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Old 02-04-2012, 06:03   #76
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Re: Satphone & HF for Ocean Crossings?

And for anyone who is interested:

Designation Frequency Wavelength
ELF extremely low frequency 3Hz to 30Hz 100'000km to 10'000 km
SLF superlow frequency 30Hz to 300Hz 10'000km to 1'000km
ULF ultralow frequency 300Hz to 3000Hz 1'000km to 100km
VLF very low frequency 3kHz to 30kHz 100km to 10km
LF low frequency 30kHz to 300kHz 10km to 1km
MF medium frequency 300kHz to 3000kHz 1km to 100m
HF high frequency 3MHz to 30MHz 100m to 10m
VHF very high frequency 30MHz to 300MHz 10m to 1m
UHF ultrahigh frequency 300MHz to 3000MHz 1m to 10cm
SHF superhigh frequency 3GHz to 30GHz 10cm to 1cm
EHF extremely high frequency 30GHz to 300GHz 1cm to 1mm
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Old 02-04-2012, 11:33   #77
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Re: Satphone & HF for Ocean Crossings?

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Originally Posted by goboatingnow View Post
but most cruisers that need occasional ocean comms seem to go sat comms given the price and complexity of a new HF setup. most modern nav stations don't even have room for the stuff any more. Given that small craft don't even have to be VHF GMDSS compliant , the sat comms at least is a useful backup to nothing.
Your probably close to the mark there. For the arc type boats doing a there and back Atlantic anyway, does the arc require sat comms these days?
. But I would say that HF radio is still alive and well for the longer term bluewater types, though. A quick look around this marina and pretty much all the long distance boats have insulated backstays. I'm fairly sure the crusing crossroads like Horta or panama would reveal a large number also.
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Old 02-04-2012, 11:57   #78
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Re: Satphone & HF for ocean crossings?

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Originally Posted by LakeSuperior View Post
More valuable is a good WIFI antenna for in marinas and near shore. We have used this bit of gear a 1000 times more than the SSB and satphone!

We have a waterproof bag next to the satphone cradle. US and British Coast Guard and search and rescue numbers are preprogrammed. The satphone is on a charging station so it is always at full charge.

In an abandoned ship situation the satphone goes into the waterproof bag and then into the ditch bag. Try this with an SSB.
Sounds good to me. What kind of WIFI antenna do you have and what satphone? Planning right now our passage and these items are on our list. Appreciate your input. Thanks, Janet
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Old 02-04-2012, 13:24   #79
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Re: Satphone & HF for ocean crossings?

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Originally Posted by lunacy View Post
Sounds good to me. What kind of WIFI antenna do you have and what satphone? Planning right now our passage and these items are on our list. Appreciate your input. Thanks, Janet
We have used the Bullet 2 since 2010 with good results. It has a 15 dB antenna which has served us well. We purchased it from Dalton at
www.wififorboats.com He has been good at supporting the unit and software.

With WIFI and Skype you will not use your satphone or SSB in most harbors and marinas.

Consequently, you can guess that the satphone and SSB are used offshore. The offshore crossings are a small fraction of the actual cruising experience and therefore the satphone and SSB are needed only a small fraction of the time.

For our party we didn't need the group communication that the SSB offers. I guess one could buy a tractor-trailor and a CB radio for that experience.

Our satphone is an Iridium 9555 with a nav station installation. That is a cradle, power, and an external antenna at the nav station. We use XGATE compression software. We downloaded GRIBs everyday on both crossings.

For the record, with XGATE a dropped transmission during a file download is picked up where it was dropped. For example, if the call is dropped 3 minutes into a 4 minute download on redial the only the remaining 1 minute is downloaded and merged seamlessly.

Also, for the record we have not had a dropped Iridium call on both Halifax to Ireland and the Canaries to Antiqua crossings. In our experience dropped calls were not part of the experience.
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Old 02-04-2012, 16:15   #80
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Re: Satphone & HF for Ocean Crossings?

