Search found 166 matches

by snn47
Thu May 23, 2019 9:38 pm
Forum: KerberosSDR
Topic: semi-passive radar
Replies: 12
Views: 2095

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: 1936

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: 2095

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: 1122

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...
by snn47
Tue May 14, 2019 4:38 pm
Forum: RTL-SDR Discussion
Topic: LNA power supply?
Replies: 6
Views: 1122

Re: LNA power supply?

linear regulated power supply (PS), .... They are less efficient, and run warmer, but generate almost no RF noise. I disagree just having a PS with linear regulator doens't mean that the DC-Output voltage has less noise or spikes (due to lack of isolation between AC Input and DC Output,) compared t...
by snn47
Sat May 04, 2019 10:06 am
Forum: RTL-SDR Discussion
Topic: confused: spectrum analizer and sdr
Replies: 7
Views: 1467

Re: confused: spectrum analizer and sdr

I thought that you should also keep Receiver Intermodulation (Rx-IM) in mind, meaning that not necessarily all signals that you receive may exist in the RF-Envrionment, but can be generated in your receiver. Since I just answered to another post in detail on the effects of Receiver-Intermodulation i...
by snn47
Sat May 04, 2019 9:59 am
Forum: Other SDR Devices
Topic: SDR Upgrade
Replies: 5
Views: 1836

Re: SDR Upgrade

-If i have a strong signal on a frequency, it repeats itself in many other frequencies. -a large amount of spurs in various bands (ie:around 145-160mhz) -plenty of ghost signals in the HF (13-30mhz) All of the above are most likely all from receiver (Rx) Intermodulation (IM). Even if you would spen...
by snn47
Wed May 01, 2019 8:20 am
Forum: Antennas
Topic: RG6 or RG8?
Replies: 6
Views: 1383

Re: RG6 or RG8?

While there a several RG6 type coax on the perfect vision webpage https://www.perfect-vision.com/WebStore/ProductList.aspx?pcid=159&menu=intl I could not find the number you referenced. RG-6 and RG-8 coax differs in addition to the attenuation, which depends on the dielectricum (air, foam, solid mat...
by snn47
Tue Apr 30, 2019 9:09 am
Forum: Antennas
Topic: Another Double Cross Antenna build (went wrong)
Replies: 16
Views: 3457

Re: Another Double Cross Antenna build (went wrong)

Most antenna pattern you find are calculated and are either for free space, meaning idefinetely high above a reflecting surface, or for a given height and a min. diameter of reflecting surface, normally 1/4 Lambda or more. Under any other condition reflections from any surface or object will change ...
by snn47
Tue Apr 30, 2019 8:04 am
Forum: Antennas
Topic: RG6 or RG8?
Replies: 6
Views: 1383

Re: RG6 or RG8?

There are different versions of RG-6 (foam dielectricum) and RG-8 see (solid dielectricum) https://en.wikipedia.org/wiki/Coaxial_cable, which can have mechanical problems or due to heat over time. The difference can be more than 2 dB at 400 MHz for 100 ft, and increase with frequency, but it depends...