So do I buy LMR-240 or mounnt my Pi on the roof?


#1

Have 35 ft of RG6 up to the peak. I have all extra adapters eliminated. The last thing I can think of is eliminating cable loss. I prob have about 2.5 db in loss right now. I could get the RG6 down to 8’ if I roof mount the Pi. That’s in the < 1 range I suspect. Plus add on all the hassle of POE and a weatherproof housing.

or

Get 35 ft of LMR400 UF or LMR 240 and get close to that db loss? Keep all the Pi inside.

Cost is almost the same after the POE stuff, housing. Roof trip regardless.

Waste of time?


#2

I much prefer having easy access to the Pi, therefore, this would be my first choice.

As for the waste of time question, are you referring to reducing the estimated 2.5 db loss? What are your ‘numbers’ now? It may not be worth the time, effort, and expense.


#3

I average at best 450-500 msg per sec. See about 2000 planes a day. I too would rather have the Pi at hand.

Waste of time to me is doing either and ending up with same numbers (or less even - yikes). Pretty much out of options for bettering my numbers. Plus…living in the hortheast, I have to putter around before it’s cold and snowy. Soon but not yet. Few weeks til snow, etc.

Scott


#4

Looks like good numbers, but how do you compare to others in the area?


#5

Much better option than locating Pi on roof + PoE
:+1: :+1: :+1:

.

Extra $$ for LMR with advantage of only 1 dB over RG6. Your ProStick has a gain of about 18 dB, and can easily cover extra loss of 1 dB in RG6.

Cable Attenuation/100 ft Attenuation/35 ft
RG6 6.5 dB 2.3 dB
LMR 240 8.4 dB 3 dB
LMR 400 4.3 dB 1.5 dB

#6

I’m at 2,189 / 306,179 with the next best feeder nearby at 2500 / 319,000. I’m was thinking even the smallest gain(s) could help improve coverage. I will have a tree cut down in the fall ( not entirely due to its blocking my antenna :slight_smile: but so be it).

Moving the whole affair to the garage could get me maybe +10’ in altitude too. Hassle factor is high but possible. Points with wife as one antenna disappears from house.

I may be hitting the max with this setup. I have been reading that others have purchased Radarcapes and the like with not that much more improvement in coverage. It’ll be some time before I do that I suspect.


#7

I would focus on this, and be happy with the setup.

As @abcd567 mentioned, too much time and expense for basically another 1 db. A Pro Stick +, if not already used, would be a better, cheaper, and simpler option. In case you prefer to keep things separate, an RTL-SDR Blog pre-amp and filter is very good too.

Keeping the wife happy is another db plus gained right there.:grinning:


#8

Yep…I’m on FA Pro Stick Plus, Rasp Pi 3, FA antenna.

Think I’ll start working on the garage hardware, LMR 400, Pi3 + (?), whack up another N connector-based spider. Already have FA Orange and filter in stock.Combine them in my account. Can’t hurt. I’ll have a working backup/failover system too.


#9

For the 3B+, the official POE hat should be available soon (08.08.18, according to the shop linked below).

It saves some space compared to a separte POE splitter, that might be useful if you do not have much space.It has a little fan too, helping to cool the CPU, but maybe that just offsets the disadvantage of the additional heat of a PCB so close to the CPU and blocking the airflow,.

https://www.rasppishop.de/PoE-HAT-Modul-fuer-Raspberry-Pi-3-Modell-B-

Edit: shop changed availability to 11.09.18


#10

That is indeed true.

However, there’s one additonal factor to take into account. Signal to Noise Ratio.

Losses in the feed line lower the received signal-to-noise ratio: a feed line loss of 3 dB degrades the signal-to-noise ratio (SNR) by 3 dB.

An example is a feed line made from 10 feet (3.0 m) of RG-174 coaxial cable and used with a global positioning system receiver. The loss in that feed line is 3.2 dB at 1 GHz. Approximately 5 dB at the GPS frequency (1.57542 GHz). This feed line loss can be avoided by placing an LNA at the antenna, which supplies enough gain to offset the loss.

Ref: https://en.wikipedia.org/wiki/Low-noise_amplifier