RX-888 report: usable BW

[NO6B]

This is more or less a mirror of my recent post to io.groups.

My RX-888 just arrived today. Had to download the drivers (actually the whole SDK, which includes the drivers for several OSs) from the Cypress website, as the Win10 drivers don't work on Win8.1. Similar to David GM8XBZ's experience with his i5, I'm having issues with BW settings over 2 MHz. My system is an i7-4770 with integrated graphics (no CUDA). It still works well up to 4 MHz, though stutters a little, but 8 MHz lags badly & is unusable.

Early indications are that the phase noise @ UHF is excellent. Looking at the output of my HP8640B I saw some strange sidebands starting +/- 30 kHz out from the carrier. Turned out those are intermodulation of the signal coming from fluorescent lights in the shack; if I turn off the lights those sidebands disappear. Impressive!!! Now if only we can get this thing to work @ 8 MHz BW.

Bob NO6B

[Max]

Hi Bob

Hope you do not mind me asking, but why Win 8.1 when upgrade to Win 10 can be done for free? Think all will agree it's an improvement and even more stable.

73

Max

[NO6B]

I've used both Win 8.1 & 10. I initially stayed away from Win 10 because of reports of forced updates, though now I think that issue can be adequately managed. So at this point I'm leaving 8.1 on this system due to the large amount of apps I have & the risk of breaking some of them. Also 8.1 has been extremely stable - I don't think I've ever seen a BSOD on this system. I have a laptop with Win 10 on it but I don't think it's as powerful as this PC.

I can see that I'm starting to hit processing limits on this system. When I run SDRC w/5 RXs on an RSP1a, ADSBSpy on an R2, Virtual Radio Server & an ATSC dongle I get close to 100% on the CPU meter. Obviously when I test the RX-888 all those other programs are closed. So it's probably time to start building a new system & of course that one will be Win 10. But in the meantime I hope I can still use the RX-888 at reasonable bandwidths.

BTW I forgot to mention: in the above screencap I posted the RX-888 had an SMA whip attached to it, so coupling to the HP8640B was through the air, not via coax, & of course the CFL lights were nearby.

[NO6B]

Also BTW here is a screencap of my RSP1a receiving the same signal from my HP8640B. Aside from the tiny bumps @ +/- 40 & 80 kHz from the carrier there is no change when I turn the shack lights off (you can see the small change in the waterfall as I turn the lights off & on just before I took the pic). THIS is just one reason why low phase noise is so important, & why I'm so excited to switch over to the RX-888.

[NO6B]

Further update: I tried enabling OpenCL on my onboard Intel graphics. That got 8 MHz working, though sometimes it lags a little. Now tried 16 MHz: still works, though the stuttering is back. At 16 MHz you can clearly see the bandwidth limitation of the R820T2. I'd say if you don't mind a little degradation at the edges you can stretch it to about 9.5 MHz.