Half Duplex and Full Duplex

Duplex simply means that the communications device will enable you to both talk to another location and have that location respond to you, using the same type of device. As an example, when you make a telephone call, you are engaging in a duplex procedure. The same is true when you use voice to voice communications through your computer.

Examples of Half Duplex Devices and How They Work

In contrast, a half duplex enables only one party to speak at a time. The best example of this is the CB equipment that was so popular in the 1970's. People could communicate, but had to press on a talk key in order to send a voice message out to someone, then be open to receiving a voice message in order to hear a response. The two parties could not send and receive at the same time. Even early speakerphone technology made it impossible for both ends of a phone connection to hear and be heard over one another, if both persons were attempting to speak at the same time. Even today, there are speakerphones that use half duplex technology, which can create some interesting problems on business conference calls.

The Advent of Full Duplex

The full duplex enables electronic audio communications to approximate real life conversations. That is, multiple people can talk at the same time voice without quality degrading.

The use of full duplex in voice communications is considered the standard these days. You find this on point to point telephone conversations, where you can easily be talking while the other party is also saying something. More often, speakerphones are being equipped with full duplex devices that eliminate echoing and fragmentation that once made speakerphone use taxing. Teleconference bridges are almost all now digital full duplex operations, a great improvement over the analog half duplexes that were the norm even as recently as 1993. Even your cordless phone at home is full duplex today.

Desktop and laptop computers once came with a half duplex sound card. With audio streaming and Internet phone services gaining in popularity each year, newer computer models are coming equipped with a full duplex sound card as a standard component. Even if you have an older model, you can easily upgrade to the full duplex sound card and enjoy the benefits of full duplex sound.