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inconsistent frequency entry

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ka3jjz

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#1
I've seen a few cases now (particularly with folks who are entering TRBO systems) of the frequencies being entered to 3 decimals. Narrowbanding, AFAIK, doesn't depend on a trunk system type, so why aren't the frequencies being entered with 5 decimals (where needed)?

Seems wholly inconsistent - definitely not a good db characteristic

Mike
 
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mmckenna

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#2
I've seen a few cases now (particularly with folks who are entering TRBO systems) of the frequencies being entered to 3 decimals. Narrowbanding, AFAIK, doesn't specify the mode per se, so why aren't the frequencies being entered with 5 decimals (where needed)?

Seems wholly inconsistent - definitely not a good db characteristic

Mike
Not sure I understand the reason for this.

I've got narrow banded frequencies at work that are 154.130MHz. Same thing as 154.13000MHz. Not sure I understand the point of adding 2 extra zeros. Why not carrying it out all the way to the 1Hz level? 154.130000MHz?

I think what you might be referring to is the splinter channels or the channels that have been interleaved between the existing 25KHz or 12.5KHz spaced channels, am I correct? I can see the need to carry those out all the way, but adding insignificant zeros doesn't seem to be necessary.
 

GTR8000

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#3
Lindsay recently made a change to the database which limits the amount of unnecessary trailing zeroes after the decimal point. So whereas the database used to present a frequency of 460.275 as 460.27500, those trailing zeroes no longer appear. The minimum number of digits past the decimal point is now three, so 450.5 would appear as 450.500.

I'm not quite sure what you're getting at when you mention narrowbanding. Narrowbanding has nothing to do with how many digits after the decimal point a frequency has; it pertains solely to the transmit deviation, aka "bandwidth" of a frequency.
 
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ka3jjz

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#4
GTR8000 beat me to the punch....I didn't know about the change Lindsay made. Still seems inconsistent from a DB point of view.

While you are technically correct about the deviation, many of the new narrowbanded channels are on splits that would require a 5 digit entry. Hence the question...

Mike
 

mmckenna

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#6
I'm not sure that you fully understand what narrowbanding actually is. :confused:
I agree. As my example above, 154.130MHz was one of our fire channels I narrowbanded back in 2012. Deviation went to 2.5KHz, however the center frequency did not change. After narrowbanding the frequency is still 154.130. 154.130 is the same frequency as 154.13000, narrow banding or not.

Sounds like a decision was made to eliminate unnecessary trailing zeros. I fail to see any issue with that.
 

GTR8000

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#7
It should be noted that the change Lindsay made merely prevents unnecessary trailing zeros, however it does not limit the amount of digits after the decimal point where necessary.

It simply means that a frequency of 770.725 would not appear as 770.72500. However, a frequency of 770.70625 would still display all five digits after the decimal point.

Again, I don't see the issue here. This has absolutely nothing whatsoever to do with narrowbanding. It appears that your gripe is with the fact that every frequency in the database is no longer carried out to the fifth position after the decimal point, regardless of whether they're all pointless trailing zeroes.
 

ka3jjz

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#8
This article makes it pretty clear, I think...

Narrowbanding - The RadioReference Wiki

Notice that the new 7.5vkhz (VHF or 6.25 khz UHF) steps are used at times when the frequency has been narrowbanded to account for the deviation changes. There will be times when an older scanner wouldn't be able to handle these new frequencies (because it can't handle the new steps), and would have to round up or down to account for this.

While it's true that there is no technical difference between 154.13 and 154.13000 - regardless of the deviation used, it's still the same - the display in the database should be consistent.

Obviously Lindsay didn't agree, but hey that's his decision...Mike
 

mmckenna

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#9
OK, got it, so what you are looking for is a comfort/consistency thing.

Not sure it really makes any sense, other than the comfort/consistency angle. I've got 5 and 6 digit house numbers in my county, but my house number is only 3 digits. While adding 3 zeros to the front of my house number might make a database look better, it doesn't really serve any useful purpose, other than a "looks" thing.

Just a person preference thing. I get it.

Some places I've still seen 2 digits after the decimal, or even one, like 162.55 or 162.4 I must admit I do a double take most times, but I figure it out.
 

UPMan

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#11
Agreed that it is used often in that context. But, in the original context:

Narrowbanding = reducing channel bandwidth.
Refarming = allocation of the spectrum freed-up by Narrowbanding (but refarming also included the consolidation of 20 different radio services into two: Public Safety and Industrial/Business).
 

blantonl

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#12
It should be noted that the change Lindsay made merely prevents unnecessary trailing zeros, however it does not limit the amount of digits after the decimal point where necessary.
Spot on.

Our intention with this change was to prevent 6.25 and 2.5KHz assigned channels mixed with other frequencies in a trunked system from causing trailing zeros to run amok.

Yes, there are trunked systems out there that are now using 2.5Khz spacing.

KABC-TV Trunking System, Los Angeles, California - Scanner Frequencies

As we went through the process internally with the admin team, we did tweak the process a bit and after settling on our new standard no one on our admin team objected further. I think we've solidified what will go forward for many years, and unless anyone has any arguments, I believe we should put this to bed.
 

GTR8000

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#13
That's technically 3.125 kHz spacing on UHF. :wink:

25 kHz -> 12.5 kHz -> 6.25 kHz -> 3.125 kHz is the progression of the ever narrowing spacing on UHF; halved each time.
 

blantonl

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#17
well, the good thing is we went through this process internally and we came to the right consensus on how to handle this.


Sent from my iPad using Tapatalk
 

DaveNF2G

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#18
At least RR is trying to get a handle on multiple channelization schemes for different bands and allocations. The radio manufacturers who preprogram allocations into their equipment rarely get them all right.
 
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