GRBAlpha - How to use digipeater or DNxD - 02. Signal sound from GRBAlpha

I think so many HAM have heard the sound of 1200bps packet like APRS.

GRBAlpha uses G3RUH 9600bps packet. The sound is very different from 1200bps packet with your ears. You can download a wav file that I recorded a response from GRBAlpha when I transmitted a DNxD message, from here. When I recorded it, I connected my PC's sound input line to the "RX9600" output line of rear "PKT" connector of my Yaesu FT-847. The data transmitting starts at the half of this wav file. You can hear something different from FM noise.

If your TRX do not have the output for 9600bps, the sound from GRBAlpha may be heard like lower than the former one. You can download a sample wav file that I recorded the signal, that is not of GRBAlpha, received with my handy TRX, from here. The data starts at the same position as above.

You will recognize the difference of these two sounds.

When you want to decode GRBAlpha packet, you must connect your PC to a discriminator output of your TRX. You can decode packet data with the first sample wave file here, but you cannnot do with the second sample. The reason is that the high frequency is cut at the output for voice. The GFSK, like G3RUH, needs wider, for example 5kHz, band width.