Sat fades

[dcaccount]

Hello,
Can you please advise your average number of sat fades?

I end up my 4.00 minutes flight with 60-70 sat fades per sat.

Is it normal in your opinion?
Thanks,
Daniele

[bad007]

Originally Posted by dcaccount

Hello,
Can you please advise your average number of sat fades?

I end up my 4.00 minutes flight with 60-70 sat fades per sat.

Is it normal in your opinion?
Thanks,
Daniele

That's 2 many please post some good pictures.
I get about 2 on my Vbar with 2 sats.

[BrainDev]

This is what Spektrum say in their user instructions:

[nickthenorse]

Originally Posted by dcaccount

Hello,
Can you please advise your average number of sat fades?

I end up my 4.00 minutes flight with 60-70 sat fades per sat.

Is it normal in your opinion?
Thanks,
Daniele

That's fine.

I'm getting anywhere between 30 and 80 fades on my 7 minute flights using two spektrum satellites.

See pictures thread for satellite placement: https://www.helifreak.com/showpost.p...&postcount=244

[bad007]

Sat fades, read fades and my brain saw switches. OMG, cant remember, cant see, got vertigo, bad back and now cant read. Just great.

[dcaccount]

Thanks everybody for them replies, daniele

[PaoloFCantoni]

In a 5 minute flight, I'm getting 256 fades on one Sat1 and 128 on Sat2 in a pretty straight linear fashion on my Protos 700 Leggero. The Sats are genuine Spektrum sats.

Should I be worried? One is sited under the Brain on the angled composite frame, the other mounted vertically on the boom, just behind the tail servo.

Will mounting them elsewhere be beneficial? Would using the Lemon Diversity Sats with the longer antennas help?

TIA,
Paolo

[Edit: Just a thought; could it be my old (somewhat beat-up) DX7s? How could I check?]

[Xrayted]

Originally Posted by PaoloFCantoni

In a 5 minute flight, I'm getting 256 fades on one Sat1 and 128 on Sat2 in a pretty straight linear fashion on my Protos 700 Leggero. The Sats are genuine Spektrum sats.

Should I be worried? One is sited under the Brain on the angled composite frame, the other mounted vertically on the boom, just behind the tail servo.

Will mounting them elsewhere be beneficial? Would using the Lemon Diversity Sats with the longer antennas help?

TIA,
Paolo

[Edit: Just a thought; could it be my old (somewhat beat-up) DX7s? How could I check?]

Keep in mind the above referenced fade info from Spektrum is for DSM2 sats. DSMX sats frequency hop rather than lock onto one specific frequency and stay there like DSM2, so it can be normal for DSMX setups to report more fades than DSM2.

With that being said, you can certainly try using dedicated carbon sats or diversity dats to reduce the values as best you can due to the longer antenna if having a hard time finding a mounting position that is not blocked by CF

[PaoloFCantoni]

Thanks, Tony,

As usual, clear explanation! However, can you define "blocked by CF"?

The rearmost Sat (on the boom) is behind the Tail Servo and the short antennas are vertical (extending beyond the boom. The front Sat is located on the slanted section of the bottom frame at rear (facing outward) so, again, I wouldn't think it would be blocked by CF.

Given your comment about DSM2 vs DSMX, are the absolute numbers I quoted within, or outside, expected levels?

Paolo

[Guapo131]

256 fades sounds like way too much. Something might be wrong there. Definitely worth continued investigation.

If you are on the fence about switching to a diversity sat (like the Lemon), go for it! I Have 1 lemon diversity sat and 1 lemon regular sat connected to my Ikon2. The diversity sat has <20 fades in a 4 minute flight. and the regular sat has <100fades. Between the two of those, I have 0 worries about lost signal due to fades/holds.

Other threads of interest:
Lemon diversity sats - note the pictures toward the bottom of page of people's sat antenna wire mounting configs. Also note how the active part of the antenna is clear of the carbon fiber and 90degrees from each other.
I mounted my lemon diversity sat like the picture below and love it. Link to the mounting stuff from mikadousa (or you can make your own, or find elsewhere)

[Xrayted]

Originally Posted by PaoloFCantoni

Thanks, Tony,

As usual, clear explanation! However, can you define "blocked by CF"?

The rearmost Sat (on the boom) is behind the Tail Servo and the short antennas are vertical (extending beyond the boom. The front Sat is located on the slanted section of the bottom frame at rear (facing outward) so, again, I wouldn't think it would be blocked by CF.

Given your comment about DSM2 vs DSMX, are the absolute numbers I quoted within, or outside, expected levels?

Paolo

You want to keep the whiskers clear of any carbon fiber if possible since CF can block the radio signal. It can tricky to place the sats in a position where there is clear line of sight to at least one of them no matter wha odd position the model may happen to be in flight. The short whisker may be clear of the CF in one viewing position, but blocked in another

I will need to see if I can find the official Spektrum info page regarding fades with DSMX. If I recall correctly it can be in the hundreds, but don't hold me to that since I'm working from memory here for now. It's expected that fades can be higher with DSMX vs DSM2 one way or the other, but no reason we can't do what we can to get them as low as possible though.

