APT decoding WX Satellites with RTL2832

[Lasse Radio]

Some folks seem to be able to recieve and decode wx satellite images (and a whole bunch of other decodings) using RTL2832. I have googled on this and all I can come up with is that this can only to be done using GNU Radio (Linux)? I found nothing about doing this in windows. None of the Apt decoding software seem to have an option for to getting the signal from the dongle inside the software. 

Anyone have a clue to how it's done using windows software without GNU Radio..?

Regards

Lasse

[Paulino Kenji Sato]

Hi,

Dont need GNU radio.
Use you favorite SDR and APT software.
Buy a copy of VAC (Virtual Audio Cable). (snd-aloop on Linux)
Configure SDR to use one of VAC channels (cable) as output,
And, APT software to use same channel as input.
On SDR adjust audio filter to 40kHz or little more.

And a adequate antenna to receive APT frequencies.


73s
Paulino

[Lasse Radio]

Thanks Paulino!!. I have not been able to test it (no satellite pass yet), but the in the Recordning options in WXtoImg,  virtual audio cable is appearing, so... crossing my fingers for tomorrow when NOAA flies by..... ;-)

Regards

Lasse

[Masanobu Tsuji]

Hi,

I have succeeded to receive NOAA/APT and make a image as follows.

Receive NOAA/APT signal: RTL2832u dongle (P160) + SDR# + IC recorder

Make NOAA/APT image: IC recorder + WXtoIMG

Virtual Audio Cable seems to be a good solution to connect the SDR# output and

WXtoIMG input, but free version inserts voice announce every few seconds and

I needed to purchase it. So, I used an IC recorder I have.

Also, antenna is important.

Dipole or whip doesn't have enough gain for clear APT image.

I made a cheap 4el yagi for 137MHz referring 144MHz design.

http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf

I used hungers of cleaning shop and pet bottle caps.

Using these materials, the antenna costs only 1USD.

Masanobu, JA1DAO

2012年10月6日土曜日 2時58分11秒 UTC+9 Lasse Radio:

[Masanobu Tsuji]

Hi folks,

I forgot to say one thing.
NETDUETTO beta is free and can be used instead of Virtual Audio Cable.

But the explanation is written in Japanese..

http://www.y2lab.com/project/netduetto/online-manual.html

Masanobu

2012年10月6日土曜日 6時32分28秒 UTC+9 Masanobu Tsuji:

[James Hall]

I've always been annoyed at VAC being the only option and having to pay for it on Windows with no alternatives. I wish I could read Japanese. Any chance of there being a guide with screenshots and english instructions for that?

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[Priyasloka Arya]

I would appreciate if one could provide download link for
IC Recorder, VAC,NETDUETTO ....

[Priyasloka Arya]

while going through the article

http://www.oz9aec.net/index.php/gnu-radio/gnu-radio-blog/477-noaa-apt-reception-with-gqrx-and-rtlsdr

i understood using Gqrxs/w we could avoid use of IC recorded/VAC...
is it correct.

[Lasse Radio]

Thanks for the tip.  Yes, I will make a QFH antenna. My airband GP is not that good for POES reception.

Regards

Lasse

On Friday, October 5, 2012 11:32:28 PM UTC+2, Masanobu Tsuji wrote:

Also, antenna is important.

[Lasse Radio]

I had NOAA 18 passing, resonably good quality reception, VAC on and WXtoImg... auto detect APT, but nothing... no image no respons...    Is there something that I've missed?

Regards

Lasse

[Lasse Radio]

Seems like I cannot get the VAC to work properly. No input..  I'm not sure what to choose except Line in.  So, no signal between SDRSharp and WXtoImg....  

Regards

Lasse

[Lasse Radio]

I finally got it to work after quite a lot if fiddling with WXtoImg, VAC and Audio Repeater...

Regards

Lasse

[Dave Bell]

On Friday, October 5, 2012 5:01:41 PM UTC-7, James Hall wrote:

I've always been annoyed at VAC being the only option and having to pay for it on Windows with no alternatives. I wish I could read Japanese. Any chance of there being a guide with screenshots and english instructions for that?

http://translate.google.com is your friend!
It can't fix up the screenshots, but the text is understandable.

