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norton1974
06-25-2009, 08:30 PM
On a clear day how far could the radios in a fighter transmit?

How many channels did they have?

norton1974
06-25-2009, 08:30 PM
On a clear day how far could the radios in a fighter transmit?

How many channels did they have?

WTE_Galway
06-25-2009, 08:45 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by norton1974:
On a clear day how far could the radios in a fighter transmit?

How many channels did they have? </div></BLOCKQUOTE>

Not all fighters even had them, they were especially rare in early war VVS fighters.

general_kalle
06-25-2009, 09:29 PM
the Japanese didnt have them either...i remember something in a documentary about how Saburu Sakai used hand signals to his pilots.

M_Gunz
06-25-2009, 09:52 PM
Altitude makes a difference too.

Tully__
06-25-2009, 09:56 PM
It varied greatly throughout the war, also depending on which nation's aircraft, weather and so forth.
The late war VHF radios were fairly close to line of sight, so at altitude you would get several hundred miles, especially if the other end of the conversation was also an aircraft at altitude.

The very early war short wave (HF) radios were also capable of very long ranges between two aircraft at high altitude but were much more dependant on weather conditions, solar activity and the radio actually being in working order.

Short wave radios did have an advantage if conditions were favourable! Short wave signals are sometimes subject to ionispheric reflection, making it possible to transmit to receivers well beyond the horizon. On the other hand, short wave radios were generally amplitude modulated where VHF radios later in the war were frequency modulated. Amplitude modulation requires much higher signal to noise ratio than frequency modulation for effective voice communication.

Waldo.Pepper
06-25-2009, 11:53 PM
Here are some details of radio range as depicted in a USN manual dating from 1944.

http://img.photobucket.com/albums/v516/WaldoPepper/book/Untitled-0.jpg

The GROUND and SKY portions of the radio wave are responsible for two different METHODS of carrying the messages from transmitter to receiver.

The GROUND WAVE is used for SHORT-RANGE COMMUNICATION at high frequencies with low power. and for LONG-RANGE COMMUNICATION at low frequencies and very high power. Day-time reception from most commercial stations is heard by the ground wave.

The SKY WAVE is used for long-range, high-frequency daylight communication. At night, the sky wave provides a means for long-range contacts at LOWER Frequencies.

THE GROUNDWAVE

The ground wave is made up of four parts-DIRECT, GROUND-REFLECTED, TROPOSPHERIC, and SURFACE waves. The relative importance and use made of each part is dependent on several factors. The chief factors are-frequency, distance between the transmitting and receiving antennas, height of the antenna. the nature of the ground over which the wave travels, and the condition of the atmosphere at the lower levels.

The DIRECT WAVE travels directly from the transmitting antenna to the receiving antenna. For example two airplanes are several thousand feet in the air and only a few miles apart. This direct wave is not influenced by the ground, but may be affected by the atmospheric conditions through which the wave travels

The GROUND-REFLECTED WAVE permits two airplanes several miles distant and at low altitudes to communicate with each other. The wave arrives at the receiving antenna after being reflected from the earth's surface. When the airplanes are close enough and at the correct altitude to receive both direct waves and ground-reflected waves, the signals may be either reinforced or weakened, depending upon the relative phases of the two waves.

The TROPOSPHERIC WAVE is the part of the wave that is subj ect to the influences of the atmosphere at the low altitudes. The effects of the atmosphere on this type of wave propagation are most pronounced at frequencies above the high end of the H-F band.
Communication by the use of the tropospheric wave is gaining in importance, both from the stand point of its usefulness, and its frequent unpredictable ranges.

The SURFACE WAVE brings most of the low and medium broadcasts to your receiver. These frequencies are low enough to permit this wave to follow the surface of the earth. The intensity of the surface wave decreases as it moves outward from the antenna. This ATTENUATION-rate of decrease is influenced chiefly by the conductivity of the ground or water and the frequency of the wave.

