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PETERTHEEATER
15-07-2010, 07:02
Communication between airfield and aircraft grew with the technology of the day through the 1930's and during WW2.

Can anyone give me a synopsis of radio communications to include the use HF communications leading to VHF communications and some kind of dateline?

When did 'voice' communication supercede Morse? Was WT Morse and RT voice?

What sort of aerial arrays (just general) were used on the ground (airfield) for transmission (Tx) and reception (Rx) of HF and VHF comms. Were dedicated 'ground' Tx/Rx units used or aircraft sets?

The main reason for my questions is to get an understanding of when ground to air visual signals were superceded by radio communications.

SNAFU
16-07-2010, 07:49
An excellent question this, and as a 'ham' one I had been planning to ask.

And just to add an extra question to this, without intending to hijack the thread..... I read that on the Dams raid Guy Gibson wanted to talk directly to the other pilots, which alledgedly had not been done before. So the Lancasters were fitted with VHF R/T radios from fighter aircraft.

And from this the book suggested that the technique of Master Bombers giving a running commentary to the bomb aimers during a raid was born.

Is this plausible, or just another urban myth springing out of the Dambusters rais ?

TIA, Snafu

PETERTHEEATER
16-07-2010, 09:55
Not directly related to my query but, I found this whilst surfing. Don't be put off by the title, there is a variety of interesting information in this guide.

Thanks to Micdrow of the Aircraft of World War Two - Warbirds Forum for the PDF:

http://www.ww2aircraft.net/forum/attachments/communication/80548d1231721071-radio-operators-information-file-radio-operators-info-file.pdf

Carnaby
16-07-2010, 10:37
Excellent find. Peter

A lot of the equipment in this book was available on the surplus market in the late 1950s. In particular the SCR 211 Wavemeter - much prized by radio amateurs of the period.

Graham

tigger
16-07-2010, 13:29
Can one of you chaps copy the file to me please? Don't really want to join yet another forum.

(also a licensed amateur)

Carnaby
16-07-2010, 15:00
Was WT Morse and RT voice?
Yes. W/T was used certainly up to and during WWII. It's big advantage (only advantage?) was that it was robust in comparison with speech transmissions. A very weak Morse signal could be understood, whereas telephony would be completely illegible. Certainly all Lancasters etc were equipped with a Morse Key, and for D/F purposes (which was very important) it was all that was required. I guess the single-seat fighter was the Achilles Heel. Sending a signal from a key strapped to the pilot's leg couldn't be easy whilst flying the plane.

Regarding dates etc, I've wondered about this for a while. Will see what I can dig up.

(Tigger - pm me with email address. Joining that forum was a real pain as it involved Yahoo)

Graham

Jim Hope
16-07-2010, 16:18
Just been looking at "the Battle of Britain Then and Now". According to them, fighters were equiped with the HF RT T/R9 sets, although its performance was poor due to lack of range and no of channels available in the set. By late 1939 a new VHF set the T/R 1133 was available and this gave an air-ground range of 120 miles at 20000ft and air-air range of 100 miles. A new and improved T/R 1143 was available by late summer of 1940. According to "Then and Now", Dowding ordered thatduring the Battle of France, all A/C were to use the old HF T/R9 sets so it wasnt until mid 1940 that VHF was used.
Ground equipment for HF was probably the transtmitter type SWB8 or T1509. These were both still in use at Watton up until Mar/Apr 1963 when the last of the Lincolns were taken out of service, and the HF site was emptied. I drove past it in the early 80's and it was still in use as it had a flagpole in front and the ensign was flying. Probably something to do with Eatsern Radar. As an aside the T1509 was still in use at Salalah in 1971. The VHF equipment was more than likely the R1392 which was also used the the VHF D/F CRDF, and the low power T1540 and higher power T1131. Afraid I cant remember the power O/Ps. I did look on the RAF Henlow Signals Museum site, and although they seem to have most of the ground equipment, the onlt photo was that of the T1131.

Hope this is of some interest

Jim

canberra
16-07-2010, 18:39
Yes Peter WT is morse aka cw, and RT is voice. As for the use of WT by aircraft, well Nimrods used morse. And some of the oceanic ATCCs had and may still have a morse capability.

