Researching the web I recognized, that even the China-lowcost Receivers are based on this module. It's just cheap and simple. But there are some remarkable projects based on this module, enabling it's SPI Interface
Researching the web ...
There was obviously an RX5808-Pro project. Using the onboard SPI functionality and an Arduino, to add some sweet functionalities like spectrum scanner to it. From this there are currently two further forks on the web:
The original project, using an arduino to access RX5808's SPI Interface."RX5808 Pro" on Google Code
RX5808 Pro OSD
This project uses an MiniOSD-Arduino, not just to controll the RX5808, but also to show the data via an OSD plugged between the receiver and the screen."RX5808 Pro OSD" on Github
RX5808 Pro Diversity
This project uses two RX5808, one receiving the signal - the other scanning the spectrum. Output is via OSD or OLED Display."RX5808 Pro Diversity" on Github
On the newer RX5808 after May 2012 (Rev 20120322), the modification is just to remove a pulldown-Resistor on SPI_EN pin.
1. First remove he metal cover (this time I was really happy about the sloppy soldering job of the manufacturer)
2. Remove the 4th resistor from the top, looking in the direction of ICs inscription.