Hi Dave and others,

I'm beginning to feel like you're responses are aimed at pulling another chapter out of me! At the risk of appearing bloodyminded:

I'm aware of the AMVAR system, but I understand it is not compulsory, and is in a testing phase at present, and is currently used on a limited number of big ships only. Maybe I have got this wrong? My guestimate is therefore that for yachts cruising close to major shipping lanes, this could be useful. Anywhere else, it will be necessary to rely on some smaller boats - without AMVAR - to be listening for the MRCC DSC alarm call to assist you.


I expect there is a lot of deliberate disinformation around regarding the complexity of marine HF/SSB radio; especially from the mouths of satellite phone salesmen/women. I saw the photos from Cat Man Do. I started with Codans not too dissimilar to the photo. The modern photo is a HAM radio, designed for radio enthusiasts who are keen to experiment with HF/SSB radio. A moden marine HF/SSB radio is much simpler, has BIG lettering so most people can see the display without reading glasses, has a lot of smart electronics, does a lot more than the old Codan, but is far more straightforward to operate than the very versatile HAM radio. For example, do a search for ICOM's M801E or M802

Here is what SailMail says about using HAM radios for marine comms:

"The Icom IC-718 and most other ham radios work with SailMail if they are equipped with a High Stability Crystal Unit, and if the radio is modified to transmit on all bands. .... Ham radios are not type accepted for use on marine frequencies and their use may not be permitted by your country's radio regulations. For US-registered vessels, the US FCC requires marine type-accepted radios (e.g. Icom M802, M710, M700Pro etc).

There is another reason why it is a bad idea to use a Ham radio... Ham radios are much more complicated to operate than marine radios because they have many features that marine radios don't need. If these options and features are set incorrectly the radio will not work. Often on a cruising boat there is only one knowledgeable HAM on-board. If that person is injured and others need to use the SSB, they will be much less likely to be able to operate a HAM radio than they would a marine radio. Note that it is perfectly legal to use Marine radios such as the Icom M802 on Ham frequencies. This is a better approach."


The people who started SailMail are HAMs; so they should know.

One reason for DSC in marine HF/SSB radios is to reduce an aspect of uncertaintly with any radio comms; "have I called on the right frequency/channel and is the intended recipient's radio turned on?" Each radio has an MMSI number and this is akin to a phone number. Yachts can call each other using the number. The radio speaker in the recipient's radio is normally muted - on DSC watch - but the radio can be scanning for a call that has it's MMSI number. If detected, the speaker mute opens, and the radio goes into an alarm/ring state. There is also a revertive tone sent back to the caller. As the caller, if you hear the tone you know you made contact with the desired radio. If you do not, then try a different frequency.

This process of calling by tones - and listening for the revertive tone to confirm you reached the desired radio - is similar to SelCall in commercial HF/SSB radios. My HAM friend who introduced me to HF radio about 35 years ago told me to get that feature in a straight forward commercial HF/SSB radio, to avoid all the background noise associated with maintaining a listening watch for calls on HAM radios, or commercial or marine HF/SSB without Sellcall or DSC. That's what DSC does for you in the marine HF/SSB radio. The radio can monitor for emergency or private calls, and there is no noise from the speaker.

I'm sure the VOR boats have a great satellite system. If I recall correctly from the previous race, the huge dish that must be aimed at the satellite occupies most of the space forward of the mast, down below. Those boats need broadband internet so they can send video etc for the benefit of sponsors, TV news etc. But I'd be very surprised if the VOR boats don't also have a modern marine HF/SSB radio with DSC.

According to a UK contact who sells marine HF/SSB radios and runs radio training courses, "On both rallies (ARC annd Oyster) all yachts must have an SSB and email and some are opting for both satellite and SSB for the email." Marine HF/SSB radios with email capability (ie: SailMail) will provide everyone with low-cost but reliable communication and keep everyone informed of rally operations, next port arrngements etc.

