Digital Enhanced Cordless Telecommunications (DECT) is a wireless communication technology used for cordless phones, baby monitors, and other wireless devices. DECT provides high-quality audio, long battery life, and secure communication over short distances, making it a popular choice for residential and small business use.
DECT was developed in the late 1980s by a consortium of European companies, including Philips, Siemens, and Ericsson, to replace the analog cordless telephony system that was prevalent at the time. The first DECT standard, known as DECT 1.0, was published in 1992. Since then, the standard has been updated several times, with the current version being DECT 6.0.
DECT operates in the frequency band of 1880-1900 MHz in Europe and 1920-1930 MHz in North America, with each band divided into ten 1.728 MHz channels. The system uses a time-division multiple access (TDMA) scheme to allow multiple devices to share the same channel without interfering with each other. Each channel is divided into 24 time slots, with each slot being 10 ms long.
DECT supports voice and data communication, with a maximum data rate of 1.152 Mbps. It uses a digital modulation scheme known as Gaussian Minimum Shift Keying (GMSK) to transmit data over the air. GMSK is a form of phase modulation that uses a Gaussian filter to reduce the sideband power and minimize interference with adjacent channels.
One of the key features of DECT is its ability to support multiple handsets on a single base station. This is achieved through a technique known as time-division duplex (TDD), which allows the base station to transmit and receive on the same channel at different times. Each handset is assigned a unique time slot on the channel, and the base station communicates with each handset in turn.
DECT also uses a spread-spectrum technique known as frequency hopping to improve the security and reliability of communication. In frequency hopping, the transmitter and receiver hop between different frequencies in a predetermined sequence, making it difficult for an eavesdropper to intercept the signal. DECT uses a hopping sequence that is determined by a unique device ID and a random number, ensuring that each device has a different hopping pattern.
In addition to voice and data communication, DECT supports a range of advanced features, such as caller ID, call waiting, three-way calling, and intercom. DECT devices can also be integrated with other home automation systems, allowing users to control lights, thermostats, and other devices from their cordless phones.
DECT devices are typically powered by rechargeable batteries, with a typical talk time of around 10 hours and a standby time of several days. Some DECT phones also include a built-in answering machine, which allows users to record and play back messages remotely.
While DECT is primarily used for cordless phones, it can also be used for other wireless devices, such as baby monitors, wireless headphones, and wireless speakers. In these applications, DECT provides high-quality audio and long battery life, making it an attractive choice for consumers.
One of the challenges of DECT is its limited range, which is typically around 50 meters indoors and 300 meters outdoors. This makes DECT unsuitable for large buildings or outdoor environments, where other wireless technologies, such as Wi-Fi or cellular, may be more appropriate.
Another challenge of DECT is its susceptibility to interference from other wireless devices operating in the same frequency band. This can lead to degraded audio quality or dropped calls, particularly in areas with high wireless traffic. To mitigate this, DECT devices often use frequency-hopping techniques and advanced error-correction algorithms to minimize the impact of interference.
