HobbyKing E-OSD A very simple OSD (On Screen Display) for FPV users who want to see their 2 or 3 cell LiPo voltage level while flying. Very easy to install; runs in line with your battery and also your video-out wire.
Features: Voltmeter & Stopwatch Double Voltage Input Manual Calibration Programmable Display Content Supports NTSC & PAL Anti-Glare Shade Control Signal
Specifications: Weight: 3.3g Dimensions: 34 x 17 x 4mm Working Voltage: 7.2~12v
Yep, I have rssi from my dragonlink coming in via port one on the OSD. The dragon link shows around 3.2 as %100 signal. You will probably have to check what the voltage for 100% rssi is on your reciever but ya, its to a 10th of a volt. Also make sure you plug into SIGNAL and GROUND not the middle pin and ground, cuz then you'll probably just see 5v that your receiver puts out
Just got mine. Works fine. It is worth the price. Pretty simple to monitor FPV pack battery or motor battery (if under 3S). There are some interesting projects to do RSSI monitor (check rcgroups). You have to to make a Y connection between camera wire and tx wire to the OSD (video input) i.e camera signal and tx signal going into video input on the OSD. Gnd can come directly from pack.