Author Topic: Can someone look over -> Russian RTL-SDR USB Filter Video Review  (Read 1239 times)

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Offline Lord of nothingTopic starter

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Can someone look over -> Russian RTL-SDR USB Filter Video Review
« on: September 14, 2018, 02:49:17 pm »
https://www.rtl-sdr.com/russian-rtl-sdr-usb-filter-video-review/
So from an Technician Perspective usefull or Fontus Style?
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Offline HB9EVI

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Re: Can someone look over -> Russian RTL-SDR USB Filter Video Review
« Reply #1 on: September 14, 2018, 03:47:39 pm »
I'm missing a common mode choke in that setup; just some random inductors in the + and - rail won't block all possible noise from the PCs SMPS
 
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Online coppercone2

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Re: Can someone look over -> Russian RTL-SDR USB Filter Video Review
« Reply #2 on: September 14, 2018, 07:37:37 pm »
I got a corning optically isolated USB cable that I was going to mod to have an isolated linear battery power supply to power the thing, but I was still worried about laser-driver noise feed through. I also wondered what effect the shitty PSU computer has on the laser demodulator, if it might send a nasty pulse that needs some kind of digital filter block to be used or such that can generate a noise spike on decoding.

I am not sure what you can do to clean up the digital signal other then lowpass filtering it outside its bandwidth, since destroying its edge might have an effect.

All I can think of is schmitt triggers with high isolation after the rise, a few in series at least so the noise of the rising edge gets attenuated, but it would need to be a fast trigger.

Any idea what schmitt triggers are appropriate for USB 3 isolation to follow up with laser isolation, if you don't trust the feedthrough from demodulation on the digital pulse?

Also does anyone have any ideas if you can make yourself a fiber adapter to use with those corning connectors, so that you can make a variable length fiber channel and get rid of the isolated ground? 

Also do you think the corning cable has attenuators or laser power which are configured per cable length? I am worried if I made a short fiber adapter it might fry the recievers.
I think there would need to be some signal delay block to prevent the HF noise burst from the demodulator to go through the triggers though, so they should delay by like 1/8th - 1/6th of a clock cycle I think?

I do think that buying this would be a better idea:
http://spec.go4fiber.com/networking/gusb-xx-xxxx_20151120.pdf

Does anyone know what chips are used and stuff so you can maybe make it with a more solid ground plane part of a unit that has a nice linear regulator and some batteries etc so you can make your own thats real nice and does not have power going into the plug?
« Last Edit: September 14, 2018, 07:51:11 pm by coppercone2 »
 

Offline Lord of nothingTopic starter

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Re: Can someone look over -> Russian RTL-SDR USB Filter Video Review
« Reply #3 on: September 14, 2018, 08:35:15 pm »
@coppercone2 If you wait ~2 Weeks (quite) everything I ordered should be arrived and I will make a review.
Made in Japan, destroyed in Sulz im Wienerwald.
 


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