#51527 - 10/14/05 05:55 AM
Re: Emergency Communications
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Rapscallion
Carpal Tunnel
Registered: 02/06/04
Posts: 4020
Loc: Anchorage AK
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PSK31 has been around a few years now. It is slow, but seems reliable enough. What really need is a linear FM system that will allow us to transmit hi-fidelity and ultrasonic audio over a carrier using less than 5 Khz of deviation bandwidth. Then we can really send data quickly.
That ought to spin the heads on a few of our techies here!!! <img src="/images/graemlins/grin.gif" alt="" />
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools. -- Herbert Spencer, English Philosopher (1820-1903)
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#51528 - 10/14/05 06:40 AM
Re: Emergency Communications
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Enthusiast
Registered: 07/06/02
Posts: 228
Loc: US
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The question that I don't see anyone asking so far is:
Who do you need to communicate with?
If it's just intra-group tactical communications, your best bet is probably GMRS. An $80 license fee covers your entire immediate family for five years, and enables you to transmit up to 50 W on UHF, with the ability to set up a repeater.
If it's extra-group health & welfare traffic, you'll want a General Class Amateur license (Morse Code currently still required, but it's only 5 words/min, pretty easy with a little bit of study, and fun, too) so you can participate in the 80 m and 40 m HF bands, where most of this traffic takes place.
If it's simply listening for info, a good AM/FM/TV/WX receiver is what you want. There are many options here.
If it's keeping tabs on the local public service operations, you'll need a scanner with trunking capabilities.
For GMRS, don't bother with the garden-variety big box store radios. Go visit a real land-mobile radio dealer, and go for the commercial quality stuff.
For Amateur Radio, well, there are as many options as there are hams!
Also, marine radios are generally only legal for use while on the water and underway, with the exception of those that are also usable on Amateur frequencies (for which you also need a license).
Edited by amper (10/14/05 06:43 AM)
_________________________
Gemma Seymour (she/her) @gcvrsa
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#51529 - 10/14/05 03:00 PM
Re: Emergency Communications
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Pooh-Bah
Registered: 09/15/05
Posts: 2485
Loc: California
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Also, marine radios are generally only legal for use while on the water and underway, with the exception of those that are also usable on Amateur frequencies (for which you also need a license). Ignorant hypothetical question from a non-radio person, but if I were floating down a street in the Ninth Ward of NO looking for survivors in my boat, would that be a legal use of the marine band even though I'm actually in a city? I know, a rather irrelevant technicality in such a situation, but I was just wondering about the general legality. And if I were stuck on a flooded rooftop in NO (without a cell phone) with Coast Guard and National Guard helos flying overhead, which would they be most likely/able to hear: my FRS, GMRS, HT, or marine radio distress call? I know, I could wave my arms and such, but that's so primitive. I mean, there's no gear involved! <img src="/images/graemlins/wink.gif" alt="" />
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#51530 - 10/14/05 03:29 PM
Re: Emergency Communications
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Addict
Registered: 04/21/05
Posts: 484
Loc: Anthem, AZ USA
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I could wave my arms and such, but that's so primitive. I mean, there's no gear involved! Elevating a notch above the primitive, while meeting the need to use "gear," how about fashioning semaphore flags from your boxers to signal the Coast Guard. Added benefit: the pleasure derived from improvising gear on-the-run. <img src="/images/graemlins/wink.gif" alt="" />
_________________________
"Things that have never happened before happen all the time." — Scott Sagan, The Limits of Safety
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#51531 - 10/14/05 03:33 PM
Re: Emergency Communications
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Namu (Giant Tree)
Addict
Registered: 09/16/05
Posts: 664
Loc: Florida, USA
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Elevating a notch above the primitive, while meeting the need to use "gear," how about fashioning semaphore flags from your boxers to signal the Coast Guard. Added benefit: the pleasure derived from improvising gear on-the-run. But do you really want to be on international news without your skivies on? <img src="/images/graemlins/grin.gif" alt="" /> <img src="/images/graemlins/blush.gif" alt="" />
_________________________
Ors, MAE, MT-BC Memento mori Vulnerant omnes, ultima necat (They all wound, the last kills)
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#51532 - 10/14/05 05:03 PM
Re: Emergency Communications
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Pooh-Bah
Registered: 09/15/05
Posts: 2485
Loc: California
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That may be fine for the Coasties, but would the National Guard crews know semaphore? No? Dagnabbit, who's in charge of training our military these days?! <img src="/images/graemlins/wink.gif" alt="" />
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#51533 - 10/14/05 05:22 PM
Re: Emergency Communications
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Old Hand
Registered: 11/10/03
Posts: 710
Loc: Augusta, GA
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Sec. 80.311 Authority for distress transmission.
A mobile station in distress may use any means at its disposal to attract attention, make known its position, and obtain help. A distress call and message, however, must be transmitted only on the authority of the master or person responsible for the mobile station. No person shall knowingly transmit, or cause to be transmitted, any false or fraudulent signal of distress or related communication.
Sec. 80.89 Unauthorized transmissions. Stations must not: -- snipped-- d) When using telephony, transmit signals or communications not addressed to a particular station or stations. This provision does not apply to the transmission of distress, alarm, urgency, or safety signals or messages, or to test transmissions. -- snipped -- (f) Transmit while on board vessels located on land unless authorized under a public coast station license. -- snipped rest of f ---
Sec. 80.177 When operator license is not required. -- snipped -- (5) A ship station operating in the VHF band on board a ship voluntarily equipped with radio and sailing on a domestic voyage.
