Here is a video that might help some of you understand your FPV antenna options a little better. The video seems painfully long for what it delivers, but the core message is good. The guy goes a little graphics crazy, but again it does get the message across well. If you're new to this stuff and want to understand what you're doing, I think it's worth watching. http://vimeo.com/8826952 ...Tiger
Good video ... although the info presentation itself was a little hard but the accuracy was dead on, YES "painfully long" {LOL} Heres a short (but good) read from Spectrum, talking about their Dual-Path technology and Path- Diversity -- http://www.spektrumrc.com/DSM/Technology/advancedFeatures.aspx --
I have been looking at ways to monitor RSSI and it appears that the 2.4 Ghz radio systems do not have analog RSSI output. Only packet loss indicator. So that leaves three choices. I will try mounting my reciever where I can see the LED light with the camera, when it starts to flicker a lot, turn around! The other is to build an RC (resistor/capacitor) circuit that holds a voltage when the LED is steady, but begins to drop voltage in relation to how much the LED flashes. This is basically a digital to analog conversion. And last you could just buy a good JR/Spektrum reciever that has a telemtry logger port and plug an Eagle Tree OSD into it (this is the expensive $200+ option).
The only thing the flashing LED on Spectrum receivers will tell us is that the Rx lost power at some point in the flight and as a result the Rx restarted/rebooted. Has nothing directly to do w/ the loss of signal ... Don't know what other Led we could be talking about ?
On my Blade 450 I did a range test by hanging the transmitter in a tree branch and walking away with the heli in my hands. at 1,000 feet the LED began to flicker a little bit, at 1,250 feet the LED was flickering like crazy and when I stepped behind a building it went out, when I stepped back into line of sight the LED came back on, but still flickered with me walking. As I headed back to the transmitter it slowly went back to a non-flickering steady state. The LED acts sort of like a busy indicator on a communications radio, but goes out when there is packet loss. It is a really bright orange so it will be easy to see in the camera. It is acutally better than analog RSSI because you can have strong signal but not capture the important stuff, this is telling you that it missed the important stuff reguardless of RF energy seen. I think it was David from RCExplorer that make the R/C circuit for a Futaba 2.4 Ghz radio: http://rcexplorer.se/page14/lostp/lostp.html You would have to do the same research he did for a Spektrum radio because the rate of flash would certainly be different.
Sorry thought you had the Spectrum DX6i Tx ?? Yeah Futaba is a different animal {LOL} Of course I should have also said I was talking about Spectrum receivers ... So where did I see the DX6i do you have one or am I mistaken entirely and it was someone else's radio I must be thinking off ?? Quote: Spectrum DOC for the AE7000 "QuickConnect With Brownout Detection Your AR7000 features QuickConnect with Brownout Detection Should an interruption of power occur (brownout), the system will reconnect immediately when power is restored (QuickConnect). The LED on the receiver will flash slowly indicating a power interruption (brownout) has occurred. Brownouts can be caused by an inadequate power supply (weak battery or regulator), a loose connector, a bad switch, an inadequate BEC when using an electronic speed controller, etc. Brownouts occur when the receiver voltage drops below 3.5 volts thus interrupting control as the servos and receiver require a minimum of 3.5 volts to operate." Also to note any frame losses you need additional equipment, SPM9540 - which is optional "Advanced Range Test Plug a Flight Log (SPM9540 - optional) into the Batt/Data port on the AR7000 and turn on the system (Tx and Rx). Advance the Flight Log until F-frame losses are displayed by pressing the button on theFlight Log. Have a helper hold your aircraft while observing the Flight Log data. Standing 30 paces away from the model, face the model with the transmitter in your normal flying position and put your transmitter into range test mode. This causes reduced power output from the transmitter. Have your helper position the model in various orientations (nose up, nose down, nose toward the Tx, nose away from the Tx, etc.) while your helper watches the Flight Log noting any correlation between the aircraft’s orientation and frame losses. Do this for 1 minute. The timer on the transmitter can be used here"
Yes, I do have Spektrum radio stuff, it has an ar6115e: http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMAR6115E I included the Futaba link because that is the only one that has been hacked so far for RSSI output, the same principal would work on the Spektrum as well. And since this is a thread concerning diversity and antenna reception my point to all this is that when I set up my big FPV system I will need to deal with the same issues as the video downlink. Since the heli has a lot more metal in it there will be blockage, multipath and dynamic antenna orientation as it flies around. I will use a diversity receiver such as the ar6210: http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMAR6210 and solder LED power leads to each board so I can place LED indicator lights in front of the camera, if both LEDs start to flicker (not flash) then it's time to turn around. I will ty to post a video of what I am talking about.
