Radio comms hobby: Weather satellite and ISS pictures, shortwave radio signals, space news

[simon43]

I realise that I have been cluttering up GG's weather thread with images that I receive from the various weather satellites.  Since satellites and all-things-radio is my hobby, I think it would be better to create a separate thread in this sub-forum for topics about this hobby.

 

I'm a radio amateur in Thailand, but I don't actually do much transmitting.  I mostly spend my time designing and testing various shortwave VHF and UHF radio antennas, mostly to receive image signals from satellites (weather satellites, ISS etc), or data signals from various small Cubesats - mostly built by students at technical colleges in Russia.

 

To be honest, Russia is far more active than the USA in building and deploying Cubesats with projects and experiments on board that 'ordinary folk' can involve themselves in.  The USA mainly has question and answer sessions between college students and astronauts on the ISS.  From time to time, the Russian sector of the ISS does transmit images, which I receive at my home in south Thailand.

 

Anyway, I will try to post interesting signals and news on this thread.  Of course, I welcome relevant posts from other forum members!

 

So to start things off, I repost the image from GG's weather thread that I posted today (Thursday 12th June).  This is an image from the USA weather satellite NOAA-15, as it passed over south-east Asia this morning..  The satellite transmits about 10 images on each pass, and the free processing software on my laptop creates the different images. The image shown has the rain storms indicated by colour - the darker the colour, the more rainy it is!

 

[TedG]

I’ve been meaning to try this.   I’ll have to dig my 2m antenna and point it to the sky. 

[simon43]

Before weather satellites existed, weather reports and maps were sent out using shortwave radio, mostly intended for ships at sea.  This was called WEFAX and it would take about 20 minutes to receive one map of the region's weather, indicating high and low pressure areas, so that ships could avoid storms.

 

Most of the WEFAX transmitting stations closed down years ago, but some still operate, including station HSW64 in Bangkok, which sends out these weather maps and shipping forecast throughout the day (and night) on the shortwave frequency of 7395KHz USB, using a 3 Kilowatt transmitter.

 

The signal is quite strong on my radio in south Thailand, and with free decoding software from a company called Black Cat Software, I received this '24 hour surface prognosis' map just now. Even with a strong signal, the resolution of the map is far below what can be received from weather satellites.

 

 

Why does HSW64 still broadcast these maps?  No idea!  Perhaps it will finally retire from service when the meteologist who creates the maps also retires...

 

This is a link to list of WEFAX stations that still operate. Apart from Bangkok, I have also received maps from stations in China and Japan.

 

https://www.weather.gov/media/marine/rfax.pdf

[TronxII]

17 hours ago, simon43 said:

Before weather satellites existed, weather reports and maps were sent out using shortwave radio, mostly intended for ships at sea.

This reminds me of the weather report pictures from the early 1980s in TV, they had such pressure maps.

[TronxII]

Today I modified my antenna, which was horizontal strips of 0.2mm thick and about 1cm large. My idea was that the signal comes from above and therefore I turned them horizontal. It seems however that this was not a good idea. In vertical position, a noaa15 pass was received better than the days before. Comparing the satellite picture on the right with the commercial weather radar website picture on the left, I would say, there is even more information in the noaa15 picture.

Still my antenna setup is not optimal. I'm not getting the nice signal in the waterfall like you posted in the other thread.

So here is a picture how the antenna should not be positioned - horizontally, but the metal strip should be turned 90°

 

[simon43]

4 hours ago, TronxII said:

This reminds me of the weather report pictures from the early 1980s in TV, they had such pressure maps.

Since it's sent on shortwave, where the signal bandwidth is far smaller than VHF etc, the resolution is very low.  It takes 20 minutes to transmit one map.  I don't know why these WEFAX stations continue to operate....

 

For NOAA:

 

Good to see that the overlay map is showing the correct region 🙂

 

NOAA-15 has a weaker signal than NOAA-19, so try to repeat with a high pass from NOAA-19.  Of course, at the beginning and end of the pass, the signal will fade out but the software will still create the country overlay.  You can set Satdump to delete these top/bottom regions automatically.

 

Next, you can add a passive reflector or director to your antenna.  This should be a single length of metal wire, taped to a bamboo support and positioned parallel to the dipole element, about 55cm behind or in front of that dipole element, (depending on whether it is a reflector or director - either is suitable).  If a director, then its overall length should be 5% shorter than the overall dipole length, and if a reflector, it should be 5% longer.

Then aim that 2-element antenna array straight up to the sky. I manually move my antenna to point it at the satellite as it passes over me, but fixing it straight up at 90 degrees will capture everything but the lowest elevation positions, where the satellite signal will be the weakest anyway.  My 137 MHz is 3-elements, a driven element, a reflector and a director.  (In previous photos, you can also see my 70cms antenna on the same boom - that had 7 elements and I added 4 more).

[simon43]

I finally got my 'big-dish' system working to receive images from the geostationary weather satellites 🙂  These satellites sit in the geostationary orbit, about 50,000 km out in space.  Satellites in this orbit revolve around the Earth at the same velocity so that the satellite 'keeps pace' with the Earth and therefore is always in the same position in the sky above you.

 

So this orbit is used especially for satellite TV, internet satellites (not the new starlink system), and weather satellies!

 

I had previously received images from these geostationary weather satellites, but I was always surprised at how weak the signal was, especially using such a large dish.  This time I went through my system design parameters and discovered that my feedhorn which receives the focussed signal from the satellite had the wrong dimensions!  Investigation proved that the online calculator which I used to obtain the feedhorn dimesions had an error in its calculations.... duh!

 

So I remade my feedhorn with the correct dimensions, mounted it on my dish and was rewarded with a signal from GK-2A, which is a weather satellite of South Korea.

 

Here's my basic receiving system:

 

 

Satdump software processed the data into a visible image, and I then added colour to my infrared image using Sanchez - another free software application.

 

... and the result is.....

 

 

 

[TronxII]

6 hours ago, simon43 said:

I don't know why these WEFAX stations continue to operate....

Might be the last ones which will still operate after a couple of high altitude nuclear tests wipe out some of the satellites. We take these satellites for granted like we believed that electric power, security, peace, cheap food and progress would always be there. But big parts of Europe have already no more GPS over the baltic sea, the electric grid breaks down, riots ... 

[simon43]

^^^ Lol true.  When I lived in Burma, my GPS on my phone often went crazy because it was being jammed by the junta...

[gamb00ler]

An article about LoRa Mesh networks caught my interest a couple of days ago.  It looks like a fun and somewhat useful hobby.  The startup costs aren't too high.  I have no background working with radio tech so learning curve starts at zero.

[simon43]

^^^ I use a kind of LoRa mesh with my shortwave transceiver.  It'a system called Winlink (winlink.org), which allows those in remote regions, especially at sea, to send/receive emails, navigational maps etc.  The sailing boat automatically establishes a radio link with my station in Thailand and I either connect them to my own internet connection, or if my internet is down, then my radio transceiver automatically establishes a 'relay' connection to the next Winlink ground station, which for me is in Taiwan or Reunion Island.

 

I've used this system for many years, allowing sailing boats in the southern Indian ocean who don't possess satellite comms equipment, (or it's too expensive to use!), to check their emails, keep in contact with family etc.