Search found 109 matches

by hotpaw2
Tue Dec 03, 2019 6:10 pm
Forum: Other SDR Devices
Topic: Airspy HF+ Discovery
Replies: 11
Views: 1893

Re: Airspy HF+ Discovery

Does the Airspy HF+ Discovery have an internal Amp? Yes. I got a Airspy HF+ Discovery a few months back. For MF and HF, it works with a small loop of wire, even with just a dozen turns of wire around a ferrite rod. So it must have a pretty decent internal RF amplifier. I'm using it to stream IQ sam...
by hotpaw2
Tue Nov 26, 2019 4:23 pm
Forum: Other SDR Devices
Topic: Airspy HF+ Discovery
Replies: 11
Views: 1893

Re: Airspy HF+ Discovery

Spyverter is an upconverter, not needed with the Airspy HF+ or HF Discovery, but perhaps useful for an RTL-SDR.
by hotpaw2
Tue Nov 26, 2019 4:14 pm
Forum: RTL-SDR Discussion
Topic: RTL-SDR as a rf analyzer?
Replies: 6
Views: 331

Re: RTL-SDR as a rf analyzer?

For 60 dB or more attenuation, try transmitting into a small 50 Ohm dummy load (with the required power rating). Put another small dummy load at the end of a coax plugged into your SDR. Then experiment with how close or far apart the 2 dummy loads can be placed while still delivering sufficient powe...
by hotpaw2
Sat Nov 16, 2019 5:44 pm
Forum: Other SDR Devices
Topic: SDRplay announces the RSPdx
Replies: 8
Views: 887

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: 34272

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: 187

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: 34272

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: 370

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: 496

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: 4046

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.