Feb 25, 2012, 01:25 PM
Team Flying Pirates
Joined Nov 2011
192 Posts
Quote:
thank you!! but so.. how can i interpret the rangelink rssi? today in very very bad condition (4.5km at 10m altitude) the rssi showed me 0.8v for 2 second but ithe link rc was ok....
 Feb 25, 2012, 01:27 PM Registered User Norway Joined Aug 2011 236 Posts ...
 Feb 25, 2012, 01:30 PM Team Flying Pirates Joined Nov 2011 192 Posts is correct if i think that the rangelink rssi is the media of rf rssi in a x time?
Feb 25, 2012, 01:32 PM
Registered User
Joined Aug 2002
25,595 Posts
Quote:
 Originally Posted by _ELLIOT_ thank you!! but so.. how can i interpret the rangelink rssi? today in very very bad condition (4.5km at 10m altitude) the rssi showed me 0.8v for 2 second but ithe link rc was ok....
For the most part, you can't. It'll indicate that it's all good, until it isn't. If the value is
anything over 0 it thinks it's still getting some packets, but in my range testing I found
that response was noticeably degraded pretty much any time it drops much below 100%
and when drops it often does so very quickly. Your 0.8v was pretty close to total
loss of link, probably due to flying behind terrain.

ian
Latest blog entry: My 2012 FPV year in Review
Feb 25, 2012, 01:34 PM
Registered User
Joined Aug 2002
25,595 Posts
Quote:
 Originally Posted by _ELLIOT_ is correct if i think that the rangelink rssi is the media of rf rssi in a x time?
What? Use the cell phone analogy above.

ian
Latest blog entry: My 2012 FPV year in Review
Feb 25, 2012, 01:44 PM
Team Flying Pirates
Joined Nov 2011
192 Posts
Quote:
 Originally Posted by Daemon What? Use the cell phone analogy above. ian
i tried some words to explain the concept.. but my english is very bad...

for example:

rangelink calculates the mean of rssi in 5 second and shows it ?

ex:

