Search found 106 matches

by hotpaw2
Sat Nov 16, 2019 5:44 pm
Forum: Other SDR Devices
Topic: SDRplay announces the RSPdx
Replies: 6
Views: 538

Re: SDRplay announces the RSPdx

Someone wrote: "I also compared SDRPlay with RTLSDRv3 and I didn't find any advantage of SDRPlay. " Was that comparison done for HF? And, if so, was the RTLSDRv3 in Direct Sampling mode or using an up-converter. In my experience, the Direct Sampling mode of my RTLSDRv3 unit seemed quite deaf on MF a...
by hotpaw2
Sun Nov 10, 2019 6:17 am
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 23
Views: 33991

Re: Long USB-cable vs long antenna-cable?

Don't forget that each USB hub, and its power supply, is likely an RF noise source. That can add up to a lot of ferrite toroids and beads. Or course ethernet switches and Raspberry Pi's are also RF noisy. So, like you said, it's a trade-off.
by hotpaw2
Sat Nov 09, 2019 7:03 pm
Forum: RTL-SDR Discussion
Topic: Understanding buffer size of the TCP server inside RTL-SDR
Replies: 1
Views: 148

Re: Understanding buffer size of the TCP server inside RTL-SDR

Reading from a network buffer 1 byte at a time is very inefficient and unlikely to be able keep up with the high SDR raw IQ data rates. You should instead try to read at least MTU sized buffers or larger, and check the amount actually returned by the network read() call. The RTL-SDR chip provides bl...
by hotpaw2
Sat Nov 09, 2019 6:55 pm
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 23
Views: 33991

Re: Long USB-cable vs long antenna-cable?

I think the key is that ethernet cable is both cheaper and works reliably over far longer runs than USB cable. Both types of cables can radiate RF noise, so need to be wound (multiple turns) around ferrite cores at both ends. So I use a Raspberry Pi 3 with the RTL-SDR plugged in directly into it, no...
by hotpaw2
Wed Oct 16, 2019 6:58 pm
Forum: RTL-SDR Discussion
Topic: rtl-sdr gain control
Replies: 2
Views: 322

Re: rtl-sdr gain control

It seems the R820T2 only has a fixed number of gain steps.
See the available gain table(s) in the source code:
https://github.com/osmocom/rtl-sdr/blob ... er_r82xx.c
by hotpaw2
Sun Sep 22, 2019 12:59 am
Forum: RTL-SDR Discussion
Topic: Compare field strength
Replies: 3
Views: 460

Re: Compare field strength

Depending on your accuracy requirements, the response of your SDR's RF front-end and ADC might not have a flat enough response for your needs without calibration. So you would have to calibrate your SDR over the frequency ranges of interest, perhaps with a decently calibrated signal generator and so...
by hotpaw2
Fri Sep 06, 2019 3:43 pm
Forum: Antennas
Topic: Signal Splitting?
Replies: 17
Views: 3830

Re: Signal Splitting?

For what bands or frequencies? For HF, QRPGuys sells an active splitter kit that buffers and amplifies multiple outputs. I ordered one, but haven't assembled or tested it yet.
by hotpaw2
Fri Sep 06, 2019 3:36 pm
Forum: RTL-SDR Discussion
Topic: mute on transmit
Replies: 4
Views: 546

Re: mute on transmit

Software squelch that cuts out the demodulator and/or output to the OS audio driver when the IQ spectrum is high and flat would work. I've experimented with that in some of my SDR software experiments, and it seems to work.
by hotpaw2
Fri Aug 30, 2019 6:04 pm
Forum: RTL-SDR Discussion
Topic: Showing wave form on an oscilloscope.
Replies: 5
Views: 1877

Re: Showing wave form on an oscilloscope.

You would likely need a very narrow band filter, as any antenna would likely pick up a bunch of other, stronger, VHF (and MF, HF and UHF) signals in your environment. I would be tempted to use a full-duplex SDR to downsample, filter, and then upsample the cleaned up signal for viewing with a high ba...
by hotpaw2
Tue Aug 27, 2019 6:31 pm
Forum: User Projects
Topic: Absolute FFT Beginner Project
Replies: 3
Views: 1618

Re: Absolute FFT Beginner Project

There are pointers to SDR DSP tutorials right on this site: https://www.rtl-sdr.com/tag/digital-signal-processing/ Plus more tutorials online, with source code, such as: https://www.g0kla.com/sdr/index.php The ARRL also has pointers to some resources: http://www.arrl.org/software-defined-radio Here'...