![]() To do this, first select RTTY by choosing "Op Mode" then "RTTY" then "Custom" from the menu: Once the initial setup process has finished, you need to set the parameters of the signal from your tracker. "Stereo Mix" or "Virtual Line 1" (see for more information). For an SDR you need to select the device that you set that up for - e.g. ![]() If you are using a real radio then that is connected to the "line in" socket (or "mic" if you don't have one) so you should select "Line In". the device that it will listen to for those 2 tones. The most important setting is the audio source - i.e. It's best to use something fairly short (say max of 8 characters) as the callsign will later appear on the live map. When you first start dl-fldigi, you will be asked to enter your callsign (which could be a Ham radio callsign, or some suitable identifier (e.g. For more information about using dl-flldigi see here. So, download and install dl-fldigi from here. Of course this only happens if you publicise your flight! By using this system, you are "crowd sourcing" the reception of your balloon telemetry and live images, meaning that even if you fail to receive part of the flight, hopefully someone else will be able to fill in the gaps. The "dl" modifications upload the demodulated data to web servers which collate information from all listeners of your payload. ![]() The "dl" part of the name stands for "Distributed Listener". These 2 tones have to be converted to digital 1's and 0's - a process is called "demodulation - and this is done by a free program called dl-fldigi, which is a modified version of fldigi. The Pi In The Sky software transmits data using 2 slightly different radio fequencies, which are converted by a radio receiver (SDR or a "real" radio) to 2 audio frequencies. The SDR software (there are several choices including SDRSharp and HDSDR) can send the resulting audio signal to a "virtual" audio cable, provided by software which you need to install (see ). You get what you pay for here, and whilst the cheap TV dongles do work, the other devices are much more sensitive and will work over greater distances. Suitable SDRs include various TV dongles (see ), the Funcube Dongle, and the AirSpy unit.Once you can hear the signal, you can proceed with connecting the radio to your PC using a 3.5mm audio jack cable, and then decoding the data. With the PITS software running, you should be able to hear the transmitted data from the radio speaker, by setting SSB mode and tuning in to about 434.450MHz (default in the PITS software). The radio or scanner needs to be able to receive SSB transmissions in the 434MHz (70cm) band. Suitable real radios include the Yaesu 817, Icom IC-R10, Icom IC-R20, AOR AR8200, Yupiteru MVT-7200.Before following this section, make sure that you can receive the UHF radio transmissions, using either a "real radio or an SDR (Software Defined Radio)
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