Messages

196

SDR - Software Defined Radio / generating waterfalls from rtl_power?

« on: June 12, 2018, 1534 UTC »

Hi all.  I'm looking for mac software to generate waterfalls from rtl_power that are more interactive than some of the unix packages.  The rtl_power software instructs a RTL-SDR stick to perform a power scan across a frequency band and log the data in a csv file:
(date, time, Hz low, Hz high, Hz step, samples, dB, dB, dB, ...).  There are several ways to generate a heatmap from this data, but the ones i've gotten to work are all static...that is they generate an image file and you have to estimate the frequency of any 'blips' you see in the data, and you can't subtract out a background scan to account for computer noise and noise from the RTL-SDR itself.

Any suggestions?  Thanks!
Robert

p.s.  what i'd REALLY like to do eventually is have the RTL-SDR act as a reactive tuner for another SDR....

197

SDR - Software Defined Radio / Today’s silly sdr question...rtl_power and SDRs

« on: June 03, 2018, 0217 UTC »

So bear with me...it’s my understanding that you can get a very broadband spectrum from a RTLSDR stick because rtl_power very rapidly samples a 2MHz chunk of spectrum and then moves to the next one and so on to the tune of ~80MHz/s.  Shouldn’t it be possible to do the same thing with a higher end SDR (an Afedri, for example?). I’m surprised i haven’t seen this in any SDR software since it’s very useful for finding sporadic transmissions.....

198

Equipment / Re: Crossed Parallel Loop Antenna

« on: April 22, 2018, 2321 UTC »

Would it work stuck up against the side of a building, I wonder?

199

Equipment / Re: Electronic Dog Fence Wire as Antenna

« on: April 22, 2018, 0132 UTC »

Just discovered an invisible pet fence installed by the previous owners of my house. I'm going to check for continuity, but if its still in one piece I'm going to see what happens when used as a "Loop UNDER ground" antenna....

200

Equipment / Re: oh masters of the RF circuit..have pity on my dual notch filter

« on: March 01, 2018, 0040 UTC »

Just for peoples' amusement. On the left, the parallel tuned wave trap for 820kHz.  On the right, the series tuned wave trap w/ an adjustable coil.  Neither did much, if anything 

201

Equipment / Re: oh masters of the RF circuit..have pity on my dual notch filter

« on: February 28, 2018, 2026 UTC »

Well my first attempts at building notch filters left much to be desired. Tried a series tuned wave trap w/ a tunable coil and a parallel tuned wave trap specifically for 820 kHz.  Didn't see any attenuation, either alone or in combination w/ my BCB high-pass filter.  Could be the cheap Amazon components (fixed value inductors & capacitors), could be my questionable wiring skills, could be the antenna is boosting the broadband signal coming in to a point where i can't notch it out.  Oh well... I don't think i'll quit my day job just yet. 

202

Clandestine Stations / Re: Denge Welat 7320 AM 2131 UTC 21 Feb 2018

« on: February 24, 2018, 1711 UTC »

I'm basing the ID off the SW schedule Chris provides in DX Toolbox.  Looking at the transmitter location in DX Toolbox and for Radyoya Denge Kurdistane (from Short-wave.info) it looks like a match for location and frequency.....

203

Shortwave Broadcast / R.VERITAS ASIA 15355kHz 2209 UTC 21 Feb 2018

« on: February 21, 2018, 2209 UTC »

Way down in the weeds (S2-ish).  Able to catch a word here and there. 

204

Clandestine Stations / Denge Welat 7320 AM 2131 UTC 21 Feb 2018

« on: February 21, 2018, 2135 UTC »

Signal down in the S2 range; can barely make out words.  No music....

205

Shortwave Broadcast / BSKSA 9555kHz AM 2116 UTC 21 Feb 2018

« on: February 21, 2018, 2118 UTC »

333.  Solid if a little weak and some minor fades.  Weaker but much more intelligible than the broadcast on 9870kHz.

206

Shortwave Broadcast / MWV Light of Life 11610kHz AM 2104 UTC 21 Feb 2018

« on: February 21, 2018, 2106 UTC »

Coming in like gangbusters solid S7 peaking to S8 with very little static.

207

North American Shortwave Pirate / Re: UNID 6925 AM 2046 UTC 21 Feb 2018

« on: February 21, 2018, 2048 UTC »

Fading in and out here.  Thought i was imaging things for awhile.

208

Equipment / Re: oh masters of the RF circuit..have pity on my dual notch filter

« on: February 21, 2018, 1517 UTC »

No, trying to notch out 700kHz and 800kHz in order to deal with the high power BCB stations near my house that are overloading my receiver.  If possible i'd like to target those two frequencies as they bleed through the high pass filter I already have. 

Perhaps I could either 1) make two filters and separate w/coax (which would give the resistance you pointed out), or 2) put a metal shield between the parallel trap and the series trap and connect them with coax (or maybe a 50 ohm resistor if i can brainstorm a way to do that inside the can). 

209

Equipment / Re: Best broadband receiving antenna below 500khz (longwave, NDB, DGPS)

« on: February 21, 2018, 1452 UTC »

I had pretty good luck with NDBs using my H-800...but that was with my PCR-1000, not the Afedri (which is sensitive to BCB overload).  Might be worth looking at LF Engineering's dedicated LF antennas, depending on your receiver.

210

Equipment / oh masters of the RF circuit..have pity on my dual notch filter

« on: February 19, 2018, 2046 UTC »

Hi folks.  i'm putting together a notch filter to deal with the two BCB hotties within about 10km of me.  I think i've done the math right and can figure out the necessary components.  Since there are two frequencies I need to notch, i'm going to set up a series tuned trap for one and a parallel tuned trap for the other.  I was thinking i would put these both in my extremely fancy project box (aka mint tin); are there any interactions or pitfalls i need to worry about?  The fine tuning will be done with a shielded tunable inductor (one on each trap) instead of a variable capacitor mainly because i couldn't find a small variable capacitor in the range i needed....

Thanks!
R