Open utterances-bot opened 3 years ago
whrzg
commented
2 years ago Prof. Bandura,
Digi-key is out of the part for R5, 541-4.70KHTR-ND, https://www.digikey.com/en/products/detail/vishay-dale/crcw06034k70fkea/1174744. Can I order this part instead: https://www.mouser.com/ProductDetail/Panasonic/ERJ-3EKF4701V?qs=MVjVSMjNRMouVvwnqrpO2w%3D%3D ? Thank you for your help. -Bill
whrzg
commented
2 years ago Hello, In the testing instructions in LightWorkMemo #28 is it necessary to connect the LNA to the antenna for the cold measurement after the 50 ohm load is disconnected from the LNA? Thank you very much for your help. Bill
GlenLangston
commented
2 years ago Hi Bill,
The Hot/Cold load tests does not use the antenna. The test is intended to show you the software is working and what type of signal you will be seeing. Remember the hot load signal will be stronger that the sky brightness, so if you can’t see the hot load, then there is not enough gain in your amplifier or something is disconnected.
The 50 Ohm Load is connected to the input of the 1st Amplifier, for Hot. Nothing is connected to the input of the 1st amplifier for the Cold measurement.
Good luck!
Glen
On Nov 18, 2022, at 5:23 PM, whrzg @.***> wrote:
Hello, In the testing instructions in LightWorkMemo #28 is it necessary to connect the LNA to the antenna for the cold measurement after the 50 ohm load is disconnected from the LNA? Thank you very much for your help. Bill
— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.
whrzg
commented
2 years ago Hi Glen
Thank you for your help. I wanted to be sure I didn’t have to connect the antenna for the cold part of the test. when I do the test, the system records the “hot” load during the first half of the test but when I disconnect the 50 ohm load from the LNA and run the 2nd half of the test, the system saves a “hot” load again. I’m going to run the electronic tests outlined in LightWorkMemo 30 to see if I can locate the issue. Do you have any other suggestions for how to investigate this problem?
Thank you.
Bill
On Nov 18, 2022, at 8:25 PM, Glen Langston @.***> wrote:
Hi Bill,
The Hot/Cold load tests does not use the antenna. The test is intended to show you the software is working and what type of signal you will be seeing. Remember the hot load signal will be stronger that the sky brightness, so if you can’t see the hot load, then there is not enough gain in your amplifier or something is disconnected.
The 50 Ohm Load is connected to the input of the 1st Amplifier, for Hot. Nothing is connected to the input of the 1st amplifier for the Cold measurement.
Good luck!
Glen
On Nov 18, 2022, at 5:23 PM, whrzg @.***> wrote:
Hello, In the testing instructions in LightWorkMemo #28 is it necessary to connect the LNA to the antenna for the cold measurement after the 50 ohm load is disconnected from the LNA? Thank you very much for your help. Bill
— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.
— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1320727152, or unsubscribe https://github.com/notifications/unsubscribe-auth/ARWUO3R32MHEQMUKUYV53YTWJAT7FANCNFSM5ES3FZEQ. You are receiving this because you commented.
GlenLangston
commented
2 years ago Hi Bill, Good question. The software assumes the signal is hot if the elevation is negative. The save the cold, set the angle to a positive value.
Good luck again, you are almost there. Glen
Make sure the bias tee is on
On Sat, Nov 19, 2022 at 10:35 AM whrzg @.***> wrote:
Hi Glen
Thank you for your help. I wanted to be sure I didn’t have to connect the antenna for the cold part of the test. when I do the test, the system records the “hot” load during the first half of the test but when I disconnect the 50 ohm load from the LNA and run the 2nd half of the test, the system saves a “hot” load again. I’m going to run the electronic tests outlined in LightWorkMemo 30 to see if I can locate the issue. Do you have any other suggestions for how to investigate this problem?
Thank you.
Bill
On Nov 18, 2022, at 8:25 PM, Glen Langston @.***> wrote:
Hi Bill,
The Hot/Cold load tests does not use the antenna. The test is intended to show you the software is working and what type of signal you will be seeing. Remember the hot load signal will be stronger that the sky brightness, so if you can’t see the hot load, then there is not enough gain in your amplifier or something is disconnected.
