CROSS BAND SYSTEMS: A few questions please

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Archie

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So back in the day, what was the advantage to having a cross band system with PD's transmitting via VHF and receiving back via UHF??? Heard one lower Westchester County city had it and it failed in the early 1970's..

So without a multi band scanner, you would need to have either two separate VHF and UHF scanners or two radio monitors. So likes it was quite awkward and costly.

Many Thanks. Happy, Safe July 4th to all.
 

Septa3371CSX1

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There are several different types of crossband systems. The most common ones are vehicular repeaters / mobile extenders. These allow the use of mobiles in one band (i.e. VHF) and portables in another (i.e. UHF) with the portables talking back to the mobile. This is often used in areas of poor coverage to make use of the high powered mobile in the vehicle while the user is outside of it. There are many agencies that still use these today. I have no idea why the system you described would have failed.
 

RFI-EMI-GUY

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So back in the day, what was the advantage to having a cross band system with PD's transmitting via VHF and receiving back via UHF??? Heard one lower Westchester County city had it and it failed in the early 1970's..

So without a multi band scanner, you would need to have either two separate VHF and UHF scanners or two radio monitors. So likes it was quite awkward and costly.

Many Thanks. Happy, Safe July 4th to all.
Operationally, for one agency back in that period, it wouldn't work well because there were no multiband radios that officers could use.

Maybe there were two separate agencies, one using VHF and one using UHF and they were dispatched from a common console operator in a patch arrangement. Or one agency had UHF portables and VHF mobiles and both repeaters were patched.

Technically there is no advantage, it was probably a work around.

Vehicular repeaters as the other poster replied, is a possibility, and is common.


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paulears

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In the UK, our old police systems had vehicle mounted UHF radios linked to the county wide VHF radios, so when the officers got out of their cars, a long way from the towns, they could still communicate via the cross band repeater. As far as I am aware, we never had cross band duplex systems - as dual band hand held radios were never commercially available - with no need or demand.
 

KD4SHK

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GA
Cross Band systems

Locally, we have several small communities way out in the county that are dispatched by the 911 Center located in the center of the county. Years ago, each of the communities used a VHF simplex freq for their local PD operations, but used a cross-band repeater for the UHF link back to the 911 Center 10-15 miles away. The system was seamless for the users (PD would use their regular VHF channel like normal, but 911 could hear them and talk back to them on UHF from 15 miles away).

Sam
 

ladn

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The California Highway Patrol (CHP) still uses extenders. Their main dispatch system is VHF-lowband which covers the area fairly well, but doesn't lend itself to efficient handhelds. The CHP uses VHF (now transition to 700 MHz) extenders.
 
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