VHF Communications
for Pilots & Crew Members
Delaware Wing
Civil Air Patrol
Capt. Gary Emeigh, CAP
Dover Composite Sq.
VHF Communications
 Review of CAP VHF Communications,
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regulations and capabilities
Air-band AM radios vs. CAP FM radios
Protocols and proper operation of aircraft VHF
resources
Repeaters – uses and pitfalls
New information on
 Altitude and frequency restrictions
 Encryption
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Air-band vs. CAP Radios
What’s different
 Authorization
 Air-band Radios are licensed by the FCC through the FAA
 Pilots operate under a radio certificate tied to tail number
 CAP mission base has a blanket authorization to operate
 CAP Radios are licensed by the NTIC through the Air Force
 CAP Radio Stations must be under the direct supervision of a properly authorized Civil
Air Patrol radio operator [i.e. have had BCUT as a minimum]
 Modulation
 Air-band: AM
 CAP: FM
 CAP radio transmissions may also be digital [P25] and encrypted
 Frequencies
 Air-band: open to the public
 CAP Frequencies designated “For Official Use Only” –
 Actual frequencies cannot be disclosed to anyone or broadcast
 Not available through the Freedom of Information Act
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Radio Basics
AM vs. FM
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Amplitude Modulation
AM
• Worldwide standard for aircraft communication
• Very old type of modulation first used in early
development of radio
• Tends to be noisy, easily interfered with. Allows lots of
static and ignition noise. Bad feature.
• Allows two stations to be heard over one another – i.e. no
capture effect as with FM.
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Frequency Modulation
FM
 FM is used by CAP for VHF radios in vehicles, aircraft,
walkie-talkies and base stations. Short range.
 The advantage is less static from ignition systems in
vehicles, and excellent audio quality.
 FM also has a “capture effect” where the strongest
station comes in over a weaker station.
 CAP also uses FM in the ISR UHF radios.
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CAP Radio Equipment
and Operation
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Types of radios
 EJ Johnson
 Base Radio
 Mobile Radio
 Portable
 Motorola
 HF
 800 Mhz
 ICOM
 ISR
 Aircraft Radios
 Aircraft use two types:
 AM – used mostly by
pilots to communicate
with Air Traffic Control.
 FM – used primarily by
Mission Observer to
communicate with
Mission Base
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Delaware Wing has the added complication of
an 800 mhz radio installed in aircraft for
communication with state agencies.
Make certain you have switched the necessary
COMM 3 select from 800 mhz (or UHF) to
Normal (or VHF) before trying to use the CAP
radio.
CAP utilizes one of the two following types of
radios installed in aircraft.
Technisonic Model TDFM-136
Aircraft VHF CAP Radio
Main: On / Off – Main volume
Guard: Guard channel volume
Squelch: Push for open squelch
MN/GD: Transmit channel select
G1/G2: Sets Guard Channel
Hi/Lo: Power – 1 or 10 watts.
1: N/A
2: Display brighter
3: N/A
4: Channel scroll down
5: N/A
6: Channel scroll up
7: N/A
8: Display dimmer
9: N/A
1, 3, #, 0, 7, 9: USED FOR
PROGRAMMING RADIO!
Main and Guard knobs for volume.
Use 4 and 6 buttons to select desired
CAP channel. 2 and 8 for display
brightness. Three switches at
bottom left are normally kept up.
NPX-138
MN Knob: On / Off and Volume for main channel
GD Knob: Guard Channel Volume in Norm position
Scan/Norm/GdTX: Keep in Norm position
GD1/GD2: Guard Channel 1 or 2 select. Usually kept in GD1 position
DISP: - Always Leave on (ID) display
CHAN: Toggle left/right to scroll main channel
BRIGHT: Display brightness up or down.
EDIT: For PROGRAMMING! (Leave in center position)
SQ: Press for open squelch
BASE STATIONS and MOBILES
PUSH TO CHANGE
POWER SETTING.
Display now shows: Command
Control 1, Zone 2, and channel 1
Keep on HIGH.
