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 Post subject: P25 NAC's
PostPosted: Sat Feb 03, 2024 4:25 pm 
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Angus Cheeseburger
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Joined: Thu Feb 19, 2004 5:09 pm
Posts: 4758
Location: CN88st
The NAC is a feature similar to CTCSS or DCS for analog radios. That is, radios can be programmed to only pass audio when receiving the correct NAC. NACs are programmed as a three-hexadecimal-digit code that is transmitted along with the digital signal being transmitted.

Since the NAC is a three-hexadecimal-digit number (12 bits), there are 4,096 possible NACs for programming, far more than all analog methods combined.

Three of the possible NACs have special functions:

0x293 ($293) – the default NAC

0xf7e ($F7E) – a receiver set for this NAC will pass audio on any decoded signal received

0xf7f ($F7F) – a repeater receiver set for this NAC will allow all incoming decoded signals and the repeater transmitter will retransmit the received NAC.

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Jim N7UAP - Bellingham, WA / InterceptRadio.com


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 Post subject: Re: P25 NAC's
PostPosted: Mon Apr 29, 2024 10:21 am 
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Joined: Sat Apr 13, 2019 9:07 am
Posts: 72
Location: New England and Travels
Has anyone with a Scanner actually had $F7E actually work ??

I've only had it work on a REAL Two-way radio, no scanners, which I rely on Auto instead
Jim wrote:
The NAC is a feature similar to CTCSS or DCS for analog radios. That is, radios can be programmed to only pass audio when receiving the correct NAC. NACs are programmed as a three-hexadecimal-digit code that is transmitted along with the digital signal being transmitted.

Since the NAC is a three-hexadecimal-digit number (12 bits), there are 4,096 possible NACs for programming, far more than all analog methods combined.

Three of the possible NACs have special functions:

0x293 ($293) – the default NAC

0xf7e ($F7E) – a receiver set for this NAC will pass audio on any decoded signal received

0xf7f ($F7F) – a repeater receiver set for this NAC will allow all incoming decoded signals and the repeater transmitter will retransmit the received NAC.


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