How the WS10 works

This section aims to provide a basic explanation of how the Wireless Set No.10 functions. If you require a further description of any of the terms used in this section, use the links to the glossary for a lay interpretation. Points considered particularly significant are expanded upon in the reference section.

Overview of how the WS10 operates

The sending of information using the Wireless Set No.10 involves two phases of operation. For explanation, equipment itself can be divided into two separate parts which in combination achieve the overall transmission. The pulser unit modulates the eight available speech channels into electrical pulses of rectangular wave form. To provide a multi-channel capability, the designers of the WS10 – some of whose own recollections have been used in the construction of this site – developed an ingenious system now know as Time Division Multiplexing. In brief, this is transmission of multiple packets of information on one radio wave by separating them with respect to time, what is called a width-modulate pulse. These rectangular shaped pulses are delivered to an ultra-high-frequency (UHF) sender unit and used to modulate a radio wave, the method by which the data is sent.

By the standards of the 1940s, the WS10 produced radio waves with a revolutionary technique, using a magnetron. This component creates short-wave energy by conducting very high voltages within a strong magnetic field. The energy generated is harnessed by positioning the magnetron in a cavity that can be tuned by an adjustable piston to resonate at a frequency which causes the magnetron to oscillate. These resulting waves are then ‘fed’ with width-modulated pulses. The output of the sender unit is coupled to a 2” flexible wave-guide on the end of which is a 4ft diameter parabolic aerial. The energy produced was considered low-power even by 1940s standards, but the following extracts illustrate precisely how much energy could be produced by a magnetron.

As can be seen, the entire set is contained within a 2-ton trailer. Despite there being two petrol-electric generators to power the unit, operators found that the WS10 was a quite piece of equipment to use; there was even sufficient space in which to lie down and sleep. If it was operationally possible, the generators would be removed from the back of the trailer to improve ventilation and reduce noise disturbance. It was also possible for the equipment to be dismantled and man-handled into position if the site was inaccessible. Click the image on the left for an impression by Capt. Coles of the WS10 in operation.

The image to the right gives an idea of where sites might be located. In the absence of the standard 60ft tower to which the dishes could be attached, this windmill outside Eindhoven made a suitable alternative. The reflecting dishes were removed from the trailer and passed up ladders to the roof and hidden from sight. The flexible wave-guide connected them to the sender unit. In addition to offering improved optical range, this arrangement also offered excellent camouflage, important so close to the front line. The lorry in the foreground of the image was used to rotate the complete windmill onto the appropriate bearing.

The sender station transmits its signal to the known location of the receiver, done simply by use of a map and compass. Once in place, the WS10 was in constant operation, ready to receive incoming signals on predetermined frequencies, which varied according to the type of magnetron value used.