Dreamcatcher v3.02: Feedback Thread


#463

the MK1 is completely watertight, it has an aluminum casting house inside with strong glue sealing installed (like all other LNBs what I’ve disassembled). The external plastic cover is just a 2nd protection.

Its very similar in build-up to this example: http://lnbreviews.blogspot.com/2017/04/sharp-bs1k1el100a-pll-lnb-review.html


#464

Thanks Zoltan about the watertight LNB part… Takes that out of my picture…

This just doesn’t seem right… the amperage draw. Do ya’ll agree?

Am I missing something obvious?


#465

I’m around 40m away from my satellite dishes and everything (DVB television and radio) works fine, indeed on the spectrum analyser it looks better with some attenuation. The drive from the LNB is good and in practice if the signal is there at 1m its there at the end of my wire. The LNB is actually powered close to the dish so the DC on the line is just for control. Although the developers want to get away from dishes and although it seems it works without one in terms of noise rejection from adjacent satellites a small dish makes sense. Of course there are issues with communities in the USA where all antennas are banned or people in Iran or the like who are anxious about their government - so in those circumstances a bare LNB could be great. Small dishes are easy to align. I have set up a lot of dishes and my 1.8m took a lot of effort. At that size and narrow beamwidth the fact that the satellites move around in their box and that there may be co-located satellites at a particular slot affects fringe reception. I don’t get snow, but water ingress is something to be avoided. Self amalgamating tape everywhere exposed works well. I’ve also been replacing bolts on the dishes with stainless steel ones which makes maintenance easier and they are available cheap off ebay.


#466

Good comments @jimwatt . Just one thing to consider on long coax runs — Ken and I were calculating the direct voltage (dc) losses on the the bias-t power needed for the lnb downblock electronics. It should be noted that there are radio frequency (rf) losses between the lnb and the receiving device (the dreamcatcher). I have only been considering the relatively inexpensive RG-6 style transmission coax that has a rated loss of around 6 dB per 100 feet at 1GHz

My experience has been that the “RF amplifier” in the typical lnb that we have been using is more than adequate for a 100 foot (or 500 feet) coax transmission line. My greatest need is to improve the signal to noise ratio (snr) that the dreamcatcher receiver requires — note it is demodulating a signal that is below the noise level (really incredible).

The second problem I have to overcome is pointing/aligning for both permanent and semi-fixed installations. The accuracy has been a problem for me since small 1 to 2 degree movements make a huge difference.

I really like your idea of making sure all exterior parts are stainless or exceptionally well water/weatherproofed.


#467

I received one of the remaining units Friday, after missing all the fun since the end of L-band and no longer being able to resist temptation.Thanks, Syed for the quick shipping. It’s a shame that USPS 2 Day Priority Mail from Chicago isn’t quite as efficient, taking 5 days, but that’s another matter!

Was able to quickly get it up and running using a conduit clamp lag bolted to a 2 X 4 block, which was bolted on top of a 2 X 4 post with one centered lag bolt. This allowed simple adjustment for azmulth and elevation. It was immediately apparent that the bare LNB does not provide sufficient signal at my location. I’m the balloon in the Southeast corner of NC. Only able to get SNR of about 15.5 - 16, I made a very rough cone about 6 inches long and probably 4 inches on the large end from a piece of aluminum mesh from the junk box. This gained a couple of dB and I was able to get very limited reception.

Yesterday I purchased some 1/4” hardware cloth and attempted a proper cone. After a little frustration, I decided on the square design seen in earlier posts. Thinking bigger is better, I used 5” X 2 1/4” X 9” as the size. Accurate aiming does appear critical. SNR does vary a bit, currently 9.25 - 11.5 but sometimes drops a little. May have to tweak a little more. My balloon is green most of the time. I have an old dish, but refused the urge to use it, as we know it will work. I’ve attached a picture of my cone/mount. It’s feeding the unit inside my garage through 15 meters of RG6. Having the unit directly at the LNB did not make any difference in performance. I also have a clear view of the sat between trees.

This appears to be a workable Outernet solution, just not with a bare LNB. But I am located on the outer edge, with coverage maps showing only a 48 dBW EIRP in my area.
(Edited to add last sentence.)

IMG_1388


#468

you mean the 900mA @5V? thats normal, the LNB itself draws about 300mA…


#469

My Dreamcatcher (board with LNB energized) draws 1.1 amps at 5 vdc, so that is 5.5 watts. Your meter appears to indicate 5.06 vdc and 4.554 watts which is about right. Ken


#470

what is the direct port used for on the unit… just curious…


#471

take a look at these guys… I wish I was a little more up on ghz antennas I have made quite a few but in the mhz range … http://www.wa5vjb.com/products5.html


#472

Added a little dish… works great now.


#473

Gavin,
I used an RF attenuator and one of WA5VJB’s log-periodic antennas [2100 - 11000 MHz: (2.1 - 11 GHz) ] as an antenna to transmit the 3rd harmonic from my moRFeus at 4GH to provide a very weak signal at 12GHz for a short distance (about 10 ft) as a reference signal. On the receive side, I used varying antenna configurations, different LNAs (MK1-PLL and some others), a bias tee, a lab supply and an RTL-SDR or HackRF to tune the IF.

I got my martini mixer cone up and running. I’m getting 4 - 4.5 dB gain over a bare LNB.

We’ll see how it does in the spring wind and rain here in Seattle.

I also use the WA5JVB 850 - 6500 MHz log-periodic antenna for EMI experiments.

I’m considering buying two of his new Vivaldis to add to my collection of microwave broadband antennas.

–Konrad, WA4OSH


#474

Gavin,
I suspect it’s an input into the LoRa chip directly, bypassing the L-band to 2.4 GHz up-converter on the DC board. I have not confirmed this yet. Maybe @Abhishek can give us some insight.

–Konrad, WA4OSH


#475

Anyone know if this is remotely accurate as of today?

https://www.lyngsat.com/SES-2.html

-liam


#476

Good question. I know the sx1280/1 Lora is actually a transceiver. I was hoping it could be used like the mini LimeSDR that I have been experimenting with to create a small topography network.


#477

@Abhishek, @Syed

Is there a way to view the weather device in US units (Fahrenheit and Miles per hour)? Perhaps a toggle is needed. Meters per second conversions to MPH boggle my mind, and since this sat is servicing North America, I think it would be fair to include this…


#478

Sure … Outernet is on TP-10 of the Ku transponder.
We are not watching DVB-S video, but are receiving LoRa, so the values are different for our protocol.

–Konrad, WA4OSH


#479

According to the date on the latest file, it is up to date. But I can only see the FTA video feeds on 11960 H tp 13. Some are open and others are encrypted. There are many more other transponders I don’t see, so I presume they are not broadcasting. Ken


#480

I would be nice to be able to use DC3.0 in a ham-only version of LoRaWan, It probably can receive LoRa in the 23, 13, 10 and 5 cm ham bands as it is. I wonder what it would take for it to be put into a transmit mode.

–Konrad, WA4OSH


#481

That’s my plan… use Lorawan… as I have noted in other posts, getting it to play in armbian is not as simple as I initially thought. The code is not open-source and the proprietary boards are only for sale dedicated to ISM frequencies. like 915 here is ITU region 2. I first wanted to try 2.4GHz but that is getting pretty busy. So I ordered the moRFeus to get me up into 3.3 or 5.6 GHz but I am not a microwave rf engineer (yet). So… it is a work in progress.


#482

@ac8dg any news on that flat attenna?