Extracts rom an article by Paul Smith. YE beacons include YG beacons, unless otherwise noted.These beacons are no longer used so present tense is used in this article for clarity.

The difficulty of navigating small aircraft at sea led to the use of homing beacons. The Type 72 beacon was used by the Royal Navy from 1936, until the USN brought into service, the  YE and YG beacons. YG beacons were also installed on ships and in  shore bases.

YE beacons are rotating directional radio beacons that give an aircraft its approximate bearing from a vessel or shore base. A ship normally uses a YE beacon (50W output) and the ships gyro-compass keeps the transmissions correctly oriented to true north.

A standby YG beacon (25W) is manually adjusted when the ship turns, unless anoptional true bearing control unit is fitted. Shore bases normally use the YG beacon. The 360° around a YE beacon is divided into twelve 30° sectors; each defined by true bearings and identified by a single letter. While the beacon antenna rotates at 2 rpm, a signal disc keys the modulating frequency (at 20 wpm) with individual sector letters.

Each letter is sent twice in its sector. (Sector letters are separated by slightly less than a second.) After nine rotations identifying the sectors, the beacon sends its two letter call sign using the tenth timeslot (ie. the callusing is sent at intervals of 5 minutes). An aircraft equipped with suitable receiving equipment can home to the ship or shore base, leading to the system sometimes being called the homer. As the transmission has a carrier frequency around 250 MHz, the service is line-of-sight.

To use the beacon, select the appropriate channel and identify the beacon by its two letter call-sign. If initially several sector letters are heard, turn down the sensitivity control until you can identify the strongest letter. This indicates your bearing sector.

The homer decode card, prepared before flight, shows the code letter of each sector and the orientation of the sectors. For each sector, the decode card also shows a central heading towards the beacon and the initial homing heading. It is likely that the aircraft will near a sector boundary before it reaches the beacon. This is indicated by the letter identifying an adjacent sector becoming louder. Adjust heading as necessary to continue homing. The receiver sensitivity must be progressively reduced as the sectors narrow, so that the chosen sector’s letter can be tracked. Overhead the beacon, all sector letters can be heard, but at reduced volume.

CHANNEL FREQUENCIES (Note 1)

Royal Navy used:              1/660, 2/690, 3/720, 4/750, 5/780 or 6/810 kHz
United States Navy used:  1/540, 2/570, 3/600, 4/630, 5/660 or 6/690 kHz
The common frequency of 660 KHz  would facilitate inter-service operations.

Homing beacon management in peacetime:

• The beacon's carrier frequency is set on 246MHz.
• The six channel numbers denote fixed modulation frequencies.
• Shore bases use a fixed channel number and two letter call-sign.
• Bearing sector boundaries and identification letters do not change..
• Initial homing headings are multiples of 30°of channel/frequency

Homing beacon management during hostilities:

• The beacon's carrier frequency can be set between 234 and 258 MHz  (Note 2)
• Six modulation frequencies between 540 and 830 kHz can be chosen  (Note 2)
• Homing beacon channel numbers and call-signs are varied.
• Bearing sector alignment and identification letter sequence are varied.

Morse code disk used in YE equipment. The order and  placement of characters on the wheel changed daily, possibly even with each mission. The transmitter used a double amplitude modulation scheme and operated around 240 MHz -  the double modulation scheme ensured that a casual eavesdropper would hear only a dead carrier unless he had the proper demodulator in the receiver. (Photo via E-bay)

USING THE YE

Edited extract from AN 01-40FAA-1 (the Dash-1 for the Douglas F3D Skynight)4-62. Homing Radio Receiver. The R-4A/ARR-2 homing radio receiver receives either navigation (MCW) or voice signals. In either case, the original signal (at the transmitter) is impressed on another signal in the frequency band between 540 and 830 kilocycles (called the modulation frequency). This in turn modulates a carrier frequency? between 234 and 258 megacycles to produce the radiated signal. The receiver demodulates the signal in reverse order. Six preset modulation frequencies are available and may be selected by remote control. When the receiver is used for navigation, a beat oscillator produces an audible beat note. When used for reception of voice modulation, the beat note oscillator is cut out. The desired operating condition (NAV or VOICE) is selected by the switch on the remote control
unit.

 Homing Radio Control Console. The modified C-116/ARR-2A homing radio control console  is located on the cockpit right-hand control console and is marked “NAVIG”. The console contains the sensitivity control marked “SENS”, the selector control marked “PITCH” and the channel selector marked “CHAN SEL”. The “SENS” control with the indicated position “INCREASE OUTPUT” adjusts the sensitivity of the receiver by varying the R-F gain. The “PITCH” control is used to connect a beat frequency oscillator into the circuit for code reception when the switch is set to “NAV”, and to disconnect it from the circuit when the switch is set to “VOICE”. The control when set to “NAV” also varies the tone of the beat frequency oscillator. The “CHAN SEL” control is used to select one of the six preset frequencies indicated by the positions marked “1” to “6”.

Operation of Homing Radio.

a. Radio master switch “ON”.
b. Turn “CHAN SEL” control on the “NAVIG” panel to the assigned channel number.
c. Turn “PITCH” control to “NAV”.
d. Adjust the “SENS” control to produce a usable weak signal, or if the desired signal cannot
be heard, to a fairly strong background hiss.
e. If a signal is present, adjust the “PITCH” control to produce a pleasing audible tone.
f. Readjust the “SENS” control to keep the signal at the lowest usable level to avoid wrong course indications.
 

YE/ZB  antenna aboard HMCS Magnificent. It was affectionately known as the "hay rake". Click on image to enlarge. (RCN photo)

 
ZB Adaptor

The YE system used the AN/ARR-2 VHF homing receiver sometimes called a "ZB receiver".

A ZB adaptor is mounted on (or near) a broadcast band receiver, from which it draws power. The ZB, tuned to the carrier frequency of the YE beacon's A2 emission, extracts the Morse signals, passing them to the receiver's antenna input socket. The receiver processes this input as an A1 emission at the original modulation frequency. If these signals are on the selected channel's frequency, an audio output of the signals is provided. The NAV / VOICE selector must be set to NAV to hear the signals

NOTES:

Note 1-  The test set uses 710 kHz.
Note 2 - No receiver adjustment possible in -flight.
 
 

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Credits and Contributors:

1) Paul Smith [pas_hba(at)internode.on.net]
2) Tom Brent [navyradiocom@gmail.com]

April 3/23