Dave

[DJ0MY]

Why do all of you guys make your life always so complicated with VAC...hi hi :-)

I usually use for such "Audio Loopback" purposes simply the on-board weapons of MS Windows:
Most Soundcard Drivers have the so called "Stereo-Mixer" Channel, which can be chosen as the audio input device channel (e.g. in your APT or other digital mode decoding software).....and the SDR app runs on the standard output device...

All sounds then audible in Windows are automatically transferred to the input device.
(including systems sounds, which I would therefore deactivate)

Works well with most digital audio modes tried...

Cheers,

Oscar

[James Hall]

What do you do when receiving nondigital signals then, where you want to hear the audio?

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[DJ0MY]

Nothing special...just listen to the demodulated audio out of the SDR software on the usual "Audio out" device and lound speakers connected to it.

The trick is that "Stereo Mixer" (mostly found as a separate channel in the audio input devices) can route what you currently hear "digitally" to the audio-in device (and therefore can be fed into decoding programms while in parallel you still listen to it on your regulr audio output device) - thats all done inside the sound driver...

Oscar

[Dragan]

   http://jackaudio.org/

   Professional OSS solution that can be used as VAC alternative.
   A pain to setup on windows ...

[Priyasloka Arya]

Hi

I am struggling to get decent signal for APT(NOAA) due to unavailability of good antenna. I am not into antenna design and do not know how to make one. In India i am not sure where to get antenna for this kind of application. Group could you suggest some international seller who could ship low cost handhled antenna to India.

Thanks

Priyasloka Arya

[Masanobu Tsuji]

Hi,.Priyaslokave

I have made a cheap 4 element yagi antenna, reffering following page.

http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf

Length of elements should be multiplied by 144.2/137.5 on the 144MHz design.

Because NOAA/APT frequency is around 137.5MHz.

I used steel hungers of cleaning shop for elements and PET bottle caps to mount

elements to boom. It costs only 1 USD.

And I got excellent quality images with RTL dongle and the antenna.

Cheers,

Masanobu @Japan

2012年10月20日土曜日 12時41分19秒 UTC+9 Priyasloka Arya:

[David J Taylor]

Hi
I am struggling to get decent signal for APT(NOAA) due to unavailability of
good antenna. I am not into antenna design and do not know how to make one.
In India i am not sure where to get antenna for this kind of application.
Group could you suggest some international seller who could ship low cost
handhled antenna to India.
Thanks
Priyasloka Arya

=================================================

Priyasloka,

I have some information on QFH antennas here:

http://www.satsignal.eu/wxsat/equipment.htm

Some of the links may still work!

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-...@blueyonder.co.uk

[Priyasloka Arya]

Thanks a lot , could you send some clips of your antenna , so that i would get a n idea , how it looks.

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[Adam Nielsen]

> I have made a cheap 4 element yagi antenna, reffering following page.
> http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf
>
> Length of elements should be multiplied by 144.2/137.5 on the 144MHz design.
> Because NOAA/APT frequency is around 137.5MHz.

I thought you needed an antenna with circular polarisation to receive WX?
This has also been my stumbling block.

Cheers,
Adam.

[Masanobu Tsuji]

Hi Adam,

Actually, NOAA/APT transmission is circular polarization and 

antennas with circular polarization might bring you better results.

But such antennas are very complex and heavy. I prefer to rotate

antenna with my hand easily.

I attach another photo.

Cheers.

Maasanobu @Japan

2012年10月21日日曜日 8時22分56秒 UTC+9 Adam Nielsen:

[Varda]

Simple antenna made of wire coil for 137 MHz not too big. But is not omnidirectional.

http://www.changpuak.ch/electronics/calc_12a.php

[Varda]

Or this one too. Really is simplest CP antenna.

http://www.changpuak.ch/electronics/calc_12b.php

[Varda]

Make sure to have right direction "thread" otherwise no signal :(

[Lasse radio]

With those coil antennas and yagi, you need to follow and point the antenna towards the satellite, either manually or by using rotors.

