Skip to main content

RECEIVING SSTV FROM ISS ! Steps involved in decoding when using MMSSTV ......


A very interesting mode in ham radio is SSTV and more interesting is the SSTV from ISS - the International Space Station ! Receiving the images from ISS is pretty simple . However many hams have some problems recording SSTV audio and decoding them using MMSSTV . My ham friends like OM Ramesh VU3RGB , OM Sulaiman VU3SMQ and OM Dhanesh VU3DHN encouraged me to make a blog post describing the various steps involved .
1) The first step is simple . Just tune to 145.800MHz in your VHF receiver and record the audio using some device like your smartphone,holding it near to your rig .It is better to use SDRs like RTLSDR to record audio using a computer. However my shack PC is QRT now , so ,I can't use SDR . Anyway be sure to use some excellent satellite tracking software like the Hamsatdroid (Android) or Orbitron (Windows) to guide you in tracking the ISS .
2) After recording , copy the recorded .amr file to your PC from phone . Use some tool to convert the amr to wav file . One excellent online conversion tool is http://media.io/ .
3) Now download the .wav file and import it into audacity . Change the project rate to 11025 Hz and ensure that the audio is mono . Slice off the noise part and silence from the audio .
4) Now export it to another wav file . After this rename the new audio file with .mmv extension instead of .wav ( You may have to change folder settings for this )
5) Open MMSSTV software and set the mode to auto . Import the newly created .mmv file into it .
6) You will be able to view the image being decoded and shown ! Bravo ! You now have the image .Export it .

I have deliberately skipped certain steps which are obvious :)

Some of the pics that I obtained are given below .
Dec 20 , 2014


Feb 1 , 2015 , 19.05 IST
April 12 , 2015 




April 12 , 2015 , Partial image 


Comments

Post a Comment

Popular posts from this blog

Bias tee modification of HiLetgo RF amplifiers

Hi folks, There are some inexpensive RF amplifiers available in the hobby market by various names. They may be called LNAs, if you consider 3 dB noise figure as low noise. I purchased two of them from Amazon from a seller called HiLetgo. However documentation is sparse and the design is not all that great. People have had frustrating experiences with this type of LNA. Information regarding power supply to this board is practically non-existent, with voltage suggestions ranging from 5V to 12V ! Some even obtained the "magic smoke". Nonetheless they are reasonably cheap and therefore modifications can be done to make them useful. Let us now take a closer look at the board. Figure 1. The amplifier without any modification. Fig.1 shows the board without any modification. There are two SMA connectors and provision to externally power the board. The active element is an MMIC, with N02 as the marking. Other users have identified the MMIC as INA-02184 from HP. It seems to m...
Post a Comment
Read more

Some experiments with double balanced mixers and GNURadio

Hi all, This post is all about frequency mixing , specifically double balanced mixers using diodes or ring mixers , commonly used in communication circuits . The circuit diagram of a ring mixer is given below . (Courtesy : Radio-electronics  ) Schematic of a double balanced mixer.  As you can see , this makes use of two transformers and a four diodes . For most of the HF work , switching diodes like 1N4148 suffice . However , for better performance Schottky diodes like 1N5711 can be made use of . For more information on the working of this mixer and construction aspects , I strongly recommend the excellent video by W2AEW on ring mixers given below .  So what I wish to explain in this video is a set of experiments carried out using a double balanced mixer which I shall call DB mixer for convenience :) The test gear consists of a DDS VFO , a crystal Colpitts oscillator , a variable  power supply , CRO , RTL-SDR and the PC sound card . The software tool...
1 comment
Read more