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APD

Opathy
Opathy Member ✭✭
in SmartSDR for Mac

After doing a few tests using the APD and the two tone tune function I noticed that the third order IMD appears to be worse with the APD activated.

The first screen shot the APD is off. The second screen shot is with APD activated.

IMG_2202.jpeg
IMG_2203.jpeg

Comments

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    To get an accurate picture of your transmitted signal, you need to open a second panadapter and use Full Duplex (FDX). Your transmit and receive antennas need to be different.

    I usually lower my power and transmit into a dummy load while listening on one of my normal antennas.

    There are some great videos on YouTube about using FDX to monitor your own signal.

  • K3CDY
    K3CDY Member ✭✭✭
    edited June 2025

    Len helped me out with FDX monitoring. You can also set up your mic EQ using this method. I used the procedure described HERE by NM9P (Ken Wells). This works fine on MacSSDR.

  • Opathy
    Opathy Member ✭✭

    I'll try using FDX for this and see I can duplicate the issue. I am under the belief that the panadater on transmit was indicative of your transmitted signal

  • Trucker
    Trucker Member ✭✭✭✭

    The information displayed during transmit ( spectrum and waterfall) is taken before any filters in the radio are inline. That's why it looks so bad. The signal after filtering is much cleaner. That is why it is suggested to look at your signal on a second panadapter.

    James

    WD5GWY

  • Opathy
    Opathy Member ✭✭
    edited June 2025

    Same on another pan adapter using FDX. The main pan adapter pattern is indicative of what your transmit signal looks like . It's quite evident when changing transit bandwidth. Try it as I have indicated using APD on and off. I view it all on my spectrum analyzer later today

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    can you post a picture of SSDR with both panadapters please with it failing.

    Make sure the 2nd panadapter receiving antenna is not the same as your transmit antenna. Use something like RXA.

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