Long range radio transmissions

[Jenisch]

Hello,

WWII bombers generally used the telegraph to send messanges to base. What was the reason for this instead of voice messanges?

 

[Matt308]

Low Frequency = Minimal bandwidth. And given ionospheric/atmospheric effects on HF transmissions, simple key-coding was less likely to result in messages being corrupted and thus misunderstood. Insert voice as the communication medium and speech intelligibility comes into play.

This same issue occurs to this date. Thus the vast majority of oceanic/remote area operators have migrated to satellite voice communication. And, in fact, extended range twin-engine operations (ETOPS) require satcom voice for qualification.

 

[bobbysocks]

during long missions over central europe one of the missions flown by fighters was radio relay. i have only read a little on this but do know the fighter would fly around a certain area..generally a boring but safe mission. i do not know if thier planes were fitted with repeaters or just their location would let the signal piggy back on.

 

[Shortround6]

As a general rule of thumb, for the same power, code transmissions had 2-3 times the range of voice transmission.

 

[Matt308]

yep

 

[VBF-13]

As a general rule of thumb, for the same power, code transmissions had 2-3 times the range of voice transmission.

..
-.. .. -..
-. --- -
-.- -. --- .--
- .... .- -

 

[tyrodtom]

Plus the morse code can be additionally in a code so the enemy doesn't know what information is being sent.

 

[fastmongrel]

Morse is less susceptible to jamming than voice. When I was in the army I was a Tank loader/radio operator and we were taught morse for when someone dropped a bucket of sunshine on Europe and EM pulse killed all voice. With enough power and a big enough aerial morse would work even in such conditions just.

 

[Elmas]

As a general rule of thumb, for the same power, code transmissions had 2-3 times the range of voice transmission.

Agree, as an ex-Ham radio operator (ISØXXD .... ) and also the CW transmitters and receivers are by far simpler than voice.

 

[Jenisch]

Very interesting guys, thanks to you all!

 

[GregP]

Good one VBF13!

Liked it a lot!

 

[krieghund]

I was under the impression that HFDL was going the way of the dodo but it is still hanging around,

ANNAPOLIS, Md., 12 Feb. 2012. Commercial aircraft operators may start using an air traffic management (ATM) communications technology called the FANS 1/A over HFDL (FOH), after officials of the U.S. Federal Aviation Administration (FAA) approved FOH as a viable means of Air Traffic Service (ATS) communications. This means commercial aircraft may start using the global High Frequency Data Link (HFDL) network to communicate with air traffic control (ATC).
This will enable pilots and air traffic controllers to exchange text and other data messages at long ranges using high-frequency (HF) radio signals, rather than VHF radio or satellite communications. FOH is an inexpensive ATC communications global alternative to satellite-based global communications, and will be most useful in controlled over-ocean airspace such as the North Atlantic and Pacific flight routes, ARINC officials say. Until now commercial aircraft could exchange only voice messages with ground controllers, not data, using HF radio signals.

 

[Aozora]

Later in WW2 the Germans started operating a data transmission system for their nightfighters in an attempt to avoid Allied jamming of their voice channels:

FuG 120 Bernhardine http://www.nonstopsystems.com/radio/hellschreiber-modes-other-hell.htm

A radio beacon signal receiver combined with the EB1 3 (part of the standard FuB1 2 blind landing receiver) and reacting to transmissions from Bernhard ground stations. The received information (bearing of the ground station and running commentary on the air situation) was recorded in code on a strip of paper by the attached teleprinter unit [which was in the radio operator's position in the nightfighter] The device operated in the 30-33.3 MHz frequency band. Range 400 km (248 miles) at 5,000 m (16,400 ft) altitude. Accuracy of reading: 0.5°. Developed and manufactured by Siemens. (History of the German Night Fighter Force 1917 - 1945, Gerhard Aders, Jane's 1979, page 246)