secon1
3.0v

second 2
1.0v

second 3
2.5v

second 4
3.2v

second 5
2.1v

3.0v+1.0v+2-5v+3.2v+2.1v / 5 = 2.3v rssi

i don't know if this concept is correct
 Feb 25, 2012, 01:56 PM Registered User Lakewood, Colorado Joined Aug 2002 25,595 Posts No, it's not correct, or even close. It's about bandwidth. The actual RC control signal does not require a lot of bandwidth to send 100% of the control packets. A strong Rf signal provides many times the needed bandwidth. Only when the Rf signal strength drops 70-75% can it no longer provide enough bandwidth for the control signal to pass 100% of the packets. The problem is, things move pretty quickly in that last 25% of Rf signal strength and if it drops below that, the % packets received drops very very fast. Since RL RSSI indicates only % packets received, it'll go from 100% to 50% to 0 in moments. Again, the cell phone analogy is still the most useful. Modern cell phones use a relatively small bandwidth digital signal to pass the voice. You can pass that voice signal without noticeable degradation all the way down to 1 bar (out of 5). Below 1 bar, the voice signal will degrade quickly or call will be lost. Rf RSSI is like the signal strength bars.. % packet loss indicator (what the RL Rx has) is like the perceived voice quality. It's good 95% of the time, and then real bad real quick. ian Last edited by Daemon; Feb 25, 2012 at 02:03 PM.
 Feb 25, 2012, 06:43 PM Team Flying Pirates Joined Nov 2011 192 Posts ok ian, i understand, thank you, you're very helpful. however i always flown with old chainlink, and today i tested the rangelink. if i also not considere the rssi, the performances of rangelink are incredible compared to old chainlink. in the places where chainlink getting some failsafe at @500mw, rangelink worked perfect @200mw... the test is made with 2 different plane and the result was always the same!! i'm so confused, i've don't understand if sid can explain this differance and i also want to know what will include the new fw and when it will installed.
 Feb 25, 2012, 07:37 PM Registered User Lakewood, Colorado Joined Aug 2002 25,595 Posts I can't speak to Chainlink (Rangelink evolved from the original Chainlink), but one thing that attracted me to Rangelink is that the specifications say that the RL Rx has a SAW filter installed, which should narrow it's view of the spectrum and block out more external interference from nearby bands (Digital TV is often broadcast on a band pretty close to this). It's possible that Chainlink Rx does not have this added filtering, and thus will have less range in a high Rf noise environment. There may be some other reason. To really do a proper comparison you should use the exact same antennas on the Tx and Rx, for both systems, mounted the same way. ian Latest blog entry: My 2012 FPV year in Review
 Feb 25, 2012, 09:29 PM Registered User Australia, NSW Joined Apr 2004 435 Posts Help!! I was out this morning with both Skywalkers. Each has the same gear: 4S-5000 motor only 3S 1800 electronics, camera, FY21ap camera servo with ferrite ring. rings on all servos Chainlink. Vtx 910mhz the vid shows the worst effected, I aborted at 5km, I couldn't hear the engine surge, rather saw the cam servo glitch, & "felt" the rudder pull to the left. I set the FY to return to launch, & experienced no further trouble. The second SW glitched once over the same area, I ignored it & returned to home. Never had this happen, any ideas?? http://vimeo.com/37451395 Last edited by muduck; Feb 25, 2012 at 09:39 PM.
 Feb 25, 2012, 09:58 PM Registered User Lakewood, Colorado Joined Aug 2002 25,595 Posts Looks/sounds like failsafe. Can't imagine how we can help. BTW, did you say Chainlink? This is the RL thread. ian Latest blog entry: My 2012 FPV year in Review
Feb 25, 2012, 10:10 PM
Registered User
Australia, NSW
Joined Apr 2004
435 Posts
Quote:
 Originally Posted by Daemon Looks/sounds like failsafe. Can't imagine how we can help. BTW, did you say Chainlink? This is the RL thread. ian
Considering Sid does occasionally hang out here..I also imagine that there are, apart from yourself, a number of former Chainlink owners who just might have a clue....
 Feb 26, 2012, 12:33 AM Registered User Lakewood, Colorado Joined Aug 2002 25,595 Posts I understand that I've become the designated bad guy for pointing out the obvious, but wouldn't you expect to find more Chainlink owners in the still active Chainlink thread? http://www.rcgroups.com/forums/showt...6367&page=1000 As someone who's owned and flown a lot of UHF control systems, I can say there's just not enough detailed information to provide a specific diagnosis. In my experience, if I get failsafes at relatively close range with clear LoS then usually it's due to one or more of 1. Antenna problem (bad connections, bad placement, bad orientation, Tx antenna too close to the ground, etc..) 2. External interference from a source onboard the plane (lots of noisy flight cameras, noisy GoPro, other noisy HD cameras including the keychain cams, noisy voltage regulators, some video Tx frequencies matched with some UHF systems lacking certain types of filtering, certain types of digital servos... etc.. ) installed too close to the UHF Rx or Rx antennas. 3. External interference from a source outside the plane (High powered digital TV broadcast towers are my nemesis, but have been hit by other UHF control systems nearby as well) While low powered or attenuated (terminator on the Tx antenna, or entire Tx placed in a Faraday cage.. ala microwave oven) range tests aren't definitive, they do have some value in diagnosing the first two categories of issues. Set a baseline range with only UHF Tx/Rx powered, and then re-test with the various other components powered up. If you have two Rx and they're behaving differently, test them in isolation and if one is still different, then it's an Rx problem. If they behave differently only when when installed on their respective planes, then it's likely a problem with something on the plane. ian Latest blog entry: My 2012 FPV year in Review
Feb 26, 2012, 04:43 AM
Team Flying Pirates
Joined Nov 2011
192 Posts
Quote:
 Originally Posted by Daemon I can't speak to Chainlink (Rangelink evolved from the original Chainlink), but one thing that attracted me to Rangelink is that the specifications say that the RL Rx has a SAW filter installed, which should narrow it's view of the spectrum and block out more external interference from nearby bands (Digital TV is often broadcast on a band pretty close to this). It's possible that Chainlink Rx does not have this added filtering, and thus will have less range in a high Rf noise environment. There may be some other reason. To really do a proper comparison you should use the exact same antennas on the Tx and Rx, for both systems, mounted the same way. ian

exactly ! my test show that the range is the same with only the rx on and in only perfect condition.
the difference on a plane is really big. i tested rangelink vs chainlink in 2 different planes and chainlink lose every time.
(same antenna).

really big difference!