100km TDD bidirectional video data wireless transmission
Table of Contents
100km TDD bidirectional video data wireless transmission Appearance
Version history
| Date | Version | Modification description |
| 20231219 | V1.0 | Initial version |
| 20240315 | V2.0 | Modify the weight dimensions, modify the total data in Table MCS & Sensitivity |
| 20240405 | V3.0 | Add multiple sets of coexistence switches. Modify the serial-to-network configuration mode. Modify the ID number length and modify the English words of background noise detection. Added the frequency matching function |
Overview
Vcan1933-8-Watt PA is a self-developed TDD bidirectional graph integrated wireless transmission device. The product has the functions of real-time interference detection, adaptive frequency selection, adaptive stream, automatic retransmission, and automatic power control, which greatly improves the ability of anti-multipath and anti-interference, and has the characteristics of high reliability, good stability, and low delay.
This product is suitable for firefighting, inspection, monitoring, and other scenarios, and can transmit 100KM under good air-to-ground vision.
Product Characteristics
- Support long-distance transmission: 4M code flow can be transmitted up to 100km.
- Supports large bandwidth transmission: Up to 17Mbps@10MHz.
- Supports automatic repeater transmission: Supports automatic trunk addition.
- Supports multi-interface design: The device has two network ports and four serial ports, supporting RS232/TTL/RS422/SBUS.
- Supports automatic frequency selection: Automatic detection of interference signals, real time selection of the optimal frequency point.
- Supports automatic retransmission: Automatic retransmission of burst error data improves data reliability.
- Supports adaptive stream: The channel modulation mode is automatically adjusted according to the signal quality in real time.
- Supports automatic power control: Close range automatic adjustment of transmission power, reduce power consumption.
- Supports automatic antenna selection: According to the occlusion situation, the optimal antenna transmission is selected in real time.
- Supports the coexistence of multiple set: Support up to 6 sets of equipment at the same time fixed frequency use.
- Supports the frequency matching function: Software can be used to configure the frequency and hardware key frequency.
Specification
| System parameter | Technical index |
| Equipment model | Vcan1933-8W |
| Working frequency | 1350~1470MHz |
| Radio frequency | 2T2R |
| Transmission power | 39dBm (8-watt PA) |
| Transmission distance | 100KM (Air-to-ground LOS) |
| Channel bandwidth | 10MHz |
| Modulation mode | QPSK/16QAM |
| Receiving sensitivity | See Table (MCS & Sensitivity) |
| Speed | 17Mbps@16QAM3/4 |
| Communication encryption | AES256 |
| Transmission delay | ≤10ms |
| Radio frequency interface | SMA*2 |
| Equipment interface | XT30PW-M |
| Equipment interface | 100Mbps Ethernet*2 |
| TTL/RS232*2 | |
| RS422*1 | |
| SBUS/TTL*1 | |
| Overall power consumption | ≤48W@4Mbps(Air uint) |
| ≤12W@1Mbps(Ground uint) | |
| Dimension(L*W*H) | 163*77*25mm |
| Weight | 340g |
| Working voltage | DC22~30V,Typical value: +24V@2A |
| Working temperature | -40~+75℃ |
| MCS & Sensitivity (10MHz) | |||
| No. | MCS | Total uplink and downlink throughput (Mbps) | Sensitivity (dBm) |
| 1 | QPSK1/3 | 4.0 | -99 |
| 2 | QPSK1/2 | 5.8 | -98 |
| 3 | QPSK2/3 | 7.1 | -97 |
| 4 | QPSK3/4 | 8.2 | -96 |
| 5 | 16QAM1/3 | 8.0 | -96 |
| 6 | 16QAM1/2 | 11.6 | -95 |
| 7 | 16QAM2/3 | 14.3 | -93 |
| 8 | 16QAM3/4 | 16.4 | -91 |
Product dimension and weight
Dimension diagram
Dimension and weight
- Dimension (L*W*H): 163mm*77mm*25mm(including SMA 10mm)
- Weight : 340g
Product interface definition
Interface diagram
The interface of the Vcan1933-8W device includes the XT30PW-M power interface and J30J-25pin data interface. The interface has RS232/TTL*2, RS422*1, SBUS/TTL*1 and 100 Mbit/s Ethernet*2.
Interface definition
Power interface: XT30PW-M. Power supply range: DC22-30V Typical value:24V@2A
| Linear order. | Pin name | Interface definition | Interface description | Signal direction |
| 1,2,3,4 | GND | Ground | Ground | |
| 5 | 422A | Serial port 3 RS-422 | Receiving data RX+ | I |
| 6 | 422B | Receiving data RX- | I | |
| 7 | 422Z | Transmitting data TX- | O | |
| 8 | 422Y | Transmitting data TX+ | O | |
| 9 | TXD_A | Serial port 1 RS232/TTL | Transmitting data TX | O |
| 10 | RXD_A | Receiving data RX | I | |
| 11 | TXD_B | Serial port 2 RS232/TTL | Transmitting data TX | O |
| 12 | RXD_B | Receiving data RX | I | |
| 13 | GND | Serial port 2 ground | O | |
| 14 | SBUS /TTL TX | Serial port 4 SBUS/TTL | SBUS/TTL sending | O |
| 15 | SBUS /TTL RX | SBUS/TTL receiving | I | |
| 16 | SBUS/TTL GND | SBUS/TTL ground | O | |
| 17 | TX1P+ | Network port 1 | Transmitting data TX+ | O |
| 18 | TX1M- | Transmitting data TX- | O | |
| 19 | RX1P+ | Receiving data RX+ | I | |
| 20 | RX1M- | Receiving data RX- | I | |
| 21 | GND | Ground | Serial port 1 ground | O |
| 22 | TX2P+ | Network port 2 | Transmitting data TX+ | O |
| 23 | TX2M- | Transmitting data TX- | O | |
| 24 | RX2P+ | Receiving data RX+ | I | |
| 25 | RX2M- | Receiving data RX- | I |
- Note 1: Signal direction I indicates radio input and direction O indicates radio output.