When rallies operate around SE Asia - some have over 100 boats - it is really frustrating for the organisers and other participants when yachts do not have a marine HF/SSB radio. It means they cannot receive information directly from organisers at skeds, they cannot send daily position reports, and they cannot take part in skeds when yachts share information. But rally participants are not willing to pay higher fees to the orgnaisers so they have the money to employ a bunch of staff to make thousands of satellite phone calls to yachts with only satellite phones and marine VHF radios. Consequently, a number of boats with marine HF/SSB must volunteer to be relay boats. They collect position reports from boatws without marine HF/SSB radios - normally via VHF - and forward to organisers via their marine HF/SSB. In the other direction, they must record info from the organisers during the HF/SSB sked, then pass it on via VHF. Apart from the effort and responsibility, these techniques regularly produce incorrect information, which can sometimes create significant consternation and problems; exacerbated because the boats without the HF/SSB radio cannot communicate direct to the organisers, by voice or through email. It's a real pain in the butt for organisers and those participants who have made the effort to properly equip their yacht.

Returning to the percieved complexity of setting up and operating a marine HF/SSB radio:

1. DSC is desgned to make operation easier, and to make it easy to maintian a 24/7 watch for distress calls from other vessels with DSC equipped marine HF/SSB radios, or from MRCCs looking for a vessel to help someone nearby.

2. In combination with email on-board - eg low-cost SailMail (or Winlink for HAMs) - the marine HF/SSB radio makes life on-board simpler and safer. Weather information, TS warnings, ordering parts to be sent to the next stop, booking marina berths and chasing up the house rent that is funding your trip, sending position reports, updating a blog etc are so much easier. And in this region, you can spend more time away from marinas, wi-fi and internet cafes, in beautiful locations where the cost of living is much cheaper. You easily get back the money invested in a marine HF/SSB and Pactor modem.

3. The KISS-USB counterpoise is a recent development that does the job of an earth connected to the Automatic Antenna Tuner (ATU). See www.kiss-ssb.com According to my (sceptical of new gismos) HAM friend who recently retired and closed his business supplying marine and aircraft radios "I can see what they are doing, using a multi wire, multi frequency "Counterpoise" as half a dipole, with the tuner adjusting the overall counterpoise and back stay or whip to resonance. A novel approach that might just work". (Yep, HAM nurd stuff that's a bit beyond me too, but it does comfirm that from his sceptical techo perspective, this is a workable solution. Others might like to comment.) This KISS-USB counterpoise removes the need to have an external earth plate or to lay copper foil in the boat. Installation will be faster and cheaper.

4. When installing a marine HF/SSB radio with DSC it usually (eg: for the ICOM M802 or M801E) requires a seperate DSC receive antenna. As confirmed by my HAM friend, this can be the AM/FM radio antenna (receiving only - but not an antenna that involves transmission, such as the AIS or VHF radio antenna) passed through a splitter box to feed both the stereo and the HF/SSB radio. Simple, cheap and quick. No need to find space for another (expensive) whip antenna.


When evaluating the seductive, instant gratification and apparently so simple comms solution offered by the satellite phone salesman, the prudent sailor might recall that experienced rally organisers (eg: ARC, & Oyster) require a marine HF/SSB radio and email; not a satellite phone. And that:

1. The satphone salesman or women gets a commission on the satellite phone sale and the call time you buy. A similar financial reward arrangement that worked very successfully to sell the sub-prime loans and other financial scams which precipitated sinking the world economy. It's hard to overcome human nature.

2. He or she will not be out there on the water trying to solve your problems.

3. But the professional mariner, search and rescue helicopter pilot, Coast Guard skipper. MRCC operator and others who helped develop the marine HF/SSB DSC system as a workable solution - and who do not benefit from your satphone or subsequent call time purchases - will be out there too. They'll be putting their lives at risk to help you. Help them by fitting the comms equipment they recommend:

"While satellites and satellite-compatible distress beacons have significantly improved the effectiveness of SAR operations, the system is NOT a substitute for carrying appropriate marine or aviation radio.

Depending on the circumstances, your initial distress alert should still be made by radio if possible. You should activate your distress beacon only if contact cannot be made by any other means or when told to do so by a rescue authority. "

And:

"Dedicated SAR facilities are limited in Australia. When necessary, other facilities are diverted from their primary function by arrangement or request."

