Search found 109 matches

by hotpaw2
Fri Sep 06, 2019 3:36 pm
Forum: RTL-SDR Discussion
Topic: mute on transmit
Replies: 4
Views: 619

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: 2004

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: 1709

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'...
by hotpaw2
Sat Aug 24, 2019 6:10 pm
Forum: Antennas
Topic: antenna related information and guidance for asking questions to improve chances for an answer
Replies: 6
Views: 3041

Re: guidance for asking antenna questions improves chances for an answer -proposal for a sticky post

Other important antenna issues might involve the possible need to get the antenna far away from any local RFI/EMI noise sources (PC, LED lamps, power supplies, etc.), and possibly the use of choke baluns to prevent coax/feedline problems (picking up local EMI/RFI, changing the antenna pattern, etc.)
by hotpaw2
Sat Aug 24, 2019 5:56 pm
Forum: RTL-SDR Discussion
Topic: Data buffering of rtl_tcp programm
Replies: 1
Views: 1119

Re: Data buffering of rtl_tcp programm

There are multiple buffers involved. All of them add latency. The RTL chip will buffer IQ samples (sometimes close to 1 seconds worth) before sending them over USB to the Raspberry Pi server. On the Pi, the USB driver and rtl_tcp buffer what they receive over USB before sending the data over the net...
by hotpaw2
Mon Aug 12, 2019 2:20 pm
Forum: Other SDR Devices
Topic: Any good full-duplex SDRs?
Replies: 8
Views: 2932

Re: Any good full-duplex SDRs?

Has anyone here tried an Afedri SDR?
Looks interesting. Appears to be full-duplex. Direct Sampling. Comes with Ethernet support built-in.
http://www.afedri-sdr.com/index.php/ord ... nformation
Ships from Israel?
by hotpaw2
Sat Aug 10, 2019 6:06 am
Forum: Other SDR Devices
Topic: Any good full-duplex SDRs?
Replies: 8
Views: 2932

Re: Any good full-duplex SDRs?

The LimeSDR Mini is available from the CrowdSupply online store: https://www.crowdsupply.com/lime-micro/limesdr-mini I had no problems ordering one, just like from any other online store. The unit arrived about a week after ordering, and worked right out of the box. The LimeSuite software library fo...
by hotpaw2
Fri Aug 02, 2019 10:09 pm
Forum: User Projects
Topic: I need some advice in creating IQ processing software
Replies: 5
Views: 1522

Re: I need some advice in creating IQ processing software

A few million IQ samples per second isn't really fast on any modern CPU (including those on mobile devices and Raspberry Pi's) which can perform Billions of floating point operations per second. You may have to use a moderately optimized FFT library, but there are many libraries (other than FFTW) av...
by hotpaw2
Fri Jul 19, 2019 2:36 pm
Forum: RTL-SDR Discussion
Topic: Data buffering of rtl
Replies: 3
Views: 1021

Re: Data buffering of rtl

Even a Raspberry Pi 3 running rtl_tcp doesn't buffer 5 seconds of data on a fast network. Depending on the sample rate, maybe 1 second or less, mostly from the USB transfer bursts. The SDR software maybe needs to buffer another half second, depending mostly on network and OS latency jitter. Audio ou...
by hotpaw2
Mon Jul 15, 2019 4:56 pm
Forum: Off-Topic
Topic: What (besides sw compatibility) is needed for SDR?
Replies: 2
Views: 1239

Re: What (besides sw compatibility) is needed for SDR?

USB hardware devices are allowed by the USB spec to have completely different profiles. Just because the connector looks the same does not mean that the profile supported is the same. A USB flash drive is quite different from a USB audiophile DAC. Different USB profiles. And you can only communicate...