The 50 Ohm Load is connected to the input of the 1st Amplifier, for Hot. Nothing is connected to the input of the 1st amplifier for the Cold measurement.
Good luck!
Glen
On Nov 18, 2022, at 5:23 PM, whrzg @.***> wrote:
Hello, In the testing instructions in LightWorkMemo #28 is it necessary to connect the LNA to the antenna for the cold measurement after the 50 ohm load is disconnected from the LNA? Thank you very much for your help. Bill
— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.
— Reply to this email directly, view it on GitHub < https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1320727152>, or unsubscribe < https://github.com/notifications/unsubscribe-auth/ARWUO3R32MHEQMUKUYV53YTWJAT7FANCNFSM5ES3FZEQ . You are receiving this because you commented.
— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1320909505, or unsubscribe https://github.com/notifications/unsubscribe-auth/AALEY7EVWWJTRESCDSIQFODWJDXSVANCNFSM5ES3FZEQ . You are receiving this because you commented.Message ID: @.***>
kbandura
commented
2 years ago Prof. Bandura, Digi-key is out of the part for R5, 541-4.70KHTR-ND, https://www.digikey.com/en/products/detail/vishay-dale/crcw06034k70fkea/1174744. Can I order this part instead: https://www.mouser.com/ProductDetail/Panasonic/ERJ-3EKF4701V?qs=MVjVSMjNRMouVvwnqrpO2w%3D%3D ? Thank you for your help. -Bill
Yes, that part should work well as a replacement.
kenric-davies
commented
1 year ago Hi Everyone,
Let preface by saying that I am a complete novice on most of the details of the operation of this project(Linux, radio telescopes, etc.) but I am always willing to learn so that I can provide experiences for my students.
I am having some issues that I'm hoping the group can help with. My high school astronomy students have built 7 of these horn telescopes and I am in the process of learning how to use the GNUradio program and trying to get them operational. The program is running and I am seeing the graph on the screen but it does not seem like I am actually receiving data from the telescope.
I am working off a Nooelec LNA (https://www.nooelec.com/store/lana.html) and I have a 3 AA (4.5 V) battery pack providing power (the power LED is lit). I also have an RTL-SDR (https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_3?crid=F24JV9EGEG41&keywords=RTL-SDR&qid=1660857000&sprefix=%2Caps%2C471&sr=8-3) plugged into the computer.
I have made the noted adjustments in the program to have the RTL-SDR instead of the Airspy but I am just not seeing any sort of change in the on screen graph while trying to operate the horn.
If it helps, here are some links to screenshots/data: Here is a screenshot of the program while running - https://drive.google.com/file/d/18olujRV0EKNldoUlaUyYd8MJZGiKUuty/view?usp=share_link
Here is the graph that was "printed" from the program - https://drive.google.com/file/d/1hSQKqxj9u_ooJuLFYjuCKo7hhA5OXw6c/view?usp=share_link
I noticed that the on screen graph is not centered on 1420 MHz which I find odd considering the goal of the program. The "heartbeat" in the top right of the screen is changing but is not at the same peak height as I have seen in some of the DSPIRA videos.
I would appreciate any help that any of you can offer me or things that I can check to help troubleshoot.
Thanks!
Kenric Davies
GlenLangston
commented
1 year ago Hi Kenric,
First of all you have made great progress!
That you have 7 horns means you have a whole observatory!
You can definitely use the RTL-SDRs and see the Milky Way. But you MUST change the center frequency to 1,420.5MHz (or about), because you are missing Galactic Hydrogen.
Note, it will be very hard to see the Milky Way, before calibration.
Also you need more gain, as the counts should range between +/- .1 counts. Right now you are seeing either interference or features in the SDR.
Set the SDR gain to max, which is around 50, I think.
You are close to success!
Make these changes and let us know how it goes.
Glen
On Sun, Feb 26, 2023 at 3:25 PM kenric-davies @.***> wrote:
Hi Everyone,
Let preface by saying that I am a complete novice on most of the details of the operation of this project(Linux, radio telescopes, etc.) but I am always willing to learn so that I can provide experiences for my students.
I am having some issues that I'm hoping the group can help with. My high school astronomy students have built 7 of these horn telescopes and I am in the process of learning how to use the GNUradio program and trying to get them operational. The program is running and I am seeing the graph on the screen but it does not seem like I am actually receiving data from the telescope.
