Search found 127 matches

by hotpaw2
Wed Apr 01, 2020 5:18 pm
Forum: Troubleshooting Help
Topic: MacOS: Stopped Detecting Device
Replies: 3
Views: 232

Re: MacOS: Stopped Detecting Device

Did you upgrade to macOS 10.15 Catalina recently? If so, you may need to rebuild libusb and rtl_tcp (included inside Gqrx), and/or reinstall recent copies and remove all the macOS quarantine flags. The instructions on how to install libusb and rtl_tcp on a Mac here: http://www.transitiontechnologyve...
by hotpaw2
Mon Mar 09, 2020 8:06 pm
Forum: RTL-SDR Discussion
Topic: Upconverter vs. Direct Samling?
Replies: 3
Views: 2641

Upconverter vs. Direct Samling?

Has anyone done any comparison testing (noise, sensitivity, etc.) of using an upconverter, such as the new Ham-It-Up, versus using RTL-SDR V.3 direct sampling for HF?
by hotpaw2
Fri Mar 06, 2020 12:24 am
Forum: RTL-SDR Discussion
Topic: Problem in project 24/7 with RTL-SDR v3
Replies: 4
Views: 3641

Re: Problem in project 24/7 with RTL-SDR v3

rtl_fm will run on a Raspberry Pi 24/7 with very little CPU load. But you might want to put a heat sink on the RTL-SDR, plus possibly run a fan nearby, depending on ambient temperatures and air flow.
by hotpaw2
Wed Mar 04, 2020 9:05 pm
Forum: Other SDR Devices
Topic: Wideband HF SDR
Replies: 2
Views: 2469

Re: Wideband HF SDR

28 MHz of 16-bit IQ samples is nearly a gigabit/sec. Trying to find an IO interface that can handle that data rate for any length of time is non-trivial. For getting a 2 MHz bandwidth slice from a DDC, something like a LimeSDR might be suitable, especially their PCI card version.
by hotpaw2
Wed Mar 04, 2020 8:52 pm
Forum: Antennas
Topic: Static shock while connecting ground-wire to radio?
Replies: 10
Views: 5622

Re: Static shock while connecting ground-wire to radio?

Any insulated antenna can accumulate a static charge (from the wind, etc.). Just like rubbing your shoes on the carpet on a dry day can generate up to a few kiloVolts. Something like a 1 megOhm resistor from the antenna or antenna feed line to ground will help bleed off the voltage before it can bui...
by hotpaw2
Fri Feb 21, 2020 3:46 pm
Forum: Signal Identification Help
Topic: How to interpret this signal?
Replies: 2
Views: 1952

Re: How to interpret this signal?

One possibility for multiple evenly spaced carriers would be some form of OFDM.
by hotpaw2
Thu Feb 20, 2020 4:34 pm
Forum: Troubleshooting Help
Topic: Dongle unusable using long wire antenna and 9:1 ballun.
Replies: 5
Views: 3168

Re: Dongle unusable using long wire antenna and 9:1 ballun.

Looks like intermodulation from multiple very strong stations nearby. You can try an AM bandstop filter. But your location (due to building wiring, power lines, other nearby electrical equipment, etc.) might be generating too much EMI/RF noise for any HF antenna there to be usable.
by hotpaw2
Tue Feb 18, 2020 8:04 pm
Forum: Antennas
Topic: Magnetic Loop distance?
Replies: 2
Views: 1152

Re: Magnetic Loop distance?

Depends on the frequency and direction of the signal you want to receive.

Certain separation distances between 2 antennas can create directional nulls at certain frequencies (depending on how you phase the antenna's). But those distances and directions change with frequency.
by hotpaw2
Mon Feb 10, 2020 2:36 am
Forum: RTL-SDR Discussion
Topic: Beginner-Want to listen air traffic
Replies: 18
Views: 5070

Re: Beginner-Want to listen air traffic

Aircraft band is moderately wide (just above the broadcast FM band to a bit below the amateur 2M band). For all those bands, I get much better results from a discone antenna in the attic or up above the roof than from any (tuned even) monopole or dipole in the office.
by hotpaw2
Sat Feb 08, 2020 5:57 pm
Forum: Antennas
Topic: Question regarding loop designs
Replies: 8
Views: 2344

Re: Question regarding loop designs

Any of your options as far away from the metal grid as possible would be best.