And the other AATCs on the site will know of the speechless procedure which uses morse.

Paul Francis
16-07-2010, 19:00
Canberra are you refering to the Hawker Nimrod, a single-seat biplane fighter which first flew in 1930, because I think Peter is talking 1930s / 1940s

PETERTHEEATER
17-07-2010, 07:46
Just been looking at "the Battle of Britain Then and Now". According to them, fighters were equiped with the HF RT T/R9 sets, although its performance was poor due to lack of range and no of channels available in the set. By late 1939 a new VHF set the T/R 1133 was available and this gave an air-ground range of 120 miles at 20000ft and air-air range of 100 miles. A new and improved T/R 1143 was available by late summer of 1940. According to "Then and Now", Dowding ordered thatduring the Battle of France, all A/C were to use the old HF T/R9 sets so it wasnt until mid 1940 that VHF was used.
Ground equipment for HF was probably the transtmitter type SWB8 or T1509. These were both still in use at Watton up until Mar/Apr 1963 when the last of the Lincolns were taken out of service, and the HF site was emptied. I drove past it in the early 80's and it was still in use as it had a flagpole in front and the ensign was flying. Probably something to do with Eatsern Radar. As an aside the T1509 was still in use at Salalah in 1971. The VHF equipment was more than likely the R1392 which was also used the the VHF D/F CRDF, and the low power T1540 and higher power T1131. Afraid I cant remember the power O/Ps. I did look on the RAF Henlow Signals Museum site, and although they seem to have most of the ground equipment, the onlt photo was that of the T1131.

Hope this is of some interest

Jim

Thanks Jim, having owned the references - to which you refer - since publication it shows how little I take in when reading and re-reading!

From that, VHF was in use (or available) much earlier than I thought and fitted predominently into fighter aircraft.

Does anyone have any idea of a typical aerial arrangement for the HF? Long wires between towers? Typical location?

PETERTHEEATER
17-07-2010, 07:57
Yes. W/T was used certainly up to and during WWII. It's big advantage (only advantage?) was that it was robust in comparison with speech transmissions. A very weak Morse signal could be understood, whereas telephony would be completely illegible. Certainly all Lancasters etc were equipped with a Morse Key, and for D/F purposes (which was very important) it was all that was required. I guess the single-seat fighter was the Achilles Heel. Sending a signal from a key strapped to the pilot's leg couldn't be easy whilst flying the plane.

Regarding dates etc, I've wondered about this for a while. Will see what I can dig up.

(Tigger - pm me with email address. Joining that forum was a real pain as it involved Yahoo)

Graham

Thanks Graham,

It seems that fighter a/c were given priority for VHF early war so the bombers would have used HF for voice transmissions even at short range.

I have been thinking through how control was exercised over aircraft carrying out practice bombing missions. Ranges had a system of visual signals ground to air; they knew (from telephone link with the user airfield) when aircraft were on the way but was there also a radio voice link very early war or just visual signals. I suspect there was a mix of the two, some simple inland PB ranges with only signals and coastal combination ranges with both signals and RT.

If it was HF (for bombers) then there must have been an HF Rx/Tx aerial. Would a long 'whip' have sufficed for the relatively short range?

canberra
17-07-2010, 10:10
No I was referring to HS/BAE Nimrod, basically I was saying how morse/cw has only recentley stopped being used for air to ground communication. But of corse still used for VOR,NDB and TACAN beacons.

Carnaby
17-07-2010, 12:08
Does anyone have any idea of a typical aerial arrangement for the HF? Long wires between towers? Typical location?
The 1945 site plan for Thornaby depicts four 70 foot wooden aerial supports. Three are W/T Masts to dwg TY445, the fourth is a W/T Tower - dwg 3735/36.

The central mast is adjacent to the SHQ. There are three wires radiating from this to two masts and a tower, each approx 90 yards distant and forming a triangle with angles very roughly 100 / 40 / 40 degrees. These towers were not present in the 1950s, when the station had the typical two large towers external to the airfield. I remember when the site closed, one was inscribed 'Thornaby Transmitter', the other was 'Thornaby Receiver'. These would have been VHF / UHF? communications facilities, and are not shown on the 1945 plan.