Lasse

[Priyasloka Arya]

Hi Friends

 

i was not sucessful in getting NOAA signal today , i am using SDR# ,WXtoImg,gpredict and Yagi(4 element suggested by Masanobu).

i am guessing few things could have gone wrong

 

1: i am using DTH coax cable(75 ohm)available in local market, i am guessing that could be lossy. length of the cable is 2.2 meter.(photo attached)

 

going ahead: what i am thinking i would lessen the coax cable to bare minimum and will be laso be using usb cable(before USB dongle, it is a passive extender)

 

2:i am NOT very sure of the SDR# setting.(photo attached)

 

BW of filter :36 K

squench off

Narrow band FM

i am not getting confused with frequency,shift  and center option(in SDR#). There is no input for FM devaition.

3:I am not doubting WXtoimg as i am not getting tone in SDR# in the 1st place.

 

Help needed!!!!!!

[Masanobu Tsuji]

Hi Priyasloka Arya,

The frequency you set on SDR# seems to be incorrect.

You have set the frequency 136.100MHz but it should be

one of 137.620MHz, 137.9125MHz, 137.100MHz. 

http://www.unkebe.com/APT_Status_Report.htm

SECTION 1: POLAR APT/LRPT REPORT -- 22nd October 2012
=============================================
Satellite Frequency (MHz) Status Image Quality

NOAA 15 137.620 (APT) on good. See Note 8.
NOAA 17 137.500 (APT) on No images. See Notes 7&8.
NOAA 18 137.9125 (APT) on good
NOAA 19 137.100 (APT) on good but see Note 6

I recommend you to remove check mark from 

the box "Snap to grid" and set "Step size" to 1kHz.

BW of filter :36 K, squench off, Narrow band FM seem to be OK.

Cable length is enough short and OK.

As for  WXtoIMG, you need to select "STEREO MIXER" for input.

Please see attached screen shot of WXtoIMG.

To confirm the SDR# output and WXtoIMG input are connected

correctly, Play SDR# and Record manually on WXtoIMG without satellites.

If you can see any sandy noise image on WXtoIMG, connection is OK.

Good luck.

 

Masanobu @Japan

[Masanobu Tsuji]

Hi Priyasloka Arya,

I forgot to attach jpg file.

Masanobu @Japan

2012年10月27日土曜日 21時24分14秒 UTC+9 Masanobu Tsuji:

[limaunion]

Hi all, very interesting topic. I'll try during this weekend to receive some images with my tape measure yagi-uda antenna. It was designed for 70cm, I wonder how bad it will perform as it's tuned for a completely different band. I'll probably make a new one following the suggestions from Masanobu (it would be great if you can post some image just to see how does your yagi perform).
73

[Masanobu Tsuji]

Hi limaunion,

Good question.

Attached file is an example of NOAA/APT images I got this month.

You can see Typhoon storm clearly on the image.

Configuration is as follows:

Antenna: 4 element yagi-uda made of hungers and PET bottle caps

PC: ASUS EeePC1000H (Atom N270)

RTL dongle: P160

Software: SDR#, WXtoIMG(Free version)

Cheers,

Masanobu @Japan

2012年10月30日火曜日 23時33分32秒 UTC+9 limaunion:

[Isaac Gerg]

What frequency was this at?

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[limaunion]

Masanobu, thanks for the image, I hope to post my results next week.

According to the filename, it's an image from NOAA-18 at 137.9125 MHz.

73

[Bob R]

Hi Folks,

A couple of suggestions for SDRSharp land.  I haven't decoded much directly, but have been somewhat indirectly involved with this.

First, setting the 'minOutputSampleRate' in the SDRSharp.exe.config file to a higher value tends to improve the output bandwidth for NFM modulation.  Just open the file and look for that setting...i generally recommend setting everything at 48khz...minOutputSamplerate and audio sample rate in the SDRSharp GUI.  If you're using VAC, ensure that your channel supports 48kHz as well (run the 'control' application).  You can get wider bandwidth with WFM of course, but the deemphasis filters muck with the signal so it is not recommended.

Second, ensure that Filter Audio is *not* checked.

Third, if you hit the sdrsharp group on Yahoo (http://uk.groups.yahoo.com/group/sdrsharp) there's some discussion about a satellite tracker plugin that I started working on a while back (but has been a bit stagnant as of late due to lack of time). It allows Orbitron and WxTrack to drive the tuner and adjust for doppler shift.  It might also allow for folks to do unattended monitoring, i haven't tried nor have heard anyone trying that yet though.