I am working off a Nooelec LNA (https://www.nooelec.com/store/lana.html) and I have a 3 AA (4.5 V) battery pack providing power (the power LED is lit). I also have an RTL-SDR ( https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_3?crid=F24JV9EGEG41&keywords=RTL-SDR&qid=1660857000&sprefix=%2Caps%2C471&sr=8-3) plugged into the computer.
I have made the noted adjustments in the program to have the RTL-SDR instead of the Airspy but I am just not seeing any sort of change in the on screen graph while trying to operate the horn.
If it helps, here are some links to screenshots/data: Here is a screenshot of the program while running - https://drive.google.com/file/d/18olujRV0EKNldoUlaUyYd8MJZGiKUuty/view?usp=share_link
Here is the graph that was "printed" from the program - https://drive.google.com/file/d/1hSQKqxj9u_ooJuLFYjuCKo7hhA5OXw6c/view?usp=share_link
I noticed that the on screen graph is not centered on 1420 MHz which I find odd considering the goal of the program. The "heartbeat" in the top right of the screen is changing but is not at the same peak height as I have seen in some of the DSPIRA videos.
I would appreciate any help that any of you can offer me or things that I can check to help troubleshoot.
Thanks!
Kenric Davies
— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1445458734, or unsubscribe https://github.com/notifications/unsubscribe-auth/AALEY7GRBO3SKIVDO63A4XTWZO35FANCNFSM5ES3FZEQ . You are receiving this because you commented.Message ID: @.***>
GlenLangston
commented
1 year ago Hi again, It is good to power the LNA by battery pack, but in that case make sure the RTL bias is off. Your screen shot shows there is too little signal getting to the SDR, so either the 1st LNA is not working or you need to set the SDR gain higher.
Again, great work! Glen
On Sun, Feb 26, 2023 at 3:25 PM kenric-davies @.***> wrote:
Hi Everyone,
Let preface by saying that I am a complete novice on most of the details of the operation of this project(Linux, radio telescopes, etc.) but I am always willing to learn so that I can provide experiences for my students.
I am having some issues that I'm hoping the group can help with. My high school astronomy students have built 7 of these horn telescopes and I am in the process of learning how to use the GNUradio program and trying to get them operational. The program is running and I am seeing the graph on the screen but it does not seem like I am actually receiving data from the telescope.
I am working off a Nooelec LNA (https://www.nooelec.com/store/lana.html) and I have a 3 AA (4.5 V) battery pack providing power (the power LED is lit). I also have an RTL-SDR ( https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_3?crid=F24JV9EGEG41&keywords=RTL-SDR&qid=1660857000&sprefix=%2Caps%2C471&sr=8-3) plugged into the computer.
I have made the noted adjustments in the program to have the RTL-SDR instead of the Airspy but I am just not seeing any sort of change in the on screen graph while trying to operate the horn.
If it helps, here are some links to screenshots/data: Here is a screenshot of the program while running - https://drive.google.com/file/d/18olujRV0EKNldoUlaUyYd8MJZGiKUuty/view?usp=share_link
Here is the graph that was "printed" from the program - https://drive.google.com/file/d/1hSQKqxj9u_ooJuLFYjuCKo7hhA5OXw6c/view?usp=share_link
I noticed that the on screen graph is not centered on 1420 MHz which I find odd considering the goal of the program. The "heartbeat" in the top right of the screen is changing but is not at the same peak height as I have seen in some of the DSPIRA videos.
I would appreciate any help that any of you can offer me or things that I can check to help troubleshoot.
Thanks!
Kenric Davies
— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1445458734, or unsubscribe https://github.com/notifications/unsubscribe-auth/AALEY7GRBO3SKIVDO63A4XTWZO35FANCNFSM5ES3FZEQ . You are receiving this because you commented.Message ID: @.***>
kenric-davies
commented
1 year ago Hi Glen, Thank you for the information, I was able to get the 1420 MHz in the center of the graph so I am at least one step closer! I adjusted the RF Gain to 50 (from 17) and that seemed to help the signal strength on the graph but I'm not sure what I am seeing (screenshots linked below).
