Spectra Precision ADLCONF User Guide - Manual (Page 33)

33 ADLCONF User Guide
All Pacific Crest radios are programmed by authorized dealers with region codes that
ensure the radios adhere to local radio regulations. To adhere to the new law, a new
US region code for 2013 prevents transmission more slowly than 19200 bps in 25 kHz
channels. If you program a radio with (a) the US region code for operation at (b) 4800 or
9600 bps in (c) 25 kHz channels, ADLCONF warns you that this is not allowed in the US:
The expression “map settings to legal values” seen in this warning message means
ADLCONF will automatically change the settings in such a way that the radio remains
both legal in the US and compatible with other brands and models of radios configured
in the same way. When you click the OK button, you will program the radio with all
the selected settings except the channel spacing is automatically reset to 12.5 kHz for
as long as the radio remains set to transmit at 4800 or 9600 bps. This is the meaning
of “These settings will be mapped to legal values.” If you later increase the link rate to
19200 bps (using ADLCONF’s Radio Link screen or by using the front panel interface
available on the ADL Vantage and ADL Vantage Pro), the radio’s channel bandwidth
automatically resets to 25 kHz. Because the radio will transmit in 12.5 kHz channels at
4800 or 9600 bps or in 25 kHz channels when set for 19200 bps, the channel bandwidth
is displayed as “Ch BW: 25 kHz Max.” The word “Max” on the front panel of an ADL
Vantage or Vantage Pro indicates that the radio is set to the US region code and so will
operate in channels that are a maximum of 25 kHz – depending on the selected radio
link rate..
Note: This is a change from pre-2013 when a single channel table would work in either
12.5 or 25 kHz channels. Now, with the region code set to “US” and a channel table set
to 25 kHz bandwidth, ADL radios will automatically switch to 12.5 kHz channels if the
link rate is set to 4800 or 9600 bps and switch back to 25 kHz channels if the link rate is
increased to 19200 bps. Thus the radio always operates in accordance with the new FCC
narrowbanding regulations.
What does this mean for radio network compatibility?
In order for two radios to communicate they must be configured for the same protocol,
frequency, modulation type, forward error correction and scrambling. In general, you
also want both radios to be set to the same channel bandwidth, but a radio set up for
25 kHz channels will receive data from a radio transmitting in 12.5 kHz channels as
long as no one is simultaneously transmitting in an adjacent channel. This ensures that
ADL radios configured with the new US region code will remain compatible with legacy
radios. Take the case of an ADL radio configured with the new US region code and a
25 kHz wide channel table transmitting to legacy radios that are programmed with the
same 25 kHz channel table. If all radios are set to operate at 19200 bps, the ADL radio
will transmit and the legacy radios will receive in 25 kHz channels. If all radios are set
to operate at 9600 bps, the ADL radio will automatically reset itself to transmit in 12.5
kHz channels in accordance with US law. The legacy radios, though still set to the 25