Are there SDRs on 2m/70cm?

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

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  1. K3RW

    K3RW Premium Subscriber QRZ Page

    Other than a Flex radio that has an option for a VHF+ SDR built-in, is there a SDR out there for 2m/432/etc.? Not considering a IC-9700. I'd like a stand-alone SDR rather than a 28MHz IF running to a 2m/432 transverter running to a 10GHz+ transverter, for example.

    I haven't seen one yet, but would like to be able to phase-lock, GPSDO, etc., on a VHF+ band when running transverters above 2GHz.
  2. W9GB

    W9GB Ham Member QRZ Page

    Not that I have seen, and likely will not exist in North America until non-FM activity increases.
    Cheap Surplus from Land Mobile Radio (LMR) market since 1950s has provided cheap FM radios for the 30 MHz to 900 MHz frequency segment.
    Europe has a larger group of radio amateurs active on VHF/UHF/microwaves (and manufacturer support). Expert Electronics, founded in 2009, is a logical company to produce an SDR, that you described.
    Expert Electronics offers SDR for multiple markets today.

    Expert Electronics
    347927, Russia, Rostov region
    Taganrog, Polyakovskoe schosse, 16-3, ABK-1, off. 408
    Telephone (Order department and technical support)
    +7 (938) 119-77-37, +7 (8634) 34-00-26

    Rostov Oblast
    Last edited: Aug 9, 2019
    AE8W likes this.
  3. W5SAT

    W5SAT Ham Member QRZ Page

    To be clear an IC-9700 is a direct sampling SDR on VHF and UHF and can be GPSDO locked either stock with a couple Hz drift or via aftermarket with no drift...
    WA0KBR and K0OKS like this.
  4. KE1L

    KE1L Ham Member QRZ Page

    Many current VHF and UHF handhelds are actually SDRs. They include some recent Yaesu handhelds and all the popular dual-band DMR radios from China. They are just not SDRs in a sense that is actually useful to hams, because you don't have access to the code or the ability to easily change it. I am not saying those handhelds are not useful radios, just that they don't deliver all the potential of an SDR to the user.
  5. AE8W

    AE8W Ham Member QRZ Page

    "I haven't seen one yet, but would like to be able to phase-lock, GPSDO, etc., on a VHF+ band when running transverters above 2GHz."

    Many xcvrs have an external connector for connecting an external clock. I have the Expert Electroncs SunSDR2 with a thermal controlled GPSDO with very clean sidebands (a few hundred $ don't remember exact & the guy in the UK doesn't make anymore). Nice is knowing the freq is always dead nuts on and to some rediculous ppm after a few hours. Ergo, a xvrtr is about as close as money can buy on a ham budget.
  6. K3RW

    K3RW Premium Subscriber QRZ Page

    On the stock IC-9700 on 1.2GHz the drift was horrible. With the firmware upgrade, its a lot better than it was. That's even GPS locked.

    This presentation isn't very good. But towards the end he talks about how they added PLL and what it comes out with in the end. Its something this almost $2k box should already have IMO.
  7. W5SAT

    W5SAT Ham Member QRZ Page

    No, they are not SDRs in any sense of the word. They are just radios on a chip.

    An SDR will sample the RF using an ADC then perform the radio functions (filtering, demodulation, etc) on the sampled data and do that in reverse on TX. The Yaesu and China radios are NOT that.
    Last edited: Aug 11, 2019
    K2NCC likes this.
  8. W6RZ

    W6RZ Premium Subscriber QRZ Page

    I have to agree with KE1L. The chip looks very much like an SDR to me.
  9. W5SAT

    W5SAT Ham Member QRZ Page

    I see an ADC and DAC but I assume that is just for in and out of the DSP - presumably at baseband frequency ranges. I'm assuming that is a simple direct conversion receiver like most of the China radios (and cheaper Yaesus) are.

    I'll be the first to admit I am no expert on this and I am making some assumptions and am happy to be educated on the subject - However, I stand by assertion that it is quite a stretch to call these an SDR. From a performance perspective these radios on a chip are going to be out-performed by a superhet receiver let alone a real SDR radio.

    I think the topic has diverged a bit. The OP seems to want a 2m/70cm SDR but APPEARS to not be willing to consider the IC-9700 because he referenced a 28 MHz IF with transverters - presumably not realizing the 9700 is direct sampling up to UHF.

    The frequency drift is a non-issue. Yes - I own a GPSDO locked 9700.
  10. W6RZ

    W6RZ Premium Subscriber QRZ Page

    You're overlooking the I and Q ADC's in the block diagram. The chip is a classic digital direct conversion SDR architecture on receive. On transmit, it's so easy to generate FM that they just modulate a VCO.

    Digital direct conversion is a very common SDR architecture. Even $12,000 professional SDR's like the Ettus N320 use direct conversion. This SDR is used for 5G development and can transmit and receive 200 MHz wide signals.

    WA0KBR, KF4VAR, EA1DDO and 1 other person like this.

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