NarrowbandWideband VHF frequencies, and DigitalAnalog Radios

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Narrowband/Wideband VHF frequencies, and
Digital/Analog Radios

• Current and future Impacts to TNCs fire programs
• Sam Lindblom, TNC Fire Initiative

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The Issue

• Increased radio frequency usage (more users)
• Limited bandwidth available on the VHF spectrum
• Much more conflict between users
• Getting walked on
• Potential increased regulation by the FCC

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The Solution

• Convert to Narrow Band radio frequencies and
  equipment
• More on equipment later....
• First, lets look at the technology and the issue
  in more detail

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What is Narrow Band?

• Narrow band frequencies use ½ the bandwidth of
  wide-band
• Normal wideband spacing is 25 Khz
• Narrowband spacing is 12.5 Khz
• For example, the TNCFIRE frequency is 151.625.
  Normally, the next frequency up would be 151.650.
  In narrow band, the next frequency is 151.6375
• Narrow banding essentially doubles the number of
  available frequencies in the VHF Business
  spectrum (148-174 Mhz)

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Sounds Great, right?

• PROS of Narrowband
• Less traffic on currently shared frequencies
• Reduces the need to use tone/code guards
• CONS of Narrowband
• Operating wideband in a narrowband environment
  can cause problems
• Requires specific radio equipment
• Could be costly (more on that in a minute)
• Its likely to be a long time before the general
  public will be forced to use narrowband and all
  wideband radios are obsolete

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Why would I want to convert to Narrowband radios?

• If you regularly burn with federal partners, you
  will likely have to convert sooner than most
• If you experience significant radio traffic where
  you work, narrowband could help (but only if
  everyone converts)
• If you intend to participate on large wildland
  fire incidents of any kind

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The FCC and Narrowbanding

• The Federal Communications Commission mandated
  that all federal agencies convert by 2005. This
  mandate was lifted until further notice
• FCC does not currently have a time schedule in
  place to change the general licenses that we have
  now.

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Equipment

• Some existing radios that we have can be
  programmed to narrowband (most likely so if they
  were purchased in the last few years)
• Bendix King EPH and GPH radios are OK
• At this point, you should avoid radios that will
  not work on narrowband frequencies
• Most radios require programming each individual
  frequency/channel as narrow or wide
• Narrowband radios alone dont significantly
  increase costs

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What about Digital?

• The problem with Analog and Narrowband
  frequencies
• Analog radios have a harder time sending and
  receiving narrowband frequencies, reducing their
  effective radiated power.
• Certain analog radios can lose up to ½ of their
  transmit distance.

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What about Digital?

• Digital radios overcome this problem with a
  better capacity to process narrowband frequencies
• They dont typically suffer from the same loss in
  effective radiated power as analog.
• Some digital radios using narrowband can
  theoretically transmit further than their analog
  counterparts using wideband
• Digital radios are expensive
• GPH Bendix King (Analog) is 500
• DPH Bendix King (Digital) is 1200

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Recommendations

• Continue to purchase analog radios unless you
  have a big budget
• Do not purchase radios that cannot process
  narrowband frequencies
• Know how to program your radios
• Know if you are working in a narrowband
  environment
• Ask all of your local cooperators
• Establish a communications plan if you contribute
  to local emergency response.