Just a heads up; CHP comm upgrades

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bryan_herbert

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The California Highway Patrol is in the process of upgrading all of their communications equipment. They've purchased new mobiles, handhelds and repeaters. The power output on the repeaters are running roughly 100 watts into omnidirectional antennas located on mountain tops. The best news of all is most of the comms are now full duplex so you can now hear both sides of the conversation. There are dozens if not hundreds of new freqs involved so I couldnt begin to post them in this thread. You can check out the California Highway Patrol Wiki page for more info or search 39-46Mhz as the all new dispatch freqs now extend up into 45MHz. The new comm system is designed to overlap patrol areas unlike the old system so its not uncommon to work repeaters on the ground from 50 miles away. I can only imagine what the rest of the country is gonna hear once the upgrades are complete and skip improves.
 

kkn50

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Don't know why the previous double posted.

Hearing CHP on 45.700/186.2 tonight. Also, a repeater with noise on 45.940/114.8 but don't know who the user is.
 

n5ims

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The best news of all is most of the comms are now full duplex so you can now hear both sides of the conversation.
I though that the issue before was that they were full duplex (base used one frequency while mobile used another frequency) so you must listen to both frequencies to hear the full conversation (assuming you're in range of both). Are you saying that with the new system they'll use half duplex (both base and mobile transmit on the repeater's input frequency and receive on the repeater's output frequency) so only a single frequency will have both sides of the conversation?
 

gmclam

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Chp

bryan_herbert said:
The best news of all is most of the comms are now full duplex
I though that the issue before was that they were full duplex (base used one frequency while mobile used another frequency) so you must listen to both frequencies to hear the full conversation (assuming you're in range of both).
Yup, full duplex means you can talk and listen at the same time because each side of the conversation is on its own frequency.

Are you saying that with the new system they'll use half duplex - both base and mobile transmit on the repeater's input frequency and receive on the repeater's output frequency
Funny thing, with the new system they are still full duplex - cars on one frequency and dispatcher on another. This is not a conventional system where cars transmit on the repeater input frequency. It's a lot more complex than that ....

Receive sites on mountain tops receive signals on the car frequency. A system "votes" as to which has the best signal and that signal is routed to the dispatcher's console. If the dispatcher has the "repeat" function turned on, then the car audio is routed back to a repeater. I should also note that dispatchers, while on the same frequency, can also transmit from one of several mountain tops. A conventional system would have a single repeater with a frequency in and frequency out. This system involves many receive locations all tied to the dispatch location with microwave links.
 
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