(from the AMSA website)

The satphone has it's useful roles - private calls to solve a shore problem so you can remain in that beautiful anchorage, in the tender or canoe, and the unlikely event of stepping up into a liferaft - but it cannot, at any stretch of the satphone salesman's imagination, replace the marine HF/SSB radio with DSC.
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Old 02-04-2012, 16:17   #81
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Re: Satphone & HF for Ocean Crossings?

Quote:
Originally Posted by cat man do View Post
Opinions?
No one have anything to say about this unit?
If it was up for the job I would try for it

Quote:
YAESU FT-857D
It is moded to go everywhere, does all 4X4 frequencies, HF Marine, that other band (see pics) and VHF Marine
(so says the seller)
YAESU FT-857D
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Old 02-04-2012, 16:31   #82
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Re: Satphone & HF for Ocean Crossings?

Quote:
Originally Posted by Wotname View Post
Slight correction - the HF band in the frequency spectrum is 3 MHz to 30 MHz, VHF is 30 MHz to 300 MHz. There were defined a long time ago by (I believe), the ITU.
Woops! You are quite right. Sorry 'bout that, all.

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Old 02-04-2012, 17:16   #83
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Re: Satphone & HF for Ocean Crossings?

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Originally Posted by cat man do View Post
No one have anything to say about this unit?
If it was up for the job I would try for it
OK, leaving aside the several legality issues and the fact that I am not a HAM nor have hands on experience with this unit, I will toss in my opinions.

Pros - small and compact, inexpensive, has been modified to use non-HAM frequencies, that's all I can think of.

Cons - complex to operate, small display and fiddly knobs.

If you are not a radio enthusiast, I would think the biggest issue will be the learning curve on understanding the various operating parameters that can be changed by the operator. Accidently get one wrong or bump the wrong button and you could be in a world of hurt. No problem if you are relaxing in a remote tropical anchorage and have all day to read the book again and again but when tired, cold, wet and stressed and needing to make contact, then this complexity may be your undoing.

Put another way:
Can this radio transmit and receive on the frequencies you need - Yes
Is it frequency stable for useful communication in non-HAM bands - Probably
Can you learn to operate it under all conditions - Your call
Is it legal - No (but if you got yourself a HAM ticket, it would become quasi-legal).

If I were a radio enthusiast (and I am not, even though I have worked in all sorts of radio repair half my life), I would be happy to have this set at home but not on-board - at least not as my sole means of comms.

BTW, you will still an antenna tuning unit as well as the radio.
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Old 02-04-2012, 17:21   #84
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Re: Satphone & HF for Ocean Crossings?

Quote:
Originally Posted by AllanR View Post
Hi Dave and others,

I'm beginning to feel like you're responses are aimed at pulling another chapter out of me! At the risk of appearing bloodyminded:

I'm aware of the AMVAR system, but I understand it is not compulsory, and is in a testing phase at present, and is currently used on a limited number of big ships only. Maybe I have got this wrong? My guestimate is therefore that for yachts cruising close to major shipping lanes, this could be useful. Anywhere else, it will be necessary to rely on some smaller boats - without AMVAR - to be listening for the MRCC DSC alarm call to assist you.


I expect there is a lot of deliberate disinformation around regarding the complexity of marine HF/SSB radio; especially from the mouths of satellite phone salesmen/women. I saw the photos from Cat Man Do. I started with Codans not too dissimilar to the photo. The modern photo is a HAM radio, designed for radio enthusiasts who are keen to experiment with HF/SSB radio. A moden marine HF/SSB radio is much simpler, has BIG lettering so most people can see the display without reading glasses, has a lot of smart electronics, does a lot more than the old Codan, but is far more straightforward to operate than the very versatile HAM radio. For example, do a search for ICOM's M801E or M802

Here is what SailMail says about using HAM radios for marine comms:

"The Icom IC-718 and most other ham radios work with SailMail if they are equipped with a High Stability Crystal Unit, and if the radio is modified to transmit on all bands. .... Ham radios are not type accepted for use on marine frequencies and their use may not be permitted by your country's radio regulations. For US-registered vessels, the US FCC requires marine type-accepted radios (e.g. Icom M802, M710, M700Pro etc).

