A8302 board
andrew....@googlemail.com
Hi All,
See https://astronomy.me.uk/a8302-amplitude-comparator-board
Probably won’t work!!!
My plans now are to:
(i) Complete hydrogen map and rotation curve of Milky Way with my current setup – as it is working – nothing more exciting that creating your own map of Milky Way with your own hands!!
(ii) I then intend to take up Alex (Pettit)’s very kind offer of help to tune my equipment – thanks Alex! Hope you don’t mind me finishing my current map first – then whatever happens I can say I’ve done it and have the plots to prove it!
(iii) Then, I would like to obtain my own interferometry fringes (using my Ptarmigan array and Nooelec 1420MHz mesh antenna) and set up a competitor to the Very Long Baseline Array in Lichfield! (Last bit is a joke obviously…)
(iv) In the meantime, I also intend to:
(v) Meteor observations are already online at RMOB – ensure that keeps working.
(vi) I want to get my SID data to load up to my website – having problems at moment – Jim Sky is helping me (thanks Jim!) – I am waiting for Jim to come back on latest log files I have sent him = however, I suspect my issue is that my website provider (IONOS) requires too much security to FTP the files onto it. I am going to try and set up free website provider and see if that works.
(vii) I also want to set up my Radio Jove again and see if I can actually detect Jupiter this time.
(viii) Also, set up INSPRE again…
(ix) I would like to try and download weather data from a satellite.
(x) Organize and run workshop for my astronomy group on radio astronomy.
(xi) Attend next SARA workshop online – can someone tell me how I get dates and access to those?
(xii) Let me know anything else I’ve missed!
Andy
Marcus D. Leech
--
--
You received this message because you are subscribed to the Google
Groups "Society of Amateur Radio Astronomers" group.
To post to this group, send email to sara...@googlegroups.com
To unsubscribe from this group, send email to
sara-list-...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sara-list?hl=en
---
You received this message because you are subscribed to the Google Groups "Society of Amateur Radio Astronomers" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sara-list+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/001401da0f63%244fe704d0%24efb50e70%24%40googlemail.com.
andrew....@googlemail.com
Thanks Marcus for that info
From: sara...@googlegroups.com <sara...@googlegroups.com> On Behalf Of Marcus D. Leech
Sent: 04 November 2023 21:51
To: sara...@googlegroups.com
Subject: Re: [SARA] A8302 board
On 04/11/2023 17:10, andrew.thornett via Society of Amateur Radio Astronomers wrote:
Hi All,
See https://astronomy.me.uk/a8302-amplitude-comparator-board
Probably won’t work!!!
Jan Lustrup has used this very board for interferometry -- see his "Amateur Radio Astronomy" facebook group.
My plans now are to:
1. Complete hydrogen map and rotation curve of Milky Way with my current setup – as it is working – nothing more exciting that creating your own map of Milky Way with your own hands!!
2. I then intend to take up Alex (Pettit)’s very kind offer of help to tune my equipment – thanks Alex! Hope you don’t mind me finishing my current map first – then whatever happens I can say I’ve done it and have the plots to prove it!
3. Then, I would like to obtain my own interferometry fringes (using my Ptarmigan array and Nooelec 1420MHz mesh antenna) and set up a competitor to the Very Long Baseline Array in Lichfield! (Last bit is a joke obviously…)
4. In the meantime, I also intend to:
5. Meteor observations are already online at RMOB – ensure that keeps working.
6. I want to get my SID data to load up to my website – having problems at moment – Jim Sky is helping me (thanks Jim!) – I am waiting for Jim to come back on latest log files I have sent him = however, I suspect my issue is that my website provider (IONOS) requires too much security to FTP the files onto it. I am going to try and set up free website provider and see if that works.
7. I also want to set up my Radio Jove again and see if I can actually detect Jupiter this time.
8. Also, set up INSPRE again…
9. I would like to try and download weather data from a satellite.
10. Organize and run workshop for my astronomy group on radio astronomy.
11. Attend next SARA workshop online – can someone tell me how I get dates and access to those?
12. Let me know anything else I’ve missed!
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/02e7f969-dda2-454d-849a-05351a886d91%40gmail.com.
