Guidance and Resources for Restorers

This section aims to provide practical advice for people restoring old ROC monitoring posts and those owning WB1400 equipment. Within this document library are the full system handbook and ROC operating procedures describing the message formats. However this is an overkill for most people owning a WB1400 receiver wishing to make it 'work'.

Overview of WB1400
System Overview

All the control signals and spoken messages originate from the Carrier Control Point (CCP). When the CCP is idle it generates a slow tick indicating it is healthy and ready for action. The CCP generates a radio frequency carrier modulated with these signals. The carrier is distributed via the telephone network to end users receivers. Along with the carrier, the electric power to operate the receiver is provided by the final telephone exchange serving the end user.

The receiver battery is trickle charged from the line. The electronics inside the receiver is basically a radio that picks up its signal from the line rather than an aerial. Additionally the receiver 'listens' for the wake up control signal and then activates the loud speaker. The test button on the speaker can temporarily wake up the receiver and the tick signal is heard indicating a connection back to the CCP.

Warning Receiver Owners Decision Time

So you just have a receiver and nothing else, so how far do you want to go to make it appear to work?

The Whole Hog

For this you will need to generate a 72kHz carrier and means of simulating the CCP control signals. This could be a laptop feeding audio to a home made oscillator / modulator. If you aren't capable of building such a device, kits or ready made oscillators are available. Audio MP3 files are available in this section to help, but you will still need to devise a way to play a loop of the monitor tone and override this with a pre-recorded Attack Warning Message and possibly other messages too.

The receiver's rechargeable battery if present is beyond its useful life and will need replacing. If you choose to replace it with another rechargeable battery pack, there are two options, remove the pack recharge and replace it or line power it. Line powering will require a 48 / 50 volt supply and means to insert the carrier via a filter. The first method would seem easier to me or use a pack of single use dry batteries.

Having done all this the receiver will appear to work, monitor tone will be heard when the test button is pressed and when a message is sent from the laptop, the speaker will spring into life.

Completely Fake It

By far the easiest way to demonstrate the carrier receiver at your ROC post is to purchase an inexpensive Bluetooth speaker and place it by the WB1400. Pair the speaker with a Bluetooth phone or tablet. Download the demonstration MP3 files and play them as you describe the warning messages to the visitors. Only experts will spot the difference from going the whole hog and its a damn sight cheaper and easier.

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Demonstration Audio Files

Hidden Speaker Files

The zip archive contains Monitor Tone, Attack Warning and Fallout Warning. These do not contain control signals as these are not normally heard by the end user.


Files Needed to Activate the Speech Receiver

The zip archive contains Monitor Tone, Attack Warning and Fallout Warning. The files fully simulate the carrier control point signals needed to activate the receiver. Only required if you are using a modulated 72kHz carrier.