Overlap （carrrier superposition）technology
The DoubleTalk Carrie-in-Carrier technology in satellite communications uses the "self-interference suppression" technology. When two satellite communication sites communicate in both directions, they can use the same transmission frequency band, and the spectra of the two transmission carriers overlap and overlap. Carrier superposition technology can greatly improve the utilization rate of satellite bandwidth resources. In addition, this technology also effectively enhances the anti-interception capability of the satellite system.
The use of satellite superposition technology can save 50% of satellite resources, reduce the cost of renting satellite resources, and save customers' tariff costs.
Technical principle
The schematic diagram of the satellite communication system is shown below:
The figure shows the communication between two satellite communication stations. Satellite communication station 1 transmits a signal (uplink frequency is fu1) to the satellite. After frequency conversion and amplification on the satellite, a downlink signal (downlink frequency is fd1) is generated. Similarly, satellite communication station 2 transmits a signal (uplink frequency is fu2) to the satellite, and after frequency conversion and amplification on the satellite, a downlink signal (downlink frequency is fd2) is generated. The frequency range of fu1 and fu2 is 13.75~14.5 GHz, and the frequency range of fd1 and fd2 is 10.7~12.75GHz.
Since the satellite used is a large-beam satellite, the coverage of the satellite beam is very wide. For example, the coverage of the ChinaSat 6D satellite around China is as shown in the figure below:
Only when satellite communication station 1 and satellite communication station 2 are both within the coverage of the satellite can the two satellite communication stations communicate normally. At this time, satellite communication station 1 will not only receive the signal transmitted by satellite communication station 2 (frequency is fd2), but also receive the signal transmitted by itself (frequency is fd1). In order to meet the conditions for normal reception, fd1 and fd2 must be staggered in conventional satellite communications, and the spectrum of the two signals cannot overlap to ensure that the two downlink signals do not interfere with each other. The spectrum relationship of the two downlink signals is shown in the figure below:
According to the above method, the two satellite communication stations occupy their own frequency bands. Assuming that the bandwidth occupied by satellite communication station 1 is W1 and the bandwidth occupied by satellite communication station 2 is W2, the bandwidth required for two-way communication between the two satellite communication stations is W1+W2, and the bandwidth required to be applied for from the satellite communication company is W1+W2.
Is there any way to reduce satellite bandwidth usage?
The same type of satellite communication modem is placed in both satellite communication station 1 and satellite communication station 2, and carrier superposition technology is adopted. Even if the transmission frequency of satellite communication station 1 and satellite communication station 2 is the same and the spectrum overlaps, the satellite communication modem can suppress the signal transmitted by itself and restore the signal transmitted by the other party. As shown in the following figure:
The actual satellite bandwidth occupancy changes from W1+W2 to MAX (W1, W2).
ZKDB-8000 Satellite Overlapping Equipment
The ZKDB-8000 wave stacking device can be used as an optional function of the modem to build an efficient satellite communication network, or it can be used as an independent device. It is compatible with the existing satellite modem interface and is particularly suitable for expanding and transforming existing satellite communication network systems. The wave stacking device can eliminate signals in the frequency band range of 0.5 to 16 MHz, and its performance in digital signal processing is excellent.
The features of the equipment are as follows:
Save satellite bandwidth usage costs, up to 50%
- Reduce the cost of leasing satellite resources
- Increasing satellite communication network capacity
- Freeing up satellite bandwidth for new applications
Increase information security
- Increased resistance to interception
Supports multiple satellite network applications without changing the existing communication system
- Frequency Division Multiple Access
- Single Carrier Channel (SCPC)
- Supports many types of modems and waveforms
- Works with all standard modulation types (spread spectrum, BPSK, QPSK, 8-PSK, etc.)
- Coding independent (can be used with Viterbi, Reed-Solomon, LDPC, Turbo, etc.)
Rich in functions and powerful in performance
- Elimination bandwidth from 0.5MHz to 16 MHz
- L-Band IF (950 to 2150 MHz)
- Standard 1U 19-inch chassis
- Front panel and remote (Ethernet SNMP) interfaces