Author Topic: Understanding RSSI (Read 7157 times)

Balders · « **on:** January 10, 2012, 12:23:18 PM »

OK, I'm getting to the stage of my FPV path where I'm pretty confident flying, and want to expand my current knowledge/setup.

I currently have a 600mw 5.8ghz VTx with a Cyclops Easy OSD 1.5. This gives me some nice data overlaid on my fatshark built-in rx goggles, but I don't really understand what RSSI is and how it's measured.

Well, I guess it's a measure of video signal, but what I don't get is, is it simply indicating what power it's transmitting at, or does it somehow know what's been received at the other end and give a measure of that? If the latter, how does it know what packets have been successfully received? Surely it just transmits? It's have to receive feedback otherwise?

A bit confused here.

Oh, has anyone wired in RSSI to CE OSD successfully? How do I identify the pins on the VTX to connect? I know the CE OSD has "holes" on the board for adding RSSI but I think there is about 4 of them from memory?

Thanks in advance.

EDIT: OK the manual online is for the v1.0 board, not the V1.5 board, making things slightly confusing. I also talks about opening up the receiver to solder wires, which I'm assuming is a typo, surely it means transmitter? Confusingmanuals.com

MrBen · « **Reply #1 on:** January 10, 2012, 05:29:02 PM »

Usually the RSSI is to monitor the RC control link not the video signal strength. Generally you would only want to use RSSI on a VRX if you were hooking it up to a RSSI based diversity system. To hook it up to your radio control receiver you need to research and find out where to connect the wires to inside the rx. When connected this will give you an indication (based on the onscreen figures) when its time to turn back.

Dusty · « **Reply #2 on:** January 10, 2012, 09:12:10 PM »

the "power" of the signal your RC transmitter sends gets lower further from the source of the transmission. the receiver can be tapped into and the power of the signal can be measured directly from the receiving equipment, then "output" via the RSSI pins inside the receiver (I think it stands for Received Signal Strength Indicator) and the OSD board can measure this value and put it on screen. as the value on screen gets to the critical point (different for different tx/rx setups) you should turn around

experts... please feel free to correct or clarify if this is right btw, this is just my understanding of it

mark1975 · « **Reply #3 on:** January 10, 2012, 09:38:29 PM »

chris nail on the head. a great feature for radio's but as more and more switch to uhf more are turning to tapping rssi from the vrx as there will never be a need really tbh on uhf.

Balders · « **Reply #4 on:** January 10, 2012, 10:21:02 PM »

so if I'm getting twitchy about my transmitter range (Dx6i) then this could be a good thing for me!? I'm just not sure how it works.

mark1975 · « **Reply #5 on:** January 11, 2012, 06:30:59 AM »

Here is a lists of receivers and there rssi ports to tap into to overlay on your osd ..this is for your RC rx not video vtx btw..it includes 2.4 ghz rx's aswell .
www.rcgroups.com/forums/showthread.php?t=923419

Balders · « **Reply #6 on:** January 11, 2012, 11:38:38 AM »

I can't access rcgroups from work (blocked) but does anyone know if a Spektrum AR7000 or AR6200 is on the list/instructions how to tap into RSSI?

It sounds EXACTLY what I'm looking for.

Ratty · « **Reply #7 on:** January 15, 2012, 06:24:31 PM »

I guess the Spektrum Rxs must give out some kind of RSSI info as i can get telemetry on my Dx8, but it does need the Telemtry module. So i guess the module works it all out but the Rx has to give it some info.

Hope that helps some, but its all i know.

Flypoppa · « **Reply #8 on:** January 15, 2012, 06:52:15 PM »

From what I am lead to believe you cannot get RSSI from Spektrum RXs. If you could I would have gone for it.
I have recently gone back to 35mhz for better range.
I have managed to get RSSI from the Corona RP6DI to the Cyclops easy OSD.
It was aa very delicate soldering job.