Tag: radio

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Arduino AM radio transmitter

update 6/2014: audio version of the AM transmitter: https://reactivemusic.net/?p=12263

original post

http://dangerousprototypes.com/2011/10/05/am-sofware-radio-using-arduino/

Forum thread which gives a sketch to generate Morse code at 1337khz, with no additional hardware.

http://arduino.cc/forum/index.php/topic,8456.0.html

Tried this sketch and it actually works – local version is:

morse_code_AM_1337_xmtr

Instructions

  • tune AM radio to around 1337 KHz
  • Plug antenna (random length piece of wire) into digital pin 8
  • open serial port set to 9600
  • type in some text and press <return> (but not too much text at once)

Here is a link to a circuit using a crystal oscillator component and a serial port from windows computer to turn it on and off to make cw, also a suggestion (below) to expand it to use audio modulation…

http://www.instructables.com/id/Build-a-computer-controlled-radio-transmitter/?ALLSTEPS

To those wanting to send audio (as in music/voice): You will need an audio transformer. The transformer has 5 leads: 3 on left, 2 on right. The 3 lead side: connect the audio jacks ground on bottom, input on top leaving the middle lead free. The right side: batteries + supply on bottom lead, the top lead connects to the oscillators input pin. What you used as the ground should be the same. Just plug it into the computers “audio out” plug. To transmit music, play it with whatever music player you like. Plug it into a mp3 player/ipod/cd player and take it with you where ever you go. To send voice, plug mic into pc “audio/mic/line in” plug.

More details on voice modulation…

http://www.instructables.com/id/Make-a-simple-AM-transmitter/

 

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Funcube with HSM upconverter

notes

After months away from this project I am at this moment listening to 40 meter cw signals via  the High Sierra Microwave (HSM) upconverter into the funcube via Max/MSP.

The Max funcube external doesn’t provide a way to turn on the bias tee current which powers the HSM device, so… I am using this version of the FCHid software to turn on bias tee, and set LNA to 0db, while using Max to tune the funcube. This is on windows and both programs can run at the same time.

http://uk.groups.yahoo.com/group/FCDevelopment/files/FCHID/

Prior versions of FCHid don’t have the checkbox for bias tee.

Next on the agenda will be to make this work in Mac OS.

First impressions: signals seem a bit weak, although it could be atmospheric conditions. Filtering isn’t great but its adequate – it just doesn’t have the ‘punch’ you get with a good selective receiver… Which is why nobody in their right might would actually design a shortwave receiver this way.

Update: got it working on mac os using version 3.2 of QtHid to toggle the bias-t – this version is the latest as of the time of this post and was bundled with the dmg.