Search found 95 matches

by snn47
Sun Jul 22, 2018 7:38 pm
Forum: Antennas
Topic: Balanced antenna for direct sampling
Replies: 5
Views: 635

Re: Balanced antenna for direct sampling

WIth a 1/2 wave dipole you only get resonance at multiples of the dipole. e.g. if it's 40m in diameter (1/2 wave for 80) m then its more or less in resonance 40m 20 m 10 m wavelength, but the antenna pattern will vary with frequency and height above ground level. Since you said you don't want to tra...
by snn47
Sat Jul 21, 2018 4:50 pm
Forum: RTL-SDR Discussion
Topic: 10 feet / 3 meters USB extension cord
Replies: 13
Views: 816

USB Filter box already offered by Würth as design kit

Würth already offers this design bag that provides you with the PCB layout and design shown in ANP024c_EN_The_USB_interface_from_EMC_point_of_view.pdf. I only wonder if replcing the plastic with a metall shield box box would not reduce RFI further. The Complete USB 2.0 EMI & ESD Solution You have tr...
by snn47
Sat Jul 21, 2018 7:47 am
Forum: RTL-SDR Discussion
Topic: 10 feet / 3 meters USB extension cord
Replies: 13
Views: 816

EMC of USB cables and extension cords

While having shielding to improve electromagnetic Compatibility (EMC) is always a good advise it is imho, if at all, hard to achieve and therefore only make believe. Unlike coax cable, you will not be able to find the necessary shielding information for USB cable or connector because the USB as syst...
by snn47
Thu Jul 19, 2018 8:57 pm
Forum: RTL-SDR Discussion
Topic: 10 feet / 3 meters USB extension cord
Replies: 13
Views: 816

Re: 10 feet / 3 meters USB extension cord

I will not recommend phone charging cables for SDR's since they have barely to no shielding.
I didn't propose to use such a cable, I was just trying to explain that cable diameter is not ameasure of resistance of the power lines.
by snn47
Thu Jul 19, 2018 4:31 am
Forum: RTL-SDR Discussion
Topic: 10 feet / 3 meters USB extension cord
Replies: 13
Views: 816

Re: 10 feet / 3 meters USB extension cord

@all Please be precise and specify if the cable you talk about are passive USB extension cables or have an active component/hub, possibly with chance to connect an external PS, I have an 30m extender Cable wo also work fine on my pc. is this a typo username, since I have never seen a USB cable of su...
by snn47
Tue Jul 17, 2018 5:02 pm
Forum: RTL-SDR Discussion
Topic: 10 feet / 3 meters USB extension cord
Replies: 13
Views: 816

Re: 10 feet / 3 meters USB extension cord

It depends how cheap the extension cable is. The Data lines should work also for longer cable, but depending on how much power is needed and how much resistance (how cheap) the power line wires are. It may or may not work, with one cable while it will not work with another. Unfortunately you cannot ...
by snn47
Mon Jul 09, 2018 8:01 pm
Forum: RTL-SDR Discussion
Topic: need to relocate RTL-SDR away from computer
Replies: 6
Views: 487

My 2 cents Re: need to relocate RTL-SDR away from computer

Imho there is a difference between - an USB cable not working for Data transmission and - an USB cable having to high resistance on the power lines in the USB cable to supply the min. input voltage needed to let the Dongle operate. A general note: In practice USB cables/hubs/extensions may (or not) ...
by snn47
Fri Jun 29, 2018 2:58 pm
Forum: RTL-SDR Discussion
Topic: Morfeus Mixer/Osc. -did anyone have the chance to measure it
Replies: 1
Views: 153

Re: Morfeus Mixer/Osc. -did anyone have the chance to measure it

The third picture show an upmix of a 1 GHz signal high gain Morfeus upmix to 6GHz with oscillating at 5 GHz.jpg The fourth picture show an upmix of a 1 GHz signal reduced gain (1) Morfeus upmix to 6GHz with oscillating at 5 GHz reduced gain-2.jpg The oscillator output was a few bit above the curve i...
by snn47
Fri Jun 29, 2018 2:50 pm
Forum: RTL-SDR Discussion
Topic: Morfeus Mixer/Osc. -did anyone have the chance to measure it
Replies: 1
Views: 153

Morfeus Mixer/Osc. -did anyone have the chance to measure it

Visiting a colleague I had the chance to do a few tests with the Morfeus Mixer using a generator an a Tectronix RSA-6100A. The first picture show the input below 20 MHz in 1 MHz steps with the oscillator at 1000 MHz. Morfeus below 20 MHz.jpg The second picture shws the oscillator set at 5 GHz genera...
by snn47
Wed Jun 13, 2018 7:23 am
Forum: Antennas
Topic: new Broadband design dc to 25 GHz to a much wider bandwidth of 10 to 110 GHz.
Replies: 1
Views: 301

new Broadband design dc to 25 GHz to a much wider bandwidth of 10 to 110 GHz.

I am not shure if one can DIY such an antenna, but it's an intersting read and could give ideas for your own antenna tests. http://www.mwrf.com/components/extending-bandwidth-elliptical-monopole-antenna?NL=MWRF-001&Issue=MWRF-001_20180612_MWRF-001_621&sfvc4enews=42&cl=article_1_b&utm_rid=CPG05000003...