Receive Eggtimer data with SDR

[JoeTekcor]

I just picked up a RTL-SDR dongle and I've been playing with various signals. I've also been a long time Eggtimer user.
I have working LCD receivers but I wanted to play around with using the SDR dongle to pick up and decode the signals from the HM-TRP transmitter on the Eggtimer modules. Maybe work on my own software to display live telemetry and GPS info.

I was able to use SDR++ and see the signal.

I've been trying to follow some of the other posts using rtl_fm ported to multimon_ng but I'm not decoding anything so obviously I'm not doing something right.
From what I can tell the transmitter uses FSK modulation.
Has anyone done this?
Can someone point me to any sources to help figure this stuff out?

Thanks!

 

[cerving]

Looks like your center frequency is 440.450, try FSK with a 25 KHz deviation and a 100 KHz bandwidth. YMMV... I have not tried decoding it with my RTL dongle either (although they are very useful for finding potential sources of interference).

 

[JoeTekcor]

With the holidays over I'm only able to work on this about an hour each evening. I was using the Universal Hacker Radio software last night to look at the signal. I was able to get some data that looked correct, but mixed with a lot of garbage. I just need to continue playing with it.

I'm using the 100k bandwidth but I'm not sure what to use for the sample rate. I know the serial connection of the Transceiver is 9.6k.
Do you know if the transmission sample rate is the same?

 

[cerving]

With the holidays over I'm only able to work on this about an hour each evening. I was using the Universal Hacker Radio software last night to look at the signal. I was able to get some data that looked correct, but mixed with a lot of garbage. I just need to continue playing with it.

I'm using the 100k bandwidth but I'm not sure what to use for the sample rate. I know the serial connection of the Transceiver is 9.6k.
Do you know if the transmission sample rate is the same?

Yes, 9600 baud. Try cutting the bandwidth down to 50 KHz, too.

 

[OverTheTop]

Since you have a SDR, are you aware you can receive GNSS signals and decide them to position? I am looking at recording them during flight and post processing to get around the regulatory limits.