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    Diogo Nunes Pereira
    creating equipment profiles for Overline Systems
    Topic posted March 24, 2013 by Diogo Nunes PereiraCompetent, last edited November 15, 2013 by AdminProficient 
    1284 Views, 3 Comments
    creating equipment profiles for Overline Systems

    Hi there,

    I'm in the process of creating equipment profiles for Overline Systems UC range of Intercom/Reporter UHF units.

    I've been messing around with the settings in the Filtering and IM tab, and I found a great array of variability in different systems, and I understand little of it! I've focused on two systems I use a lot (Shure UR4D and HME Pro850) to get some settings going on, although "I understand" they may not be real for the specific equipment I'm building the profile for.

    So, a couple of questions?

    a) Should the filter be set to Fixed or Tracking, and what's the difference?

    B) Why is there such a great variation on filter selectivity values in diferent systems? Example: (UR4D: -30 to 30 ; HME 850 : - 100 to 100; More Robust collumn), and how do I know what settings are good for my system?

    c) Each band of Overline UCs has a fixed selection of 22 frequency presets, picked to be IM free within the band (much like channels in Shure Systems). Does this mean I can disregard IM products completely or is this just an insane idea?

    I'm ataching the frequency plans for the systems, since it's no longer in the webpage, and the profile I'm working on.

    Thank you very much in advance.



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    • hautzir
      Hi Diogo,

      Thanks for your request.

      a) I believe that the system you are talking about has a fixed filter whereas this is an information you should try to gather directly from Overline Systems. Systems which work mainly with a high tuning range (e.g. UHF-R) use tracking filters to increase the RF linearity of the system when working. The wider the filter, the higher the problematics that could occur due to interferences etc.

      To figure out settings for your system to be set up that are adequate I would propose to use a system's template that has a similar number of compatible frequencies per a certain kind of tuning bandwidth. As you said that the system has 22 compatible frequencies per frequency range, I would use a system as template that has a similar number of compatible frequencies per frequency range to make things not too complicated.

      c) Disregarding IMs is a bad idea. Each standard system creates intermodulations.


    • Diogo Nunes Pereira
      Hi Ron,

      thank you for the quick reply.

      a) Now that I know a little bit more about front-end filters than yesterday, your answer makes a lot more sense. These systems have a pretty narrow tuning range (16MHz), so I guess you wouldn't need a tracking filter here. Still, there could still be a really narrow tracking filter, closer to the bandwidth of the modulated signal, am I right?

      Anyway, I'll be with a coleague next week who has a closer contact with the Overline Systems guys (and speaks french better that I do); I'll get his input into this question.

      B) or B) Working on it. I'm compiling a bunch of frequency tables from different manufacturers (with profiles already in WWB6) to see if I can get one that's similar to the UC specs, these being:

      16MHz tuning range, 22 frequency presets, spacing 250kHz. Any help, anyone?

      c) Yeaahh... I felt it wasn't my smartest question of all time, but anyway...

      From looking at the different settings (and my own common sense) I figured out that the more space, the better, and I understand that 3rd orders are the "louder" IM products out there: 2Tx/3rd order being worse than 3Tx/3rd order, and this being worse than 2Tx/5th order... But, how much is enough?

      For example, the settings for a Sennheiser 3000 system in Sennheiser SIFM are:

      2Tx IM(3) = 75kHz
      2Tx IM(5) = 75kHz
      3Tx IM(3) = 75kHz

      And in WWB6 for the same system we have:

      2Tx / 3rd Order = 200kHz
      2Tx / 5th Order = 150kHz
      3Tx / 3rd Order = 150kHz

      It theory SIFM should find more frequencies, but this would mean those frequencies would be more prone to IM interference, right?

      I guess I also might need to have someone from Overline Systems to tell me how narrow those filters are in order to get the apropriate values in the profile.

      Thank you again, hope to ear more on this topic soon.


    • hautzir
      Hi Diogo,

      a) I strongly don't believe that this system uses track-tuning filters.

      To be honest, I would try to gather the direct values to be used for the equipment profile directly from Overline Systems as the comaptibility values they claim seem to be very optimistic. I don't recall a system with 22 compatible frequencies in a bandwidth of 16 MHz. For reference: A typical system that has 22 compatible frequencies per frequency band has a rypical bandwith of about 30 MHz which is about twice the bandwidth of the Overlie Systems system.

      c) The most relevant IM products are the 3rd order ones. As said, I would propose to directly get in touch with Overline Systems here.

      Thnaks and good luck in gahering appropriate data!



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