I am still thinking that I am not actually passing a signal to the computer and here is why. I mentioned that I am using a battery pack to power the LNA connected to the horn and this one has an LED showing when it is receiving power. When I have the battery pack connected, the LED is turned in showing power. When I connect the input side to the horn, the LED is still lit; but, when I connect the cable that runs to the SDR, the LED goes off! This makes me think that the LNA is not actually on and passing a signal to the computer.
Another reason I think I am not actually seeing anything is that nothing will change on the program graph output when I am moving it around the sky or even pointing at the ground!
Here are more screenshots to help you all see what I am doing wrong...
screenshot of the Gnuradio program flow (upper half) - https://drive.google.com/file/d/17BiHWTEJUNPpRiBXIGjRGwFhVY2EQZgY/view?usp=share_link
screenshot of program while running - https://drive.google.com/file/d/1gEqABn765-w8TNxX8wkZCvUyVKxAh_52/view?usp=share_link
graph output - https://drive.google.com/file/d/1bDn9tj0r-EuJ9GYPjN3FwwVcuItjuZln/view?usp=share_link
I have tried following the video and doing the calibration but I am just not seeing any change on the graph so I can't find a place with "no Hydrogen" bump to do the Cold Calibration step.
Any help you can give would be much appreciated!
Kenric
GlenLangston
commented
1 year ago Hi Kenric,
It seems like there is a problem with the power to the LNA when you have the SDR connected.
Note that the RTLSDRs have plenty of power to drive the amplifier, so that no additional battery pack is connected. There is a software step to turn the RTLSDR power on and off.
Please take a look at LightWork memo 28 https://github.com/WVURAIL/lightwork/blob/master/memos/LightWorkMemo028-r7-NoiseTemp.pdf
Which has an example using the RTLSDR, showing the bandpass shape. Look at page 8 in the memo.
Probably you need to set the “BIAS-TEE” OFF if using your battery pack, but without the battery pack, and the BIAS-TEE ON, the light should be on on the LNA you have. Then you should see a band pass shape like is shown in the memo. Note that both the software I use and spectrometer_w_cal should give similar results.
For my tests, I used a program that we wrote called NsfIntegrate24.grc (and .py) that sets the RTLSDR for 2.4 MHz, which I’d also recommend. It appears you’re using 2.0 MHz.
The linux commands for the bias T are
rtl_biast -b 1
To turn the bias tee on and rtl_biast -b 0 to turn it off.
These commands are probably already installed in your system if you’re getting any data at all.
Glen
Summary: Try turning the bias tee on with these commands, while disconnecting your batter pack. If the light goes on on the amplifier, you are good to go.
On Feb 28, 2023, at 7:14 PM, kenric-davies @.***> wrote:
Hi Glen, Thank you for the information, I was able to get the 1420 MHz in the center of the graph so I am at least one step closer! I adjusted the RF Gain to 50 (from 17) and that seemed to help the signal strength on the graph but I'm not sure what I am seeing (screenshots linked below). I am still thinking that I am not actually passing a signal to the computer and here is why. I mentioned that I am using a battery pack to power the LNA connected to the horn and this one has an LED showing when it is receiving power. When I have the battery pack connected, the LED is turned in showing power. When I connect the input side to the horn, the LED is still lit; but, when I connect the cable that runs to the SDR, the LED goes off! This makes me think that the LNA is not actually on and passing a signal to the computer. Another reason I think I am not actually seeing anything is that nothing will change on the program graph output when I am moving it around the sky or even pointing at the ground! Here are more screenshots to help you all see what I am doing wrong... screenshot of the Gnuradio program flow (upper half) - https://drive.google.com/file/d/17BiHWTEJUNPpRiBXIGjRGwFhVY2EQZgY/view?usp=share_link screenshot of program while running - https://drive.google.com/file/d/1gEqABn765-w8TNxX8wkZCvUyVKxAh_52/view?usp=share_link graph output - https://drive.google.com/file/d/1bDn9tj0r-EuJ9GYPjN3FwwVcuItjuZln/view?usp=share_link I have tried following the video and doing the calibration but I am just not seeing any change on the graph so I can't find a place with "no Hydrogen" bump to do the Cold Calibration step. Any help you can give would be much appreciated! Kenric — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.Message ID: @.***>
GlenLangston
commented
1 year ago Hello again Kenric,
I now see that you have the bandwidth set at 2.4MHz which is good.