Thanks for the clarification ... ... as I was missing the hardware being used and I certainly don't have any of the newer Rx's specifically the ar6115e so this is definably NEW information. Although I haven't been out of range w/ my own equipment thus never seen what you describe. So now I'll take you at your word. That said I think teh video is telling the story best So until I get around to testing my Rx's although I only have only have one Rx that ain't a Park Flyer, later bud. And SORRY if I sounded a little GRUFF around the edges but this is just they way I am ... ... {LMAO} Working on it though, NOT J/K Safe to say I DID learn something today [glow=maroon,2,300]w00d[/glow]
This is interesting. I have read and also seen on the park flyer receivers that the blinking indicates a loss of signal. The number of blinks indicates how many times you lost the signal. It says that clearly on the Spektrum site. What I have never checked is what the light is doing when you are actually dropping the packets. I think I have an RPSMA terminator I can put on my transmitter to give it a try. I know I've flown and had it land blinking the number of losses. PP - Is there more than one LED on your receiver? Is there anything in the 6115 manual about it blinking the number dropouts when you land again? I'm not sure why they would blink on packet loss since nobody is in the plane to see it when it happens. I can see where it could be handy for FPV like PP is saying. ...Tiger
No worries Wood, I found out about the blinking by mistake when I was doing a ground range check at 1:00 in the morning when I was curious how far it would go and then it started flickering. Being a radio guy I instantly thought about the busy light on a voice radio flickering when driving in the mountains and getting a low signal. Tiger, my current (and possibly wrong) understanding of the packet loss is that there are 80 packets per second (80 Hz) and when you lose 70 of the packets it goes into fail safe, but then can recover and keep flying. When you land it will blink to show the times it went into this fail safe mode. Mine has only one LED, but later I will let it drop out for a longer duration of time and see what it does.
Thanks PP and I'm going to check my Rx's tomorrow In the mean time this thread made me think of it, for our Serchers'n Lurkers ---> DX6i Hidden Service Menu DX7 Hidden Service Menu - Google FYI: [glow=maroon,2,300]w00d[/glow]
Ok we tested three of my receivers today and I had to improvise the testing method somewhat because I don't have a Metal Filing Cabinet. So for the testing I put my transmitter into teh Microwave (LOL it blocks radio, right) but being VERY careful NOT to HIT the micro's Quick-ON button ;D Regardless it worked for our purposes here The first Rx was my newest teh AR6115-6ch and the LED most certainly DID flash when we started loosing the signal then went OUT completely when the signal was lost The second Rx also relativity new was my AR7010-7ch and it also started to flash upon loosing it's signal then went completely. I have another 7ch Rx I can test although I'm not sure if it's an AR7010 or the older AR7000 Last up was my oldest Rx, the AR6100e but this one DID NOT flash. The servos just went a little jittery before loosing the signal completely but at ALL times the LED remained ON solid I have another AR6100e and will test that and my other 7ch Rx tomorrow. I would say given this round it would seem the latter generation of Rx's do not support the feature. Thus I would also suspect the older AR7000 7ch Rx would also be the same but I would still need to correctly identify my second 7ch receiver tomorrow FYI: [glow=red,2,300]w00d[/glow]