There is another reason why it is a bad idea to use a Ham radio... Ham radios are much more complicated to operate than marine radios because they have many features that marine radios don't need. If these options and features are set incorrectly the radio will not work. Often on a cruising boat there is only one knowledgeable HAM on-board. If that person is injured and others need to use the SSB, they will be much less likely to be able to operate a HAM radio than they would a marine radio. Note that it is perfectly legal to use Marine radios such as the Icom M802 on Ham frequencies. This is a better approach."

The people who started SailMail are HAMs; so they should know.

One reason for DSC in marine HF/SSB radios is to reduce an aspect of uncertaintly with any radio comms; "have I called on the right frequency/channel and is the intended recipient's radio turned on?" Each radio has an MMSI number and this is akin to a phone number. Yachts can call each other using the number. The radio speaker in the recipient's radio is normally muted - on DSC watch - but the radio can be scanning for a call that has it's MMSI number. If detected, the speaker mute opens, and the radio goes into an alarm/ring state. There is also a revertive tone sent back to the caller. As the caller, if you hear the tone you know you made contact with the desired radio. If you do not, then try a different frequency.

This process of calling by tones - and listening for the revertive tone to confirm you reached the desired radio - is similar to SelCall in commercial HF/SSB radios. My HAM friend who introduced me to HF radio about 35 years ago told me to get that feature in a straight forward commercial HF/SSB radio, to avoid all the background noise associated with maintaining a listening watch for calls on HAM radios, or commercial or marine HF/SSB without Sellcall or DSC. That's what DSC does for you in the marine HF/SSB radio. The radio can monitor for emergency or private calls, and there is no noise from the speaker.

I'm sure the VOR boats have a great satellite system. If I recall correctly from the previous race, the huge dish that must be aimed at the satellite occupies most of the space forward of the mast, down below. Those boats need broadband internet so they can send video etc for the benefit of sponsors, TV news etc. But I'd be very surprised if the VOR boats don't also have a modern marine HF/SSB radio with DSC.

According to a UK contact who sells marine HF/SSB radios and runs radio training courses, "On both rallies (ARC annd Oyster) all yachts must have an SSB and email and some are opting for both satellite and SSB for the email." Marine HF/SSB radios with email capability (ie: SailMail) will provide everyone with low-cost but reliable communication and keep everyone informed of rally operations, next port arrngements etc.

When rallies operate around SE Asia - some have over 100 boats - it is really frustrating for the organisers and other participants when yachts do not have a marine HF/SSB radio. It means they cannot receive information directly from organisers at skeds, they cannot send daily position reports, and they cannot take part in skeds when yachts share information. But rally participants are not willing to pay higher fees to the orgnaisers so they have the money to employ a bunch of staff to make thousands of satellite phone calls to yachts with only satellite phones and marine VHF radios. Consequently, a number of boats with marine HF/SSB must volunteer to be relay boats. They collect position reports from boatws without marine HF/SSB radios - normally via VHF - and forward to organisers via their marine HF/SSB. In the other direction, they must record info from the organisers during the HF/SSB sked, then pass it on via VHF. Apart from the effort and responsibility, these techniques regularly produce incorrect information, which can sometimes create significant consternation and problems; exacerbated because the boats without the HF/SSB radio cannot communicate direct to the organisers, by voice or through email. It's a real pain in the butt for organisers and those participants who have made the effort to properly equip their yacht.

Returning to the percieved complexity of setting up and operating a marine HF/SSB radio:

1. DSC is desgned to make operation easier, and to make it easy to maintian a 24/7 watch for distress calls from other vessels with DSC equipped marine HF/SSB radios, or from MRCCs looking for a vessel to help someone nearby.

2. In combination with email on-board - eg low-cost SailMail (or Winlink for HAMs) - the marine HF/SSB radio makes life on-board simpler and safer. Weather information, TS warnings, ordering parts to be sent to the next stop, booking marina berths and chasing up the house rent that is funding your trip, sending position reports, updating a blog etc are so much easier. And in this region, you can spend more time away from marinas, wi-fi and internet cafes, in beautiful locations where the cost of living is much cheaper. You easily get back the money invested in a marine HF/SSB and Pactor modem.