My main guess is that the RTLSDR is shorted with the battery pack. Fortunately it has a good current limiting circuit. so probably no damage is done to the RTL or amplifier.
My guess is also you need to change the Osmocom block to have input to rtlsdr=0,bias=1
And remove the battery pack.
See what your signal looks like. Make sure the amplifier light is on.
I just tested building spectrometer_w_cal.grc and these changes built fine, but i could not test them.
Glen @. @.>
Note I use VNC for all my telescopes and have a raspberry pi computer at each of the 4 of them. This allows login from anywhere in the world.
On Feb 28, 2023, at 10:48 PM, Glen Langston @.***> wrote:
Hi Kenric,
It seems like there is a problem with the power to the LNA when you have the SDR connected.
Note that the RTLSDRs have plenty of power to drive the amplifier, so that no additional battery pack is connected. There is a software step to turn the RTLSDR power on and off.
Please take a look at LightWork memo 28 https://github.com/WVURAIL/lightwork/blob/master/memos/LightWorkMemo028-r7-NoiseTemp.pdf
Which has an example using the RTLSDR, showing the bandpass shape. Look at page 8 in the memo.
Probably you need to set the “BIAS-TEE” OFF if using your battery pack, but without the battery pack, and the BIAS-TEE ON, the light should be on on the LNA you have. Then you should see a band pass shape like is shown in the memo. Note that both the software I use and spectrometer_w_cal should give similar results.
For my tests, I used a program that we wrote called NsfIntegrate24.grc (and .py) that sets the RTLSDR for 2.4 MHz, which I’d also recommend. It appears you’re using 2.0 MHz.
The linux commands for the bias T are
rtl_biast -b 1
To turn the bias tee on and rtl_biast -b 0 to turn it off.
These commands are probably already installed in your system if you’re getting any data at all.
Glen
Summary: Try turning the bias tee on with these commands, while disconnecting your batter pack. If the light goes on on the amplifier, you are good to go.
On Feb 28, 2023, at 7:14 PM, kenric-davies @.***> wrote:
Hi Glen, Thank you for the information, I was able to get the 1420 MHz in the center of the graph so I am at least one step closer! I adjusted the RF Gain to 50 (from 17) and that seemed to help the signal strength on the graph but I'm not sure what I am seeing (screenshots linked below). I am still thinking that I am not actually passing a signal to the computer and here is why. I mentioned that I am using a battery pack to power the LNA connected to the horn and this one has an LED showing when it is receiving power. When I have the battery pack connected, the LED is turned in showing power. When I connect the input side to the horn, the LED is still lit; but, when I connect the cable that runs to the SDR, the LED goes off! This makes me think that the LNA is not actually on and passing a signal to the computer. Another reason I think I am not actually seeing anything is that nothing will change on the program graph output when I am moving it around the sky or even pointing at the ground! Here are more screenshots to help you all see what I am doing wrong... screenshot of the Gnuradio program flow (upper half) - https://drive.google.com/file/d/17BiHWTEJUNPpRiBXIGjRGwFhVY2EQZgY/view?usp=share_link screenshot of program while running - https://drive.google.com/file/d/1gEqABn765-w8TNxX8wkZCvUyVKxAh_52/view?usp=share_link graph output - https://drive.google.com/file/d/1bDn9tj0r-EuJ9GYPjN3FwwVcuItjuZln/view?usp=share_link I have tried following the video and doing the calibration but I am just not seeing any change on the graph so I can't find a place with "no Hydrogen" bump to do the Cold Calibration step. Any help you can give would be much appreciated! Kenric — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.Message ID: @.***>
kenric-davies
commented
1 year ago Hi Glen,
I am still not getting the light on the amplifier to turn on. I have tried using the linux command before starting Gnuradio with the battery pack off and get the following message:
Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN:00000001
Using Device 0: Generic RTL 2832U OEM Found Rafael Micro R828D tuner
But the light on the amplifier is still off.
I started Gnuradio and made the adjustments there but still no light and the signal again like I'm not getting anything.
I feel like yesterday, when I was trying it, I was able to get the light to stay (with battery pack) on when plugging the SDR into one specific port on my laptop but today cannot reproduce this. The light (if battery pack connected) immediately goes out if SDR is connected.
