Архив за 11.01.2018

Antennas • Re: LNB Power insertion

Thank you for your response, I was thinking that since the v3 official rtl-sdr dongle has an integrated bias tee, wouldn't I be able to amplify that or at least feel fairly assured that it has some sort of protection circuit in it already? I read on the user guide it has a safety device in it. Also, I may have accidentally bought 2 of those thinking they were only LNAs but they have a dc input on them. https://www.amazon.com/HiLetgo-0-1-2000 ... +amplifier. I'm sure the v3 can run this off the internal bias tee. if it's only set up for 5v maybe I can mod the other one considering it has some smas already soldered on.

Statistics: Posted by KE7EWO — Thu Jan 11, 2018 10:47 pm


Antennas • Re: LNB Power insertion

If you're okay with building something then why not build an external bias tee with 12v input yourself? A simple bias tee only consists of a capacitor and inductor.

https://en.wikipedia.org/wiki/Bias_tee

There are also several cheap external bias tees available on eBay that you could buy or copy the circuit of https://www.ebay.com/sch/i.html?_from=R ... e&_sacat=0.

Just be careful and double check that the 12V is definitely not feeding back into the dongle.

But about the 22 kHz signal, i'm not sure about that. You'd need to research the LNB and find exactly what type of control signal it needs. Then you could look at a way to generate and inject that signal. Probably there would also be a way to modify the LNB circuit itself to change the output, but I wouldn't know how.

Statistics: Posted by rtlsdrblog — Thu Jan 11, 2018 10:12 pm


RTL-SDR Discussion • Re: problem kalibrate for rtl sdr 2832 once worked in kali and win7

You mean it works fine the first time, but then the second time you try it doesn't work?

What model RTL-SDR are you using? Perhaps if you're using one without a TCXO then the offset drifts too far after having warmed up for a few minutes. That could cause Kalibrate to not find any frequencies.

Statistics: Posted by rtlsdrblog — Thu Jan 11, 2018 10:01 pm


RTL-SDR Discussion • Re: rtl-sdr CHEAP

The V3 actually has vastly less noise and spurs on VHF and above.

He might be talking about using the HF direct sampling mode which doesn't exist on the V2. Direct sampling gets you HF for free but it can be fairly noisy.

Statistics: Posted by rtlsdrblog — Thu Jan 11, 2018 9:58 pm


Comment on RTL-SDR Direct Sampling Mode by sb

Sorry forgot to do some corrections:
1) R9 is not a part of amp, but a load equivalent of RTL chip
2) forgot to put couple of load decoupling capacitors serial with R7/R8. Something 2nF .. 22nF will be fine there.

Comment on RTL-SDR Direct Sampling Mode by sb

Hi, I want to share schematics of my balanced preamp for direct sampling with (optional) Butterworth low-pass fillter: https://cdn1.savepice.ru/uploads/2018/1/11/81f91e6024e54a8f1392b8ffa4c467e8-full.png
Note, that its input impedance is ~24 Ohm

Antennas • LNB Power insertion

New forum user here,

I have plenty of clean sources of dc in the form of 5-12-13.8 regulated power supplies I've acquired over the years. I have an Avenger dual LNBF (PLL322S-2) and the RTL-SDR.com dongle v.3 I read that there is a bias t inside but it only can output 5v. Now realistically, there has to be a way with this hardware, a soldering iron, and some patience to get 12-13v to the LNB without buying anything else. I have loads of coax and rg6, crimper, f connectors, a sup-2400 (probably irrelevant). Bottom line, bare minimum instructions to get this working or a link to a CHINESE bias tee. I'm not interested in buying any of these purpose built units out of convenience, I prefer hacking together what I have. I don't need any "you could break this if you don't do it the right way" type of responses. The LNB was 5 dollars and the dongle was 20. I already have an exact duplicate v3 and a fc0012 lying around so I'm open to experimentation. I figure it's resistors and diodes since diodes only allow power to flow one way. ALSO I read that a 22khz signal is required to tell the LNBF what mixer to use or else it defaults to 9.57Ghz?
I've been playing with SDRs for a few months now (long time ham) and have successfully decoded a multitude of digital signals in both Linux and windows environments. I have a dedicated pager decoder running on a raspberry pi. I would not consider myself a "new" user as I have achieved excellent quality weather fax from NOAA sats on my home made pvc QFH (was a hell of an experience building that). I'm ready to make the jump from 854 km to 36000 km. And yes, I realize HRPT from GOES and NOAA polar orbiters (15-18-19) is L band 1698Mhz about, that also is not what I'm asking, just how to hack power into an LNB with scavenged hardware , please advise. Thank you in advance for your on-topic, prompt, courteous response.

Statistics: Posted by KE7EWO — Thu Jan 11, 2018 9:19 pm


Comment on December High Powered Rocket Flight with RTL-SDR used for GPS Measurements by Philip Hahn

Philip here! Blog post about the flight in December is here: http://sdrgps.blogspot.com/2017/12/december-flight-test.html . The GNURadio link only speaks to the earlier February flight. At the blog I have a link to the RF and receivers for people who want to experiment. If you know gnss-sdr and can advise where we might be having trouble I am all ears!

Comment on Receiving SSTV Images from the ISS with a V-Dipole and RTL-SDR by David Burnard

Very interested, as to which antenna to use with the RTL-SDRplay RSP2pro.
Many thanks
Dave Burnard G0OXI

Ask the group you can Listen to HF, UHF and VHF RTL-SDR or a better option.

Ask the group you can Listen to HF, UHF and VHF RTL-SDR or a better option.



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