A couple of local operators have asked for technical details on relaying pilots talkback during the Southport Air Show through shoutcast.com
The normal rig that receives GB3OA transmissions is a Baofeng UV-3R. Its audio output is pumped through a sound card attached to a Raspberry Pi v.2. This uses the audio level controller Alsamixer program and then DarkIce to convert the analogue audio to digital and send it to shoutcast.com.
However, the UV-3R does not have AM nor airband to be able to receive the pilots transmissions. So a Kenwood TH-F7 HT will be used instead of the Baofeng. This rig has wide-band receive from 100kHz to 1.3GHz, and can receive CW, SSB, AM and wide and narrow FM. It can only transmit on 2m and 70cms, using wide or narrow FM.
A test with this rig was carried out earlier in the week tuned to Manchester Airport Area Control Centre on 128.050MHz and streamed to shoutcast.com. All worked well. The main frequency that will be used for the Southport Air Show will be 121.175MHz although other frequencies will be monitored and the TH-F7 retuned should another frequency be more interesting.
Note that once the TH-F7 is set up during this afternoon it will be left as is until the Air Show completes on Sunday at around 17.00BST. Therefore there will be no relaying of GB3OA during that period.
Also, the introductory announcement on the stream to shoutcast.com will change, to explain the new relay for those listening in worldwide.