Mike Otte
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/002701da0f6e%243864cbc0%24a92e6340%24%40googlemail.com.
Marcus D. Leech
Proof of concept. 2 - 3M dishes separated by 44.2M with sawbirds on each feed into an AD8302 board with 12 bit A/D in a PIC18F26K80 logging every 2 sec.
The first plot (Sun1) was created on Libre Calc and i could see the noise spikes were going to be a problem.
The second plot(Figure) was done using python and median filter ,signal.medfilt(y1,11) which took a lot of the spikes out. This was a different data set too.
Haven't been able to capture any other sources.
73Mike
Jan was able to use that part to get quite-good fringes from Cygnus A on 1.9M dishes. I think he's band-limiting ahead of
the AD8302 to only a few MHz. The SawBird+ H1 has about 65-70MHz of 3dB bandwidth, which means it's "seeing"
outside of the strict radio astronomy band, and indeed, it's possible that sources outside the band are dominating
the phase response, depending on your location.
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/CA%2BG65tQO_PXmSJ1qE0XiWV2nPDAU5J-nWZaKLyahf8v0UYrG5g%40mail.gmail.com.
Mike Otte
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/d3df9d73-6f70-4713-a862-ec43560e0ff5%40gmail.com.
Marcus D. Leech
Marcus,"With a 44.2M baseline, the Sun will be quite solidly into "resolved" territory, so one would expect muted fringes."
Please explain this statement more fully . What is "resolved" and why is this bad? I know this has been alluded to before.Or give me a reference that explains why this is bad?
"resolved" (or heading that way). In interferometers with variable spacing, that "feature" allows you to determine the
size of an object (by taking multiple transit measurements with increasing spacings until the fringes start to diminish).
Your fringe spacing at 21cm with a 44.2M baseline will be approximately 0.3Deg, and the Sun is about 0.5Deg.
Maybe it explains what I got today from the sun.In this case I added "5-6000" amplifiers after the sawbirds and before the AD8302. Phase is blue and magnitude is green.
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/CA%2BG65tT6EmqYTq7RJJPjrdX3EfW8OTHcuv4eCyhkeU_vtfXe0Q%40mail.gmail.com.
Mike Otte
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/d0f421b7-28d4-4ca3-8d5c-9838df7d3819%40gmail.com.
Marcus D. Leech
5-6000 Mhz "lna"s are sold on ebay right next to the spf5189z and 50-4000's. These are the lna s I was using before the sawbirds and they are said to give 21db gain.Noise figure may not be great but i was looking for gain. I thought I might be able to "see" something besides the Sun.
Yes, so if your cable runs are long, having some more gain will help drive the cables.
I don't know what signal levels the AD8302 requires, might be good to get in touch with Jan to see what his
layout is. I do know he's running with reduced bandwidth ahead of it, and the 60-70Mhz bandwidth of
the sawbird might be too much in a "busy" RF environment.
Quick perusal of the data-sheet says minimum input level is -60dBm, which is fairly "loud" as ordinary receivers
go. Might need a couple of gain stages behind the SawBird.
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/CA%2BG65tQ56_eKj36Ah%3D-f3KWa5gjD4HRkVVLSuA9XzjSQmGd6CQ%40mail.gmail.com.
Andrew Thornett
Sent: Sunday, November 5, 2023 2:13:48 AM
To: sara...@googlegroups.com <sara...@googlegroups.com>
jan Lustrup-LA3EQ
Hi Andrew….
The AD8302 will work for interferometry. Here is my layout and some observations witn two 1.9 meter dishes + Sawbird+H1 LNA.
The Sawbird built in filter are very wide and let in lots of interference. Also for interferometry you don’t want the pass band to be that large as the fringe rates are different in the low and high part of the pass band and your fringes might be smeared out a bit.
Attached are my layout drawing, and observations of Cygnus A, Cassiopeia A, 3C392 and 3C348 (Hercules A). All using the AD8302 board.
Good luck,
Jan Lustrup
--
jan Lustrup-LA3EQ
I forgot to say, I use two 3MHz wide interdigital filters in front the inputs of the AD8302 board.
Jan
To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/00d001da0fe5%24aa2415f0%24fe6c41d0%24%40no.