Telemetry antenna suggestion
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes. Would receiving the 460mW beacon from EO-88 require a steerable antenna? Thanks for your help.
Larry N1MIW
z man asked:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes.
That's pretty much my experience - using a non-directional antenna for satellite telemetry decoding was a dismal failure. In several years of listening, the number of packets decoded could be counted on the fingers of one hand. I used several different antennas with similar results (or lack thereof).
73 ----- Jim Walls - K6CCC jim@k6ccc.org
Did you try adding a preamp to your rx setup?
73 Jeff kb2m
On 5/3/2022 10:08 AM, jim@k6ccc.org wrote:
z man asked:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes.
That's pretty much my experience - using a non-directional antenna for satellite telemetry decoding was a dismal failure. In several years of listening, the number of packets decoded could be counted on the fingers of one hand. I used several different antennas with similar results (or lack thereof).
73
Jim Walls - K6CCC jim@k6ccc.org
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This is an Excellent point. I use and antenna-mounted pre-amp with a bandpass filter. I have a Quadrafilar helix in my attic (I live in FL so do that for lightning and hurricane protection). I use a bias-T to power the preamp via the coax. This setup works very well even under my roof.
73, Ken N2WWD
On May 3, 2022, at 10:25 AM, jeff griffin kb2mjeff@att.net wrote:
Did you try adding a preamp to your rx setup?
73 Jeff kb2m
On 5/3/2022 10:08 AM, jim@k6ccc.org wrote:
z man asked:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes.
That's pretty much my experience - using a non-directional antenna for satellite telemetry decoding was a dismal failure. In several years of listening, the number of packets decoded could be counted on the fingers of one hand. I used several different antennas with similar results (or lack thereof).
73
Jim Walls - K6CCC jim@k6ccc.org
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Jeff asked:
Did you try adding a preamp to your rx setup?
Yes. Made no difference. If I used my tracking antennas, it worked great, so I know the receive / decode system worked. BTW, this was APRS long ago on PCSAT-1 - NO44.
73 ----- Jim Walls - K6CCC jim@k6ccc.org
On 5/3/22 08:21, z man wrote:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having
Let me quote Burns Fisher (WB1FJ) from Feb of last year:
It depends on your goals.
If you want the absolute maximum telemetry, then you want a regular beam and rotator, same as you would use for QSOs. I have that for normal SatCom and some coax switches/relays to switch it from my radio to my FunCube Dongle/FoxTelem.
Normally, I use homemade Lindenblads for my FoxTelem telemetry and also the same set with a splitter for my SatNogs station. The most recent AMSAT Journal had two designed for 3D printed 70cm Lindenblads, although the ones I am currently using are AA2TX's (search for AA2TX Lindenblad--there are two different articles/designs, one for each band).
I have also mentioned in the past that I have had surprisingly good luck with an Arrow Antennas dual-band J-pole. It is not going to pull in as much as a beam and has a few null spots (like right off the end), but it is inexpensive, dual-band, no building required.
I've also had good luck with a "plumber's delight" J-pole on 2m and a relatively simple home-brew 2m preamp to set the system noise figure at the antenna.
A couple of leads:
"Ed Fong WB6IQH VHF/UHF Dual Band J-Pole" https://www.youtube.com/watch?v=JyW_CCzPXSQ
"LNA for all - Low Noise Amplifier for many applications from 28 MHz to 2500 MHz" http://lna4all.blogspot.com/2013/04/lna-for-all-low-noise-amplifier-for.html (depending on location -- cell towers and FM transmitters, you may need additional filtering to avoid overload.)
"2 meter Preamplifier with Band Pass Filter" https://antennas-amplifiers.com/product/low-noise-preamplifier/2m-bandpass-f...
As always: Cheap, Fast, Good. Pick any two.
--- Zach N0ZGO
On 5/3/22 09:36, Zach Metzinger wrote:
I've also had good luck with a "plumber's delight" J-pole on 2m and a relatively simple home-brew 2m preamp to set the system noise figure at
One additional link from W6PQL:
"LNAs (preamps) and MMICs" https://www.w6pql.com/LNAs%20(preamps)%20and%20MMICs.htm
His note at the bottom of that page applies to omnidirectional antennas for satellite work. They'll happily pick up interfering sources on the ground, which could then interfere with the signal you're actually trying to receive. You can't do much about signals which are in the band of interest (144-148) without some antenna nulls, but out-of-band interference can be dealt with using filters.
When I installed my 3-d printed Lindenblad in the attic for 70cm, I was surprised at the greatly increased level of noise when I turned it on. It seemed to be a HNA (high noise amplifier)!
Turns out that a nearby water tower, bristling with cellular antennae blasting out digital garbage at 550-700MHz, was overloading the front end of my FT-847 due to the additional gain provided by the LNA. Additional filtering before and after the LNA has solved this problem.
http://www.n0zgo.net/lna/70cm/max2640/70cm_lna_max2640_annotated.jpg
(The BAR64 PIN diodes were added to protect the MAR3-SM+ output gain block when transmitting. Without those, the MAR3 was dead within a few minutes of use at >10W TX.)
--- Zach N0ZGO
Hi Larry,
Over the last several months I've had decent results with the following: Antenna: Arrow dual band ground plane GP146/440 - 1/4 Wave Ground Plane - (2 Meter) - (70cm OSJ)
Preamp: dual band preamp SSB-Electronic DBA 270 Duo-Band-Preamp. 2m + 70cm (I have this in the shack, needs to be outside of course, but better than nothing in my installation).
