12: Talk Sets

Written by Bruce Robertson, 97. Reviewed Dec 2005. © Kingfisher International

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This application note adresses a number of questions about Optical Talk Sets, which are commonly used during commissioning and repair work on communications systems.

Practical Issues

There are a number of practical issues that should be understood:

Basic principles

From these points, it becomes very clear that operational reliability is a major issue, involving many factors. Talk sets generally work on the following principles:

Sound Quality

The difference in sound quality between digital and analogue techniques is not very significant. The reasons for this are:

“Handsfree” operation is achieved with many units by use of a headset. This gives limited convenience, because a technician working on fibers, is not going to find a headset very convenient due to restricted movement. Kingfisher uses another method of achieving true handsfree operation via a built-in speakerphone. This is generally much more convenient, and offers much greater freedom of movement to the operator because the operator is not attached to the Talk Set via a headphone.

One limitation of a speakerphone is that intermittent background noise will cause operational problems (the speakerphone interprets it as speech). Steady background noises (such as a fan) will be cancelled by the speakerphone circuit, however it may be required to talk louder to overcome the noise.

Common applications

The most common application is where one person ( eg in an exchange ) is giving instructions to another, who is working on a system. In some situations, it is convenient to operate over 2 repeater spans while doing this, since a repeater may not be operational. Therefore, long range is very useful.

Another situation that is less common, is restoration work. In this situation, it may be preferable to use a clip-on probe so a talk set can be clipped onto a link without accessing the end. Clip on probes are not terribly reliable, and have an insertion loss of 15 – 30 dB, depending on the colour and nature of the fiber acrylate coating. Some talk sets offer “multi party” use for this application. An analog talk set will allow 3 people to do multi party work, however we find that this feature is often specified, but rarely used in practice.