3. The KISS-USB counterpoise is a recent development that does the job of an earth connected to the Automatic Antenna Tuner (ATU). See www.kiss-ssb.com According to my (sceptical of new gismos) HAM friend who recently retired and closed his business supplying marine and aircraft radios "I can see what they are doing, using a multi wire, multi frequency "Counterpoise" as half a dipole, with the tuner adjusting the overall counterpoise and back stay or whip to resonance. A novel approach that might just work". (Yep, HAM nurd stuff that's a bit beyond me too, but it does comfirm that from his sceptical techo perspective, this is a workable solution. Others might like to comment.) This KISS-USB counterpoise removes the need to have an external earth plate or to lay copper foil in the boat. Installation will be faster and cheaper.

4. When installing a marine HF/SSB radio with DSC it usually (eg: for the ICOM M802 or M801E) requires a seperate DSC receive antenna. As confirmed by my HAM friend, this can be the AM/FM radio antenna (receiving only - but not an antenna that involves transmission, such as the AIS or VHF radio antenna) passed through a splitter box to feed both the stereo and the HF/SSB radio. Simple, cheap and quick. No need to find space for another (expensive) whip antenna.


When evaluating the seductive, instant gratification and apparently so simple comms solution offered by the satellite phone salesman, the prudent sailor might recall that experienced rally organisers (eg: ARC, & Oyster) require a marine HF/SSB radio and email; not a satellite phone. And that:

1. The satphone salesman or women gets a commission on the satellite phone sale and the call time you buy. A similar financial reward arrangement that worked very successfully to sell the sub-prime loans and other financial scams which precipitated sinking the world economy. It's hard to overcome human nature.

2. He or she will not be out there on the water trying to solve your problems.

3. But the professional mariner, search and rescue helicopter pilot, Coast Guard skipper. MRCC operator and others who helped develop the marine HF/SSB DSC system as a workable solution - and who do not benefit from your satphone or subsequent call time purchases - will be out there too. They'll be putting their lives at risk to help you. Help them by fitting the comms equipment they recommend:

"While satellites and satellite-compatible distress beacons have significantly improved the effectiveness of SAR operations, the system is NOT a substitute for carrying appropriate marine or aviation radio.

Depending on the circumstances, your initial distress alert should still be made by radio if possible. You should activate your distress beacon only if contact cannot be made by any other means or when told to do so by a rescue authority. "

And:

"Dedicated SAR facilities are limited in Australia. When necessary, other facilities are diverted from their primary function by arrangement or request."

(from the AMSA website)

The satphone has it's useful roles - private calls to solve a shore problem so you can remain in that beautiful anchorage, in the tender or canoe, and the unlikely event of stepping up into a liferaft - but it cannot, at any stretch of the satphone salesman's imagination, replace the marine HF/SSB radio with DSC.

I think this response speaks to users of satphones especially the wrt the SSB learning curve part.
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Old 03-04-2012, 00:06   #85
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Re: Satphone & HF for Ocean Crossings?

Quote:
Originally Posted by Wotname View Post
Cons - complex to operate, small display and fiddly knobs.

.
And here was me thinking a smaller more compact device would be easier.

Doesnt matter now, its been taken off but thanks for the reply.
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Old 25-06-2012, 11:43   #86
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Re: Satphone & HF for Ocean Crossings?

Sattelite phone communication is no longer "point to point". Now with the popularity of social networks like facebook and twitter, the text message you send from a sat phone can reach all the right people - and quickly be "retweeted" to thousands more.

There are probably already CLODs (Cruisers Living on Dirt) who are running twitter accounts for cruisers in specific areas - so all cruisers have to do is subscribe to the CLOD for the area, and they will receive SOS messages from others in the area.

The future is clearly text messages combined with social networks. And i now see some sat phones for $300 and monthly plans for $40 UNLIMITED talk and text - from companies like Global star. But unfortunately it looks like global star coverage is not global in that they don't cover enough of the pacific ocean to even make a crossing from CA to HA.