I'm rarely in this group, so you may need to cc me or stop by the sdrsharp group if you need any more info.  Just wanted to drop these few hints.

Good luck!

On Friday, October 5, 2012 1:58:11 PM UTC-4, Lasse Radio wrote:

Some folks seem to be able to recieve and decode wx satellite images (and a whole bunch of other decodings) using RTL2832. I have googled on this and all I can come up with is that this can only to be done using GNU Radio (Linux)? I found nothing about doing this in windows. None of the Apt decoding software seem to have an option for to getting the signal from the dongle inside the software. 

Anyone have a clue to how it's done using windows software without GNU Radio..?

Regards

Lasse

[David J Taylor]

-----Original Message-----
From: Bob R
Sent: Thursday, November 01, 2012 8:35 AM
To: ultra-c...@googlegroups.com
Subject: [ultra-cheap-sdr] Re: APT decoding WX Satellites with RTL2832

Hi Folks,

A couple of suggestions for SDRSharp land. I haven't decoded much directly,
but have been somewhat indirectly involved with this.

[]

Third, if you hit the sdrsharp group on Yahoo
(http://uk.groups.yahoo.com/group/sdrsharp) there's some discussion about a
satellite tracker plugin that I started working on a while back (but has
been a bit stagnant as of late due to lack of time). It allows Orbitron and
WxTrack to drive the tuner and adjust for doppler shift. It might also
allow for folks to do unattended monitoring, i haven't tried nor have heard
anyone trying that yet though.

I'm rarely in this group, so you may need to cc me or stop by the sdrsharp
group if you need any more info. Just wanted to drop these few hints.

Good luck!

============================================

Bob,

I'm delighted to hear that WXtrack is now supported as a number of people
have asked me about this. Excuse my ignorance, but where can this plug-in
be downloaded? I looked on the SDRSharp Yahoo group and in the SDRsharp
downloads page, so I'm obviously missing something! What's the DLL called?

Thanks,

[Priyasloka Arya]

Orbitron is working with SDR# and providing doppler compensation

 

Check this

http://uk.groups.yahoo.com/group/SDRSharp/messages/1984?threaded=1&m=e&var=1&tidx=1

i am able to plugin orbiton with sdr sharp , works cool

download

http://public-xrp.s3.amazonaws.com/SatelliteTracker2.zip

and follow readme

On Thu, Nov 1, 2012 at 3:54 PM, David J Taylor <sats...@gmail.com> wrote:

-----Original Message----- From: Bob R
Sent: Thursday, November 01, 2012 8:35 AM

To: ultra-cheap-sdr@googlegroups.com

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[Priyasloka Arya]

Hi

 

Today i again could not grab NOAA satellites.

The setup is SDR#+VAC+WxtoImg+Gpredict/Orbitron+USB extender

 

I do not doubt any of the setup but thinking my yagi design could be problematic. I have followed the yagi design from http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf and suggestion from Masanobu.

 

Original design for 144 MHZ

 

                                   Ref            DE        D1        D2

4 Element    Length      41.0          38.5      37.5     33.0

                  Spacing       0              8.5       19.25   40.5

---------------------------------

For NOAA

Multiplication factor

144.2/137.5=1.04872

 

                                   Ref           DE        D1       D2

4 Element    Length      43            40.3      39.3     34.6

                  Spacing      0            8.91      20.18   42.47

 

I am not unable to get the FM TONE from SDR# so i am not thinking there could be problems in wxtoimg/vac.I haved captured my setup details in the attached pdf file.

Going ahead:  with my limited electronics knowledge: I am guessing my antenna is not tuned or designed properly(or i am doing some fundamental mistakes). So I have purchased 200 inches 8 swg GI wire to try out another yagi antenna. In this case, antenna elements will be straight and firm. But still i do not know, it will work or not. One more thing, my boom is soft iron tube and i have ensured the elements are insulated from the boom.

