GOES 16 reception help

General discussions
Post Reply
bab5871
Posts: 1
Joined: Thu Nov 29, 2018 4:11 pm

GOES 16 reception help

Post by bab5871 » Thu Nov 29, 2018 4:23 pm

Hi all,

I just started playing with reception of GOES 16 from upstate NY. As it sits from my house I'm looking at ~40deg elevation and around a 185 heading. This puts it just at the tops of the trees in my back yard.

First question is, will a few sticks in the way really kill my signal that much? I understand leaves will be a whole other story which I'll likely find myself climbing a tree with a chainsaw later to tackle.

I have the 2.4GHz 24dbi parabolic grid antenna currently. Also running a NESDR SMArTee XTR (alternatively I tried a RTL-SDR v.3 dongle), also running a SAWBird+ GOES LNA. I can't seem to get any signal at all, or at least any compared to my noise floor. I'm trying to figure out if it's the LNA or the antenna causing the issues. I'm basically running the thing direct to the antenna, so no coax loss.

I've tried flipping the sub-reflector, placing the dish diagonal, horizontal, vertical, etc. The only thing I haven't done is extended the dipole for 1694mhz to get it closer to the freq. So I'm running out of options here and it seems hard to find people that know what they're talking about with this kind of thing even in the amateur radio community.

Last night was my first success even seeing anything on the waterfall... Unfortunately after switching to the v.3 dongle and back to the XTR I wasn't able to replicate the signal reception again... and it was cold and my fingers were frozen so I gave up.

So, where to go from here? Attached some photos.
IMG-6349.JPG
IMG-6349.JPG (502.55 KiB) Viewed 9801 times
IMG-6349.JPG
IMG-6349.JPG (502.55 KiB) Viewed 9801 times
Attachments
IMG-6350.JPG
IMG-6350.JPG (353.41 KiB) Viewed 9801 times
Last edited by bab5871 on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

RSP2user
Posts: 108
Joined: Mon Oct 09, 2017 7:11 am

Re: GOES 16 reception help

Post by RSP2user » Sat Dec 01, 2018 10:20 pm

Looks like you are receiving the GOES HRIT signal fairly well, though it is hard to tell for sure based on the scale you have selected. The signal circled in red below is the GOES HRIT signal (when sending its "null" data pattern and not yet transmitting images). You need an SNR of around 6.5 dB or more to decode the signal well. If you can change your scale to 1 dBm per division and take a screen shot of the signal, it will be easier to tell if the signal will be good enough for proper reception. Also, you may want to rotate your antenna using the feed tube as the axis about 45 degrees counterclockwise when facing the GOES 16 satellite in order to achieve the optimum polarization and best reception (rotate the position of the grid antenna and feed tube together on the mounting bracket, which has 8 holes to allow for a 45 degree position). The NOAA specification for GOES 16 HRIT is for vertical polarization; however, many have found that using a 45 degree polarization offset as described here works better for GOES 16. For GOES 17, a vertical polarization works well. It is best to check the signal level for comparison once the antenna has been adjusted for the appropriate satellite signal polarization. Do also tweak the antenna position for best reception on a scale showing 1 dBm per division.
Screen Shot.jpg
Screen Shot.jpg (61.5 KiB) Viewed 9777 times
Image showing the optimum polarization setting for the antenna for GOES 16:
IMG_3271FA v2.JPG
IMG_3271FA v2.JPG (40.81 KiB) Viewed 9777 times
Image showing the signal level (note the scale used and that the sample rate was 4 MSPS for testing). For testing, the filter bandwidth was set less than 10kHz, since the decoding software uses the IQ samples directly and applies different receiver and IQ streaming software:
G16 SNR 7.9dB.JPG
G16 SNR 7.9dB.JPG (221.47 KiB) Viewed 9752 times
To ensure that you are pointing your antenna at GOES 16 (75.2W), you can use the online tool here: http://www.dishpointer.com/
As an additional reference, there is an article on using the Premiertek ANT-GRID-24DBI antenna for GOES satellite HRIT signal reception here: https://www.sdrplay.com/community/viewt ... f=5&t=3262
There is also another good article for GOES HRIT reception reference here: https://www.sdrplay.com/community/viewt ... f=5&t=2674
Off-the-shelf decoding software that runs under the Windows OS is available as of the date of this post, for a fee, through USA-Satcom: https://usa-satcom.com/contact_form/
Check with USA-Satcom for compatibility of the decoder software with SDRs and PCs. The USA-Satcom decoder software has been found to work well with the SDRplay RSP1A, RSP2, and RSPduo.

Reason: No reason

Post Reply