TO CHANGE CHANNEL:
Press SELECT knob to
move cursor above
channel. Turn knob to
desired channel.
Channel description
changes when you
change channel
On/Off
Volume
ALL DEWG CHANNELS
ARE IN ZONE 2
TO CHANGE ZONE
Press SELECT knob to move
cursor above Zone as shown.
Turn knob to desired zone.
Radio is now in SCAN mode
which is a configuration not
normally used during SARs.
Press SCAN button to scan all
channels, or to stop scanning.
This icon shows
radio is scanning
Repeaters
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Simplex vs. Duplex
 Simplex
 Transmit and receive on
the same frequency
 Line of sight – Buildings
and terrain block signals.
 Duplex
Transmit on one
frequency and receive on
another
Single Frequency One Station at a
Time
R
T
Two Frequencies One Station at a Time
 Repeaters – Duplex mode
 Used to extend coverage and
get over obstacles
Repeater increases the range of mobile
stations due to its high profile location
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DEWG VHF Communications
 Delaware Wing maintains 3 VHF repeaters
 Locations were chosen to give statewide coverage
 Bethel - Northern Delaware
 Woodside - Central Delaware
 Rehoboth - Southern Delaware
 Highbird Repeater * – Utilized by aircraft as
assigned by the IC. Requires ACUT operator
 VHF Frequencies [Channels] are programmed to show
the repeater location [Tag], not the frequency
 Frequencies are FOUO – do not say frequencies on the air
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Aircraft use of Repeaters
 Primary mode of operation should be
simplex
 Only use the repeater if simplex is not
possible
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Delaware Wing
Communications
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Aircraft VHF-FM Radio Channel Plan *
Note: Aircraft Radios do not use Zones
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CC1
CC2
AIR1
AIR2
Guard
TAC1
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R67
R68
R69
R70
R63
R64
ALT R65
ALT R66
SIMPLEX
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Woodside
Rehoboth
Bethel
Salisbury
Easton
Harford
Lakehurst
Hammonton
REPEATERS
[DUPLEX]
REPEATERS
[DUPLEX]
CAPGUARD is restricted to use ONLY for initial contact
Aircraft should monitor CAPGUARD to maximum extent possible
* Subject to change
Current as of 30 Jan 2010 for Technisonic TDFM 136 Radio
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Operating Procedures
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Identifying Which Radio You
Are On
 When calling a station on the CAP Assigned FM
frequencies, use the Channel Designator in your initial
call-up
 “Dover Base this is CAP Seven Twenty-Two on Air 1, over.”
 DO NOT use “VHF, FM, Foxtrot Mike” to identify the radio
equipment you are using
 This avoids confusion at Mission Base which may be monitoring
different frequencies on several different radios
 When calling on the Air-band radio, use normal pilot
protocol or announce the frequency
 Dover base this is CAP Seven Twenty-two on 122.9.”
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PROWORDS
Prowords are a special set of words used for clarity
and brevity in communications.
Some of the most commonly used prowords are:
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THIS IS
ROGER
OVER
OUT
WAIT
SAY AGAIN
CORRECTION
WILCO
AFFIRMATIVE
Preface to your call sign
Last transmission received OK
I’m done, go ahead
I’m done, bye
I will be back in a few seconds
Say that again
Oops! I really meant to say
ROGER and I will comply
Yes
CAPF 100-1 dictates use of pro-words on CAP Frequencies
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I SPELL / FIGURES / INITIALS
 Use “I SPELL” to clarify words or when signals are weak
 Example: LODI
 “I SPELL LODI LIMA OSCAR DELTA INDIA LODI”
 Use “FIGURE(S)” AND “INITIAL(S)” for non-words
 Example: N46 26.15
 “INITIAL NOVEMBER FIGURES FOUR-SIX, TWO-SIX DECIMAL ONE FIVE ”
 Corrections
 Use proword “correction”
 Example:
 “… Turn right at next corner … CORRECTION Turn left at next corner…”
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QUESTIONS?
Questions?
Lt. Bill Mervine during Form 5 in
Dover Squadron’s new Highbird
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