Search found 58 matches

by hotpaw2
Sun Dec 02, 2018 8:21 pm
Forum: Troubleshooting Help
Topic: Accessing sdr_rtl output stream programatically in a buffer
Replies: 1
Views: 203

Re: Accessing sdr_rtl output stream programatically in a buffer

The stream generated by an RTL-SDR (which can be accessed by librtlsdr) is baseband IQ data, not audio. So your best bet is the latter: a pipe from rfl_fm.
by hotpaw2
Mon Sep 10, 2018 4:55 pm
Forum: RTL-SDR Discussion
Topic: SDR - Bandwidth
Replies: 4
Views: 1393

Re: SDR - Bandwidth

Even an analog AM radio has a non-zero bandwidth, usually around 10 kHz wide. An SDR is designed and built with much wider filter bandwidths than your typical analog AM/SW radio. An SDR also uses much higher sample rates (240 ksps to 3.1 msps in the case of a typical RTL-SDR) compared to typical aud...
by hotpaw2
Sat Aug 11, 2018 5:26 pm
Forum: RTL-SDR Discussion
Topic: RTL-SDR dongle over Ethernet
Replies: 10
Views: 2850

Re: RTL-SDR dongle over Ethernet

I use a Raspberry Pi 3 to send USB data from an RTL_SDR via rtl_tcp over the network to my iPhone. If your rtl_tcp server (Raspberry Pi 3, Zero W, et.al.) can't be wired to your ethernet router, and is some distance from your WiFi access point, you could try WiFi with two directional WiFi antenna's ...
by hotpaw2
Tue Aug 07, 2018 4:36 pm
Forum: Antennas
Topic: HF Loop antenna with differential amplifier
Replies: 1
Views: 1155

Re: HF Loop antenna with differential amplifier

Small HF loop antennas are by nature narrow-band. If you remove the tuning capacitor, then that will just let whatever stray capacitances tune the antenna to some random frequency, but the antenna will still have a narrow-band selectivity, not be un-tuned or wide-band. For a wide-band HF antenna, yo...
by hotpaw2
Tue Jun 26, 2018 4:59 pm
Forum: Troubleshooting Help
Topic: problem with iSDR app on iphone X
Replies: 0
Views: 691

Re: problem with iSDR app on iphone X

The iSDR app does not appear to have been updated for iOS 11.
by hotpaw2
Fri Jun 01, 2018 3:21 pm
Forum: Troubleshooting Help
Topic: Spectrum Display Noise Floor Randomly Lowers
Replies: 6
Views: 1080

Re: Spectrum Display Noise Floor Randomly Lowers

Computer fans, power supplies, voltage regulators, plus USB, network, and video cables (especially cheap ones) can radiate a ton of broadband RF noise into a nearby antenna or unshielded SDR. Motors and LED lightbulbs in the room can be another problematic RF noise source. Nearby radio stations, as ...
by hotpaw2
Wed May 30, 2018 4:26 pm
Forum: Off-Topic
Topic: Question about frequency mixer?
Replies: 1
Views: 945

Re: Question about frequency mixer?

It's trigonometry. If you combine two frequency sinusoids by adding them, it won't mix them, you will end up with just 5 and 20. However, if you multiply two sinusoids, then this modulation will produce two side-bands. This is because of the trigonometric product-sum identity: sin(a) * sin(b) == 0.5...
by hotpaw2
Wed May 30, 2018 4:13 pm
Forum: Troubleshooting Help
Topic: Spectrum Display Noise Floor Randomly Lowers
Replies: 6
Views: 1080

Re: Spectrum Display Noise Floor Randomly Lowers

With or without the antenna plugged in? If the noise floor only cycles when the antenna is plugged in, then it could be from some periodic RF noise source in your room, building, or neighborhood.
by hotpaw2
Thu May 17, 2018 3:01 pm
Forum: RTL-SDR Discussion
Topic: Q branch
Replies: 3
Views: 903

Re: Q branch

If using rtl_tcp, you can send a 5 byte command sequence to the open tcp/ip port, with 9 in the first byte, and zeros in the following 4 bytes to disable Q-branch direct sampling.
by hotpaw2
Wed May 16, 2018 4:25 pm
Forum: Other SDR Devices
Topic: SDRplay to announce a new product at Hamvention
Replies: 6
Views: 1892

Re: SDRplay to announce a new product at Hamvention

The issue I have with SDRPlay is that I heard from other software developers that their device library either doesn't link or doesn't connect to the device on one or more recent versions of macOS or the latest Raspberry Pi OS release. Have they fixed this so that SDR software developers can write ap...