Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 27-07-2014, 18:38   #61
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,042
Re: EPIRB Thoughts?

a64-
I think the problem is licensing. 243 Guard is a military aviation frequency, AFAIK. So civilian transmitters sold for other purposes under other licenses, won't transmit on it. Even if receiving it is allowed. 121.5 is still the non-military equivalent though, which is why responding SAR aircraft would continue to monitor 121.5 even if that is obsolete for satellite services.
__________________

__________________
hellosailor is offline   Reply With Quote
Old 27-07-2014, 19:24   #62
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,050
EPIRB Thoughts?

I'm not abdicating trying to transmit on 243.0, just saying that while the military radio monitored guard freq automatically, I know of no such civilian radio that does.
I don't know of anyone that leaves a radio set to 121.5, that means you have one less radio to use. Most Airliners crossing oceans will leave a radio set to 123.45 as that is sort of the official / un-official hailing freq. I've used 123.45 to contact Airliners to have them pass on a position report for me when I was ferrying aircraft and didn't have an HF.
If your trying to get an Airliner on a remote chance you have an aircraft handheld VHF, you'll have far more luck with 123.45 than 121.50

Sort of off topic anyway.
But would the Coast Guard responding to an EPIRB, be monitoring 121.5, and Aviation only emergency freq?
__________________

__________________
a64pilot is online now   Reply With Quote
Old 27-07-2014, 20:13   #63
Registered User

Join Date: Mar 2011
Boat: R&C, 2015 Leopard, 48
Posts: 19
Re: EPIRB Thoughts?

I think the more important point than military or civilian is the equipment compatibility. 243.0 is UHF versus 121.5 which is VHF frequency bands.


Sent from my iPad using Cruisers Sailing Forum
__________________
vida nueva is offline   Reply With Quote
Old 27-07-2014, 21:23   #64
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,042
Re: EPIRB Thoughts?

a64-
"I'm not abdicating trying to transmit on 243.0, just saying that while the military radio monitored guard freq automatically,"
I expect that military aviation radios do that for the same reason that military vehilces have 12V electrical systems. Someone decided a long time ago (in the 1940's) that this would be a good idea and wrote a procurement regulation saying "We're not gonna buy it unless it has a 12v electrical system" and in the same way, someone decided a common guard channel would be a good idea--and then simply wrote a procurement spec that said "We're not gonna buy it unless..."
That's all it takes. Clever, really.

" I know of no such civilian radio that does."
Well of course not. Civilians are a herd of cats, there's no one to write procurement regs for them. However, many marine VHFs have the capability to automatically dual- or tri-monitor multiple channels at the same time, and 16 is usually a one-touch setup for those. Not 121.5, because that's still an aviation channel.

"I don't know of anyone that leaves a radio set to 121.5, that means you have one less radio to use."
You are kidding me, right? What, you retired when crystal-bound radios were still the standard? These days, radios are digital and monitoring two or ten or scanning a hundred channels pretty much in a second or two, is normal. Ham radio, marine VHF, ICOMs and other that do air bands...my ham h/t will scan all the tower and ground frequencies for an airport, and 121.5, and run through them all in a second or two.
No one dedicates a whole radio to one frequency, unless it is a rich or obsolete military installation. Yeah, I know, B52s and missile silos are still using 1960's technology...that's not the real world.

"Most Airliners crossing oceans will leave a radio set to 123.45 " Rich owners with obsolete equipment.(G)

"If your trying to get an Airliner on a remote chance you have an aircraft handheld VHF, you'll have far more luck with 123.45 than 121.50" And the wonderful thing is, I don't have to dedicate a radio to it, or buy crystals for it. Just change the channel.

"But would the Coast Guard responding to an EPIRB, be monitoring 121.5, and Aviation only emergency freq?" Apparently, from published reports, all SAR air responders do. The reason that EPIRBs are mandated to broadcast a 121.5 signal, is so that approaching aircraft can d/f on the 121.5 signal. RDF is still a more certain way to find something, than "well we got these numbers from some guys who got these numbers from some guy who..." and with fond memories of LORAN C and timing skip, numbers can be worthless compared to a needle[sic] that says "THAT WAY".
__________________
hellosailor is offline   Reply With Quote
Old 28-07-2014, 06:02   #65
Registered User

Join Date: Mar 2011
Boat: R&C, 2015 Leopard, 48
Posts: 19
Re: EPIRB Thoughts?

Again, I was only pointing out that it's not about military versus civilian. It's about the equipment, thus compatibility you have, VHF for EPIRB.

Many military aircraft have BOTH VHF and UHF radios on board. Some only have one or the other. Therefore FAA Air Traffic Controllers - civil - also have both. Each also monitors "Guard" (243.0 UHF, 121.5 VHF). The FAA controllers typically simulcast on both UHF and VHF so everyone knows what's going on.

Whether you make a distress call on UHF or VHF Guard is immaterial. If they hear you they will respond, and nobody is going to ask if you're military or civilian.


Sent from my iPhone using Cruisers Sailing Forum
__________________
vida nueva is offline   Reply With Quote
Old 28-07-2014, 13:47   #66
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,042
Re: EPIRB Thoughts?

"Again, I was only pointing out that it's not about military versus civilian. It's about the equipment, thus compatibility you have, VHF for EPIRB. "

It is very much military versus civilian. Or rather, GOVERNMENT versus civilian. Check the NTIA frequency allocation chart, and you'll find that 243MHz is in a block reserved for GOVERNMENT USE ONLY.

Radios that are sold to civilians, and licensed to transmit, will not have that frequency available.

Typical coverage, such as from Icom, is:
TX/RX: 118.000-136.975 MHz (civilian aviation)
RX Only: 161.650-163.275 MHz (government use only, the weather channels, no transmission for civilians)

In the US civilian world, the military aviation guard channels can be received--but it is extremely unlikely you will be transmitting on them, or owning equipment that can do so without modification.

You may find some ham radio operators have modified their radios for emergency use (the only allowable civilian use) on those channels, but plain sailors, plain civilian aviators? Extremely unlikely. It is illegal for radios commercially made and sold for other intended markets to even be able to transmit on that frequency.
__________________

__________________
hellosailor is offline   Reply With Quote
Reply

Tags
epirb

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
EPIRB recall (GME EPIRB's manuf from 2005-2008 Recaledl) ka4wja Marine Electronics 3 23-07-2014 15:52
USED EPIRB Matt Hager Marine Electronics 27 14-01-2009 14:42
Wrong Country EPIRB?? jemsea Rules of the Road, Regulations & Red Tape 0 11-01-2006 08:38
Latest EPIRB Report just release Jon D Health, Safety & Related Gear 3 11-11-2005 15:19
EPIRB vs. PLB Curtis Health, Safety & Related Gear 7 30-01-2005 11:57



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:57.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.