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Old 23-01-2014, 06:41   #1
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Best Way to Receive Weatherfax?

I guess there are really three questions here:

1. Does a Pactor modem do a significantly better job decoding weatherfax broadcasts than sound card methods?

2. Is a dedicated weatherfax receiver really such a boon as to justify the expense, space, etc.?

3. Assuming you have Sailmail anyway, and a Pactor modem, is it better yet to get weatherfaxes sent by email? Is email over Pactor a more efficient method than receiving the FSK weatherfax broadcasts?
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Old 23-01-2014, 06:49   #2
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Re: Best Way to Receive Weatherfax?

I'll follow this one. In past years (long time ago) I had a dedicated weather fax as well as a Pactor modem. I did get some weather on my Pactor but it was a text format. All my weather faxes were by a dedicated stand alone machine which I really liked. This time out no fax machine...so will be interesting what others have to say!
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Old 23-01-2014, 07:45   #3
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Old 23-01-2014, 07:49   #4
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Re: Best Way to Receive Weatherfax?

I have a program on my wife's Nexus 7 that is supposed to decode the weather fax from the speaker and show it on screen but we are in a marina with lousy reception so I haven't tried it yet....how well do they work?
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Old 23-01-2014, 07:57   #5
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We use a SSB receiver coupled with a laptop and a Xaxero USB demodulator and wefax software. If you feel the need to be fancy this same software will tune an icon radio for you.
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Old 23-01-2014, 08:15   #6
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http://www.cruisersforum.com/forums/....php?p=1264792
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Old 23-01-2014, 08:20   #7
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Re: Best Way to Receive Weatherfax?

Cool, thanks for that
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Old 23-01-2014, 14:21   #8
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Quote:
Originally Posted by Sailmonkey View Post
We use a SSB receiver coupled with a laptop and a Xaxero USB demodulator and wefax software. If you feel the need to be fancy this same software will tune an icon radio for you.
+1. I've used Xaxero for years....back before there was such thing as USB via their previous versions. I still have the sound card version as a back up should my USB demodulator fail.
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Old 23-01-2014, 22:04   #9
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Re: Best Way to Receive Weatherfax?

Quote:
Originally Posted by Dockhead View Post
I guess there are really three questions here:

1. Does a Pactor modem do a significantly better job decoding weatherfax broadcasts than sound card methods?

2. Is a dedicated weatherfax receiver really such a boon as to justify the expense, space, etc.?

3. Assuming you have Sailmail anyway, and a Pactor modem, is it better yet to get weatherfaxes sent by email? Is email over Pactor a more efficient method than receiving the FSK weatherfax broadcasts?
I can't say for sure that SCS TNC's decode weatherfax any better than soundcards, assuming you are talking about direct reception of wefax signal. The TNC may be better at weak signal decoding, but soundcard software and soundcard quality affect the ability of soundcard mode to decode weak signal too. A lot of people tend to disregard the soundcard, but a quality recording type soundcard with better dynamic range and s/n will outperform the basic on board sound of a typical laptop. How much depends, but it certainly makes a difference with weak signals. Then there's the setting up of the audio levels, is the transceiver audio out direct to the computer, or is it more properly, coupled with less noise? These simple settings, make soundcard mode a little more complicated than if the TNC is decoding it, but on the otherhand, it really isn't rocket science. Even with crappy soundcards & poorly adjusted audio/radio settings, it's still pretty reliable.

The one thing that jumps out at me when receiving weatherfax from Sailmail is that you must be able to make two way communication with the sailmail server to receive the weatherfax message. Seems less reliable than just receiving to me.

A dedicated weatherfax receiver will use hardware decoding in the radio and undoubtedly outperform the TNC & soundcard with weak signals. Personally, I can't say for sure if a dedicated wefax receiver is worth it or not, but it seems that if you already use Sailmail, it wouldn't take much effort or cost to add free soundcard software and a low cost interface to utilize direct soundcard reception as well as Sailmail.
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Old 24-01-2014, 04:19   #10
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Re: Best Way to Receive Weatherfax?

Quote:
Originally Posted by El Rubio View Post
I can't say for sure that SCS TNC's decode weatherfax any better than soundcards, assuming you are talking about direct reception of wefax signal. The TNC may be better at weak signal decoding, but soundcard software and soundcard quality affect the ability of soundcard mode to decode weak signal too. A lot of people tend to disregard the soundcard, but a quality recording type soundcard with better dynamic range and s/n will outperform the basic on board sound of a typical laptop. How much depends, but it certainly makes a difference with weak signals. Then there's the setting up of the audio levels, is the transceiver audio out direct to the computer, or is it more properly, coupled with less noise? These simple settings, make soundcard mode a little more complicated than if the TNC is decoding it, but on the otherhand, it really isn't rocket science. Even with crappy soundcards & poorly adjusted audio/radio settings, it's still pretty reliable.

The one thing that jumps out at me when receiving weatherfax from Sailmail is that you must be able to make two way communication with the sailmail server to receive the weatherfax message. Seems less reliable than just receiving to me.

A dedicated weatherfax receiver will use hardware decoding in the radio and undoubtedly outperform the TNC & soundcard with weak signals. Personally, I can't say for sure if a dedicated wefax receiver is worth it or not, but it seems that if you already use Sailmail, it wouldn't take much effort or cost to add free soundcard software and a low cost interface to utilize direct soundcard reception as well as Sailmail.
Thanks, well, I have a Pactor III TNC, too, so I will certainly experiment with that as well. I guess one could use a hybrid approach -- get your weatherfaxes by email from Sailmail, and if you have any trouble accessing your email, then start receiving the broadcasts directly.

I am still interested in the relative efficiencies of receiving by email versus receiving the broadcasts, for example -- "Oh, yes, you can get a full set of weatherfaxes in 2:30 minutes by email if you have a good connection, which would take a half hour to receive by broadcast" or whatever the real facts are. I wonder if anyone has been bothered by the radio being tied up receiving weatherfaxes when something else needed to be done with it.

The fourth approach might be to use a black box weatherfax receiver -- Furuno make one, for example. This would keep the radio free for other things. How long does it take to receive a weatherfax broadcast?
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Old 24-01-2014, 04:25   #11
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Re: Best Way to Receive Weatherfax?

Quote:
Originally Posted by Dockhead View Post
How long does it take to receive a weatherfax broadcast?
Depends on conditions obviously, but not much longer than receiving an email.
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Old 24-01-2014, 04:28   #12
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Re: Best Way to Receive Weatherfax?

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Depends on conditions obviously, but not much longer than receiving an email.
Since a weatherfax broadcast is a one-way communication, I bet it doesn't depend on conditions -- I bet they are broadcast over a set period of time.
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Old 24-01-2014, 05:20   #13
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Weatherfax is my preferred method. For that I recommend a low power PC with suitable program set up to receive fax via SSB on a schedule. Then the weather charts and alerts are always on the PC when you need them including previous day's charts. The time to receive isn't that important as you don't sit there and watch. Just remember to take a moment to check if they all received ok. If not just enable the next scheduled reception slot later in the day. Most weather services send the same data more than once. Also, the charts only update twice a day in most areas. I always get the multi-day predictions in case tomorrow's charts don't come for some reason. At least you have something to go on until tomorrow.

GRIB files by Sailmail are nice. Read www.morganscloud.com article about how to request detailed custom data sets for your area with minimal air time. The defaults aren't very clever but their article teaches that you can create short but very detailed requests.

The Pactor modem is the way to go if you have one. A sound card works too but the Pactor is already set up and so it's easier. It also controls frequency of the Icom radios which is nice.

If you are really clever you can rig a timer to turn on the SSB radio (and thus the modem) at the right time for reception. Most PCs have a bios wake up timer so you can save amp-hours there too. I find most fax schedules coincide with my sleep schedule.
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Old 24-01-2014, 11:12   #14
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Re: Best Way to Receive Weatherfax?

Quote:
Originally Posted by Dockhead View Post
I guess there are really three questions here:

1. Does a Pactor modem do a significantly better job decoding weatherfax broadcasts than sound card methods?

2. Is a dedicated weatherfax receiver really such a boon as to justify the expense, space, etc.?

3. Assuming you have Sailmail anyway, and a Pactor modem, is it better yet to get weatherfaxes sent by email? Is email over Pactor a more efficient method than receiving the FSK weatherfax broadcasts?
I have a Pactor II and Sailmail. The "Get Fax" module in Airmail v3.4 does a great job of receiving wx faxes and if the propagation is a bit off you can quickly check the other frequencies used by the station are receiving the fax from. Email is good for receiving the gribs and text weather via saildocs.
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Old 24-01-2014, 13:46   #15
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Re: Best Way to Receive Weatherfax?

Dockhead,
Don't have the time to go into details at the moment, but have enough time to definitively answer your questions about WeFax chart broadcasts and ways to receive them...and I addressed the various ways to receive wefax (and other offshore/hi-seas weather) in a thread here last summer (see below for link)....
Quote:
Originally Posted by Dockhead View Post
The fourth approach might be to use a black box weatherfax receiver -- Furuno make one, for example. This would keep the radio free for other things. How long does it take to receive a weatherfax broadcast?
1) A typical weather chart broadcast takes about 8 minutes...depending on the size of the chart, it varies a bit, from 6 minutes to as much as 10 minutes...
But, figure about 8 minutes....

{BTW, just a fun fact....facsimile is the oldest form of "image" communication....the patents date back to 1843...yes that's the 19th Century!!! And, first commercial "telefax" service started in 1865!!!
And, radiofax dates back to the 1920's/30's.....
Modern radiofax/wefax is a robust form of one-way communications...and with modern receivers, it still works great!!!

Oh, and further according to the 2012 survey by the WMO/jcomm Joint WMO-IOC Technical Commission for Oceanography and Marine Meteorology, HF WeFax is used my a majority of commercial ocean-going vessels daily and will continue to be used by them daily, for at least the next decade....

So, HF wefax isn't going anywhere, any time soon!!!}


If you look at the broadcast schedules you'll see about 10 - 13 minutes between chart transmissions, the two that I use regularly, are USCG wefax broadcasts from Boston and New Orleans...
Boston Radiofax Schedule with Links
New Orleans Radiofax Schedule with Links




2) As for a stand-alone wefax receiver, this is the approach that I used starting in the 1970's and still use today....
And, is still the preferred way for many professional commercial mariners...

Although nowadays, some like the idea of a standalone "black box" connected to a laptop, etc....but this adds the issue of a "laptop" now being a necessity in order to "get weather", and if you're going to do that, why not simply use your HF transceiver(s) for the receiver, or another HF receiver, and save the $$$???

It is a pricey way to go....but VERY effective and reliable...
A new Furuno FAX-408 will set you back about $2000....(I know, I bought one a few years ago, when my Alden MarineFaxIV's automatic timer would no longer function...it's nice to program it to turn-on and receive just the charts that you want, whether you're on-board or not, or on-watch, or asleep, etc...and I REALLY like my Furuno FAX-408...)

My FAX-408, as well as my old Alden can be seen in these photos of my Nav Station...
Nav Station




3) As for the "advantage" of receiving wefax charts (synoptic weather charts and forecasts prepared by seasoned maritime meteorologists) via an e-mail (saildocs) thru a PACTOR-modem radio link, rather than received directly from the USCG, UK Met/GYA, etc. etc..

If using Sailmail, the saildocs e-mail wouldn't take nearly as long as the open WeFax transmission takes....about a minute or so, per chart ....
But, this DOES use up some of your daily 14 minutes (90 minutes/week) of Sailmail access....
(I've not heard of many that choose to use up their precious Sailmail minutes by getting wefax charts this way....unless they're having reception problems from the broadcasts and/or missed the chart they wanted!!)

The only advantage to using the PACTOR-connection (thru Sailmail, etc.) is that the chart is clean / clear of any "static"...as the PACTOR error correction makes sure that there are no errors received....so noise / static is removed...
BUT...
But, this does NOT mean that the PACTOR connection is better....just that it can produce a clean/clear chart...

Since the Sailmail stations are typically 150 watts PEP (50-100 watts average in PACTOR-II and PACTOR-III), vs. the USCG wefax transmitters being 4000 watts average, and UK, etc. stations as much as 10,000 watts average....
http://www.nws.noaa.gov/om/marine/rfax.pdf
And, further since the USCG, Aus, UK, SA, Japan, etc. etc. wefax transmission antennas are designed to provide gain on their freqs, and point their signals to the areas they're sending weather forecasts for, vs. the unknown antennas of Sailmail stations......and even worse the totally unpredictable antennas of WINLINK stations (possibly wide-band, zero-gain)....
In these cases, the real S/N "advantage" of PACTOR (theoretically as much as 15 -16db, typically 8-10db) is easily compensated for by the more powerful transmitters and better antennas of these HF WeFax transmission facilities...




4) Now last summer I spent some time writing a rather detailed posting on the SSCA Disc boards about "how to get weather" when offshore.....this was prompted by a specific question from an SSCA poster....
And then when I decided to re-post this information here I was rightly taken to task for using the word "accurate" in my posting.....but since I included some very brief opinion, I found myself flamed for voicing such heresy as stating that if still works well for many/most commercial ocean vessels (and I've been successfully using it for decades), then this is what I primarily recommend.....
In any case, that is all water-under-the-bridge....

But, you can read what I wrote there about WeFax, etc. here....
Obtaining Accurate Offshore/Hi-Seas Weather data/forecasts, while at sea




I hope this helps clarify things a bit....

Fair winds.

John
s/v Annie Laurie
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