User's Manual

20-496 Owner’s Manual Draft Page 60/78
The “CPU” and “DSP-Voc” firmware versions are permanently installed at time of manufacture and cannot
be updated in the field. The “DSP-App” version is field upgradeable. The original factory version is
indicated by “F” preceding the version number. The DSP-App version number will be preceded by “U” after
the DSP version is updated via Internet download.
A GENERAL GUIDE TO FREQUENCIES
Reception of the frequencies covered by your scanner is mainly “line-of-sight.” That means you usually
cannot hear stations that are beyond the horizon.
US Weather Frequencies (in MHz)
162.400 162.425 162.450
162.475 162.500 162.525
162.550
Ham Radio Frequencies
Ham radio operators often transmit emergency information when other means of communication break
down. The chart below shows the frequencies the scanner receives that ham radio operators normally use.
Wavelength Frequencies (MHz)
10-Meter 28.000 — 29.700
6-Meter 50.000 — 54.000
2-Meter 144.000 — 148.000
70-cm 420.000 — 450.000
33-cm 902.000 — 928.000
23-cm 1240.000 — 1300.000
Birdie Frequencies
Every scanner has birdie frequencies. Birdies are signals created inside the scanner’s receiver. On rare
occasions, birdies can cause interference to channels you want to listen to.
Birdies typically occur with approximately equal strength with and without the scanner’s antenna attached.
If you receive an interfering signal and suspect that it is a birdie, try removing the scanner’s antenna. If the
interference disappears, the interference may be the result of other electronic equipment in the vicinity of
the scanner. If the interference remains, it is likely a birdie signal.
It may be possible to adjust the squelch control and/or attenuator to minimize the effects of a birdie signal
on scanning operation. Both of these methods will likely have some effect on the signal you are trying to