Am I wrong in thinking that the Input side of the amplifier should be connected to the Horn and the output connected to the SDR? If I hook it up the other way, the light stays on but no change in signal.
Thanks for all of the troubleshooting.
Kenric
Any other ideas?
glangsto
commented
1 year ago Hi Kenric,
Glad you’re keeping at this. But I’m now puzzled. Are there any filters between the amplifier and the SDR? A high pass filter will block the DC voltage from reaching the Amplifier.
Also look for any shorts in your RF cabling.
The messages (below) look good. What command did you use to get these messages?
Did you use:
rtl_test
or
rtl_biast
?
Please try the following.
Completely turn off python spectrometer_w_cal.grc (or.py)
Connect the amplifier to the RTLSDR (via coaxial cable). Note there may also be an issue with the coaxial cable. What type of cable (and how long) are you using.
ON the Linux command line run:
rtl_test
then, run
rtl_biast -b 1
See if the light goes on and also capture all messages, including the commands you used to get the messages. Please send us your results.
We continue to hope you have good luck with this!
Best regards
Glen glen.i.langston -at at at- gmail.com
From: kenric-davies @.> Sent: Thursday, March 2, 2023 10:41 AM To: WVURAIL/dspira-lessons @.> Cc: Langston, Glen @.>; Comment @.> Subject: [EXTERNAL] - Re: [WVURAIL/dspira-lessons] dspira-lessons/forum/electronics/ (#8)
This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Hi Glen,
I am still not getting the light on the amplifier to turn on. I have tried using the linux command before starting Gnuradio with the battery pack off and get the following message:
Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN:00000001
Using Device 0: Generic RTL 2832U OEM Found Rafael Micro R828D tuner
But the light on the amplifier is still off.
I started Gnuradio and made the adjustments there but still no light and the signal again like I'm not getting anything.
I feel like yesterday, when I was trying it, I was able to get the light to stay (with battery pack) on when plugging the SDR into one specific port on my laptop but today cannot reproduce this. The light (if battery pack connected) immediately goes out if SDR is connected.
Am I wrong in thinking that the Input side of the amplifier should be connected to the Horn and the output connected to the SDR? If I hook it up the other way, the light stays on but no change in signal.
Thanks for all of the troubleshooting.
Kenric
Any other ideas?
— Reply to this email directly, view it on GitHubhttps://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1452076223, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AADRXGGQ3XFXU4TEI3TJVKLW2C5PNANCNFSM5ES3FZEQ. You are receiving this because you commented.Message ID: @.**@.>>
kenric-davies
commented
1 year ago I used the rtl_biast command.
I will try your suggestions when I get a chance and let you know the outcome. In the meantime, I'll let you know something that I just found that might be the issue. I have been googling around to see what might be going on with the biast command since you indicated that I "should" have the commands installed with Linux and came across something strange. Apparently the RTL-SDRs have been counterfeited and being sold from other sources with the reviews saying many things around the bias t not working like it should. Looking at mine against the ones shown on the RTLSDR.com website and I believe, when my school ordered these, I have the counterfeit ones because they apparently did not use the specific link to amazon that I gave them (which would be just me luck!).
I will be ordering one myself from the link provided on the source website to see if maybe that is it before trying to get my school district to send the 7 we purchased back and reorder new ones (which will be an uttur pain!).
Thanks again for all of the help and I'll keep you posted!
Kenric
GlenLangston
commented
1 year ago Hi Kenric,
Another thought on what might be going on with your telescopes.
I think the “clone” RTL-SDRs still work, but I’m not sure about the bias-tee.
When you battery-power the amplifier, I think the voltage is also on the coaxial line back to the RTL-SDR. The SDR may act as a short, stopping the battery pack from powering the amplifier.
In this case you may need a high-pass filter between the amplifier and the RTLSDR.
There are some specifically for Neutral hydrogen, which will also reduce your sensitivity to interference.
I’ve not yet tried this filter, available on Amazon, but it is $26.00 and could greatly help your project. To find it, go to amazon.com http://amazon.com/ and search for: "RF Filter Module 1420MHz BPF Band Pass Power Distribution Control Electronic"
If you put this between your SDR and the amplifier, the light on the amplifier should stay on when you use your battery pack.