As it passes over the ground, the surface wave induces a voltage in the earth, setting up eddy currents. The ENERGY to create these currents is pirated or taken away from the surface wave. In this way, the surface wave is weakened as it moves away from the antenna, increasing the frequency rapidly increases the rate of attenuation. Hence surface wave communication is limited to the lower frequency.

http://img.photobucket.com/albums/v516/WaldoPepper/book/Untitled-1.jpg

SeaFireLIV
06-26-2009, 05:38 AM
wow. Informative stuff, fellas. Thanks.

RPMcMurphy
06-26-2009, 06:40 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by norton1974:
On a clear day how far could the radios in a fighter transmit?
</div></BLOCKQUOTE>
It depends on alot of things like weather and time of day etc. Sometimes a thunder storm so far from your position that you cant even see it will blcok the signal. I have transmitted HF signals up to 400 miles using manportable systems on the ground. 2000 miles with an automatic link establishment type sytem. HF being 2-29.9 MGhz with about 4 amps transmit power if I remember correctly with 24 volt system in my most common radio I would cut the transmitting antenna to length with diffferent configurations to choose from. You must have it on azimuth to the home station for best results. My most effective was a strait longwire antenna that put out a 'cone shaped' pattern from the ends and a terminating resistor at one end would draw the signal in that direction so a slight offset of the azimuth would produce better results in that the edge of the 'cone' was stongest. The conditions of the various spheric layers above the earth play an important roll in transmitting long-range HF. The suns energy causes ionization during the day and is bad for radio waves so night is better for long range but the signal must still bounce up and down from the ionosphere to reach over the horizon and the recieving station must be in the footprint of one of the down-shots of a signal bounce. I would say that a Corsair for exaple probably uses a 'Longwire' antenna as you can see it stretches from the vertical stab to the pole near the cowling and its ability to transmit to a home station may depend on the direction the plane is going in relation to the home staion inthat the planes structure itself can draw the siganl stronger in one direction but there are so very many conditions that effect the ability to transmit long range it is really difficult for me to say how far a fighter could transmit at any given time or place especially since my experience is mostly from being a ground pounder not in aviation. I better stop.

K_Freddie
06-26-2009, 12:20 PM
AFAIK, The a/c-to-a/c radio link was somewhere between 50-100 miles. Ground-to-a/c had longer ranges as the ground transmitters were more powerfull.
The a/c transmitters were not that powerfull and thus ranges were a lot less. As mentioned.. weather, height and a/c (aerial) orientation effected the receiver sensitivty/range.
http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

mortoma
06-26-2009, 04:19 PM
Someone said that later in the war that some transceivers were FM. As a pilot and Advanced class Ham radio operator, I'm not aware that aviation radios ever operated in FM mode. To this day they still use AM as a modulation method. And there is a reason for using AM and it's because FM has a capture effect while AM does not. So if two pilots transmit at the same exact time, with AM both might be understood, although a bit garbled. With FM the strongest signal of the two would knock out the weaker one at the receiving ground station and only one would be heard.

It is possible that FM was used for a while and then was changed later but I'm not aware of this. They might have found out later that FM was not as good for aircraft and switched back to AM.

mortoma
06-26-2009, 04:25 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by K_Freddie:
AFAIK, The a/c-to-a/c radio link was somewhere between 50-100 miles. Ground-to-a/c had longer ranges as the ground transmitters were more powerfull.
The a/c transmitters were not that powerfull and thus ranges were a lot less. As mentioned.. weather, height and a/c (aerial) orientation effected the receiver sensitivty/range.
http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif </div></BLOCKQUOTE>That sounds about right but I'd go with 150 miles for VHF, depending on the altitude of the aircraft. With the older HF it could be over a thousand miles in some circumstances. When I lived in Indiana I used to listen to the Coast Guard aircraft and comsta stations talk to each other way out in the Atlantic and I could hear both sides for the conversation. Usually it was a search and rescue mission. And of course Ham radio operators regularly use HF freqs to talk extremely long distances under good conditions. Hams use VHF and UHF for short distance local stuff. But even that can go pretty far when repeater towers are used.