Are there SDRs on 2m/70cm?

Discussion in 'Software Defined Radio (SDR)' started by K3RW, Aug 8, 2019.

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  1. AF7TS

    AF7TS Ham Member QRZ Page

    The 'cheap Chinese radios' use digital and dsp techniques to inexpensively provide their features. They share many features with 'true' SDR radios, with the _huge_ caveat that there is no flexibility and no way the _change_ the software. They are digital/mathematical 'firmware' defined radios :)

    I would love to see a really clean approach to 2m SDR. I'd like to play with dynamic beamforming by phasing several different units....

    K3RW and N3AWS like this.
  2. EA1DDO

    EA1DDO Ham Member QRZ Page

    AF7TS likes this.
  3. VE7BPB

    VE7BPB Ham Member QRZ Page

    John, you might like the SDRPlay RSP-DUO. Two independent receivers, phase coherent with separate antenna inputs, and the software to use it in diversity reception.

    There are some more articles on that site, just search for "diversity".

    regards, Roy
    K3RW and AF7TS like this.
  4. AF7TS

    AF7TS Ham Member QRZ Page

    Interesting. I have an RSP and like it... and on the RTL-SDR site they have their KerberosSDR which combines 4 linked RTL-SDR units. Some interesting things are happening here. :)

  5. AF7TS

    AF7TS Ham Member QRZ Page

  6. VE7BPB

    VE7BPB Ham Member QRZ Page

    The Kerberos is indeed interesting but I would hesitate to use it for HF work. The SDRPlay is much superior in this area.

    The RTL-SDR is marginal on HF, lacking filtering and sensitivity.

    I know, I have 4 of them, hi.

    regards, Roy
  7. K3RW

    K3RW Premium Subscriber QRZ Page

    Forgive my ignorance, but does diversity reception combine the reception of two antennas (like a vertical and a dipole) and come up with the combined image? Not sure how this magic works or what it is.
  8. K3RW

    K3RW Premium Subscriber QRZ Page

    That Kerberos thing is neato. Wish it wasn't just for Linux, but I do have a Raspberry Pi 3B+ so perhaps I can use that. Never thought I could do passive radar!

    When I've used the RTLs, some of them (and there are clones and bad ones out there) put a DC voltage spike center of the waterfall. It was always right there. HackRF didn't do that. And with the RTLs I've used, it really couldn't pull more than the 2MHz bandwidth with any stability--might have been my PC.

    I do wonder if having the 4 RTLs if it is still the same DC voltage spike issue, and if the bandwidth is still at 2MHz. Its more of a problem when I'd want to monitor 927 and 902/3 to see where contest operators might hang out--that a single RTL doesn't have the bandwidth to see both--though plugging in 2 seems to solve that. Same with a 432, 440, 446 spread for a 70cm contest.
  9. VE7BPB

    VE7BPB Ham Member QRZ Page

    With the RSP-DUO you can use two antennas and use the software to either add the signals together for best reception, or use one of the antennas in a subtractive mode to reduce interference.

    The video link and the other videos on the site explain all of that.

    regards, Roy
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