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Re: The FFT and nuclear weapons
Here's another article, tangentially related. I love the tidbit about Tukey and Hamming.
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-- Dave On 5/20/25 11:56, Larry Dodd via groups.io wrote:
Dave, |
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Re: LINEARITY - MEASUREMENTS
Dave The non-linearity isn¡¯t in SDR Console for sure. You¡¯re using a single frequency stepped calibration where we use Jim Sky¡¯s stepped wide band noise calibrator spanning ~8 MHz. If you have a known calibrated power meter you could check your HP output. That would help to tell you where the non-linearity lies. Larry _______________________ On Wed, May 21, 2025 at 9:48?PM W0LEV via <davearea51a=[email protected]> wrote:
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Re: Views of the Solar "Storm" from the Dark Sky Observatory May 13, 2025
Richard.? Your right. In the SDRc2RSS middle window you will see where the RX888 noise floor is.? It¡¯s probably around -135 or so. In that case you¡¯re going to have to set the dB threshold to -140 or -145 to get out out of the black hole your RSS is in. Then your plot may suffer some but you should then be able to adjust SDRc2RSS gain higher so you can get RSS offset off zero to get some adjustment room to the right. Use RSS gain to set the white bar and RSS offset to set the black end. Even if the plot isn¡¯t perfect you want to get the range of black to white in your spectrograph close. So the spectrographs you share will look right even though the recorded .sps file isn¡¯t well calibrated. You can work on the calibration plot to get your recorded files calibrated later.? Larry _______________________ ? On Wed, May 21, 2025 at 9:04?PM Richard Gray via <grayro=[email protected]> wrote:
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Re: Views of the Solar "Storm" from the Dark Sky Observatory May 13, 2025
Richard Increase your RSS offset to the right to brighten up the dark end.? Larry K4LED _______________________ On Wed, May 21, 2025 at 6:06?PM Richard Gray via <grayro=[email protected]> wrote:
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Re: Views of the Solar "Storm" from the Dark Sky Observatory May 13, 2025
Hi Huub,
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I worked a bit more on the calibration today, and had a bit more success.? You can see the result in the attached image.? It is a bit closer to linearity than yours, but still a bit flat on the lower end.? Here is what I ended up with:
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SDRconsole:?
HF attenuation: 0
HF Gain: 20
Visual Gain: -30
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SDRc2RSS:
FFT Window: None
dB Threshold: -145
Gain: 2.2
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There is an interesting article on the web:
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which discusses the noise floors in different environments.? The Dark Sky Observatory is best described as "quiet rural".? In that case the noise floor may be -130 dB or lower.? In more noisy environments it can be quite a bit higher.? The dB Threshold on SDRc2RSS corresponds to that noise floor, and one should not raise it above the actual noise floor else some faint signals will be lost.? That article suggests that in low noise environments, RX-888 Mk II might benefit from a small amount of RF pre-amplification before the SDR.? Larry Dodd also suggested the same.
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I am not completely satisfied with this calibration.? These settings result in a very dark background on the RSS output, in some places black.? This may be partially a function of our radio-quiet background at the Dark Sky Observatory.? I think trying out a small amount of pre-amplification is a good idea, and I have ordered an RF pre-amp and will give it a try when it comes.
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Richard |
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Re: Calibration curve using RSP1B
Alfi Your calibration looks great Alfi.? Raising the dB threshold to -140 makes senes as that matches the receiver noise floor. Thanks. Larry K4LED
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Re: Calibration curve using RSP1B
¿ªÔÆÌåÓýDear Alfi and Larry, and all, ? ? Thanks for the great information. Alfi, your calibration curve looks excellent, and I will try those settings for my backyard setup. ? ? To be clear, calibration is a very useful way to make your data more scientific. It allows you to determine a background level for your observing site (i.e., how radio quiet is your site). Also, your data can then be directly compared with data from other observers. This is an advanced project, but a worthy one. We are hear to help you, so please ask questions. ? ? For those interested in a calibrator, we have plans to build-it-yourself. See the Wiki page:? /g/radio-jove/wiki/36273. The Build-it-yourself Calibrator Manual is attached. ? Happy Observing! ? Chuck ? ? Chuck Higgins The Radio JOVE Project Middle Tennessee State University 1301 E. Main St., MTSU Box 412 Murfreesboro, TN ?37132 ? ?
? From: [email protected] <[email protected]>
On Behalf Of Alfi Hasan via groups.io
Sent: Tuesday, May 20, 2025 9:16 AM To: [email protected] Subject: [EXTERNAL] Re: [Radio JOVE] Calibration curve using RSP1B ? [Edited Message Follows] I would also like to show the calibration results with RSP1B receiver and Jovecal 1, I think the results can be considered linear. Hopefully the settings I gave look correct. ? ? ? ? ? ? ? |
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Re: Views of the Solar "Storm" from the Dark Sky Observatory May 13, 2025
Sabine,ALL, It is not the calibrator, nor SDRc2RSS, nor SDR Console. It is the difference between a consumer product and a scientific grade instrument. Highly accurate circuit design, quality parts, and an effort to achieve linearity are the difference. Here is the calibration plot from my $5k receiver.. Plot using Jim Sky's DIY Calibrator, