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Dockhead 07-04-2015 15:03

Receiving Weatherfax Directly From the Satellite
 
I spent the flight from London to Helsinki this evening reading the Pactor manual once again. My God! How much technology is packed into that little device! I wonder how many people have ever used 90% of the functions?

One thing which really struck me, was this:

"The most interesting signal sources of AM-FAX are mainly the weather satellites (NOAA-Satellites on 137 MHz or the geostationary Meteosat 5 or GOES (USA) on approx. 1.7 GHz.

"To receive these satellites, it is recommended that a special receiver is used with an IF bandwidth of approx. 30-50 kHz. For the 1.7 GHz band, a small dish or Yagi-antenna with a low noise LNA or LNC will also be required.
Meteosat 5 for example, transmits almost continuous IR and VIS pictures with a resolution of 2.5 to 5 km in a format of 800 x 800 pixels. Many programs are able to automatically sense the beginning of each picture by using additional digital information, and to make very impressive weather films. These films are interesting not only for amateur meteorologists, but also for sailors, mountain climbers etc."


Has anyone received these satellites directly? I doesn't sound like it would be that hard -- a UHF ham transceiver, a small yagi antenna . . .

CarstenWL 07-04-2015 15:17

Re: Receiving Weatherfax Directly From the Satellite
 
... 'we' (a group of radio amateurs and persons interested in radio astronomy) do:

DL?SHF
Click in the British Flag to read in English
Click on METEOSAT weather films or NOAA satellites

The NOAA-satellites are polar orbits at altitude of about 800 km with period of about 2 hrs. During this time they observe the Earth surface in 5 (later 8) different spectral bands. The data are transmitted in strongly reduced form on 137 MHz and in full detail on 1.7 GHz
Reception on 137 MHz is possible without excessive effort, using a crossed dipole antenna and a somewhat modified of-the-shelf scanner.
Reception of the full data (HRPT) on 1.7 GHz requires the tracking of the satellite by the antenna via computer. The required orbital data needs to be updated from NASA at least every three weeks. To receive the digital signals a special broad-band receiver is necessary.

Regards,

Carsten

Dockhead 07-04-2015 15:24

Re: Receiving Weatherfax Directly From the Satellite
 
Quote:

Originally Posted by CarstenWL (Post 1795483)
... 'we' (a group of radio amateurs and persons interested in radio astronomy) do:

DL?SHF
Click in the British Flag to read in English
Click on METEOSAT weather films or NOAA satellites

The NOAA-satellites are polar orbits at altitude of about 800 km with period of about 2 hrs. During this time they observe the Earth surface in 5 (later 8) different spectral bands. The data are transmitted in strongly reduced form on 137 MHz and in full detail on 1.7 GHz
Reception on 137 MHz is possible without excessive effort, using a crossed dipole antenna and a somewhat modified of-the-shelf scanner.
Reception of the full data (HRPT) on 1.7 GHz requires the tracking of the satellite by the antenna via computer. The required orbital data needs to be updated from NASA at least every three weeks. To receive the digital signals a special broad-band receiver is necessary.

Regards,

Carsten

That's very interesting! You can't use a normal ham UHF transceiver for this?

I'm sorry to hear that you have to track the satellite -- I guess that means you can't receive it at sea :(. You can't just use a yagi as suggested by SCS?

CarstenWL 07-04-2015 15:29

Re: Receiving Weatherfax Directly From the Satellite
 
... to start it would be easiest to do on 137MHz with a omni directional antenna. Some of the marine ICOM radios cover the 137MHz band ...

On 1.7GHz we are using a 1.2m dish (I think), you could do with a YAGI for this frequency range (e.g. http://www.amazon.co.uk/Shf-1633-Met.../dp/B00LN6TFR4) but the yagi is than 1.xm long already (plus you need a receiver for that frequency range) ...

Carsten

PS: Over some hours/days you do not need to track on 1.7GHz but the beamwidth of the yagi antenna at 1.7GHz is already quite small, you will not be able to position it easily (on a calm day maybe ;-))

Paul Elliott 07-04-2015 15:38

Re: Receiving Weatherfax Directly From the Satellite
 
Here's a posting from someone who directly received and decoded the satellite images:
http://www.cruisersforum.com/forums/...ing-21991.html

I know there are more examples out there.

Dockhead 07-04-2015 15:44

Re: Receiving Weatherfax Directly From the Satellite
 
Quote:

Originally Posted by CarstenWL (Post 1795489)
... to start it would be easiest to do on 137MHz with a omni directional antenna. Some of the marine ICOM radios cover the 137MHz band ...

On 1.7GHz we are using a 1.2m dish (I think), you could do with a YAGI for this frequency range (e.g. http://www.amazon.co.uk/Shf-1633-Met.../dp/B00LN6TFR4) but the yagi is than 1.xm long already (plus you need a receiver for that frequency range) ...

Carsten

PS: Over some hours/days you do not need to track on 1.7GHz but the beamwidth of the yagi antenna at 1.7GHz is already quite small, you will not be able to position it easily (on a calm day maybe ;-))

Is there any reason why you could not use a normal ham UHF transceiver like the Kenwood TM-D710?

Is the signal so weak that you would need such a narrow beamwidth antenna?

CarstenWL 07-04-2015 15:51

Re: Receiving Weatherfax Directly From the Satellite
 
... the Kenwood will work too ...

The spec says:

Description: The TM-D710 Data Communicator 144/440 MHz Dual Bander has the following features:
• APRS Ready
• APRS Weather Station ready
• KSS II+ (kenwood Skycommand II+)
• NMEA 0183 GPS I/O port
• Built-in 1200/9600 bps TNC
• Echolink Ready
• High RF Power Output (V/U: 50 watt)
• 1000 multifunction Memory Channels
• Dual Receive on same band (V+V, U+U)
• NOAA Weather Alert/RX (US Only)
• Voice Guidance & Storage option (VGS-1)
• MCP Compatible with ARRL "TravelPlus"

So even if the EU version might not have the NOAA alert function it will receive fine.

On 1.7GHz you need 'some' antenna gain to receive the signal because it is 'not really strong' so a 6dB whip will not do it.

137MHz is pretty straight forward and a fun project to start receiving weather satellites.

Carsten
Carsten

El Pinguino 07-04-2015 17:03

Re: Receiving Weatherfax Directly From the Satellite
 
4 Attachment(s)
I've been getting the NOAA sats on 137MHz for some years... bonzer stuff...However... they aren't putting up any more satellites and it is now a legacy system ( 3 sats still working) with a life expectancy up to about 2019..... so don't over-invest.
I use an Icom R1500 and a Wrasse MX 137 ant with WxtoImg software.

socaldmax 07-04-2015 21:06

Re: Receiving Weatherfax Directly From the Satellite
 
I think you can do it for pretty cheap.

Get a USB RTL-SDR radio, a 25 MHz to 1.7 GHz unit sells for $5-8 on Ebay, or you can get a 100 KHz to 1.7 GHz Full band unit with dual antenna inputs (.1-25 MHz and 25-1700 MHz) for about $59. This one will allow you to listen to HF SSB, weatherfax, everything a LW/MW/SW radio will do, for an extra $50.

Full Band 100KHz 1 7GHz UV HF Rtl SDR USB Tuner Receiver R820T 8232 Ham Radio | eBay

The beauty of an SDR radio is the spectrum and waterfall displays allow you to see large chunks of the band and jump over to new signals nearly as soon as they pop up, or you can set it to scan a band quickly, or scan through your preset memory channels. If you're adept at signal analysis, just looking at the waveform on the IF spectrum and waterfall displays will give you a good idea if you're looking at SSB, Narrow or wide band FM, AM, CW etc before you even tune to it.

Build your own QFH antenna for under $40, probably much less. To be honest, one of my biggest expenses with my SDR radio was the antenna cable. At 137 MHz, RG8X or LMR240 isn't too lossy, but as you go up in freq., especially in the GHz range, signal attenuation goes up quickly. I decided on 50ft of Wilson400 (the cheapest version of LMR400 I could find) and it cost me about $50.

I currently have a discone antenna (25-1700MHz omnidirectional coverage) with great results, but I'm going to add a home made QFH antenna on a 50 ft length of LMR240 for satellite reception. Speaking of reception, that's another advantage of SDR, it has a 0-50 dB adjustable gain, so rather than having a fixed 20 dB LNA up near the antenna and getting your receiver front end overloaded or nearly deaf from cutting a 20 dB amp in/out, you can smoothly adjust the gain for your particular signal with the little slider and your mouse. Once you've played with all of the adjustable features like bandwidth, noise reduction, I&Q swap, receiver gain, audio gain, sampling rate, etc, a regular radio will feel like driving a horse and buggy.

I'm an old ESM operator, so give me anything with a spectrum analyzer display and I get all excited! LOL

socaldmax 07-04-2015 21:07

Re: Receiving Weatherfax Directly From the Satellite
 
Quote:

Originally Posted by El Pinguino (Post 1795554)
I've been getting the NOAA sats on 137MHz for some years... bonzer stuff...However... they aren't putting up any more satellites and it is now a legacy system ( 3 sats still working) with a life expectancy up to about 2019..... so don't over-invest.
I use an Icom R1500 and a Wrasse MX 137 ant with WxtoImg software.

Those look amazing!!

El Pinguino 08-04-2015 02:28

Re: Receiving Weatherfax Directly From the Satellite
 
2 Attachment(s)
Quote:

Originally Posted by socaldmax (Post 1795679)
Those look amazing!!

Thankee... my favourite ever is 'The Trombone'... see below ( the yellow '+' marks the ship's location).

Some thoughts... this isn't 'Wefax' in any sense...ok it involves the weather but not facsimile or any human intervention... its a picture 'right now' of what is happening... not only will it give you a nice pic of the clouds it can be 'enhanced in a variety of ways.... including precipitation ( the red bits in one of the pics)... it all works ( I think... I just uses this stuff.. :) ) on sensing the infrared temp of stuff. It can be even used with a clear sky to see the sea temperature..

Given a choice of gribs, wefax, and noaa sats I would put Noaa sats at the top of the list.

They take a bit of practice to relate what you see with what you are going to get.. frinstance in my sailing grounds solid cloud above a 'low' on the pic suggests to me a settled NW airstream... fluffy looking stuff which might imply fair weather cumulus actually indicates hard squalls and mega nasty stuff.

I have no experience with the geostationary sats with yagis and dishes etc but I don't think they will really work on a yacht..

Receivers? Apart from the R-1500 I have used assorted RTL dongles and Funcube dongles. Great fun ashore but a bit fussy afloat. The R1500 is hassle free and a bit middle of the road...you have to manualy change frequency while stop/start of reception is automatic with the wxtoimg software. The duck's guts are the Wraase receivers which automatically change frequency but maybe a bit XE considering the system life expectancy...

trifan 08-04-2015 10:09

Re: Receiving Weatherfax Directly From the Satellite
 
Can't do 1.7 GHz on a boat? Antennae too directional? Anyone ever considered using new (21st century) tech and do a "gyro-stabilized" antenna mount? It really isn't gyro stabilized, it uses sensors that mimic gyros and they are bunches cheaper and last a lot longer... anyway, it can be done for a fraction of what the big yachts spend for stabilized dish mounts for their satellite receivers (and 2 way internet in the US footprint). Google is your friend ...

trifan 08-04-2015 10:11

Re: Receiving Weatherfax Directly From the Satellite
 
And, if worse comes to worse and you absolutely, positively can not find anything on rolling one of these yourself, pm me and I'll try to direct you.

conachair 08-04-2015 10:52

Re: Receiving Weatherfax Directly From the Satellite
 
I've had readable images (just) using an icom ic7000 and wxtoimg with just the backstay as an antenna. The software is very cool, it auto tunes the icom as the satellite passes to compensate for Doppler shift.
Not really wide enough bandwidth, though maybe a quadrifiler antenna would make it useable. Great fun! :cool:

El Pinguino 08-04-2015 11:32

Re: Receiving Weatherfax Directly From the Satellite
 
Quote:

Originally Posted by trifan (Post 1796089)
And, if worse comes to worse and you absolutely, positively can not find anything on rolling one of these yourself, pm me and I'll try to direct you.

I think we would all be interested in some direction.

I tried Google... it brought me back here, oh, and it also threw up some stuff such as this Predicting fruit fly’s sensing rate with insect flight simulations :smile:


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