UHF Trunking

[DickH]

Does anyone know the channel nymbers for 453-454MHz and 460-461MHz with 6.25kHz spacing?

 

[SCPD]

Does anyone know the channel nymbers for 453-454MHz and 460-461MHz with 6.25kHz spacing?

Do you want P25 or Motorola channel numbers? The base and offset are chosen by each system's administrator. There is no standard table.

 

[DickH]

Do you want P25 or Motorola channel numbers? The base and offset are chosen by each system's administrator. There is no standard table.

It's an analog Motorola system in Umatilla, Oregon. The Base Spacing and Offset are in the RR database, but the spacing is 6.25kHz and some scanners will not accept that spacing. We've tried 12.5kHz but it won't work.
If we know the channel numbers we may be able to work around the problem.
Thanks for your help.

 

[SCPD]

The Base Spacing and Offset are in the RR database, but the spacing is 6.25kHz and some scanners will not accept that spacing.

That is unfortunate.

If we know the channel numbers we may be able to work around the problem.

Calculate the LCN / frequency pairs yourself using a spreadsheet program like Excel.

F = Base + (LCN - Offset) * Spacing

Be sure Base and Spacing are in the same units (eg. don't mix kHz with Mhz).

 

[DickH]

That is unfortunate.
Calculate the LCN / frequency pairs yourself using a spreadsheet program like Excel.
F = Base + (LCN - Offset) * Spacing
Be sure Base and Spacing are in the same units (eg. don't mix kHz with Mhz).

I'd like to know the LCN for 453.00000, 453.00625, 453.01250, 460.00000, 460.00625, & 460.01250 - OR - where can I find them?

 

[SCPD]

I'd like to know the LCN for 453.00000, 453.00625, 453.01250, 460.00000, 460.00625, & 460.01250 - OR - where can I find them?

Remember algebra?

LCN = Offset + (Frequency - Base) / Spacing

The first table reads
Offset = 380
Base = 453.0125
Spacing = 6.25 kHz which also equals 0.00625 Mhz

A base of 453.0125 implies no channels on the system with a lower frequency. Using a few published frequencies from the DB as examples: 453.1 Mhz, 460.1 Mhz and 460.6 Mhz.

For 453.1 Mhz, solving for the LCN is ...
Offset + (453.1000 - Base) / Spacing =
Offset + (453.1000 - 453.0125) / Spacing =
Offset + 0.0875 / 0.00625 =
Offset + 14 =
380 + 14 = 394.
So the channel number of 453.1 Mhz is 394.

The second table reads
Offset = 380
Base = 460.0000
Spacing = 6.25 kHz which also equals 0.00625 Mhz

Crunching 460.1 through the same formula (but with the second table) yields 536 + 16 = 552.

Crunching 460.6 through the above formula yields 536 + 96 = 632.

All of this assumes (a) the published band plan is correct and (b) the published frequencies are correct.

 

[DickH]

Remember algebra?

Could you after not using it for 50 years?

LCN = Offset + (Frequency - Base) / Spacing

The first table reads
Offset = 380
Base = 453.0125
Spacing = 6.25 kHz which also equals 0.00625 Mhz

A base of 453.0125 implies no channels on the system with a lower frequency. Using a few published frequencies from the DB as examples: 453.1 Mhz, 460.1 Mhz and 460.6 Mhz.

For 453.1 Mhz, solving for the LCN is ...
Offset + (453.1000 - Base) / Spacing =
Offset + (453.1000 - 453.0125) / Spacing =
Offset + 0.0875 / 0.00625 =
Offset + 14 =
380 + 14 = 394.
So the channel number of 453.1 Mhz is 394.

The second table reads
Offset = 380
Base = 460.0000
Spacing = 6.25 kHz which also equals 0.00625 Mhz

Crunching 460.1 through the same formula (but with the second table) yields 536 + 16 = 552.

Crunching 460.6 through the above formula yields 536 + 96 = 632.

All of this assumes (a) the published band plan is correct and (b) the published frequencies are correct.

Thanks very much.

 

[WayneH]

Try my spreadsheet out. Link. Use the first tab and enter the known details. It will list all the "LCNs" for the useable freqs.