Search found 147 matches

by snn47
Sun Dec 09, 2018 7:13 pm
Forum: Antennas
Topic: 1090 Antenna real or Fake?
Replies: 6
Views: 15710

Fake 1090 Antenna

There is a difference between theoretical and real meassured gain, and here it is a placebo gain to bait buyers, because you can't cheat physics. To give you an idea of the necessary size for an vertically polarized omnidirectional antenna with meassured 10 dBi gain look at https://www.kathreinusa.c...
by snn47
Sat Dec 08, 2018 7:52 am
Forum: Off-Topic
Topic: Just boring stuff above 868?
Replies: 22
Views: 39381

Re: Just boring stuff above 868?

It depends on what you find interesting, but RADAR and military are just a minute part of systems and equipment in use. Consult the ITU RR and you will find out, how many services there are abaove 868 MHz, terrestrial on land, sea airborne and in space. However your antenna needs to be outdoor, high...
by snn47
Sat Dec 08, 2018 7:44 am
Forum: Antennas
Topic: Flat Spiral Loop VS Box Loop
Replies: 1
Views: 14604

Re: Flat Spiral Loop VS Box Loop

Im am not familiar with your description flat spiral loop antenna or the box style wrapped loop antenna, can you explain them or lik to them? Do you intend to tune the antenna with a capacitor or not? Which frequency range do you want to cover with a single antenna? Only active antennas would cover ...
by snn47
Sat Dec 08, 2018 7:15 am
Forum: RTL-SDR Discussion
Topic: Monitor and detect RF signals over a longer period of time
Replies: 8
Views: 4223

Re: Monitor and detect RF signals over a longer period of time

Unless we have an idea of what type of signals you want to detect/monitor it is hard to advise. Which senitivity do you need? For all detector-sensor, SDR or Spectrum analyzer, the achieveable bandwith is limited. Which dynamic range do you need between weakest and strongest signal is radiated by th...
by snn47
Sun Dec 02, 2018 7:34 am
Forum: RTL-SDR Discussion
Topic: Search for my lost car key
Replies: 4
Views: 2996

Re: Search for my lost car key

There are car keys where you still insert the card key in the lock, which I assume has a RFID chip and those without lock and the car is unlocked when you stand in front of it, for which I assume that a different ISDN frequency is used. While I read a few articles on the attack on those cars via a r...
by snn47
Thu Oct 25, 2018 7:33 pm
Forum: Antennas
Topic: COAX Stub notch 88-108 bandstop filter for stock antenna
Replies: 2
Views: 14195

Re: COAX Stub notch 88-108 bandstop filter for stock antenna

Depends on what Parameter you need if a stub is the solution for you, since a coax stub would also attenuate the 70 to 80 MHz MHz segment somewhat to, varying on design. I'm not specific because it depends on many factors. In short a Notch filter or coax stub is a piece of cable of n * 1/4 wavelengt...
by snn47
Sun Oct 21, 2018 4:42 pm
Forum: Other SDR Devices
Topic: TV adapter brings DVB-T2 for the Raspberry Pi
Replies: 1
Views: 14581

TV adapter brings DVB-T2 for the Raspberry Pi

https://translate.google.de/translate?s ... edit-text=

However this will work only with unencrypted DVB-T2 programms.
by snn47
Wed Oct 03, 2018 5:55 am
Forum: RTL-SDR Discussion
Topic: SDR - Bandwidth
Replies: 4
Views: 4147

Re: SDR - Bandwidth

To help you get an idea what to look for There are different types of receiver designs, with and without selectivity 1. a single resonant circuit tuned to the the receive frequency and a dector diode works for AM-BC if BC stations are separated sufficiently Bandwdith and therefore receiver RF select...
by snn47
Wed Oct 03, 2018 5:33 am
Forum: RTL-SDR Discussion
Topic: AGC and rtl-sdr dongles
Replies: 3
Views: 3501

Re: AGC and rtl-sdr dongles

Receiver designs may or may not employ AGC, since as said before the dongles are designed with a specific task (DVB-T) in mind, when all DVB-T signals are strong, not changing in strength and therefore you don't need to receive weak signals in presence of much stronger signals. Lack of a large dynam...
by snn47
Wed Oct 03, 2018 4:54 am
Forum: User Projects
Topic: Potting ADS-B LNA
Replies: 4
Views: 16553

Re: Potting ADS-B LNA

You have all the advice on condensation, except for adding heating with temperature control to get rid of condensation. Keep in mind that the coax connectors are also sensitive to weather too. Consider using a bucket upside down, acting as a sleever to protect Preamp and coax connector from weather....