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    dchandler
    difference between ULXD4Q scan/deploy vs. WWB^
    Topic posted October 20, 2015 by dchandlerNovice 
    342 Views, 3 Comments
    Title:
    difference between ULXD4Q scan/deploy vs. WWB^
    Personal Computer:
    Dell Precision M4300, Windows 7, 4mb, wired static IP
    Shure Hardware:
    Shure ULXD4Q WWB 6.11.2.13
    Description:

    Co-worker performed a scan from networked units Shure ULXD4Q and deployed automatically from device to all networked units.  I hooked up WWB6 and performed a scan of the bands being used and then "analyzed" the freqs previously deployed from device scan. The result was "incompatable" according to WWB.  I did notice that the freqs the device chose fit neatly in between a couple of distant TV stations that still showed up on scan.  The WWB scan placed a couple of the freqs within those channels after repeated scans (see attached freq plot).  Just curious why they see freqs so differently and place them in such different spaces in RF plane.  Repeatedly lowered the exclusion threshold while doing additional scans in WWB 6.11.2.13

    File 1:

    Answer

     

    • buhmanb

      To best answer your question regarding your specific scenario I'd have a few questions to clarify with you first.

      Here is what I imagine happened:

      1. Your configuration consists of 4 ULXD4Q units from the L50 RF Band.  All networked together.
      2. Co-worker used the Group Scan feature on one of the ULXD4Q units and selected (for example) Group 02, then "Deployed" to the rest of the units.

      As a note - the Group/Channel maps are pre-coordinated such that all of the channels within a group are compatible with one another.

      The ULXD4 Group Scan measures the RF Level (RSSI) of ALL of the Group/Channel maps:
      If the RSSI < GroupScanThreshold (-85 dBm), the Channel is considered "OPEN" and can be deployed to a receiver.  (e.g. G:02 Ch:02 Freq:633.325 is at -97 dBm)
      If the RSSI >= GroupScanThreshold, the Channel is NOT_OPEN and will not be deployed to a receiver. (e.g. G:02 Ch:01 Freq:632.500 is at -72 dBm)

      Group Scan Deployment only sends out channels that are OPEN.

      1. At this point all of the ULXD4Q channels are operating on: (for example)

      G:02 Ch:02 Freq:633.325
      G:02 Ch:04 Freq:634.775
      G:02 Ch:07 Freq:637.700
      .... etc ...
      G:02 Ch:56 Freq:688.575

      1. Later, you connected WWB and the units showed up in the Inventory Tab.
      2. Changed to the Frequency Coordination Tab
      3. Used the "Select Frequencies From Inventory" and chose all of those ULXD channels
      4. Used the "Recent Scans" dialog to capture a scan from one of the ULXD4s.
      5. At this point you can see the overlay of the channels on the Scan.  The RED line is WWB's configurable Exclusion Threshold.
        1. From the attachment, it looks like you lowered the Exclusion Threshold to -99 dBm.
      6. Among several other factors - when WWB does Analysis it uses that Exclusion Threshold to identify which frequencies to avoid. Operating a channel on a frequency who's RSSI was measured over the Exclusion Threshold will trigger an Analysis warning. 

      So I suspect that your WWB analysis is using a threshold that is lower than the one used by the Group Scan.

      A more general note:
      Group Scan / Channel Scan - on the devices is simple and effective for most configurations and RF Environments.  The pre-programmed Group/Channel maps are pre-coordinated and assessed against a simple scan and fixed threshold.

      WWB's Frequency Coordination enables tailoring for more challenging configurations and RF Environments.  The output of coordination (CFL) is essentially a customized Group/Channel map specific to your run-time environment.

      WWB's Frequency Coordination also allows you to select the TV channels you wish to avoid via either a lookup, or you can manually check them.

       

    • dchandler

      Your assumptions are close,  I also just opened an instance of WWB and analyzed freqs prior to any scan and the results were "incompatible". The device scan placed the freqs neatly in the 638>644 and the 662>685 range, which avoided the noise seen in pdf for surrounding areas and is why I performed a couple of additional scans and repeatedly lowered threshold to see if WWB would avoid the noise (that was above threshold).  I do start all of my scans in robust and "open it up"  when using more than 30 frequencies or as required.  Didnt have any issues with show at all but I did notice that when I did the unit scan the rf was completely clean even when turning on power to all devices  compared to the WWB scan/deploy where I saw a little noise on multiple devices prior to turning transmitters on..  

    • buhmanb

      Here are a few more notes that I hope will answer your questions:

      Regarding Analysis:

      • The pre-programmed Group/Channel maps are typically created (a) adhering to the Standard or More Frequencies compatibility profile and (b) assuming clean spectrum (i.e. assumes no other high power transmitters in the same spectrum). 
        • (a) If you use WWB and analyze the channels using the Robust compatibility profile, it is quite likely the Analysis will identify conflicts because the Robust spacing rules are wider.
        • (b) If the run time scan done by WWB identifies a "high power" transmitter (> -60 dBm), the Analysis will take the theoretical intermods created by those in addition to the theoretical itermods from the planned channels.  So those theoretical intermods may be the cause of the conflicts.
      • If you click the check-box next to the Analysis button that will create a detailed report which can be saved.  Sending a copy of that report, along with a copy of the Show File and Scan File would make it easier to specifically pinpoint why you're seeing conflicts.  You may see the reason by looking at the detailed report yourself.

      Regarding why you see a little noise with the WWB Scan/deploy vs clean after the ULXD Group Scan & deploy.  Here's my theory:

      • ULXD Group Scan:
        • I'm going to assume for example that the Group Scan was run on ULXD L50, and you chose Group 01, which has 67 "potential" channels, of which maybe 40 of them were deemed OPEN
        • When the Group Scan deploys, it pics the lowest RSSI from those 40 OPEN channels to send to your 16 physical channels.   
        • So those channels show up as very clean.
      • WWB Scan & Deploy:
        • I'm going to assume that the live scan was taken, using an Exclusion Threshold of -85, and that only 16 channels were requested for coordination  (i.e. no additional backups were requested)
        • The coordination found 16 channels that are compatible, and under the Exclusion Threshold.
        • When it comes time to Deploy, WWB has those 16 frequencies to pick from - some of which might see a little noise.  Essentially this deployment had fewer channels to pick from.
        • You could try requesting more backups, then when performing the Assign & Deploy there will be more channels to chose from.  By default the Assign and Deploy picks the lowest RSSI.
        • Note the Rank (stars) in the Assign & Deploy dialog.  Three stars means lowest RSSI, with one star you might see a little RF activity. 

      Hope that is helpful for you!  Best luck with your coordination!

     

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