EDIT: So here is a comment directly from Horizon regarding fades on DSMX. It appears fades are less significant and more should be expected with DSMX as stated, although a specific number isn't mentioned. Frames and holds are the more important things to look for so it appears we may be focusing on and worrying too much about the wrong value.

»Flight Log Recording - Fades Higher than DSM2
Note: The DSMX moves through the band while DSM2 finds two quiet channels and remains on those channels. Consequently because DSMX operates on quiet and noisy channels, it's common to have more Antenna Fades than when using DSM2, when used in busy 2.4GHz environments. When taking flight log data readings, the Frames and Hold Data are important and should be used as a reference while Fades are less significant due to the nature of frequency agile systems. A 10-minute flight will typically result in less than 50 Frame Losses and no Holds.

[PaoloFCantoni]

Thanks again, Tony,

As I said, my Sats are genuine Spektrum and so the aerial leads are not longer than 30mm (a bit over an inch). So it's a bit difficult to keep them "always in view".

Paolo

[Xrayted]

Originally Posted by PaoloFCantoni

Thanks again, Tony,

As I said, my Sats are genuine Spektrum and so the aerial leads are not longer than 30mm (a bit over an inch). So it's a bit difficult to keep them "always in view".

Paolo

Yes I agree, and switched over to the longer diversity sats just to be on the safe side myself.

[Guapo131]

Originally Posted by Xrayted

EDIT: So here is a comment directly from Horizon regarding fades on DSMX. It appears fades are less significant and more should be expected with DSMX as stated, although a specific number isn't mentioned. Frames and holds are the more important things to look for so it appears we may be focusing on and worrying too much about the wrong value.

»Flight Log Recording - Fades Higher than DSM2
Note: The DSMX moves through the band while DSM2 finds two quiet channels and remains on those channels. Consequently because DSMX operates on quiet and noisy channels, it's common to have more Antenna Fades than when using DSM2, when used in busy 2.4GHz environments. When taking flight log data readings, the Frames and Hold Data are important and should be used as a reference while Fades are less significant due to the nature of frequency agile systems. A 10-minute flight will typically result in less than 50 Frame Losses and no Holds.

So does this mean I should not even bother logging fades (on my Ikon2)? Just log the Frame rate, and if I see a reduction in frame rate corresponding to an issue when debugging something, then that would signify a tx/rx issue? (bonus, this could free up 2 of my logging channels)

[Xrayted]

Originally Posted by Guapo131

So does this mean I should not even bother logging fades (on my Ikon2)? Just log the Frame rate, and if I see a reduction in frame rate corresponding to an issue when debugging something, then that would signify a tx/rx issue? (bonus, this could free up 2 of my logging channels)

I will need to defer that answer to someone else. To my understanding, frame rate and frame losses are two completely different things. My experience when logging frame rate with my spektrum is that it never changes even if I turn the transmitter off. I know what my frame rate is bound as in the transmitter, so that information was never useful to me from the logging standpoint since it appeared to be a fixed value. Maybe I'm misunderstanding something in the regards to that logging function, hence my reason to see what others have the say on the subject

[PaoloFCantoni]

I've come to the conclusion that recording DSMX Sat fades does not yield any useful data. (BTW: is there a maximum value recordable per flight - say 256?)

So I'm going to recover two channels and use them for more useful data.

Thanks for all your help above.

Paolo

[denis747]

If one sat faded for too long, would that trigger fail safe or would Brain/Ikon use the other sat?

Sent from my SM-G920F using Tapatalk

[jrman83]

I usually see 0 sat fades on all of my systems. I do see a frame rate of 10 vs 11 sometimes, which I assume that is a frame rate loss of 1 which I assume I would have had to have sat fades somewhere. If I understand it correctly. Frame rate goes down, sat fades should go up?

In the recent problem I had with one of my systems going into fail safe and shutting down, you could not see the sat fades unless you did live logging, and I use 50hz only. In my case, I would see both sats hit 250+ near instantly after starup and then it would cause a fail safe trigger. My issue turned out to be caused by static...at least after some proper grounding it seems to have gone away.

[BrainDev]

Fades are not calculated by Brain but is a value sent by Spektrum receivers/satellitels.
Because is an 8 bit unsigned value, the maximum allowable value is 255.
So, the "real" fades can be higher than this value.
If a user see in the logs the 255 value, must investigate because the "real" value can be very high!

Here from the public Spektrum documentation downloadable from the Spektrum web site:


Rx Frame Rate is calculated by Brain and is the time between two received frames. Because there are no decimals, also a very little variation in the transmission time due to the transmitter clock or due to the receiver clock, can make change the value from 10 to 11.

[mkucuksari]

Originally Posted by BrainDev

Fades are not calculated by Brain but is a value sent by Spektrum receivers/satellitels.
Because is an 8 bit unsigned value, the maximum allowable value is 255.
So, the "real" fades can be higher than this value.
If a user see in the logs the 255 value, must investigate because the "real" value can be very high!

I know it is an old thread but need a confirmation about max value of fades. Does the max value,255 for fades change ?

One of my friend seems to have a transmitter communication problem. While we were testing, we have seen the following values.

Transmitter : DX9
FBL Unit : Brain2
Used 2 DSMX Satellites