Search found 128 matches

by snn47
Wed Jan 30, 2019 6:13 am
Forum: Signal Identification Help
Topic: RFI? Or something else?
Replies: 3
Views: 3335

Re: RFI? Or something else?

A OTH can also look like the chineese OTH around 7 MHz http://www.arrl.org/news/chinese-over-the-horizon-radar-qrming-low-end-of-40-meters http://www.arrl.org/images/view/News/Chinese%20OTH-R%20on%206999.JPG As the newsletter reported: “A jumping Chinese OTH radar covered the CW DX-edge of our exclu...
by snn47
Tue Jan 29, 2019 8:16 am
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 16
Views: 8801

Re: Long USB-cable vs long antenna-cable?

Similar to Coax cable, there are high quality cable and there are cheap low quality cable, though the price of many cable may be high it is not necessarily a way to get a good USB cable. So you might have been just unlucky with the USB cable you bought. You have two (three) reasons for problems: 1. ...
by snn47
Tue Jan 29, 2019 3:02 am
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 16
Views: 8801

Re: Long USB-cable vs long antenna-cable?

I know of a max. of 40 m (~131 ft) if you cascade active USB 2.0 cables, like Delock Kabel USB 2.0 active 20 m USB cable Art.-No. 82690 price ~30 €. I used one cable with a Haupauge video grabber, but I never checked for RFI. While a USB 3.0 port is rated 900 mAh vs. 500 mA for a 2.0 port it is the ...
by snn47
Mon Jan 28, 2019 5:05 pm
Forum: RTL-SDR Discussion
Topic: Long USB-cable vs long antenna-cable?
Replies: 16
Views: 8801

Re: Long USB-cable vs long antenna-cable?

I obviously want to minimize any unwanted radio-signals, but I'm not sure if more noise will be picked up by a long USB extension or a long antenna-cable. While wavelength and therefore antenna get smaller with increasing frequency the attenuation of the cable will increase. The higher the frequenc...
by snn47
Mon Jan 28, 2019 12:46 am
Forum: Off-Topic
Topic: Freq Count and Regen Rx
Replies: 1
Views: 2983

Re: Freq Count and Regen Rx

I have never built a regen Rx, but from what I read unlike the tube designs solid state designs can be tricky even without trying to load such a circuit with a frequency counter. Maybee you should read up on regen Rx e.g. QST www.arrl.org/files/file/Technology/tis/info/pdf/9811qex026.pdf https://www...
by snn47
Thu Jan 24, 2019 11:53 pm
Forum: RTL-SDR Discussion
Topic: Will it be ok, located here.
Replies: 3
Views: 3331

Re: Will it be ok, located here.

The point of having a preamp as close to the antenna as possible, is to improve the overall noise factor of a receiving system. Any additional attenuation by a cable, (attenuation =length of cable times attenuation of cable type used in dB per meter found in the cable specs operating frequency) will...
by snn47
Tue Jan 22, 2019 2:31 am
Forum: RTL-SDR Discussion
Topic: RTL-SDL Pan Adapter - HDSDR / FTDX-3000
Replies: 1
Views: 2992

Re: RTL-SDL Pan Adapter - HDSDR / FTDX-3000

The antenna port works only about 30 MHz and up. EIthe use and upconverter or you have to use the direct sampling input. Both are explained can be found on rtl-sdr.
by snn47
Mon Jan 21, 2019 5:14 pm
Forum: Signal Identification Help
Topic: Demodulating 4LFSK
Replies: 1
Views: 3033

Re: Demodulating 4LFSK

What is a "Satelline tranceiver module"? How do you conclude that the depicted Signals form a 4FSK. Frequency distribution of xFSK are in my understanding symetrical and of same amplitude unless there is additional modulation on the FSK signal itself. Two examples for 2 and 4 FSK are shown in the pi...
by snn47
Mon Jan 21, 2019 4:06 pm
Forum: Signal Identification Help
Topic: Mystery 'drifting' signal
Replies: 1
Views: 2926

Re: Mystery 'drifting' signal

At the part of the ATC-COM band only AM DSB (25 kHz or 8.33 kHz spacin) is used so it is very unlikely usebs by civil or military ATC. While Europe is aiming to shift also for the lower airspace to a 8.33 kHz wide channel spacing the rest of the world is using 25 kHz channel spacing, Did you check i...
by snn47
Mon Jan 21, 2019 1:30 am
Forum: Other SDR Devices
Topic: Nonlinear junction detector
Replies: 4
Views: 3324

Re: Nonlinear junction detector

uses harmonic radar to detect electronics by transmitting highpower uhf 1-3.6 GHZ to specific nearfiled area. A simple explanation and DIY design can be found here https://web.archive.org/web/20130718061802/http://servv89pn0aj.sn.sourcedns.com/~gbpprorg/mil/non/ and a more detailed Tutorial here ht...