Drone repeater solution of long-range wireless video transmitter and receiver TX900-10W PA

TX900-10W PA introduction and solution as the Drone repeater

TX900-10W PA power amplifier support drone repeater and FHSS function. Let me introduce the details at the below.

1. TX900 has consisted of a core modem (Vcan1681, two-ways wireless video and data link module) and a 2-watt, 5-watt, or 10-Watt RF power amplifier inside. (a core modem and 2-watt PA inside picture)

2. There are two versions of the core modem (the same hardware with different Soc firmware): One is the star wireless network version, another one is the Mesh wireless network version.

Part number	Frequency band(MHz)	Network type
K150	1420~1530	Star wireless network version. (P2P, P2MP) It can be used for point-to-point transmitting, point-to-multiple point transmitting, and one-node relay transmitting. The maximum transmitting distance between two points is 150km.
S150	806~826 1427.9~1447.9 2401.5 – 2481.5
MK50	1400~1529.9	Mesh wireless network version. Mesh network mode. The maximum transmitting distance between two points is 50km.
M50	806~826 1427.9~1447.8 2401.5 – 2481.5

Only the same core modem can communicate with each other, different core modems can‘t communicate with each other.

3. 10-Watt RF power amplifier is available for 806~826MHz, 1427.9~1447.9MHz, 2401.5 – 2481.5MHz, 1420~12470MHz, 1470~1530MHz. So, we can have TX900-10W to work in 806~826MHz, 1427.9~1447.9MHz, 2401.5 – 2481.5MHz, 1420~12480MHz, 1470~1530MHz.

To note, For the 1420~1530MHz band, we need to separate it into two sub-bands (1420~1480MHz, 1470~1530MHz) since the 10-Watt RF power amplifier can’t support the whole 1420~1530MHz band in the same hardware board.

4. 1.4/3/5/10/20MHz bandwidths configurable, the larger working bandwidth supports more transmitting bitrates in the same condition. For 150km video transmitting, we suggest using 20MHz bandwidth (at least 10MHz).

5. For TX900-10W(1420~1480MHz) or TX900-10W(1470~1530MHz), when setting the working bandwidth is 20MHz, it has about 6 central working frequency points; when setting the working bandwidth as 10MHz, it has about 12 central working frequency point;

The central working frequency will hop when it detects frequency noise. If the current working frequency channel is clean, it will not hop. That means the frequency hopping is not as regular as x times/second.

6. There are two solutions for 150km+150km relay transmitting:

  Solution A:

  Solution B:

We suggest solution A since it supports more bitrates transmitting than solution B. It is more reliable on video transmitting when the RF signal is weak (low SNR).

On Oct. 25^th , we tested solution B. During the testing, it had little RF noise on the seaside and we can see A Mobile communication base station tower just about 100m nearby. 

Signal reporting on the seaside:

We can see the SNR is about 2~4 on the seaside.

Signal reporting on the mountain side:

We can see the SNR is about 4~7 on the mountainside. The different SNRs on the two sides also approved that it had little RF noise on the seaside.

However, the video was transmitted very fluent with little RF noise.

Star Networking Vs Mesh Networking for Drone or Robot.

STAR Network	MESH Network
• Point to Point Connection between nodes	• Multi-point to multi-point connection between nodes
• Infrastructure based	• Infrastructure or Ad hoc based
• Central control point is present	• Infrastructure based will have control center where as Ad hoc based does not have it.
• It is not self configuring.	• It is self configuring.
• Single hop from node to central point	• Multi hop communication
• Devices or nodes can not move freely.	• In Ad hoc mode, devices are autonomous and free to move. • In Infrastructure mode, movement of nodes are restricted around the control center.
• Links between nodes and central control points can be configured.	• Inter node links are intermittent.
• Nodes communicate via control center.	• Nodes relay traffic for other nodes on the path.