Re: Remote SDR for MW DXing


jdow
 

Um, define what you mean by "theoretical minimum noise floor", please. The quiet areas on the Earth typically have noise levels that tend to be quite high. Atmospheric noise shows a minimum at 1.5 MHz, a peak at about 5 MHz, and drops rapidly thereafter. However, the man made noise at a quiet receiving site tends to be 45 dB to 60 dB above kTB noise at 2 MHz and 500 kHz respectively. City noise in a business area is about 45 dB higher. So you could probably gain that 45 dB back. But the rest of it is probably what anybody is stuck with at MW.

That said if you are near really high voltage power lines in a damp area the noise can, indeed, be very much higher. Even 12.6 kV has arcing problems near the ocean. In aggressively dry (most of the year) Phoenix that should not be so much a a problem. Neighbors with Plasma TVs might be worse as much power line internet tools or DSL. 70 dB above a quiet area bothers me as a concept. Antenna designs that are less susceptible to static electricity generation from breezes or winds should be explored. A good small loop antenna might worthwhile experimenting with. (And it's a shame it's socially frowned upon to use .50 caliber weapons on noisy automobiles on the roads near you.)

{^_^} Joanne

On 2017-11-04 21:44, Eric Oyen wrote:
well, depending on weather conditions, you can probably use a raspberry pie with the appropriate packages installed to act as the remote. I would recommend using ethernet cable and a 120 volt power line inside some weather shielded conduit. the enclosure can be one of several types available from Home Depot.
This setup will allow you to have the SDR right at the antenna and if the enclosure is properly shielded, you won't incur any additional noise in the antenna. you could probably get away with burying the conduit only a few inches under the turf.
I'll tell you what, I wish I had an RF quiet plot near me. I live right here in west phoenix and we have 12.6 KV overhead lines with 220 v drops to each house. HF around here is pretty noisy (at times more than 70 db above theoretical minimum noise floor. on MW, its bad and on LF (below 500 Khz, its ridiculous.  what further doesn't help my situation, is the 3 grow operations located within 500 feet of me. their grow lights pretty much wipe out everything up to the 20 meter band.
anyway, I hope some of my suggestions are usable.
DE n7zzt Eric
a totally blind ham and member of the Technomage Guild
On Nov 4, 2017, at 9:12 PM, Les Rayburn wrote:

Like many DX’ers I live in a subdivision, and the noise levels make MW DXing difficult to impossible. I have a vacant plot of undeveloped wetlands adjacent to my home that is “RF Quiet” at least compared to the rest of the area. I’ve located three different receiving antennas in this area, but then have to struggle with burying coax, putting chokes on both ends, etc..etc.

Lately I’ve been wondering about the possibility of putting an SDR receiver directly at the antenna in this area-in a weatherproof enclosure, and accessing that SDR remotely.

This area is within range of my wireless N router, and it would also be possible to run ethernet cable.

Has anyone else tried something like this? Are there guides available online to help guide someone though the process?
Any help would be gratefully accepted.


73,

Les Rayburn, N1LF
121 Mayfair Park
Maylene, AL 35114
EM63nf

Member WTFDA, IRCA, NRC. Former CPC Chairman for NRC & IRCA.

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