Quick Fleetnet Trunking Question

[ve3opc]

Are input frequencies Static or dynamic controled by the tower. In lay terms does the input change by the tower when rx frequecies are trunked by the system. Ie 142.43500 Rx changes to 142.74000 does input freq allso change

 

[Forts]

Inputs and outputs on each tower site are a pair, they don't change.

 

[ve3opc]

But in a sence they would lets take a rough example asuming you are right. lets make up a couple of bogus frequencies in example. the offset lets pretend is +- 4.020 Rx Trunk changes from 142.0350 to 142.4350 so with a offset of 4.020 the input would change from 138.0150 to 138.4150 acomodating the 400 KHZ frequency change of the trunking RX. or is the inut allways static IE 142.0350- 138.0150 = - 4.020 but when moving to next RX frequency 142.4350- 138.0150 would = a changed offset of -4.620 So I guess I am trying to asertain if the offset changes or is allways constant logic dictates to me that the offset would allways be constant and dynamic to the frequency pair as dicated in example 1.the only way I would know for sure would be to moniter input frequecies but am to far from the source to pick them up.

 

[Forts]

I'm really not sure what you are looking for... are you trying to figure out how the system channel numbers are converted into a frequency used by the system? If you run Trunker, Trunk88, UniTrunker etc it will gather the input and output channel numbers in use for the system. Then by using a little math with the base frequency and step size you can determine the actual frequency.

For Fleetnet here is how channel #'s are translated to a frequency:

Input frequencies: Take the channel number in decimal. Multiply by 0.015, then add to 138.015

Output frequencies: Take the channel number in decimal. Subtract 380, multiply by 0.015 and add to 141.015.

For example... output channel #458, which uses input channel #10...

Output: 458-380 = 78. 78*0.015 = 1.17. 1.17+141.015 = 142.1850.

Input: 10*0.015 = 0.15 Add to 138.015 is 138.1650.

 

[gary123]

If you are asking if the control freq changes like on most 800meg systems the answer is no. it is very rare for a contol channel to change and this is usually for maintainance or equipment failure only.

 

[mikewazowski]

But in a sence they would lets take a rough example asuming you are right.

You don't have to assume anything since Forts is correct.

Nothing is dynamic.

Each output frequency has a matched input frequency that never changes.

The frequencies are programmed into the repeaters by techs so it would require a tech to go out and reprogram the repeater and retune the multi coupling equipment.

There are no set offsets like amateur radio repeaters.

In fact, some repeaters have inputs past 148Mhz.

 

[ve3opc]

Awsome thanks.