Search found 113 matches

by hotpaw2
Sat May 13, 2017 6:56 pm
Forum: RTL-SDR Discussion
Topic: Multiple FM station recording RTL-SDR Dongles + Raspberry pi
Replies: 5
Views: 5075

Re: Multiple FM station recording RTL-SDR Dongles + Raspberr

How many FM stations do you want to record? You might want to consider more than one Raspberry Pi (e.g. one or two RTL-SDR USB sticks per Pi), as each Pi can only supply limited power and bandwidth over the shared USB hub.
by hotpaw2
Sat May 06, 2017 6:47 pm
Forum: RTL-SDR Discussion
Topic: C++ and RTL SDR RT820T2
Replies: 5
Views: 6672

Re: C++ and RTL SDR RT820T2

I wanted to write some basic SDR DSP code in C and in Swift, and without worrying about USB drivers, hardware chip register settings, and such. So I just installed and ran the rtl_tcp utility. The rtl_tcp utility is included as part of various RTL-SDR software distributions (on github, etc.), with p...
by hotpaw2
Sat Apr 08, 2017 6:25 pm
Forum: Troubleshooting Help
Topic: IP Address Format & Source
Replies: 4
Views: 4526

Re: IP Address Format & Source

Is the RTL-SDR plugged into your PC's USB port?

Are you trying to connect from your Android phone to a server on your PC?

Is your PC running a firewall?
by hotpaw2
Sat Apr 08, 2017 6:17 pm
Forum: User Projects
Topic: Using satellite doppler effect to determine position
Replies: 4
Views: 5391

Re: Using satellite doppler effect to determine position

This requires a frequency reference much more stable than the amount of satellite doppler shift. Not sure the oscillator ppm spec on an RTL-SDR meets this criteria. Maybe by wiring in an external higher quality frequency reference?
by hotpaw2
Sun Mar 19, 2017 5:14 pm
Forum: Troubleshooting Help
Topic: "usb_claim_interface error" occurred
Replies: 9
Views: 22020

Re: "usb_claim_interface error" occurred

"rtl_test" does not work on Raspberry Pi3 properly. >usb_claim_interface error -6 >Failed to open rtlsdr device #0. I got a similar error under the latest Raspian, I found I had to change the build script to use this line: cmake ../ -DINSTALL_UDEV_RULES=ON -DDETACH_KERNEL_DRIVER=ON Not sure why...
by hotpaw2
Wed Mar 15, 2017 4:51 pm
Forum: RTL-SDR Discussion
Topic: How to count and identify carrier frequencies?
Replies: 13
Views: 8341

Re: How to count and identify carrier frequencies?

The source of the interference would be interesting. Any idea how to locate them with simple tools? If you are using a USB RTL-SDR, the simplest tools to start with to find the source(s) might be 2 cables and some ferrites. Use a USB extension cable to move the RTL-SDR as far away from any computer...
by hotpaw2
Thu Mar 09, 2017 1:27 am
Forum: Troubleshooting Help
Topic: rtl-sdr/tcp
Replies: 6
Views: 9048

Re: rtl-sdr/tcp

That error message might imply that you have a firewall enabled on the computer running rtl_tcp. You might want to look up the command to turn off the firewall for port 1234 (or whatever port you are using). One huge reason to use rtl_tcp is that opening a network socket may be far simpler than tryi...
by hotpaw2
Wed Mar 08, 2017 6:21 pm
Forum: RTL-SDR Discussion
Topic: Why does LTE use so much bandwidth?
Replies: 4
Views: 3943

Re: Why does LTE use so much bandwidth?

IIRC, LTE uses a variation of OFDM, which is the equivalent of splitting up and spreading the data out over many many channels simultaneously. That provides both bandwidth and resistance to interference and multi-path nulls, and might be easier to demodulate if have a chip that can do tons of very f...
by hotpaw2
Wed Mar 08, 2017 5:48 pm
Forum: RTL-SDR Discussion
Topic: How do I use RTL-TCP?
Replies: 10
Views: 18888

Re: How do I use RTL-TCP?

Basic use of the rtl_tcp protocol is extremely simple. Open a generic bidirectional TCP socket (default port 1234). Uplink control is by sending 5 byte units, 1 byte command, 4 bytes of data (32 bit integer in little-endian format). You can get by with as few as 4 or 5 commands. Here are a few of th...
by hotpaw2
Wed Mar 08, 2017 5:34 pm
Forum: RTL-SDR Discussion
Topic: Replace vehicle radio with rPi and RTL-SDR?
Replies: 3
Views: 3365

Re: Replace vehicle radio with rPi and RTL-SDR?

A vehicle radio has lots of front-end filtering (band-pass for the broadcast spectrum of interest) and shielding (from vehicle generated RFI and power-bus noise). Adding all that to a rPi + RTL-SDR would likely be required to get a decent signal. A cheap FM tuner hat for the rPI might be another pot...