Wireless telegraphy (wt)

Carnaby;49351 wrote:

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?

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.

PETERTHEEATER;49435 wrote:

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

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.

PETERTHEEATER;49507 wrote:

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

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.

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.

Having worked on a bombing range Peter I can say thats exactly how the comms worked.

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