md/notes/sdr/gnu_radio_receive_am.md


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title:GNU Radio Receive AM
keywords:sdr,am,demodulation,gnuradio

#

Lets listen to AM radio stations with AirSpyHF

## Frequencies

For frequencies search at http://websdr.org/ find the nearest receiver
on the map that support AM broadcast frequencies as it will give a clue
if propagation of time of the day is ok around your location.

In this example I found only few AM station in 17Mhz range at day time
to test receiver. 

## GNU Radio blocks

### Main blocks

Base blocks for the AM receiver. This blocks have 2 channels and those 
are to test switch between two radio stations.

![AM receiver blocks](/img/sdr/airspyhf_am_receiver_blocks.png)

### Block parameters

| Name | Value | Note |
| --- | --- | --- |
| band | 192000 | AirSpy samplerate, closely follows the bandwidth |
| freq | 1749000 | The channel0 stations frequency |
| f_channel0 | 0 | If the stations is there, no need to change main frequency |
| f_channel1 | 10000 | offset from the channel1 find offset from waterfall |
| fir_dec | 4 | nicely match 48kHz for audio |
| fir_bw | band/(2*fir_dec) | auto filter calculations for Xlate FIR blocks |

![AM receiver block params](/img/sdr/airspyhf_am_receiver_params.png)

Example when the blocks are running, with arranged GUI's

![AM receiver block params](/img/sdr/airspyhf_am_receiver_gui.png)

## Links

1. [http://websdr.org/](http://websdr.org/)