Search found 136 matches

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: 9317

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: 1706

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: 6775

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: 6775

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: 6
Views: 4632

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: 2
Views: 1734

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: 3241

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...
by hotpaw2
Sun Jul 14, 2019 4:12 pm
Forum: Other SDR Devices
Topic: SDR radio kits to assemble?
Replies: 2
Views: 3219

SDR radio kits to assemble?

Are there any electronics kits available, requiring assembly from schematics, PCB(s) and components, for SDR experimentation? Or do all the surface-mount components required make this too difficult?
by hotpaw2
Mon Jul 01, 2019 4:26 pm
Forum: Troubleshooting Help
Topic: Spikes on HF frequency
Replies: 8
Views: 4434

Re: Spikes on HF frequency

Those periodic spikes and waves look like the symptoms of electronic switching RF noise. This kind of RF noise can be generated by LED lights, power supplies, network equipment (cable modem, WiFi/ethernet hubs, etc.), PCs, monitors, printers, and etc. Not only in your place, but from inside any near...
by hotpaw2
Mon Jul 01, 2019 12:38 am
Forum: Troubleshooting Help
Topic: Has anyone managed to get a Raspberry Pi 4 working with an RTL SDR?
Replies: 13
Views: 12563

Re: Has anyone managed to get a Raspberry Pi 4 working with an RTL SDR?

A bunch of us are probably still waiting for more Pi 4's to be in stock and ship.