With the continuous improvement of people's material living standards,the viewership of television programs and programs Loops of a higher quality, the use of the growing popularity of digital microwave transmission.Following is a system widely used in digital microwave radio and television transmission equipment.
Point-to-point data transmission equipment
Equipment can pack multiple high-speed data flow distal to resume transmission after, several can relay signals without error.The equipment is widely used in various industries.
20M - KU-band high-speed data transmission continued to flow fired 50mw power, transmission distance of 20 km for example :
Data flow approach using QPSK modulation, forward error correction and interference with the advantage,meet international standards for data transmission related technical parameters of microwave transmission equipment
- Keyword frequency: Sub options 11GHz-13GHz
- Transmitting power: 50mW
- Phase Noise: 110dBc
- Modulation : Microwave direct PLL FM
- Frequency stability : 1 ×
- Sending and receiving antennas : 0.6 meter dish plate
Planning bandwidth
20M frequency bandwidth occupied by the data flow : 20/(188/204)/(7/8)/2*1.35=16.7M
With roll-off factor of 1.35, RS coding efficiency of the goat. Coding efficiency 7/8
Rate for QPSK symbol rates by 2.
Digital Microwave System Routing Design
Carrier to Noise Ratio C/N=PT+GT-L-LA+GR-N-NF- Δ
PT ： DBm transmitter power, Sent aircraft to be used 50mw, Power of 17dBm
GT ：
Gain antennas,
0.6 m for the collection plate dish antennas.
Fired surface antenna gain of 35 dBm/
L ：
Ld=92.4+20lgf+20lgD
When f=11GHz frequency,Ld=113.4+20lgD
LA ：
Feed system loss dollars 1dBm
GR ：
Receiving antenna gain 35 dBm / surface
N ：
Picture take -97.4 dBm power converter under import (power bandwidth of 45MHz)
NF ：
Down Converter noise figure 4dB
11G transmission over 20 km,
Rain by rainstorms,
Δ =20 dBm
C/N=17+35- （ 113.4+20lgD ） -1+35- （ -97.4 ） -4-20=50-20lg
20lgD=50-19=31 lgD=51/20=2.55 D=35km
From the above calculation, a highly stable operating system reliability.
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