Help required on part of antenna design. (I am bit envious of Masanobu as he getting good signal :-))

Thanks

Priyasloka Arya

[Lasse radio]

First of all, do you get a reception of the satellite? Can you hear the signal? It does not need to be that strong just to test the apt reception, software working.  How do you know where to point the antenna?. The yagi has a very narrow beam and if you do not point that directly to the satellite and keep exact track you will loose the signal or get very low signal.   I have receieved signal and got an image with only a 50 cm stick, mounted on a 5 m high telescopic fishing pole. Ok, the image was pretty bad, but I manage to test my configuration.  If you don't know where to point the yagi exactly, that is the worst kind of antenna to use....

Lasse

[Priyasloka Arya]

you are correct, i do not hear the signal tone(i have heard many wav file of NOAA tone from you \tube). Moreover to track signal manually and see laptop is difficult and i do not have any friend to help me to read out the azimuth(azimuth is easy to find with compass ) and elevation(do not get the feel of elevation angle). I have to find some another way to track signal(wide beam, more handy antenna). what is the antenna you have used(50 cm stick?)

 

 

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[Lasse radio]

I have used a ground plane antenna centered on 125 MHz for the airband http://www.hamuniverse.com/2metergp.html  Adjust the length of the antenna and radials to your frequency (137 mhz).  There is also the possibility that the satellite did not transmit during the pass. It happens quite often.  You have to check if the satellite is active  http://www.oso.noaa.gov/daily-news/   It's the POES satellites, check their status  http://www.oso.noaa.gov/poesstatus/

Lasse

[KD9GN]

I too want to try decoding WX satellites with my EzCap dongle. I was
thinking of trying to build a simple Quadrifilar Helix Antenna out of
some surplus copper wire (12/14 gage home electrical wiring). If I
understand correctly some of the designs are reported to work from
horizon to horizon. I was thinking this may be a quick and easy way to
at least get started testing.

I was wanting to use WxToImg and rtl_fm under linux but I am not sure if
I can pipe the output of rtl_fm into WxToImg?
I have been using rtl_fm with multimonNG to decode POCSAG and it works
like a champ.

If I use a QHA / QHF antenna, do I still need to account for doppler shifts?

73 - Dave
KD9GN

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[Masanobu Tsuji]

Hi Priyasloka,

Antenna size which you have calculated seems to be correct.

Unit in the design is "inch".

Other point I found inappropriate is "Frequency" and "Center" in "Radio" tub of SDR#.t

For NOAA-18 "Frequency" is 137.9125MHz. You have set it correectly.---OK

But "Center" should be a little bit apart from 137.9125MHz. 

Usually, I set it 137.850MHz . "Center" and "Frequency" shoud be different to avoid

DC noise appeared at "Center" and better signal to noise ratio.

Another important point is time and satellite operation schedule as Lasse wrote.

Please adjust your clock and check the schedule before going to field.

Actually, I missed satellite signal in Thursday afternoon. I guess the sat didn't transmit..

 

To detect NOAA satellite signal, you don't need to use yagi-uda antenna. Just a dipole

antenna or a whip antenna is OK. Attached jpg file shows NOAA satellite signal on SDR#

with a dipole antenna in September.

Good luck in your next trial.

Masanobu @Japan 

2012年11月4日日曜日 0時58分01秒 UTC+9 Lasse radio:urI have used a ground plane antenna centered on 125 MHz for the airband http://www.hamuniverse.com/2metergp.html  Adjust the length of the antenna and radials to your frequency (137 mhz).  There is also the possibility that the satellite did not transmit during the pass. It happens quite often.  You have to check if the satellite is active  http://www.oso.noaa.gov/daily-news/   It's the POES satellites, check their status  http://www.oso.noaa.gov/poesstatus/

[Masanobu Tsuji]

Hi Dave,

I haven't tried to decode NOAA APT with QHA/QHF antenna

but would like to show you my experience in early trials.

Attached jpg file is NOAA APT image I  got with dipole antenna.

I can see sync pattern slightly on the image but the image quality

is quite bad. As hams know, the difference between dipole antenna

and 4 element yagi-uda is only 7 or 8dB and it looks just small

on 10dB span FFT screen of SDR#. But it brings me big difference

on NOAA/APT images.

After my some trials, one of my friends tried to get NOAA/APT image

with turn style antenna and his result was pity too.

Cheers.

Masanobu @Japan

2012年11月4日日曜日 3時51分19秒 UTC+9 David Lolling: