scu functionality

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  • Updated 1 year ago
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I have searched the site library so hopefully I did not miss a previous post. My question is this, can scu performance and overall receive performance be increased if an scu was limited to capture a single band vice it's current role as a wide band scu ? I do not know just how much bandwidth a scu currently captures, but in theory would it's performance increase if  it was commanded to just capture say the 15m band or  just 21.000 to 21.150 ? Just curious.

Please note, this does not imply that an scu is underperforming in anyway, but, emphasizes if an scu's performance can be even better if it's capture parameters were allowed to be customized.

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km9r.mike

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Posted 3 years ago

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Bill -VA3WTB

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I hope Steve has time to answer this in detail. If I understand things a bit, the SCU is trimmed down to work a portion of what it can. It is filtered to only capture the amature radio bands. Other wise it can capture way beyond that.
(Edited)
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Tim - W4TME, Customer Experience Manager

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The short answer is no.  The SCU (ADC) performs better when it has a lot of signal to process as long as it does not exceed the saturation point.  The 6700/6500 SCU is sampling at 245.76 Msps.

And the preselectors on the 6700/6500 are not brick wall bandpass filters.  They only perform a function to limit aggregate out of band signals to prevent signal saturation of the ADC in a high signal environment. 
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km9r.mike

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Thanks Tim.

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Norm - W7CK

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Since the 6700 has 2 SCUs (receivers) is there a way to set the RF Gain independently for each SCU?

Is it possible for a future release of the software to enable the user to assign a specific SCU to a panadapter?  At present, I have no control over it and it really messes with me when trying to have a combination of panadapters using 2 meters and HF.
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Tim - W4TME, Customer Experience Manager

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Yes.  Select the panadapter menu associated with the SCU and change the RF gain.  SCUs are connected to antennas, so of you have ANT-1 on one panadapter and ANT-2 on another pandapter, then adjusting the RF gain via the panadapter menu adjusts the RF gain for the associated SCU.
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Norm - W7CK

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Geez, I can't believe it.....   After you said the SCU was associated with the antenna, I realised - Shoot, I actually knew that!

One of the other problems I'm having is working 2m and hf between panadapters.  More often than not, when I change something, all of the panadapters go to 2m and it gets all screwed up.   Is this something that is fixable or is it just something we have to get use to?
(Edited)
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Tim - W4TME, Customer Experience Manager

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For the time being, it is something you have to workaround. 

I recommend you  "force" an SCU to be associated with the 2nd Nyquist zone that includes 2m.  I do this by using the RX Loop and using a coax jumper between RX-IN and RX-OUT.  I "assign" the 2nd SCU by using ANT-2 (it could be ANT-1, this makes no difference) and the use LOOP-B to associate 2m with the second SCU.  

This way, HF is associated the other ANT-x port that is on the first SCU.  How you should be able to change HF bands without an SCU change, which is what is happening based on your description above.

You should also save this configuration as a global profile so it is easily recalled.