In fact, i am about to make this crossing from CA to HA, and am in the market for a sat phone. Something i can use to post to my social network as well as downloading GRIB files. I'm doing more research tonight, but so far it looks like Iridium and Inmarsat are my only options for coverage across the pacific.....which looks like about $600 for a new phone on Ebay, and about $1 per minute for a pre-paid card (no contracts or obligations).

Has anyone found something better than that?
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Old 25-06-2012, 12:23   #87
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Re: Satphone & HF for Ocean Crossings?

Just another thought i feel inclined to add.....

Before too long, society will realize that communication and the sharing of information is a basic human right.......not something that must be "earned" and only available to those with the $$ to afford it.

At that point, once we have the phone, there will be no charge for monthly service. The social networks, satellites, and infrastructure will be owned by the people for the people - rather than by corporations for profit...

So i think anyone who wishes to invest and function coherently in the future, will be setting up social networks on twitter, etc......and figuring out some way to post to them. Whether it be a satellite phone, or an SSB and sailmail, really makes little difference. Twitter is free, extremely simple, and there are no barriers to entry.....and your network will exist for an eternity in "the cloud"......easily transferable to the newest twitter like social network, which will eventually be ONE single network owned by the people for the people.
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Old 25-06-2012, 12:38   #88
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Quote:
Originally Posted by Wotname
And for anyone who is interested:

Designation Frequency Wavelength
ELF extremely low frequency 3Hz to 30Hz 100'000km to 10'000 km
SLF superlow frequency 30Hz to 300Hz 10'000km to 1'000km
ULF ultralow frequency 300Hz to 3000Hz 1'000km to 100km
VLF very low frequency 3kHz to 30kHz 100km to 10km
LF low frequency 30kHz to 300kHz 10km to 1km
MF medium frequency 300kHz to 3000kHz 1km to 100m
HF high frequency 3MHz to 30MHz 100m to 10m
VHF very high frequency 30MHz to 300MHz 10m to 1m
UHF ultrahigh frequency 300MHz to 3000MHz 1m to 10cm
SHF superhigh frequency 3GHz to 30GHz 10cm to 1cm
EHF extremely high frequency 30GHz to 300GHz 1cm to 1mm
Just for knowledge sake, what would be the size of the transmission antenna for an equipment using something like ELF?
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Old 25-06-2012, 14:00   #89
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Re: Satphone & HF for Ocean Crossings?

Submarines tow a long inductively-loaded antenna for ELF (http://www.dtic.mil/dtic/tr/fulltext/u2/754949.pdf). The one described in this document is 300 meters long -- definitely not your standard resonant antenna! Newer designs seem to be using Superconducting Quantum Interference Device (SQUID) elements, requiring liquid Helium cooling. (http://torpedo.nrl.navy.mil/tu/ps/pd...der?dsn=353579)

I think these are receive-only antennas though. Here is a description of a Navy ELF transmitting station (land-based): http://www.fas.org/nuke/guide/usa/c3i/fs_clam_lake_elf2003.pdf . They mention "more than 28 miles of over-head signal transmission line".

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Old 25-06-2012, 14:39   #90
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Re: Satphone & HF for Ocean Crossings?

Quote:
Originally Posted by morgan3 View Post
Just another thought i feel inclined to add.....

Before too long, society will realize that communication and the sharing of information is a basic human right.......not something that must be "earned" and only available to those with the $$ to afford it.

At that point, once we have the phone, there will be no charge for monthly service. The social networks, satellites, and infrastructure will be owned by the people for the people - rather than by corporations for profit...
I'm going to give you the benefit of the doubt and assume you mean sharing of information already in the public domain and not IP.

Secondly, what logic did you use to arrive at such a conclusion? Thirdly, do you mean everyone be issued an IPad for free? Should WIFI or 4G connectivity be provided by private companies for free? Would the government pay for private companies to provide computers and connectivity.

Consider that if you have the IPad or computer and connectivity then much information on the www is already free. IP and/or proprietary information would be the exception.
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