Analysis of the influence of unmanned aircraft on radio communication

Hello,

The main radio services used by unmanned aircraft are wireless remote control, telemetry, and transmission of collected information. There was no unified plan for the frequency of its use.

1- Frequency Planning of Unmanned Aircraft System

A- Frequency of use and services

There are three frequency bands for use by unmanned aircraft systems, namely: 840.5-845MHz, 1430-1444MHz and 2408-2440MHz. among them:

840.5-845MHz can be used for the uplink remote control link of unmanned aircraft system; 841-845MHz can also be used for the uplink remote control and downlink telemetry link of unmanned aircraft system in time division mode.

The 1430-1444MHz frequency band can be used for the downlink telemetry and information transmission link of unmanned aircraft systems. Among them, the 1430-1438MHz frequency band is used for unmanned aircraft and helicopter video transmission, and other unmanned aircraft use the 1438-1444MHz frequency band.

The 2408-2440MHz frequency band can be used as a backup frequency band for the uplink remote control, downlink remote measurement and information transmission link of the unmanned aircraft system.

B- Relevant requirements

a- 2408-2440MHz related radio stations shall not affect other legal radio services when working in this frequency band, nor shall they seek protection from radio interference. Relevant radio stations shall not affect other legal radio services while working in this frequency band, nor shall they seek protection from radio interference. 

b- The channel configuration of the above frequency bands, the transmission power of the radio equipment used, the limit of unwanted emission and the adjacent channel selectivity of the receiver should meet the relevant requirements. Frequency usage, radio station settings, and radio transmission equipment used shall comply with the relevant regulations of the state radio management and unmanned aircraft system management.

c- For technical requirements, see the attached table "Unmanned Aircraft System Wireless Channel Configuration and Radio Equipment RF Index Requirements".

2- Impact analysis on radio communication security

Compared with the impact on the clearance protection area and related personal and property safety, the impact on radio communications is not obvious. For the time being, there are no relevant interference complaints in our city. However, with the development of technology and applications and the increase in the number of aircraft, the hidden dangers are existing.

A- Interference to other wireless services in the same frequency band

Due to the relatively mature solutions on 2.4GHz, most domestic

Numerous drones use 2.4GHz signal radio remote control to control and transmit data. In this frequency band, wireless local area network, Bluetooth, some engineering medicine and other services all use this frequency band. The state stipulates that the transmission power of unmanned aircraft in this frequency band does not exceed 27dBm (500mW). Generally speaking, the transmission distance is not very far. However, if there are other equipment related to the same frequency band business (such as wireless AP) within a short distance on the ground, they may interact with each other. Have an impact, such as unstable outdoor wireless Internet access in some areas.

B- The possible impact of unqualified launch technical indicators

If the manufacturer increases the transmission power without authorization in pursuit of remote control distance, or

If the index is unqualified, adjacent channels are generated or the power of spurious signals is too large, it may affect other frequency band services. Taking the transmission frequency band 1430-1444 MHz as an example, it is adjacent to the frequency band 1447-1467 MHz planned to meet the needs of government affairs, public safety, social management, emergency communications and other broadband digital trunking private network systems. If the adjacent channel leakage ratio is too high, it may Interference to the online signal of the digital private network.

C- Impact on the development of future radio services

The frequencies allocated for unmanned aircraft are all located below 3GHz

The golden frequency band, with the explosive development of radio services, the frequency resources of this frequency band are extremely tight, and conflicts may arise in the future. For example, the 840-845MHz frequency band was allocated to unmanned aircraft. According to the needs to promote the development of the Internet of Things and RFID technology industries, it was also allocated to the 800/900MHz radio frequency identification services. As the international mainstream technology standard does not have this frequency band, it is temporarily not occupied. However, the exhaustion of frequency resources, China's vigorous support of independent standard patents, and the construction of a relatively closed RFID network have enabled this frequency band to be used as the frequency of RFID services. Since the transmission power of unmanned aircraft is higher than that of RFID, interference will be extremely high. possible.

Schedule

Unmanned aircraft system wireless channel configuration and radio equipment radio frequency index requirements

1- Channel bandwidth and center frequency

2- Radio frequency indicators of radio equipment

A-Transmitter transmit power

Note : Under the conditions that can meet the working conditions of the unmanned aircraft measurement and control and information transmission system, low power should be used for transmission as much as possible; the 2408-2440MHz frequency band is only used as a backup frequency band.

B- Unwanted emission from transmitter

a- Transmitter adjacent channel leakage ratio 

 b- Unwanted emission limit

c- Spurious emissions in other frequency bands

 C-Adjacent channel selectivity of receiver 

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