3.125KHz Step Size Support?

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jonwienke

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Now that the x36 scanners support NXDN, is it going to be possible to set a 3.125KHz step size in Sentinel so that extra-narrow NXDN frequencies can be correctly identified and entered?

Also, will the SDS100 support NXDN with a 6.25KHz channel width option? I would think that if any arbitrary IF filter width can be set in SDR#, that correctly supporting 6.25KHz channels could be done in software, if not via a physical crystal filter.
 

kruser

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Now that the x36 scanners support NXDN, is it going to be possible to set a 3.125KHz step size in Sentinel so that extra-narrow NXDN frequencies can be correctly identified and entered?

Also, will the SDS100 support NXDN with a 6.25KHz channel width option? I would think that if any arbitrary IF filter width can be set in SDR#, that correctly supporting 6.25KHz channels could be done in software, if not via a physical crystal filter.

The x36HPs seem to support it now Jon, somewhat.

When I was messing with that site this morning that was spewing out Alias's, I found the sites frequencies were wrong.

When I went in to the site to edit, Sentinel and the radio let me enter the first four digits right of the decimal point but it would truncate the last two digits for a 3.125 channel.

At least it does take them but who knows if the radio rounds the missing last two digits or not.

Actually, Sentinel does take all six digits right of the decimal point but the radio will truncate anything more than four digits.
The radios follow NXDN just fine like this and I doubt the radio has the selectivity to use say 454.4218750 instead of a strong signal on 454.4250.
At least that is what I'm seeing with a NXDN signal on 454.271875 and a neighbor P25 CC on 454.4250.
The radio is decoding the NXDN site but when I tune it to 454.4250, the audio sounds horrible and I do lose NXDN decode. I've not tried to see if it will decode the P25 signal that lives there or if I must purposely tune it 3.125 higher or 454.428125.
 
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jonwienke

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You can't set 3.125KHz steps in the bandplan settings, either in the scanner menu or in Sentinel.
 

Voyager

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3.125 is a relatively new use, so the scanners will have to catch up.

But I've never seen any Uniden model round frequencies. Mask, yes. Round, no.

So, not seeing the last two digits is not proof of being off frequency.
 

jonwienke

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Agreed, but you can't yet do a band search on those frequencies--they follow the frequency steps in the band plan settings.
 

kruser

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Agreed, but you can't yet do a band search on those frequencies--they follow the frequency steps in the band plan settings.

That is very true and something I did not think of. Don't do a lot of band searches.
I also don't think the x36HP's round the 3.125 freqs as entered as they take them but just truncate the last two digits.
So at least they do take 3.125 freqs but band searchs and limit searches will be a problem.
 

kevino

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Confirming 3.125 kHz Splits

I've found that a dongle and SDR# are very valuable when it comes to seeing/confirming the actual center frequency. A local NXDN trunked system uses a good number of 3.125 kHz splits, and it would have been impossible to determine this with a scanner alone.
 

Ubbe

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It would be terrific if the SDS100 could have an indicator to show if a frequency is more than 2KHz off. Either the system has a problem or the wrong frequency is entered into the scanner if that happens.

/Ubbe
 

Voyager

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Agreed, but you can't yet do a band search on those frequencies--they follow the frequency steps in the band plan settings.

True. you can't yet. I don't know if it will be added or not. But at least you can program them.
 
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