Search found 101 matches

by hotpaw2
Tue May 14, 2019 7:36 pm
Forum: RTL-SDR Discussion
Topic: LNA power supply?
Replies: 6
Views: 1153

Re: LNA power supply?

Yes, a linear regulator can pass supply RF noise through its transformer and drop-out impedance. But it's far less likely to generate RF noise of its own, as do almost all switching power supplies.
by hotpaw2
Mon May 13, 2019 3:40 am
Forum: RTL-SDR Discussion
Topic: LNA power supply?
Replies: 6
Views: 1153

Re: LNA power supply?

Most 12V wall-wart power supplies use switching regulated voltage converters. A consumer-grade switching voltage regulator generates tons of RF noise, possibly not even meeting FCC part 15 RF emission regulations with the most cheaply made ones. Best bet, other than a primary battery, would be a lin...
by hotpaw2
Thu May 09, 2019 8:34 pm
Forum: Troubleshooting Help
Topic: I can't hear anything on MW and SW
Replies: 14
Views: 2596

Re: I can't hear anything on MW and SW

How big an antenna?

I barely hear any signals at all below 30 MHz (in Q/Direct Sampling mode) with an indoor whip antenna.

But I do hear some signals if I connect the RTL-SDR up to a 20M long wire antenna in the back yard.
by hotpaw2
Sat May 04, 2019 7:27 am
Forum: User Projects
Topic: rtl_tcp compatible server for the LimeSDR Mini
Replies: 0
Views: 746

rtl_tcp compatible server for the LimeSDR Mini

I recently acquired a new LimeSDR Mini USB SDR module. Not much bigger than an RTL-SDR, 10 MHz to 3.8 Ghz frequency range, 12-bit sampling, full-duplex, capable of a wider bandwidth than a Raspberry Pi can use. In order to test the receive function of the LimeSDR Mini using my existing SDR applicati...
by hotpaw2
Wed May 01, 2019 3:17 pm
Forum: Troubleshooting Help
Topic: About heat
Replies: 2
Views: 618

Re: About heat

Different brands of RTL-SDR dongles seem to require different amounts of power. Some dissipate significantly more heat than others. In my experience, the E4000 dongles run cooler, and one of my smaller NooElec dongles got so hot, it burned itself out.
by hotpaw2
Wed May 01, 2019 3:13 pm
Forum: RTL-SDR Discussion
Topic: RTLSDR2832U IF bandwidth
Replies: 2
Views: 577

Re: RTLSDR2832U IF bandwidth

The 3.2 MHz bandwidth maximum seems to be a limitation of the RTL2832's back-end digital logic, not the front-end analog bandwidth or anything to do with the R820T.
by hotpaw2
Wed May 01, 2019 2:53 pm
Forum: Other SDR Devices
Topic: SDR Upgrade
Replies: 5
Views: 1956

Re: SDR Upgrade

No SDR upgrade will help with spurs if they are due to locally generated RF pollution (your digital electronics, network wiring and LED lights (etc.), or those of your neighbor's). Getting an antenna high above or well away from all this local RF noise is a better solution. You might also want to co...
by hotpaw2
Wed May 01, 2019 2:48 pm
Forum: Antennas
Topic: Who has a Discone in the Attic?
Replies: 5
Views: 1557

Re: Who has a Discone in the Attic?

Yes, I have a discone antenna in a 2nd story attic. Getting it high above ground, and also above all of the house's electrical wiring, helps a lot. It pulls in tons of VHF signals that a dipole near a ground floor window won't.
by hotpaw2
Tue Apr 23, 2019 4:12 pm
Forum: RTL-SDR Discussion
Topic: WFM Squelch
Replies: 2
Views: 626

Re: WFM Squelch

The signal bandwidth and subcarriers (for stereo, data, etc.) in WFM broadcasts interfere with the typical capture algorithms/filters used for NFM squelch. Those same capture algorithms work extremely poorly for AM.
by hotpaw2
Tue Apr 16, 2019 6:11 pm
Forum: RTL-SDR Discussion
Topic: Use demodulated signals with electronics, off-pc
Replies: 5
Views: 993

Re: Use demodulated signals with electronics, off-pc

Depends what you mean by a PC. I plug my RTL-SDR directly into a Raspberry Pi 3 B. A Raspberry has enough USB bandwidth and enough processing speed to demodulate the raw IQ data from an RTL-SDR, and to detect many types of signals. A Raspberry Pi also has digital IO pins, similar to an Arduino, to c...