Search found 178 matches

by hotpaw2
Wed Dec 30, 2020 7:13 pm
Forum: Other SDR Devices
Topic: FunCubeDongle
Replies: 4
Views: 1132

Re: FunCubeDongle

I have a FunCube Dongle Pro+ that I acquired about 7 years ago. According to http://www.funcubedongle.com/?page_id=1225 , FCDP+ units did seem to be still available for purchase earlier this year. The basic API seems to be to use USB HID commands to set the frequency, and then it shows up as a 192k ...
by hotpaw2
Wed Dec 02, 2020 6:22 pm
Forum: RTL-SDR Discussion
Topic: Understanding hetrodyning complex values in gnuradio
Replies: 2
Views: 948

Re: Understanding hetrodyning complex values in gnuradio

Any non-zero strictly real signal is really two signals in the complex frequency domain, a positive spectrum signal, and a complex conjugate negative spectrum signal. They have to be complex conjugate pairs for the imaginary part to cancel out, and result in anything strictly real. If not, you get l...
by hotpaw2
Sat Nov 28, 2020 7:26 pm
Forum: Troubleshooting Help
Topic: RTL-SDRv3 vs Nooelec NESDR Mini2+, trouble picking up FM Radio broadcast
Replies: 2
Views: 1163

Re: RTL-SDRv3 vs Nooelec NESDR Mini2+, trouble picking up FM Radio broadcast

There perhaps might be some differences in build quality and manufacturing variation. I noted the exact opposite temperature problem with my two specimens, a narrow Noolec and an RTL-SDRv3. The Noolec dongle got very hot and eventually burned itself out. Whereas the RTL-SDRv3 has currently been runn...
by hotpaw2
Thu Nov 19, 2020 9:55 pm
Forum: User Projects
Topic: Ideas for new projects?
Replies: 4
Views: 5852

Re: Ideas for new projects?

One interesting project for the RSPDuo is active noise cancellation. A lot of people have problems with interfering RFI noise covering up more interesting signals. With two antennas and two receivers, one can try experimenting with phase cancellation of various outside RFI noise sources.
by hotpaw2
Sat Nov 14, 2020 2:46 am
Forum: RTL-SDR Discussion
Topic: What is simplest software that will direct sample with an appropriate sample frequency?
Replies: 5
Views: 1391

Re: What is simplest software that will direct sample with an appropriate sample frequency?

It's not a software issue. It's a hardware interface issue. The RTL2832 chip in the RTL-SDR directly samples at 28.8 MHz, but it can't send that much data across its USB 2.0 port. So the chip mixes down to baseband and filters a slice of the full directly sampled spectrum, to just 240k to 3 MHz IQ s...
by hotpaw2
Mon Nov 02, 2020 1:56 am
Forum: User Projects
Topic: Low frequency SDR spectrum analyzer
Replies: 5
Views: 2072

Re: Low frequency SDR spectrum analyzer

Airspy provides an open source library on GitHub for the HF+ and HF+ Discovery. If you do Android development, you might be able to build an Android version of the library (libairspyhf) and connect it to hfp_tcp (also open source on GitHub). hfp_tcp will allow any RTL-TCP app that supports the AirSp...
by hotpaw2
Mon Oct 26, 2020 9:14 pm
Forum: RTL-SDR Discussion
Topic: Hard Question: Is it worth all the headaches?
Replies: 6
Views: 1984

Re: Hard Question: Is it worth all the headaches?

Methinks the problem isn't with the inexpensive SDR hardware, but with overly complicated software that isn't written for humans on top of crummy OS installations. I've had better luck running rtl_tcp on a Raspberry Pi, and then use an Android or iOS app to connect. Also, some of the cheaper RTL-SDR...
by hotpaw2
Sat Oct 24, 2020 5:28 pm
Forum: RTL-SDR Discussion
Topic: Newbie Question: Computer System Requirements
Replies: 5
Views: 1456

Re: Newbie Question: Computer System Requirements

The requirements for merely showing that an RTL-SDR works are very low. Even an old Raspberry Pi 2 is plenty fast enough to run simple SDR code for a 240k wide spectrum and do some airband (etc.) scanning. I use a Raspberry Pi 4 for WSPR decoding, which requires a bit more CPU performance. However, ...
by hotpaw2
Fri Oct 16, 2020 8:38 pm
Forum: RTL-SDR Discussion
Topic: Direct sampling to bandwidth output, how done?
Replies: 10
Views: 3787

Re: Direct sampling to bandwidth output, how done?

What is your exact question that isn't already in the current answers? Basic preliminary concepts (can be google'd) to study include heterodyne mixing, filtering, and resampling. Do you understand any of those terms or concepts? If not, the answer might better fit in a basic DSP textbook or tutorial...
by hotpaw2
Mon Oct 12, 2020 10:48 pm
Forum: RTL-SDR Discussion
Topic: Help understanding use of "Upconverter"
Replies: 5
Views: 1491

Re: Help understanding use of "Upconverter"

Yes. The manufacturers description is technically correct, but confusing and not useful. It can pass-thru signals that you can't use (with a basic RTL-SDR).