Glen
I just ordered the filter to try it out. It will arrive in a week. I’ll let you know if it is any good.
On Mar 2, 2023, at 12:03 PM, kenric-davies @.***> wrote:
I used the rtl_biast command. I will try your suggestions when I get a chance and let you know the outcome. In the meantime, I'll let you know something that I just found that might be the issue. I have been googling around to see what might be going on with the biast command since you indicated that I "should" have the commands installed with Linux and came across something strange. Apparently the RTL-SDRs have been counterfeited and being sold from other sources with the reviews saying many things around the bias t not working like it should. Looking at mine against the ones shown on the RTLSDR.com website and I believe, when my school ordered these, I have the counterfeit ones because they apparently did not use the specific link to amazon that I gave them (which would be just me luck!). I will be ordering one myself from the link provided on the source website to see if maybe that is it before trying to get my school district to send the 7 we purchased back and reorder new ones (which will be an uttur pain!). Thanks again for all of the help and I'll keep you posted! Kenric — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.Message ID: @.***>
kenric-davies
commented
1 year ago Hi Glen,
Looking back at the reviews of the SDR that was actually purchased, it seems like the bias-tee is non-functional on these cloned versions. I received an authentic RTL-SDR today (thank you Amazon Prime) and the bias-tee has worked. The light on the LNA stays lit while connected to the SDR and without the battery pack. I now have a different graph on the screen but have some similar issues.
Here is what the screen looks like now - https://drive.google.com/file/d/1iogD_1enPfiFbrxYBPTWWT6xkVNBkPpl/view?usp=share_link
I tried going through the calibration process detailed in one of the YouTube videos and, again, no matter where I point in the sky, the graph stays the same. This has me thinking that the construction of the horn is incorrect in some manner. Reviewing the instructions for assembling the horn, I believe that the antenna is in the wrong place. My students put it on the short side of the can instead of the middle of the long side. The copper wire is still the same length detailed in the instructions (5.5 cm I think).
Here is a picture - https://drive.google.com/file/d/1Nq9xednT9Mg3LxMZlgk1mQklPlKJN6d_/view?usp=share_link
Thank you so much for the help so far and I am grateful if you have any other thoughts about what might be happening.
Kenric
glangsto
commented
1 year ago HI Kenric and all,
Thanks for the pictures you sent. I think these explain a good bit. Your DISPRA Spectrometer spectrum does show a reasonable spectrum for the SDR. The RTL-SDRs always have three broad peaks which are due to the SDR electronics, not due to the sky.
These features are completely removed by calibration.
However your students will need to move the “feed probe” to the wide side of the can. That will probably allow detection of the Milky Way. You will need to calibrate to see the Milky Way, which will be a peak in the spectrum at about 1420.4 MHz.
Also note that you will need to make a “Long integration” both for calibration and for your observation of the Milky Way.
Note that the Milky Way signal varies by a factor of about 50, depending on where/when you are looking at the sky.
In the Galactic Plane the signal will be up to 50 Kelvins (calibrated) and down to about 1 or 2 Kelvins when you are looking at Milky Way South or North Pole.
Note that over most of the Northern Hemisphere you can see both north and south galactic poles, because the Earth (and solar system) are oriented sideways to the rotation of the Milky Way.
The single level about +/-0.1 counts (in the System Heartbeat plot is about right, but could be just a little stronger maybe as much as +/- 0.2 counts. The signal might increase when your students move the feed probe.
So, you’re getting there. Good Luck,
Keep us posted on your progress,
Best regards
Glen
PS Where are you? I’m in West Virginia, right next to the Green Bank Observatory.
From: kenric-davies @.> Sent: Saturday, March 4, 2023 7:02 PM To: WVURAIL/dspira-lessons @.> Cc: Langston, Glen @.>; Comment @.> Subject: [EXTERNAL] - Re: [WVURAIL/dspira-lessons] dspira-lessons/forum/electronics/ (#8)
This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Hi Glen,
Looking back at the reviews of the SDR that was actually purchased, it seems like the bias-tee is non-functional on these cloned versions. I received an authentic RTL-SDR today (thank you Amazon Prime) and the bias-tee has worked. The light on the LNA stays lit while connected to the SDR and without the battery pack. I now have a different graph on the screen but have some similar issues.
