Search found 135 matches

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: 5988

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: 4187

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: 11
Views: 10175

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: 3
Views: 3203

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: 4871

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: 2257

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: 21
Views: 9779

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: 4112

Re: Question regarding loop designs

Any of your options as far away from the metal grid as possible would be best.
by hotpaw2
Thu Feb 06, 2020 3:58 am
Forum: Signal Identification Help
Topic: A lot of signals on 800mhz
Replies: 5
Views: 10498

Re: A lot of signals on 800mhz

Looks like a wide OFDM modulated signal. DVB-T uses OFDM.
by hotpaw2
Sat Feb 01, 2020 4:57 pm
Forum: RTL-SDR Discussion
Topic: Lots of activity on RF, is it all real?
Replies: 6
Views: 2988

Re: Lots of activity on RF, is it all real?

The periodically repeating lines in the RF spectrum waterfall are extremely likely to be just noise from the electronics and power converters in your near vicinity, in the same room or building, or near your antenna. Computers, network equipment, LED lights and USB chargers, etc.