Graham

PETERTHEEATER
18-07-2010, 08:38
Thanks Graham, I should have thought those were HF aerials due to length.

Somewhere,in a thread on ranges I mentioned two 'redundant' timber towers that had been dismantled (from Warmwell?) and shipped to Salisbury Plain for use as target supports. These were probably HF related and superceded by VHF.

Carnaby
18-07-2010, 12:40
Thanks Graham, I should have thought those were HF aerials due to length.
I have rewritten my post above. Assuming the masts are sited 'efficiently', then the 90 yard separation could well mean an aerial length of say 80 metres, which would give a working wavelength of 160 metres (= 1.8 MHz). This isn't HF, which is 3 - 30 MHz, but Medium Frequency, MF. I find this a bit surprising but is probably what was in use when the station was first built pre 1939.

Just checked my 'Aircraft Radio', by DH Surgeoner (undated but pre 1941) which describes International Telecoms Convention (1934) allocating the following aviation frequencies:
320 - 365 KHz (=838-833 metres).

The 'Standard' R9 / ATR14 (civil?) radio equipment operated on 322, 327. 333, 348, 363 and 500 metres.

The Marconi AD63 for Fighter Aeroplanes, featured an electrically heated microphone! and operated between 75 - 110 metres (4 to 2.7 MHz).

This is all a bit confusing.

Graham

Peter Kirk
18-07-2010, 21:20
Haven't found much on early war equipment but a write up of the state of Jurby's ranges in 1949 listed G.P.O lines to all quadrant shelters and W/T and R/T in what they called the "Officers (Night) Control Tower" I assume from the descriptions that this was all the wartime fit and implies that only the Control Tower had W/T & R/T the rest bing linked by G.P.O. lines (That's telephones and BT's predecessor for the youngsters).

Even after all these years I still refer to the telephone lines as G.P.O. - confuses the hell out of Broadband call centres not based in the UK :)

PETERTHEEATER
19-07-2010, 10:10
Thanks Carnaby, that makes more sense to me. I perpetuated HF to differentiate from VHF since HF is still in use for long range comms. It really comes down to the actual sets installed in aircraft (bombers). If the usual fit were sets that operated in the MF range - which I suspect is the case - then they communicated on MF. Given the trailing aerial system used then it would have provided adequate range. Meanwhile, the fighters moved to the line-of-sight VHF which suited their short range missions and simplified pilot operation.

MF would also explain the lack of high and long aerial systems at airfields.

When communicating on MF at short ranges (say, ground to air on ranges) then even cropped aerials would probably give adequate range and quality.

PETERTHEEATER
19-07-2010, 10:18
PNK - In my experience and from my research, only the Master Quadrant had radio comms and was linked to other range buildings (quadrant shelters, marker shelters etc) by field telephone. The Master also had a land line to the user airfield, some combined ranges had more than one Master QS so each would have had radio comms.

The pre-war and early war Air to Ground range (gunnery) in which so called 'bulletproof' shelters in line with the targets were provided for the 'controller' and markers seemed to have used only visual signals to aircraft. I am convinced that 'system' was superceded by a QS located out of the line of fire and on the 'foul line' and that communication was by radio.

canberra
19-07-2010, 10:50
Having worked on a bombing range Peter I can say thats exactly how the comms worked.

Carnaby
09-08-2010, 10:49
Noticed a display of WWII radio equipment at the Brooklands Museum yesterday. It stated that the pilot (via wireless operator) would use speech communication on the High Frequency band (short wave) typically to communicate to the watch office when he was close to his airfield. Other transmission would be W/T (Morse) used on Medium Wave band (= medium frequency) typically to communicate long-range to HQ etc. An excellent example of that was of course 617 Sqn informing 5 Group HQ of their progress on the Dams Raid in the film (Gonner, N****r etc)

Later in the war, VHF sets replaced HF for short range communication.

All falling into place

Graham