Real-time voice compression and decompression method for Narrow Band Internet of Things

Abstract

The invention discloses a real-time voice compression and decompression method for Narrow Band Internet of Things. The compression method comprises the following steps: continuously cutting voice datawith a total length t in real time, and getting 2n points from the voice data at an interval time t/2n as Nth frame data; carrying out high-frequency pre-emphasis on the Nth frame data, converting time domain data into frequency domain data, calculating a power spectrum modulo so as to obtain a frequency spectrum, selecting each harmonic wave amplitude value from the frequency spectrum, and calculating by virtue of each harmonic wave amplitude value, so as to obtain a total attenuation coefficient; dividing each harmonic wave amplitude value by the total attenuation coefficient, so as to obtain each harmonic wave amplitude ratio; combining the Nth frame data with the frequency spectrum, and carrying out fundamental wave analysis, so as to obtain a total wave frequency value; and arrayinga fundamental wave frequency value, each harmonic wave amplitude ratio and the total attenuation coefficient, so as to generate a transmission sequence code column, wherein t is 20ms-60ms, n is equalto 7, 8 and 9, and N represents a positive integer. The voice compression method is strong in instantaneity and high in compression ratio and can be similar to a call-up communication effect.

Description

technical field [0001] The present invention relates to the technical field of voice communication in the narrowband Internet of Things, more specifically, to a method for real-time voice compression and decompression in the narrowband Internet of Things, and an application in walkie-talkies. Background technique [0002] With the explosive development of information technology, today's world has entered the era of the Internet of Everything, and various Internet of Things technologies emerge in endlessly. However, due to the inherent narrow bandwidth, low transmission rate and long delay of NB-IoT. As a result, there are great difficulties in transmitting voice signals using communication methods such as Zigbee, LoRa, and NB-IOT. How to effectively use the limited bandwidth resources of the narrowband Internet of Things to realize voice transmission and reception with a data volume of more than 22KB / s has become an urgent need solved problem. [0003] 1. Take LoRa as an e...

AI Technical Summary

Problems solved by technology

However, due to the inherent narrow bandwidth, low transmission rate and long delay of NB-IoT

As a result, there are great difficulties in transmitting voice signals using communication methods such as Zigbee, LoRa, and NB-IOT. How to effectively use the limited bandwidth resources of the narrowband Internet of Things to realize voice transmission and reception with a data volume of more than 22KB / s has become an urgent need solved problem

[0003] 1. Take LoRa as an example: when using LoRa technology to transmit data, if the transmitted code rate is less than 8B / s, the transmission distance can reach 25 kilometers (open space), and when the code rate reaches 960B / s, under the same conditions The transmission distance has dropped below 1Km, and the data volume of general voice communication reaches 22KB / s. Under uncompressed conditions, it is basically impossible to transmit through LoRa

[0004] 2. The theoretical bandwidth of Zigbee is 256KB / s, but the data packets of various protocols in the transmitted data actually occupy a large proportion, and the bandwidth that can be reserved for voice communication is very limited. If it is not suitable for voice data up to 22KB / s Compression, even if Zigbee can barely transmit, it will bring a lot of delay

[0006] (1) The real-time performance is not strong: MPEG2 needs to sample at least one complete voice syllable data before the compressed data is enough to ensure the quality of the call, and a complete syllable is at least 0.4-0.7s long, plus the call time Delay, usually the total call delay is at least 1s, and our real-time voice compression technology completes one frame compression every 50ms, so the real-time nature of the call is much stronger than MPEG2

[0007] (2) Insufficient compression ratio: the compression ratio of MPEG2 is 12:1--10:1, and the insufficient compression ratio cannot be used in real-time voice transmission technology in the narrowband Internet of Things

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