicing taxi and delivery services as well as police and fire dispatch. The US government has a set of the band reallocated for governmental services such as the Bureau of Land Development and the Forest Service. Additional applications in todays markets may extend to US homeland security and Boarder Patrol operations as well as unmanned sensor systems that monitor pipelines and infrastructure as well as rail road switch control and disaster avoidance.
Disclaimer: The 220 SMR network can provide low bandwidth data and voice to a broad coverage area. This means that the technology can provide voice and text capability. It does not however imply that the 220 SMR network is capable of streaming any high bandwidth applications such as video streaming or internet surfing.
Resurrecting Old Spectrum with New Possibilities: The Opportunity
The opportunity for growth is propped up thought the need for more bandwidth and more spectrum capable of serving it. Its no small secret that information has value in todays market however, there are still several underserved markets that do not meet the traditional model or coverage area of a cell phone network. Agile Radio has heard the call of these customers and have decided to answer it in several ways.
1. A flexible business model capable of opening up new lines of revenue for existing spectrum owners and operators.
2. Provide the ability to augment cell phone coverage capabilities over a larger coverage area in rural locations.
3. Deliver a capability that allows spectrum owners and small business owners the ability to service rural locations within minimal capital and low operating costs.
4. The ability to interlink repeaters to offer a nation wide coverage never before seen in this spectrum.
The integration and interoperation with cell phone technologies. Our radios work directly with current cell phones via Bluetooth, Wifi, or cable tethering to provide voice and text service in places traditional cell phones cannot.