Signals Procedure and Security
Signallers and officers using the Battalion wireless net had to maintain security and observe signal procedure. Code-signs when referring to formations, units and sub-units and code-names for commanders and specialist identifications always had to be used:
Sunray when linked with a call-sign would indicate whether Battalion or Company Commander; or in conversation My Sunray or using Sunray Minor when indicating the second-in-command.
Map reference codes had to be used if they referred to our own troops but not when referring to the enemy; enemy locations were sent uncoded. Map reference codes linked with identifiable objects like named villages, woods, rivers and other geographical features offered no security but helped to break down the security code; indeed, it was axiomatic that any position known to the enemy must not be referred to in code.
Conversations on the wireless net were best kept short and pre-arranged code-words used, i.e.; Orange = ? Village, Green = road clear. In 1943 a code for use in messages and conversations was introduced. Slidex consisted of a set of subject specific cards printed in a grid layout with words and short phrases appropriate to the subject, together with letters and numbers. Each cell of the table was identified by a two-letter bigram from 'slides' along the top and down one side, on the same principle as giving a map reference.
Officers and signallers had been trained in basic signal procedure for the conduct of wireless conversations for the smooth, uncomplicated operation of the battalion net. Over when a reply was expected; Out for end of transmission; Wait (usually meant a pause for a few seconds); Say Again for a repeat of the transmission; Wilco meant will co-operate and message understood and will comply; and Roger indicated the message received and understood.
It was a general rule that no one station should be on the air longer than a minute. All unwritten messages or conversations taking longer than that had to be broken into portions of about a minute. An example: Hello L2 message for L1 sending a one-minute segment and ending with Roger so far L2 to L1 over. The receiving station acknowledges in reply L1 Roger over. The transmitting station continues message or conversation saying Hello L2 and ends the message with Over, acknowledged with the reply L1 Roger out.
Officers required to speak on the set followed that same procedure. Hello L1 fetch Sunray L1 over. Signaller replies Hello L1 wait out. When officer is at the wireless set Hello L1 Sunray listening over.
Signallers were trained in signal security and made aware that whenever they spoke into a microphone they could be speaking to the enemy. When using radio telephony and morse conversations signal operators had to cut out unnecessary chit-chat and avoid non-standard procedure which enemy listening stations could associate the identity of the net and relate this to a particular battalion. Nicknames of signal operators were an easy giveaway to labeling a net. Intelligence could be gathered by the enemy's intercept system by listening to operators chat which could provide information about the unit and morale ('we have a had a bad night') or about the weather or hints about wounded or casualties, shortage of stores and ammunition, or 'something big is coming up'.
Signallers had to be mindful, too, that the enemy used direction-finding (DF) systems. The longer you were on the air the greater the opportunity for the enemy to pick up your frequency, its directional antenna searching until it could detect your best signal. This technique enabled the direction finder to pin-point your location with an accuracy to less than one degree wrong. This kind of intelligence was an open invitation to bring down artillery fire on your HQ, a visit from enemy bombers (Stukas) or a fighting patrol equipped with flame-throwers to destroy your headquarters.
Wireless Logs were kept at every Station. It was a daily diary recording events, like changing frequency, switching to morse and to note details of all messages on the net whether they applied to your station or not.