Search found 192 matches

by snn47
Sat Aug 10, 2019 7:29 pm
Forum: Antennas
Topic: Antenna for encrypted scanner frequencies
Replies: 5
Views: 1999

Re: Antenna for encrypted scanner frequencies

For your understanding: Antenna are passive they don't care about what signals are transmitted or received by the it. It's Transmitter and Receiver that provide en-/decoding of signals. a) its illegal b) there is a reason for why its encrypt c) depending on laws of the country you try to receive suc...
by snn47
Sat Aug 10, 2019 7:23 pm
Forum: Antennas
Topic: Folded dipoles and quad loops with SDRs
Replies: 6
Views: 2247

Re: Folded dipoles and quad loops with SDRs

Those antenna types do not necessarily create a short for the DC path, but It depends on how the antenna is matched to the transmission. But mostly they do, but you can also add a a DC isolation via e.g. a HP-filter.
by snn47
Sat Aug 10, 2019 7:15 pm
Forum: Antennas
Topic: Signal Splitting?
Replies: 17
Views: 4094

Re: Signal Splitting?

As always, if you ask for advice you should explain what you need/want to do. We do not have a crystal ball to find out what you want. This is for you to decide and tell us before anyone can give you an advise. Similiar if you say I need transportaion is a motorcycle or a car sufficient, dou you nee...
by snn47
Sat Aug 10, 2019 10:28 am
Forum: Antennas
Topic: Signal Splitting?
Replies: 17
Views: 4094

Re: Signal Splitting?

Every splitter will attenuate the signal strength coming from your antenna somewhat. The more ports you want the higher the attenuation so you need to add a preamp to compensate the losses.
Search for splitter combiner and you'll find versions with e.g N or SMA connectors.
by snn47
Wed Aug 07, 2019 4:48 pm
Forum: Antennas
Topic: Folded dipoles and quad loops with SDRs
Replies: 6
Views: 2247

Re: Folded dipoles and quad loops with SDRs

Every antenna has a more or less limited bandwidth within which they function well.
Discone and Log Periodic about one octve, other antennas bandwidth depend on the operating frequency. You can consult HAM Radio literature for easy information.
by snn47
Mon Jun 10, 2019 7:33 pm
Forum: KerberosSDR
Topic: Feasibility of a Passive Weather Radar
Replies: 11
Views: 2980

Re: Feasibility of a Passive Weather Radar

For other RADARS look at radartutorial.eu and for the WSR-88D here:
http://www.radartutorial.eu/19.kartei/1 ... 11.en.html
https://www.weather.gov/iwx/wsr_88d
by snn47
Thu May 23, 2019 9:38 pm
Forum: KerberosSDR
Topic: semi-passive radar
Replies: 12
Views: 2804

GPR/WPR

Assuming "1000V" is a peak voltage (plus and minus), that is 354 Vrms and into a 50 ohm load would be 2.5 kW. According to http://www.radartutorial.eu/02.basics/Ground%20penetrating%20radar.en.html, a page I found to be correct on PSR and SSR RADAR so far, Ground Probing RADAR that use a short puls...
by snn47
Sat May 18, 2019 1:44 pm
Forum: KerberosSDR
Topic: Feasibility of a Passive Weather Radar
Replies: 11
Views: 2980

Re: Feasibility of a Passive Weather Radar

Wx-RADAR come in different forms, e.g. not only (rain)clouds but also as windprofiler. While reflection come from from clouds it does not mean that the clouds produce rain. A L- band PSR will produce diffetent cloud formations compared to a S- or C-band PSR. Also polarosatiom will change echos recei...
by snn47
Thu May 16, 2019 11:42 am
Forum: KerberosSDR
Topic: semi-passive radar
Replies: 12
Views: 2804

Re: semi-passive radar

What do you want to detect, position (distance and angle to a target) and/or speed? RADAR (Radio Detection and Ranging)is either primary (meaning you process passive echos on a target, for this you need transmitter(s) to illuminate a target to receive an echo(s)) or active using interrogations of tr...
by snn47
Thu May 16, 2019 10:47 am
Forum: RTL-SDR Discussion
Topic: LNA power supply?
Replies: 6
Views: 1598

distinctions between RF-/AF-noise/-interference -- LNA power supply?

@hotpaw2 and all One cannot judge that switching PS generates more AF/RF noise/interference than any linear regulated PS design, without having tested a PS or used it to supply a LNA. Depending on design and components used, also linear regulator circuits can generate substantial AF noise on the sup...