Sec. 80.115 Operational conditions for use of associated ship units. (a) Associated ship units may be operated under a ship station authorization. Use of an associated ship unit is restricted as follows; (1) It must only be operated on the safety and calling frequency 156.800 MHz or on commercial or noncommercial VHF intership frequencies appropriate to the class of ship station with which it is associated. (2) Except for safety purposes, it must only be used to communicate with the ship station with which it is associated or with associated ship units of the same ship station. Such associated ship units may not be used from shore. -- snipped -- (b) State or local government vehicles used to tow vessels involved in search and rescue operations are authorized to operate on maritime mobile frequencies as associated ship units. Such operations must be in accordance with paragraph (a) of this section, except that the associated ship unit: May be operated from shore; may use Distress, Safety and Calling, Intership Safety, Liaison, U.S. Coast Guard, or Maritime Control VHF intership frequencies; and may have a transmitter power of 25 watts.
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From what I read, if it's an emergency, no problem. This goes for all radio services. You can run into trouble if after you've been recognized and someone has taken your information, if you keep transmitting and interfering.
As for your scenario, I could not find an adequate notion of where the maritime service is located. It may be in another part of the FCC code. Martime Radio Service is defined in Part 80. There is no clear description of what "land" is. I expected something like "mean high tide" or something. I looked at this, for curiosity sake for myself, over 30 minutes.
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#51534 - 10/14/05 05:44 PM
Re: Emergency Communications
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Addict
Registered: 09/19/05
Posts: 639
Loc: San Francisco Bay Area
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When the SHTF what would be the point to point communications routine. I am going to assume HAM. Won't be able to rely on cellular phones, Dial up, or internet. @ cans and a string won't go very far, so.... Assuming it is HAM, I have a few questions. I assume that's a good assumption. Eliminate repeaters that are currently in existance as batterries will eventually go dead. What band is going to be best? Most of the repeaters in my area have diesel generator back up that's _supposed_ to be good for three days. shrug. Who knows. In my area, most hams have 2M/70cm handhelds and many have mobile radios that use one of those bands. Most hams here are techs who can't use HF frenquencies. I'd suggest talking to local hams and seeing what they use. What radio manufacturer seems to make the best equipment? You won't go wrong with a radio from Icom, Kenwood, or Yaesu. Alinco makes cheaper radios, and you could consider one of them as a 'loseable' radio. Are there models that are fairly portable that cover more than one band, or is a seperate unit required for each band? The three makers I mention above all make dual and tri-band handheld radios. Whether you get any benefit from whatever the third band is depends on what hams are doing in your area. My suggestion is to stick with a dual band 2M/70cm handheld, and be sure you can use it with AAs. Since someone will eventually setup a repeater in the aftermath what would the most likely choice of bands be? Same: 2M/70cm. What band in the most portabel size unit allows for the longest distance communictions? That's too dependent on local geography. _Generally_, 2 meters will carry further than 70cm, but you don't want to count on my generalization. Check with hams in your area. I have noticed that marine band radios usually have higher wattage output, is this a fair alternative? My first question is, who would be listening? Not many people in my neighborhood, I fear. My next question is, in a handheld? Generally, handhelds have a maximum of 5 or 6 watts. It's a question of battery life. Phil
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#51535 - 10/14/05 05:45 PM
Re: Emergency Communications
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Pooh-Bah
Registered: 09/15/05
Posts: 2485
Loc: California
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Thanks for looking that up, ki4buc.
It still does seem very murky, though. For example, if I boat into the flooded neighborhood and use a marine handheld to communicate with another small boat several blocks away, I'm neither in distress nor trying to make my position known (to be rescued, that is).
Then the whole definition of "land" and "on shore" is also murky. If I'm in my boat in the middle of whatever-street, is that "on the water" but if I step into a house (perhaps directly onto the second floor!), is that "on shore"? Dunno.
Anyway, just a legal curiosity. I'd be happy just to have the boat in that situation. <img src="/images/graemlins/smile.gif" alt="" />
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#51536 - 10/14/05 07:13 PM
Re: Emergency Communications
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Enthusiast
Registered: 07/06/02
Posts: 228
Loc: US
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From what I read, if it's an emergency, no problem. This goes for all radio services. You can run into trouble if after you've been recognized and someone has taken your information, if you keep transmitting and interfering.
As for your scenario, I could not find an adequate notion of where the maritime service is located. It may be in another part of the FCC code. Martime Radio Service is defined in Part 80. There is no clear description of what "land" is. I expected something like "mean high tide" or something. I looked at this, for curiosity sake for myself, over 30 minutes. Bear in mind that while in an "emergency", any means of contact is OK, the definition of "emergency" may not be what you think it is. The standard is usually "imminent danger to life", or similar. Being stuck in your attic in the middle of standing water does not necessarily meet this criterium. Think of it this way, if the situation would not justify sending "SOS" or "Mayday", it probably doesn't really qualify as an "emergency", per se, for these purposes.
_________________________
Gemma Seymour (she/her) @gcvrsa
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