High fades and frames reading

  • Dear Richard,

    I recently bought an Evolution Spektrum power box and installed it on a Hottrigger aircraft 2.4m. The three satellite receivers are of the DSMX type as recommended. I use a DSM 2 transmitter model JR DSX 11. I already flown the model without any problems and the power box works as it is intended. However, I am very concerned with the high values of fades and frames the flight log is registering. I am attaching the data recorded for the first five flights. I am using the same set up when I used previously a DSM 2 receiver and the readings logged where according to the limits specified. As most DSM 2 receivers have been discontinued I chose the Evolution Spektrum instead as a replacement.

    Do you think it is safe to continue to fly with these high fades and frames.Radio link Strength.pdf

    Thanks and best regards

    Emmanuel Vella

  • Hello,

    That really doesn´t look good. But you must know: as long as you are using a DSM2 radio: the binding is in DSM2 and also the data transmission is in DSM2.

    The difference is only that the satellites would be able to handle also DSMX - but in your case they don´t.

    As it´s a wood plane without special areas this values are realy bad. Can you please do following: check the values before you start - just to avoid that this comes from startup/turn on phase

  • Hi,

    Thanks for your prompt reply. Yesterday I made some on-ground range checks. When I started up with the engine off and close to the aircraft all fade and frame readings were zero. The values of fades and frames then started to increase as I moved further away from the model. At distances of 100 meters and over the very high values are recorded.

    This appears as the strength of the radio link weakens the further away the aircraft is. Holds are only registered when I switch off the transmitter. Other than these I experienced no abnormality in flying the model.

    I know this may me difficult to answer but for sure DSM 2 and DSMX are not fully compatible. I experienced a similar problem with an AR7010 DSMX receiver where fades and frames where also high. The below is a quote from Spektrum's Data sheets and they recognise that when using DSM 2 transmitter one may get higher readings. At least my frame losses are within that specified by Spectrum.

    Flight Log Recording-Fades Higher than DSM2

    Note that DSMX hops 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 a reference while Fades

    are insignificant due to the nature of frequency hopping. A 10-minute flight will

    typically result in less than 50 Frame Losses and no Holds.

    Thanks again for your support


  • Be VERY carefull with this TX. Me and my friend both owned a DSX 11 once and it had low output power compared to other systems. I lost a plane due to it. After a lot of pressure JR exchanged them and the new one was much better, but still less then a Spektrum transmitter in range. I never used it afterwards and bought a Spektrum TX.

    We normally see VERY low values on frameloss and antenna fades using DSM2. DSMX is a bit higher normally. Antenna fades above 50 was rare, lost frames (with 3 receivers) less then 5 normally. These low values are not uncommon. I have seen many flights when one or more receivers had 0 fades and 0 lost frames was normal :)

  • Thanks for sharing your experience, I will perform some more on-ground range checks and decide from there. If the high readings persists I will purchase a DSMX transmitter. Flight log recordings are designed to work on DSM 2 systems and I had almost zero readings before DSMX was introduced. Anyway DSMX systems are going to stay for a long period with us so it worth the move.