What is this sound?

[jrtl92]

Ive noticed when monitoring trunked Motorola Type II systems i hear this "plink" sound at the end of transmissions, its not the mic switch clicking, but sounds like something generated by the system or some type of signalling. anyone know what this sound is or if it has a specific purpose?

 

[W8RMH]

Probably a disconnect tone.

 

[firefive76]

Sounds like a voter releasing to me

 

[MTS2000des]

Comparator. Seems to be common with Quantar/Astro-TAC/Digi-Tac systems. many have that sound. My old Smartnet .89X did. Kinda miss it since migrating to Astro 25, but then I don't miss the static, the long nights of "we're in failsoft" calls, or constantly having to do mod comps every month to keep the system in spec.

 

[Adamwalsh627]

i can’t download your clip, but by what you are describing, it sounds like Data Operated Squelch (DOS) if listening on a two way radio. if MDC 1200 is enabled, the radio shortens the sound of the identifier. You can remove it by disabling DOS or putting the values at zero.

 

[mikewazowski]

i can’t download your clip, but by what you are describing, it sounds like Data Operated Squelch (DOS) if listening on a two way radio. if MDC 1200 is enabled, the radio shortens the sound of the identifier. You can remove it by disabling DOS or putting the values at zero.

You don't use MDC1200 on a trunking system.

 

[canthonysmith]

I have often wondered the same thing!

Sent from my SM-N950U using Tapatalk

 

[mikegilbert]

To elaborate on what others have posted, you're hearing a voting comparator shutting off a voting receiver after a transmission.

The voting receivers are placed over a specified coverage area to increase talk-in range of a system. When the receiver is sitting idle and not receiving a transmission, it sends a continuous 2175hz tone down the leased line, microwave or RF link.

That 2175hz tone tells the comparator to "ignore me." When a voting receiver does receive a transmission, the tone disappears and passes the received audio. When the transmission ends, it again sends the 2175hz tone.

The "plink" you're hearing is the period of time after a transmission has ended, but before the comparator has muted the site from voting.

Correct me if I'm wrong, Eric, but you can head multiple clicks depending on how many layers of comparators you're going through.

Comparator. Seems to be common with Quantar/Astro-TAC/Digi-Tac systems. many have that sound. My old Smartnet .89X did. Kinda miss it since migrating to Astro 25, but then I don't miss the static, the long nights of "we're in failsoft" calls, or constantly having to do mod comps every month to keep the system in spec.

I miss that sound after leaving Seattle. They're still running an analog SZ system. However, several of the conventional systems here in LA use AstroTAC/DigiTACs. As an added bonus, they're all T-Band, so it's nice wideband audio.

LAFD has a conventional voted 800mhz analog system with voting receivers. They've turned off reverse burst for some reason, so you hear a squelch crash, then the "plink" from the voting comparator shutting off.

https://www.youtube.com/watch?v=YKdb7owvA7A


Bonus round:

JPL voters have their own characteristic "growl" at the end of transmissions:
https://www.youtube.com/watch?v=Unzf_zkw5do

And a BNSF rail dispatcher clicks after dekey:
https://www.youtube.com/watch?v=6B0ne24hlmo

 

[MTS2000des]

Our old Smartnet II .89x simulcast, a mix of Quantar and MSF5000s, with a DigitTac comparator.

 

[Giddyuptd]

To elaborate on what others have posted, you're hearing a voting comparator shutting off a voting receiver after a transmission.

The voting receivers are placed over a specified coverage area to increase talk-in range of a system. When the receiver is sitting idle and not receiving a transmission, it sends a continuous 2175hz tone down the leased line, microwave or RF link.

That 2175hz tone tells the comparator to "ignore me." When a voting receiver does receive a transmission, the tone disappears and passes the received audio. When the transmission ends, it again sends the 2175hz tone.

The "plink" you're hearing is the period of time after a transmission has ended, but before the comparator has muted the site from voting.

Correct me if I'm wrong, Eric, but you can head multiple clicks depending on how many layers of comparators you're going through.



I miss that sound after leaving Seattle. They're still running an analog SZ system. However, several of the conventional systems here in LA use AstroTAC/DigiTACs. As an added bonus, they're all T-Band, so it's nice wideband audio.

LAFD has a conventional voted 800mhz analog system with voting receivers. They've turned off reverse burst for some reason, so you hear a squelch crash, then the "plink" from the voting comparator shutting off.

https://www.youtube.com/watch?v=YKdb7owvA7A


Bonus round:

JPL voters have their own characteristic "growl" at the end of transmissions:
https://www.youtube.com/watch?v=Unzf_zkw5do

And a BNSF rail dispatcher clicks after dekey:
https://www.youtube.com/watch?v=6B0ne24hlmo

I know a couple places out west where the crash is horrid due to the reverse burst not enabled. It's more of a noob type thing for them. We told them but they are like we don't care as long as we can talk. It sounds even worse on couple channels thst use dpl and turn off code isn't enabled.

Isn't too bad in that clip but can be annoying.

 

[EWC_BDN]

I have spent a lot of time trying to get Kenwood and motorola's reverse burst to work right when talking from why brand to the other. I'm sure no customer notices much, but it drives me nuts!