Changing Spreading Factor / Beam Type

#1

We will be conducting reception tests with lower gain antennas. This will require changing Beam Type to 55. I’m not planning on this being a permanent change. It’s mostly to test reception with various LNBs without a horn. One antenna, for example, will be a Bullseye that is cutoff just below the corrugated horn. Another will be with just the monopole feeds of the LNB. And we also have an old internally designed LNB with coin-sized patch antenna (single element).

The LoRa parameters will change to SF12 and CR7 (4/8 long interleave code rate). The bandwidth of 200 kHz will remain the same. These changes will result in a gross throughput of 230 bits per second. That is not a typo.

This testing will take place next week.

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#2

Ist this only on SES-2 or also on Astra 3?

1 Like
#3

It will be on both, in case anyone wants to fiddle around with their own antennas.

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#4

That is very very very very very … very very … very very slow :slight_smile:

But let’s see what we can get from that in terms of signal strength, could be interesting!

#5

Reception at even lower SNR will be possible, if using a bare LNB.

#6

This is happening now.

#8

We are using Coding Rate of 4/8 and Spreading Factor of 12. This maps to beamtype: 55

#9

I can definitely see the slower packet rate. This is after I changed the beam type.

Screenshot 2022-05-17 190509
Screenshot 2022-05-17 1905092046×1390 112 KB

#10

Now you can start experimenting. Probably the easiest way to experiment is using a bare LNB and then slowly pointing away from the satellite. These new settings should allow reception at around -19 SNR. You might be able to point the LNB straight up and still pick up a packet or two. Maybe.

#11

I changed my configuration just now to Beam type 55 on SES-2 and am up on the air with my 80 cm dish. So far no downloads are coming in. I’ll reconfigure with just a bare Bullyseye and get you a report. Ken

image

#12

I wouldn’t be too concerned with the downloads. This is just reception-testing, so it’s best to focus on the SNR and Valid Packets.

#13

Can you bottom line this for me? Does this effect the DC 3.05 and should I change the settings? I’m using a dish. Or should I not bother with any of this as this is only temporary, and things will return to normal?

#14

Here’s my Status screen with bare Bullseye - -

image

with this LNB setup Ken

LNB Bare

#15

Here’s Status screen again for the bare LNB just sent -

image

#16

@Cheaha This is purely for experimental purposes. What we want to understand is the lowest possible SNR that provides reliable file delivery and then testing progressively lower-gain antennas. No need to do anything if you are not interested. Everything will be back to normal next week.

#17

@kenbarbi Can you point your LNB away from the satellite? I’ll eventually be doing the same, but it’s raining today. Alternatively, it might be possible to receive indoors through one wall.

#18

Here’s the same set up with aluminum horn - -

image

cone

#19

OK - - I’ll do it without the horn. Ken

#20

No go for me. I have a digisat satellite finder that I used to point my dish. I hooked that up to the bare lnb and checked a few places around my backyard and did not get enough signal from any satellite. So only testing with a dish for me.

#21

Here you go - - no horn - - I can take the beam aim from optimum for my location of 207 deg Mag to 189 to 225 deg (plus or minus 18 degrees) and still have lock in that range as shown here but a bit more and SNR drops below -20 dB - - this screen shot is right before SNR goes South at 189 degrees. At that point, I get SNRs below -20 dB and no lock, but still have respectable Rssi levels. Ken

image

PS - - The Packet Errors are an accumulation of my LNB movements, If I reset my DC after each LNB move, I’d get 100% each time, but didn’t do that here for my pictures.

Also, I’m leaving my system on this marginal setting (just did a DC reboot) so you can see it at http://98.204.166.71/