Search found 113 matches

by hotpaw2
Sat Nov 09, 2019 6:55 pm
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 23
Views: 34998

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

I think the key is that ethernet cable is both cheaper and works reliably over far longer runs than USB cable. Both types of cables can radiate RF noise, so need to be wound (multiple turns) around ferrite cores at both ends. So I use a Raspberry Pi 3 with the RTL-SDR plugged in directly into it, no...
by hotpaw2
Wed Oct 16, 2019 6:58 pm
Forum: RTL-SDR Discussion
Topic: rtl-sdr gain control
Replies: 2
Views: 476

Re: rtl-sdr gain control

It seems the R820T2 only has a fixed number of gain steps.
See the available gain table(s) in the source code: ... er_r82xx.c
by hotpaw2
Sun Sep 22, 2019 12:59 am
Forum: RTL-SDR Discussion
Topic: Compare field strength
Replies: 3
Views: 638

Re: Compare field strength

Depending on your accuracy requirements, the response of your SDR's RF front-end and ADC might not have a flat enough response for your needs without calibration. So you would have to calibrate your SDR over the frequency ranges of interest, perhaps with a decently calibrated signal generator and so...
by hotpaw2
Fri Sep 06, 2019 3:43 pm
Forum: Antennas
Topic: Signal Splitting?
Replies: 17
Views: 4694

Re: Signal Splitting?

For what bands or frequencies? For HF, QRPGuys sells an active splitter kit that buffers and amplifies multiple outputs. I ordered one, but haven't assembled or tested it yet.
by hotpaw2
Fri Sep 06, 2019 3:36 pm
Forum: RTL-SDR Discussion
Topic: mute on transmit
Replies: 4
Views: 760

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: 2174

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: 1863

Re: Absolute FFT Beginner Project

There are pointers to SDR DSP tutorials right on this site: Plus more tutorials online, with source code, such as: The ARRL also has pointers to some resources: 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: 3799

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: 1197

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: 3302

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. ... nformation
Ships from Israel?