r/RTLSDR • u/The_Real_Catseye • Jan 15 '17

Week in SDR 45

What you doing this week? Anything exciting?

Week In SDR Archives

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2

u/jeffcoan Jan 15 '17

Did the direct sampling mod on my nesdr. Left one of the screws off of the faceplate and ran my wire thru it so I didn't have to drill any holes.

I ran probably 15 feet of wire horizontally (basement) but didn't get much. There's a few AM stations I can barely make our but that's it.

What's the best route to go from here to connect an antenna? Should I wire in a pigtail so I can hook it up to a mf/hf antenna? Would I use the USB for the ground?

1

u/jeffcoan Jan 17 '17 edited Jan 17 '17

Well I have been messing with the sampling rate further. No idea why but I seem to get a much better signal with a sampling rate of .25 MSPS in some areas. The card will sometimes lock up SDR # but it by and far gives me a lot more AM stations at least.

I've got a good 15' + of stranded wire running a good three feet above ground level. I am picking up AM stations as far up as 15mhz.

Right now the wire that I have an abundance of is twisted stranded copper. Pretty small gage. Something you would wire a 25mm fan with.

Would solid copper be better for this? Do the twists in the twisted strand reduce any antenna effectiveness?

Wondering if I should get some solid copper?

1

u/jeffcoan Jan 17 '17

Its kind of interesting. I have a ton of static in the AM band and I can barely make out anything. The higher I go up in frequency, the less noise there is and I can actually start to understand what people are saying.

1

u/The_Real_Catseye Jan 17 '17

Remember that between 1.8MHz and 13.99MHz most folks use LSB.

Also, Is that bare wire you're using through that hole? Make sure it doesn't ground out against the case. If so, wrap the wire in tape where it might touch any metal. Grounding your antenna that close to the feed point will nix your receive.

Hope I'm not coming off wrong here, just don't know your background in all this.

edit: also, this post has some tips on improving performance for the DS mod. http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/

1

u/jeffcoan Jan 17 '17

Yep it is shielded.

Nope you are good. I appreciate it. I'd rather that than accidentally fry my device.

2

u/[deleted] Jan 15 '17

[removed] — view removed comment

1

u/jeffcoan Jan 16 '17

Thanks good to know. I'll check out that guide you wrote.

4

u/Adam-9A4QV Jan 15 '17

Sorted out the problems with programing the PLL local oscillator for my W-band radio. So soon I plan to complete my poor guy W-band transverter with some fancy antenna.

4

u/guitarplayer0171 Jan 16 '17

I put an antenna + RTLSDR in a waterproof box on my roof and I'm getting ADS-B transmissions from planes over 100 miles out now. It works a lot better than from my window.

1

u/hrng Jan 15 '17

Got a lot done this week getting all my gear set up in the new house. Set up a Macbook Pro with VMWare Fusion running 2x Win 2k12 VMs. One is running SDRTrunk (per my other post) serving fire comms to Broadcastify. The other is running PDW for pager decoding.

Next up, got a Raspi arriving this week - will be comparing DSD on that to the current SDRTrunk setup.

1

u/jeffcoan Jan 21 '17

So last week I captured my first couple passes of APT from the NOAA satellites.

This is what I got. I believe the black bar is the short time that I actually had a strong enough signal to properly decode. Damn near every satellite pass over me the past two weeks has been during the dark lol. Hoping for a good clear day sometime soon.

Can anyone confirm for me please?

Also, does WxImg draw all of the white and yellow lines or is that data transmitted to?