Survivalism & Self Sufficiency Topics > Communications

NOAA style alerts for Prepper Communities?

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cidyl:
Sounds like you're talking about selective calling, CTCSS/DCS tones are the simplest form of that.  Most part 90 commercial radios have added selective calling capability, 5-tone or DTMF used for opening the squelch only on radios in a particular group, or to call a single radio.  Mostly it's to help manage many users sharing a single frequency so everyone isn't hearing traffic unless it's designated for them, for smaller groups and with many frequencies to choose from it never made much sense to me. 

Maybe I'm missing something but what about just designating an emergency channel and CTCSS/DCS tone for it, have users monitor that channel, and transmit that annoying alarm/1750 Hz tone most HTs have for a few seconds to get everyone's attention before sending the announcement? 

Greekman:
I am thinking on signalling a prepper community on regional matters(i.e active shooter in the region's high school).
The simplest way for the receiving end would have to have an AM/FM broadcast radio always on, and getting a NOAA style alert. but in our case from a designated member.
(over here we have no thing like this, and as far as I understand the NOAA special radios interrupt the channel and switch automatically in a NOAA alert one)

cidyl:
In the US weather information is broadcast 24x7 on 7 different frequencies around 162 MHz, if there is a severe weather warning or other emergency then the normal weather information is interrupted and two different alert signals are sent.  One alert signal is a newer digital/analog packet and the other an older 10 second 1050 Hz tone.  How the weather alert radios (receivers) with alert capability respond varies depending on the receiver and how it's configured, but typically the receiver is left on but the audio is muted (squelch closed), when the alert signal is received the audio is unmuted (squelch opened) so the message can be heard.  This is basically the same as setting a digital or tone coded receive squelch on a ham radio, unless the sender transmits that tone it won't open the squelch of the receiving radio.  Some GMRS/ham radios with weather alert capability will switch to the weather frequency if it was tuned to a different channel when an alert is received, which is basically the same as the 'dual watch' capability of many GMRS/ham radios - monitoring two different frequencies and it switches to the one with activity, or to the one set as the 'primary' channel if both have activity.

So guess I'm wondering why you wouldn't just use a cheap Chinese ham radio as the alert receiver?   Seems to me just about any ham radio has all the functions you're looking for.  If there's a concern the user might inadvertently change the settings, then a part 90 radio that you can program to a single frequency and squelch settings, and disable the transmit and front panel programming so they can't transmit or change anything.  I think the $30 Baofeng UV-82C allows that, or if not then I know the $70 Puxing UV9R/973 does.

iam4liberty:
Does it have to be voice?  You can use inexpensive APRS technology to send text messages on non-ham frequencies as well as designated ham frequencies.  This can include gps position data for the incidents location too.



Greekman:

--- Quote from: cidyl on November 03, 2019, 06:58:59 AM ---So guess I'm wondering why you wouldn't just use a cheap Chinese ham radio as the alert receiver?   Seems to me just about any ham radio has all the functions you're looking for.  If there's a concern the user might inadvertently change the settings, then a part 90 radio that you can program to a single frequency and squelch settings, and disable the transmit and front panel programming so they can't transmit or change anything.  I think the $30 Baofeng UV-82C allows that, or if not then I know the $70 Puxing UV9R/973 does.

--- End quote ---

hmmmm I think it can be done....An external speaker, and the radio turned to Fm radio (having an everyday usability is a bonus). A CTCSS coded signal will shift to the alert designated frequency. yes I think it can work.

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