The walkie-talkie is the key device in the wireless intercom system. The walkie-talkie acts as the link of voice transmission in a wireless communication system. The digital walkie-talkie can be divided into frequency division multiple access(FDMA) and time division multiple access (TDMA) channels. So here we start with the pros and cons of the two models and the differences between digital and analog walkie-talkies:
1. Two-channel processing modes of digital walkie-talkie
A. TDMA (Time Division Multiple Access): the dual-slot TDMA mode is adopted to divide the 12.5KHz channel into two slots, and each time slot can transmit a voice or data.
1. Double the channel capacity of an analog system through a repeater
2. One repeater undertakes the work of two repeaters and reduces the investment of hardware equipment.
3. Using TDMA technology allows walkie-talkie batteries to operate for up to 40% longer without continuous transmission.
1. Voice and data can not be transmitted at the same time slot.
2. When the repeater in the system fails, the FDMA system will only lose one channel, while the TDMA system will lose two channels. Thus, the failure weakening capability is worse than FDMA.
B. FDMA (Frequency Division Multiple Access): FDMA mode is adopted, and the channel bandwidth is 6.25KHz, which greatly improves the frequency utilization.
1. Using a 6.25KHz ultra-narrow band channel, the spectrum utilization rate can be doubled compared to the traditional analog 12.5KHz system without a repeater.
2. In the 6.25KHz channel, voice data and GPS data can be transmitted at the same time.
3. Because of the narrowband sharpening characteristic of the receiving filter, the receiving sensitivity of the communication id effectively improved in the 6.25KHz channel. And the effect of error correction, the communication distance is about 25% larger than the traditional analog FM radio. Therefore, for direct communication between large areas and radio equipment, the FDMA method has more advantages.
The difference between a digital walkie-talkie and an analog walkie-talkie
1. Processing of voice signals
Digital walkie-talkie: a data-based communication mode optimized by a digital signal processor with a specific digital encoding and baseband modulation.
Analog walkie-talkie: a communication mode that modulates voice, signaling, and continuous-wave to the carrier frequency of the walkie-talkie and is optimized through amplification.
2. Utilization of spectrum resources
Digital walkie-talkie: similar to cellular digital technology, digital walkie-talkie can load more users on a given channel, improve spectrum utilization, and make better use of spectrum resources.
Analog walkie-talkie: there are problems such as low utilization of frequency resources, poor call confidentiality, and a single type of business type, which can no longer meet the communication needs of industry customers.
3. Call quality
Because digital communications technology has in-system error correction capabilities, and compare to an analog walkie-talkie, it can achieve better voice and audio quality in a wider range of signal environments and receive less audio noise than an analog walkie-talkie. In addition, the digital system has excellent suppression of environmental noise and can listen to clear voices in boisterous environments.