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Dual Bandwidth Capable. Wide and narrow-band explained.

Raveon Technologies data radio modems can have either wide band IF filters, which are used on 25kHz or 30kHz spaced channels, or narrow-band IF filters, which are used on 12.5kHz spaced channels.

 

As the picture above illustrates, it is possible to have twice the number of radio channels, when everyone uses 12.5kHz narrow band radios.

So, why is this important?  There are two big reasons:

1. Your radio system must have receivers with the proper IF bandwidths to perform properly and meet regulatory specifications.

2. In the USA, the government has mandated that all all Part 90 Business, Educational, Industrial, Public Safety, and State and Local Government VHF (150-174 MHz) and UHF (421-512 MHz) private PLMR (Private Land Mobile Radio) system licensees convert to narrow-band operation by 2013.

Raveon Technologies is here to help you migrate your system to narrow-band technology.  Our M7 series of radios supports both wide and narrow-band operation, and our new VHF M7 supports both in the same radio.

  Wide Band Narrow Band
Channel Spacing 25kHz or 30kHz 12.5kHz
Actual receiver IF filter bandwidth 15kHz 7.5kHz
Maximum data rate with  standard modulation 9600 baud 4800 baud
Maximum data rate with  4-level modulation 19200 baud 9600 baud

Because the IF bandwidth in a narrow-band radio must be 1/2 the bandwidth of a wide-band radio, the over-the-air data rate will be 1/2 also.   And unlike other brand radio modems that loose sensitivity when operating on narrow channels, the M7 series of radios has the same high receiver sensitivity on both wide and narrow-band channels.

Raveon’s UHF data radio modem, the RV-M7-U, may be ordered as either a wide-band or a narrow-band radio.  It is configured at the factory for one or the other.

Raveon’s new VHF data radio modem, the RV-M7-V, is dual-bandwidth capable and user-configurable for either  wide-band or narrow-band .  It has 6-channel memories in it, and each channel may be set to either wide or narrow band.

A narrow-band radio can usually communicate with a wide-band radio, if they are set to the same over-the-air data rate as the narrow-band radio.  But because the wide-band radio has overly-wide IF filters for the signal, the communication range will not be as good as two narrow-band or two wide-band radios communicating.

A wide-band radio will not communicate with a narrow-band radio.  In the voice world it might work, but in the data world, the narrow IF filter in a narrow-band radio will filter off the wide-band signal, and no reliable communications will be possible.

So, if you are migrating your wire data system, SCADA system, or telemetry system from wide to narrow-band, you must make sure all radios in the system have the same IF bandwidths and over-the-air data rates.  Please contact Raveon Technologies for either wide-band or narrow-band data radio modems.

Links to FCC Documents regarding the narrow-band migration:

< http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-04-292A1.doc>

< http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-04-292A1.pdf>

< http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-04-292A1.txt>

Filed under: Data Radio Technology | Posted on January 26th, 2010 by John Sonnenberg

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