Search found 34 matches

by AD5NL
Mon Jan 09, 2017 11:25 pm
Forum: RTL-SDR Discussion
Topic: New to RTL-SDR
Replies: 6
Views: 4717

Re: New to RTL-SDR

One small correction, the v3 rtl-sdr.com dongle has direct sampling that can be enabled through software, but this is still an experimental feature.

This doesn't change my advice re: upconverter.
by AD5NL
Mon Jan 09, 2017 7:09 pm
Forum: RTL-SDR Discussion
Topic: DIY coax antenna switchers
Replies: 5
Views: 5751

Re: DIY coax antenna switchers

For receive only most switches should work. Only concern I would have would be at high UHF and above, where the switch itself is going to start to look like a significant fraction of the wavelength. Come to think of it, I might add a switch to my cross-polarized yagi project for 144 MHz, just to be ...
by AD5NL
Mon Jan 09, 2017 7:06 pm
Forum: RTL-SDR Discussion
Topic: Rtl-sdr for Ham Radio use?
Replies: 3
Views: 3514

Re: Rtl-sdr for Ham Radio use?

There are a few SDRs that *can* transmit, but not the RTLSDR. The HackRF has been out for a few years. Would not necessarily recommend for new hams because it lacks filtering and power is pretty low (I believe it peaks out somewhere around 15 dBM, which is like 20 mW). The LimeSDR should actually st...
by AD5NL
Sun Jan 08, 2017 4:21 am
Forum: RTL-SDR Discussion
Topic: New to RTL-SDR
Replies: 6
Views: 4717

Re: New to RTL-SDR

It is theoretically possible to modify most dongles to do "direct conversion", circumventing your tuner chip. I only tried this once, on a Nooelec blue, and it was a bit of a disaster. I was able to touch a wire to the appropriate pin, and pick up local AM broadcasters. But when I tried to solder it...
by AD5NL
Thu Jan 05, 2017 10:24 pm
Forum: RTL-SDR Discussion
Topic: 2ghz sampling - this is highly lossy, right?
Replies: 2
Views: 2861

Re: 2ghz sampling - this is highly lossy, right?

I did some research and I was mistaken. The 1st IF on an RTL2832U/R820T, according to superkuh, is 3.57 MHz or 4.57 MHz. The sampling rate of the RTL2832U is 28.8 Mbps, and that is where the 28.8MHz crystal clock comes in to play. (Usually a crystal on a radio board is for the LO, but in this case i...
by AD5NL
Thu Jan 05, 2017 10:09 pm
Forum: RTL-SDR Discussion
Topic: 2ghz sampling - this is highly lossy, right?
Replies: 2
Views: 2861

Re: 2ghz sampling - this is highly lossy, right?

The GHz signal is mixed with a Local Oscillator (LO) signal in a mixer stage to yield an Intermediate Frequency (IF). The IF is usually something in the MHz range. The ADC then samples the IF. This is how most radio receivers today work, including most SDRs. Some will even have multiple IFs. The "ur...
by AD5NL
Thu Jan 05, 2017 9:27 pm
Forum: RTL-SDR Discussion
Topic: Running a dongle on a networked PC ?
Replies: 13
Views: 10290

Re: Running a dongle on a networked PC ?

FWIW, I've used rtl_tcp to stream from a Linux desktop (as well as a Raspberry Pi) to a Windows laptop running SDR#.

I have always used rtl_tcp on Linux but there is a Windows build floating around of the Osmocom RTLSDR utilities. You'll need to find that to use rtl_tcp as a streaming IQ server.
by AD5NL
Thu Jan 05, 2017 9:22 pm
Forum: RTL-SDR Discussion
Topic: Running a dongle on a networked PC ?
Replies: 13
Views: 10290

Re: Running a dongle on a networked PC ?

There are a few options here, in approximately-decreasing order of network bandwidth used: 1. TCP transport of raw IQ data. You could run rtl_tcp and pipe the data over the network. Note: You're probably going to get somewhat crummy performance unless (maybe) you are using your wired gigabit etherne...
by AD5NL
Wed Jan 04, 2017 9:18 pm
Forum: RTL-SDR Discussion
Topic: Raspberry Pi Transmit Filters
Replies: 1
Views: 2713

Re: Raspberry Pi Transmit Filters

There's this kit (you'll have to do your own soldering with tiny, tiny parts): https://shop.languagespy.com/products/pi-lpf-low-pass-filter-kit-for-the-raspberry-pi They have kits for 40, 30, 20 and 17 meters. Also, LPFs are not terribly hard to build. Here is a calculator for designing a Chebyshev ...
by AD5NL
Wed Dec 28, 2016 8:20 pm
Forum: Troubleshooting Help
Topic: How do I correct all those spikes?
Replies: 5
Views: 5863

Re: How do I correct all those spikes?

Looking at your photo, it looks like you might have ferrites on your USB cable. (Good job, that is step #1). Generally you will also want to put one on your antenna coax as well, to prevent common mode interference. My standard procedure is to put one near the terminating connector and one near the ...