Search found 180 matches

by hotpaw2
Mon Feb 22, 2021 5:58 pm
Forum: Antennas
Topic: Best antenna for HF
Replies: 8
Views: 2661

Re: Best antenna for HF

Check the noise floor at your antenna location. If you can see a raised noise floor on your SDR's spectrum display when you attach a small loop antenna, then a larger quarter or half wavelength antenna won't really improve your reception. Physics says that not only will a better antenna pick up more...
by hotpaw2
Mon Feb 15, 2021 7:07 pm
Forum: User Projects
Topic: A potential work-around for multiple RTL devices with their own spyserver
Replies: 5
Views: 5101

Re: A potential work-around for multiple RTL devices with their own spyserver

My overly-simplified method of running multiple SDR dongles without any device ID issues is to use a separate Raspberry Pi for each USB dongle. I co-locate the Pi's and SDRs near my antenna distribution panel. Then I run all the networked Pi's remotely from a Mac.
by hotpaw2
Thu Feb 04, 2021 5:18 am
Forum: RTL-SDR Discussion
Topic: RTL-SDR as a down-converter?
Replies: 1
Views: 486

RTL-SDR as a down-converter?

Has any one tapped the output of the R820T2 to use an RTL-SDR as a downconverter from VHF or UHF to HF? That way one could use an HF-only receiver or direct-sampling SDR to receive higher frequencies than the receiver supports. For instance, one could use an HF SDR with a 16-bit ADC instead of using...
by hotpaw2
Sun Jan 31, 2021 4:44 pm
Forum: RTL-SDR Discussion
Topic: Major interference from computer
Replies: 7
Views: 1620

Re: Major interference from computer

You could try looping various cords and cables connected to your PC through a ferrite toroid, one at a time, and see which, if any, connector is leaking the RFI.
by hotpaw2
Sat Jan 30, 2021 7:37 pm
Forum: Antennas
Topic: Loop on ground question
Replies: 3
Views: 1073

Re: Loop on ground question

The answer (not that I know) likely depends on (1) the noise floor in your environment versus the sensitivity of your receiver, (2) the frequencies over which you wish to receive, and (3) whether you care about true omnidirectivity (versus directional lobes and nulls). Too large a loop wire length i...
by hotpaw2
Wed Jan 20, 2021 3:33 pm
Forum: RTL-SDR Discussion
Topic: Record whole bandwith spectrum and review later
Replies: 5
Views: 1545

Re: Record whole bandwith spectrum and review later

The bandwidth of the broadcast FM band is 20 MHz, or 2.4 GB of data per minute, which requires more expensive SDR hardware (Lime PCI, et.al.), and a fast computer storage system. An RTL-SDR can reliably transfer over USB 2 only about 2 MHz of spectrum, or only about 10% of the entire FM broadcast sp...
by hotpaw2
Wed Jan 13, 2021 6:47 pm
Forum: Troubleshooting Help
Topic: Has anyone managed to get a Raspberry Pi 4 working with an RTL SDR?
Replies: 15
Views: 19770

Re: Has anyone managed to get a Raspberry Pi 4 working with an RTL SDR?

Just re-compiled rtl_tcp on a Raspberry Pi 4 running the latest Raspberry Pi OS with no issues. The source code I used was from this GitHub repository: https://github.com/osmocom/rtl-sdr Since I wasn't running as root user pi, in the file /etc/udev/rules.d/rtl-sdr.rules , I had to change MODE="0660"...
by hotpaw2
Thu Jan 07, 2021 10:37 pm
Forum: RTL-SDR Discussion
Topic: HF sensitivity of Blog V3
Replies: 5
Views: 1420

Re: HF sensitivity of Blog V3

I have both, and the HF+ Discovery is a very nice upgrade over the RTL in terms of dynamic range, S/N, sensitivity, and IQ offset. The RTL-SDR is mostly for when I need frequencies outside of the range of the HF+ (6M ham band, or UHF) or a wider max bandwidth.
by hotpaw2
Thu Jan 07, 2021 5:47 pm
Forum: RTL-SDR Discussion
Topic: HF sensitivity of Blog V3
Replies: 5
Views: 1420

Re: HF sensitivity of Blog V3

Since there's no built-in LNA in Direct Sampling mode, a long wire antenna (or other large enough HF antenna) may be required to pick up enough signal. However, I've found the it's very easy for any nearby broadcast stations or other strong signals to overload the RTL-SDR V3 in Direct Sampling mode,...
by hotpaw2
Thu Jan 07, 2021 3:30 am
Forum: RTL-SDR Discussion
Topic: AIRSPY basic question
Replies: 3
Views: 886

Re: AIRSPY basic question

If it's an Airspy HF+ or HF+ Discovery, then you can use hfp_tcp (source code on GitHub) to have the Airspy emulate an RTL-SDR running rtl_tcp. And then use any RTL application that supports HF+ sample rates.