Here is what the screen looks like now - https://drive.google.com/file/d/1iogD_1enPfiFbrxYBPTWWT6xkVNBkPpl/view?usp=share_link
I tried going through the calibration process detailed in one of the YouTube videos and, again, no matter where I point in the sky, the graph stays the same. This has me thinking that the construction of the horn is incorrect in some manner. Reviewing the instructions for assembling the horn, I believe that the antenna is in the wrong place. My students put it on the short side of the can instead of the middle of the long side. The copper wire is still the same length detailed in the instructions (5.5 cm I think). Here is a picture - https://drive.google.com/file/d/1Nq9xednT9Mg3LxMZlgk1mQklPlKJN6d_/view?usp=share_link
Thank you so much for the help so far and I am grateful if you have any other thoughts about what might be happening.
Kenric
— Reply to this email directly, view it on GitHubhttps://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1454928847, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AADRXGGAN2OL7ZWKZA4F3PLW2PJXZANCNFSM5ES3FZEQ. You are receiving this because you commented.Message ID: @.**@.>>
kenric-davies
commented
1 year ago I think that I have had a successful test! I hope :)
I brought a horn home to do more testing and I had the means to move the antenna. I just took it out and the graph did change as I moved the horn around the sky so I was able to successfully go through the calibration process. Here are the results:
Screenshot of program - https://drive.google.com/file/d/1gjiFOkjEndto3Rw4mMVlb6sWx1FC5chL/view?usp=share_link
Graph print to file - https://drive.google.com/file/d/1XkodF1_qxEaTKY3A6pC-mD2dhRFqEsLZ/view?usp=share_link
The data is rough even on long integration probably because I was in my front yard with trees and such around so not a real good clear sky (if that matters). I was pointed in the general direction of Cygnus (around 270-290 azi and below 45 alt at 6:00 pm from Frisco, TX). I think I am seeing a bump in the graph at 1420.31 indicating galactic hydrogen with a doppler shift showing around -20 km/s of speed. I would love if anyone would have a chance to check to see if these readings are valid.
Glen - to officially answer your questions, I am in Frisco, TX (north Dallas area).
Thank you for the help in getting this project moving forward! I appreciate the community here and the willingness to help the novice.
Kenric
P.S. - I have been using the lessons on measuring the speed of the Earth around the Sun and I have been pretty impressed. Thank you to all of you who have been a part of that process.
GlenLangston
commented
1 year ago Hi Kenric,
Congratulations!
Yes, your seeing parts of the Milky Way moving at great velocity.
As you observe, the peak of the doppler velocity will change.
Great work,
Glen
On Mar 5, 2023, at 7:19 PM, kenric-davies @.***> wrote:
I think that I have had a successful test! I hope :) I brought a horn home to do more testing and I had the means to move the antenna. I just took it out and the graph did change as I moved the horn around the sky so I was able to successfully go through the calibration process. Here are the results: Screenshot of program - https://drive.google.com/file/d/1gjiFOkjEndto3Rw4mMVlb6sWx1FC5chL/view?usp=share_link Graph print to file - https://drive.google.com/file/d/1XkodF1_qxEaTKY3A6pC-mD2dhRFqEsLZ/view?usp=share_link The data is rough even on long integration probably because I was in my front yard with trees and such around so not a real good clear sky (if that matters). I was pointed in the general direction of Cygnus (around 270-290 azi and below 45 alt at 6:00 pm from Frisco, TX). I think I am seeing a bump in the graph at 1420.31 indicating galactic hydrogen with a doppler shift showing around -20 km/s of speed. I would love if anyone would have a chance to check to see if these readings are valid. Glen - to officially answer your questions, I am in Frisco, TX (north Dallas area). Thank you for the help in getting this project moving forward! I appreciate the community here and the willingness to help the novice. Kenric P.S. - I have been using the lessons on measuring the speed of the Earth around the Sun and I have been pretty impressed. Thank you to all of you who have been a part of that process. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.Message ID: @.***>
Electronics Forum – Digital Signal Processing in Radio Astronomy - Lessons Portal
Lots of lessons
https://wvurail.org//dspira-lessons/forum/electronics/