Receiver: Airspy mini
Software:
SDRSharp with DDE plugin for frequency and Doppler control, hooked to SatPC32
SDRSharp with virtual audio cable out to three programs: FoxTLM, and a decoder for both EO-88 and AO-73. Easy to add more, just use the same virtual audio signal for all of them.
EO-88 is pretty loud so it's easy to get frames. AO-73 is hard when in low power telemetry, but easy when full power. AO-95--at my home QTH I have a silly "birdie" right at it's downlink, so it's hard to copy, but I get a few frames.
This setup lets me track 2M and 70cm birds, using SatPC32 to schedule which birds and in what priority, while using whatever audio decoder software you need to receive the virtual audio cable out of SDRSharp. Key is the DDE plug-in...
All of this pales in comparison to a tracking array, but it's low tech and gets some things uploaded to their respective aggregators..
73!
Mark L. Hammond [N8MH] AMSAT Director and Command Station
On Tue, May 3, 2022 at 9:22 AM z man zm1267@gmail.com wrote:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes. Would receiving the 460mW beacon from EO-88 require a steerable antenna? Thanks for your help.
Larry N1MIW
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I have just spent some time with EZNEC modelling various antennas. Using the elevation pattern results and calculating path loss for the various birds I have been able to predict what the received signal strengths and hence SNRs should be. Hopefully I'll put it all together for a Journal article. If you wanted a simple system try a J-Pole with Preamp at the antenna.
73, Terry Osborne ZL2BAC
On 4/05/2022 1:21 am, z man wrote:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes. Would receiving the 460mW beacon from EO-88 require a steerable antenna? Thanks for your help.
Larry N1MIW
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Larry,
The type of antenna depends on how well you expect to receive the telemetry signals.
As a rule of thumb, the bigger the antenna the more packets you will receive.
This means that yagies are the way to go. The more elements the better.
If you track the satellite as well, then you will receive more packets.
Here, I use an eight element yagi and I could get more packets than I do, if I had more elements.
Its most frustrating to watch the incoming packets in the waterfall and not be able to decode them because they are too weak.
A preamp can be a help BUT remember the preamp is only there to overcome the feed line loss.
Putting a preamp at the receiver end of the coax is a waste of time. I have a preamp at the antenna end, but as I have helix cable from the antenna to the receiver the preamp is never turned on.
There was a pass this morning of EO-88 that never got more than two degrees above the horizon. I managed to decode fifty-six packets with this pass. The average distance to the satellite was 2200Kms.
Summing up, If you want peak performance then you need to put the effort into maximising your receive system. Long Yagies, low loss coax, N type connectors and tracking yagies. Anything less than this degrades your performance. By the way, make your own yagies and put a lot of effort to tune them for peak performance.
David
On 2022-05-03 11:21 pm, z man wrote:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes. Would receiving the 460mW beacon from EO-88 require a steerable antenna? Thanks for your help.
Larry N1MIW
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On 5/3/22 23:34, David Hopkins wrote:
A preamp can be a help BUT remember the preamp is only there to overcome the feed line loss.
I respectfully disagree. The LNA, sometimes called a "preamp", is there to set the noise figure (NF in dB) of your receive system. Your NF determines, ignoring interference, the signal-to-noise (SNR) ratio of the signal going into your demodulation setup (FoxTelem).
https://www.rfcafe.com/references/electrical/noise-figure.htm https://www.microwaves101.com/encyclopedias/noise-figure
SNR is what actually determines how many packets are decoded. You can have a strong signal which has a terrible SNR and no packets will be decoded. Conversely, you can have a very weak/faint signal with a great SNR and you'll get 100% decodes.
https://en.wikipedia.org/wiki/Bit_error_rate
(SNR and Eb/N0 are different ways of expressing the same ratio: https://en.wikipedia.org/wiki/Eb/N0)
Putting a preamp at the receiver end of the coax is a waste of time.
I agree, assuming usual feedline losses which would add directly to the NF of your receive system.
Summing up, If you want peak performance then you need to put the effort into maximising your receive system. Long Yagies, low loss coax, N type connectors and tracking yagies. Anything less than this degrades your performance.
Type N connectors are not necessary for good/excellent performance at sub-1GHz frequencies. The clunky-but-common SO/PL-259 connector will work just fine, as it represents a minimal impedance bump in the line.
https://www.iz2uuf.net/wp/index.php/2016/01/08/pl-259-vs-n-on-430-mhz/
Sure, if you're wanting to eek out that last 0.1dB in your setup, go whole hog with N connectors. However, that shouldn't stop the casual amateur who just wants a workable setup on 2m/70cm.
--- Zach N0ZGO
Hi Larry,
I'm using from long time a Diamond QFH antenna for 137 Mhz for AO-73, Nayif and in the past also for Fox sats. It give me good results without any preamp.
'73 de Piero IZ1ERR
Il 03/05/22 15:21, z man ha scritto:
Hi all, I am in search of an antenna that I could use to receive the 2 meter telemetry signals from AO-73, Nayif-1, etc. While I am having good success with my Yagi setup, I would like to eliminate any computer control of the antennas. My question is what would be a suggested antenna I could possibly build? I'm testing out a Lindenblad in RHCP, but so far (2 days in the air) I'm not seeing any decodes. Would receiving the 460mW beacon from EO-88 require a steerable antenna? Thanks for your help.
Larry N1MIW
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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participants (9)
-
David Hopkins -
jeff griffin -
jim＠k6ccc.org -
Ken Ernandes -
Mark L. Hammond -
Piero Baudino -
Wendy and Terry Osborne -
z man -
Zach Metzinger