Search found 128 matches

by hotpaw2
Tue Apr 02, 2019 4:55 pm
Forum: RTL-SDR Discussion
Topic: quick question about RTL SDR dongle
Replies: 5
Views: 1699

Re: quick question about RTL SDR dongle

The bandwidth of an RTL-SDR is far too narrow to allow listening on two widely separated frequency bands. However your server might have enough USB ports to allow plugging in 2 RTL-SDRs, each tuned to a different band, one for 1090, the other for airband, etc.
by hotpaw2
Tue Apr 02, 2019 4:44 pm
Forum: RTL-SDR Discussion
Topic: RTL-SDR Samplerate
Replies: 2
Views: 1472

Re: RTL-SDR Samplerate

An RTL-SDR outputs 8-bit IQ components, which, at 2 components per sample, adds up to 16 bits per IQ sample. The lowest sample rate the RTL2832U supports for USB data is 240ksps. To stay under 1 a megabit network cap would require a sample rate of under 1M/16, or 62.5k samples per second (or 0.0625 ...
by hotpaw2
Tue Mar 26, 2019 7:43 pm
Forum: Antennas
Topic: Multi-purpose Dipole loose pivots?
Replies: 1
Views: 1135

Multi-purpose Dipole loose pivots?

The two longer antennas on my RTL-SDR Blog Multipurpose Dipole Antenna Kit just flop over to the side.
Can the antenna pivot points be tightened up?
If so, what kind of screwdriver (Phillips, Torx, hex, size?) should be used to tighten them?
by hotpaw2
Wed Mar 13, 2019 8:29 pm
Forum: User Projects
Topic: New SDR app for iOS (iPhone)
Replies: 5
Views: 10387

Re: New SDR app for iOS (iPhone)

An update to my rtl_tcp SDR app for iOS (iPhone) should now be in Apple's App store. https://itunes.apple.com/us/app/rtl-tcp-sdr/id1351164646?ls=1&mt=8 The rtl_tcp SDR version 1.0.7 update includes: - support for the SDRPlay rsp_tcp 16-bit mode for a better signal-to-noise ratio - a much improved co...
by hotpaw2
Tue Mar 12, 2019 5:40 pm
Forum: RTL-SDR Discussion
Topic: FM Radio reception
Replies: 7
Views: 10442

Re: FM Radio reception

The issue is likely the antenna size, orientation, and location in your dwelling. I can make some FM stations disappear just by turning the antenna on my RTL-SDR sideways. Even with more expensive rtl_tcp work-alike SDRs, such as the Airspy HF+ or SDRPlay 2.
by hotpaw2
Sat Mar 02, 2019 4:46 pm
Forum: User Projects
Topic: IQ to frequency spectrum with FFT - half of bandwidth?
Replies: 2
Views: 1987

Re: IQ to frequency spectrum with FFT - half of bandwidth?

Make sure you are sending both I and Q channels to a single complex-to-complex FFT. Use N samples of I and N samples of Q to create N complex samples for a length N FFT. Don't use 2 real-only FFTs or a complex FFT with all the imaginary components zero, instead of Q data. (Read up on complex numbers...
by hotpaw2
Wed Feb 20, 2019 12:54 am
Forum: User Projects
Topic: How exactly are the IQ channels supposed to be calculated/processed?
Replies: 2
Views: 7345

Re: How exactly are the IQ channels supposed to be calculated/processed?

Note that: (x+iy)*(x-iy) = x^2 + y^2 so a * (cos(w) + i*sin(w)) * (cos(w) - i*sin(w)) = a * (cos(w)^2 + sin(w)^2) = a * 1 = a where w = 2 * pi * f * t Both e^iw and e^-iw are used to get e^0, which leaves the original RF signal unchanged. Note that simple multiplication can be used for the first het...
by hotpaw2
Fri Feb 01, 2019 4:23 pm
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 23
Views: 36126

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

Yet another possibility for connecting to a remote antenna is to plug an RTL-SDR directly into a tiny computer, such as a Raspberry Pi 3 or Zero W, and put that near the antenna. Then run rtl_tcp on the Pi, and use either a long ethernet cable or WiFi from the Pi to connect to your router or desktop...
by hotpaw2
Thu Dec 27, 2018 5:00 pm
Forum: RTL-SDR Discussion
Topic: HF/VHF spyverter and RTL
Replies: 4
Views: 2876

Re: HF/VHF spyverter and RTL

The easiest (and close to the cheapest, since well-constructed antenna switches seem to be expensive) is to simply use 2 RTL-SDR dongles, one for each antenna. The only problem might be that the spacing of the USB ports on your computer is too close for side-by-side RTL-SDR dongles, so you'd also ne...
by hotpaw2
Sun Dec 16, 2018 7:30 pm
Forum: RTL-SDR Discussion
Topic: RTL-SDR V3 long wire problems (SOLVED)
Replies: 12
Views: 7748

Re: RTL-SDR V3 long wire problems

Try putting a 1 MegaOhm resistor between the long wire antenna and a good Earth ground.