Westchester Trunked System & Base/Spacing/Offset

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#1
With the new trunked system set to go live this Monday can anyone verify that the base/spacing/offset settings are correct for this http://www.radioreference.com/modules.php?name=RR&sid=1744 system? I know no one has been able to track it yet because it is not live, but I am asking if anyone can verify the calculations for the settings given the frequencies listed.

As an FYI while we are on the subject of calculations, Westchester County has an application for an emergency STA for two new frequencies for the South Zone of the System. FCC file #0003130723 asks for this STA, and the County states that in file #0003004004 the FCCA coordinator has approved the use of 470.0250 & 470.2000Mhz at 110 watts for use in the South Zone. The South Zone (WQBR539) currently has six freq's listed, four are listed at 110 watts (476.0750, 476.1125, 476.2125, 476.2375Mhz) and two at 60 watts (470.0750, 470.1000Mhz). I would guess that the two 60 watt freq's listed would be dropped replaced by the two new 110 watt freq's.

If these two new freq's are added I would guess that all the base/spacing/offset calculations would change. From this information the frequencies for both zones would be:

North - 470.03250, 470.3500, 470.3750, 470.5250, 470.5500, 470.5750Mhz
South - 470.02500, 470.2000, 476.0750, 476.1125, 470.2125, 476.2375Mhz
All of these frequencies are listed for 110 watts.
The Control Channels are 470.5750(North) and 476.2375(South).

With this new information can anyone calculate the new base/spacing/offset settings?

Thanks
 

tbendick

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#2
Ok is someone who knows this stuff well wants to check my math. Here is what I came up with after I tracked it with trunker.

North Zone...
F1 = 470.575 / Dec 1 426
F2 = 470.375 / Dec 2 410

Step 12.5Khz is figured by.
Step in Khz = 1000 x (F1-F2) / (DEC1-DEC2)
so in excel just put in
=SUM(1000*(470.575-470.375)/(426-410))

Converted to MHZ
0.0125
=SUM(12.5/1000)

BASE = F1-(( DEC1-380 ) x OFFSET (in MHz))
So in excel put in.
=SUM(470.575 - (( 426 - 380) * 0.0125))
So Base = 470 / 380 for the offset
Step = 12.5
Now to the 380.

So if you just going to monitor North zone in one bank you can put this in and it will work with no problem. South Zone has two ranges so you need more info for it and you can't use 380 twice.
--------------------------------------------------------------------------------------
Now for South Zone range 1
F1 = 470.075 / Dec 1 424
F2 = 470.100 / Dec 2 426

Step 12.5Khz is figured by.
Step in Khz = 1000 x (F1-F2) / (DEC1-DEC2)
so in excel just put in
=SUM(1000*(470.075-470.100)/(424-426))

Converted to MHZ
0.0125
=SUM(12.5/1000)

BASE = F1-(( DEC1-380 ) x OFFSET (in MHz))
So in excel put in.
=SUM(470.075 - (( 424 - 380) * 0.0125))
So Base = 469.525 Which is 380 Channel number
Step = 12.5

-------------------------------------------------------------------------------------------
Now for South Zone range 2
F1 = 476.2375 / Dec 1 539
F2 = 476.0750 / Dec 2 526

Step 12.5Khz is figured by.
Step in Khz = 1000 x (F1-F2) / (DEC1-DEC2)
so in excel just put in
=SUM(1000*(476.2375-476.0750)/(539-526))

Converted to MHZ
0.0125
=SUM(12.5/1000)

BASE = F1-(( DEC1-380 ) x OFFSET (in MHz))
So in excel put in.
=SUM(476.2375 - (( 539 - 380) * 0.0125))
So Base = 474.250 Which is 380 Channel number
Step = 12.5

-------------------------------------------
So here is how I come up with the new offsets.
Take your base and add 0.0125 to it.
Then I backed off a few and just picked a random channel number below the lowest used.
475.750 which is 500 South Zone Range 2
470.250 which is 400 North Zone
469.525 left at 380 South Zone Range 1
 
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#5
Using info from tbendick's Trunker captures above, came up with the following settings for the North Zone.

Base 470.0
Spacing 12.5
Offset 380

Today I am tracking 60 Control testing with various units on the North Zone.
 

tbendick

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#6
So far we have been able to track the North Zone with no problems.
South zone seems to be working but still need to hear something on the 470's to confirm. Only audio heard has been on the 476's.

The next question will be. can we mix the south and the north in one bank and just lock out the CC which we don't want..
 

ff026

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#7
only chatter i am picking up is the B-Line buses been experimenting with all of the different settings.
 
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#8
i also am receiving bus line radio checks and signal reports??!! No ems/or ambulance ?? Is this a gradual active system or are the offset/base numbers listed wrong?? Has the south site replaced the 2 frequencies which had 60 watt output?? Are the re-configured base/offsets correct?? I tried with original settings posted before they went live and tried the new values with NO difference??!! Any ideas??
 
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#10
so does this mean the majority of the talkgroups are NOT active yet? and are we to enter the system info listed at this website PRIOR to the newest calculations for offset/base numbers?
 
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#11
I would guess that all the assigned TG's would be active. All Fire and EMS vehicles have had the radios installed. So all they need to do would be to click through to the TG they want to access. The BeeLine buses were busy testing today, heard them on four TG's on their own Bank.

You can enter the prior info but it does not seem to work. As stated in the above posts the settings we have posted DO work for this system. We have not been able to calculate the settings for the South Zone 470 freq's yet.
 

ericcarlson

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#12
The following should work for both zones based on tbendick's trunker data. The configuration for the south zone is a bit unusual though; I'm curious to see the raw trunker data for both sites. Anyway, assuming the trunker data is good, try this:

North Range 1: Base = 470.0 MHz, Step = 12.5 kHz, Channel = 380

South Range 1: Base = 469.525 MHz, Step = 12.5 kHz, Channel = 380
South Range 2: Base = 476.075 MHz, Step = 12.5 kHz, Channel = 526

In the absence of additional information, this is equivalent to what tbendick posted. If other frequencies are added, then this might need to be tweaked depending on what the new frequencies are.

-Eric
 
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ff026

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#16
north zone settings seem to be working for me. logging all kinds of chatter now FD and non FD. system sounds good from rockland nice audio even with voting going on.
 

tbendick

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#17
Eric.

What info from trunker would you like to see? I have all the files and can e-mail them.

It seems that the 60watt 470's are set in some form of pecking order to be used only if the 110w 476's are in use. over the past few days I got over 5000 hits on the 476's with only 2 hits on one of the 470's.
This is the reason we can't confirm the settings by listening for the audio, they are just not being used.

The other question I have is can someone mix the north and south zones in one bank on a scanner or must they treat them as two completly diffrent system. I have a few 800 trunked systems and just lock out the control ch depending one my location.

Tommy
 
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#18
mixing both sites in one bank

Yes,I have had success entering both site info,locking out the north site control channel and hearing the traffic on the system. I am using the uniden bc296d.
 
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#19
Heard fd talkgroups doing radio and emergency button checks. Looks like the system will be used for more than bus traffic! I must congratulate westchester government for finally getting this done.I never thought they were serious enough to get a new system off the ground! This will help fd departments BIG time for large scale disasters and communication reliability! Good job!! Now if only nassau county can LEARN?!!
 

Dave520

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#20
Looks like the name of the system will have to be changed to just Westchester County, now that we know that there will be more than just fire and EMS on the system. You never know maybe the police will eventually use the system!!
 
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