- Note 2: When using the serial port 1/2 of the device, please check whether it is TTL level or RS232 level.
Indicator Meaning
Power light PWR（green）
When the PWR light is on, the device is powered on.
SYNC（green）
Out of sync state, light flashing.
After synchronization, the light is steady on.
Network port light : LAN1, LAN2 (green）
The network port light blinks when data is being sent or
received.
Receiving signal energy light(RSSI 3 green lights)
The greater the number of energy lights, the greater the
signal reception strength.
| The RSSI light represents the strength of the received signal | |
| Number of RSSI energy lights on | Received energy dBm |
| 3 RSSI lights on | about -50dBm |
| 2 RSSI lights on | about -80dBm |
| 1 RSSI light on | about -95dBm |
| Module type | Mode | Vcan1933-8W light status | |||
| PWR | SYNC | LAN 1 LAN 2 | RSSI 123 | ||
| master | Un-sync | Powered on | Flashing | Data sending and receiving, flashing | Off |
| master | Sync | Powered on | Steady on | Data sending and receiving, flashing | Proportional to the strength of the received signal |
| slave | Un-sync | Powered on | Flashing | Data sending and receiving, flashing | Searching |
| slave | Sync | Powered on | Steady on | Data sending and receiving, flashing | Proportional to the strength of the received signal |
When the master and slave devices are not synchronized, the PWR indicator of the master and slave devices is steady on, the SYNC indicator is blinking, and the RSSI indicator of the master device is off. The RSSI of the slave device will always be in the search state. After the master/slave synchronization, the SYNC indicator of the master/slave is steady on. The master-slave RSSI lamp displays the received signal energy intensity. When the network port is sending or receiving data, the master and slave devices correspond to LAN1, and the LAN2 indicator blinks.
More information about the product
TDD (Time Division Duplexing) is a communication technique used in wireless systems where the uplink (transmitting data from the ground control station to the drone) and downlink (transmitting video and data from the UAV to the ground receiver or GCS) share the same frequency channel but operate in different time slots. This allows bidirectional communication without requiring separate frequency bands for each direction.
TDD Protocol Optimization
- Ensure proper time slot allocation between uplink (sending data) and downlink (receiving data) for efficient bidirectional communication.
- Adaptive TDD allows dynamic allocation based on data traffic needs.
- Useful in applications where uplink and downlink traffic are asymmetric (e.g., video streaming).
Comparison Between TDD and FDD
| Feature | TDD | FDD |
|---|---|---|
| Spectrum Usage | Single frequency band | Separate bands for uplink and downlink |
| Traffic Adaptability | Highly adaptable to asymmetric traffic | Fixed uplink/downlink ratio |
| Equipment Complexity | Lower cost and simpler hardware | Requires duplexers, increasing cost |
| Channel Reciprocity | Yes, supports advanced techniques like beamforming | No |
| Interference | Requires strict synchronization | Less prone to interference |
TDD is widely used in modern communication systems, including those requiring long-range bidirectional video transmission due to its efficiency and flexibility.
Power and Size Constraints:
- Lightweight hardware to minimize the impact on drone flight performance.
- Low-power consumption design to maximize drone battery life.
- Compact form factor to fit within the drone’s payload.
Antenna System:
- On Drone: Fiberglass omnidirectional or small directional patch antennas.
- Ground Station: High-gain parabolic, Yagi antennas or flat panel antennas with tracking systems for long-range communication.
Applications
- Surveillance and Security: Real-time video streaming from drones for law enforcement or border control.
- Broadcasting: High-definition aerial footage for live events or media.
- Agriculture: Monitoring crops and livestock over vast areas.
- Disaster Response: Sending live video from disaster sites for better coordination.
The transmission range of an 8-watt power amplifier (PA) depends on a variety of factors, including:
- Frequency Band: Higher frequencies experience more signal loss over distance (higher free-space path loss).
- Antenna Gain: The type and gain of the antenna at both ends (transmitter and receiver) significantly impact the range.
- Environmental Conditions: Factors like terrain, buildings, weather (rain, fog), and line-of-sight (LoS) can affect range.
- Modulation Scheme and Data Rate: More complex modulation schemes (e.g., QAM) and higher data rates may reduce effective range due to higher sensitivity to signal degradation.
- Receiver Sensitivity: The ability of the receiver to detect a weak signal at a specific distance.
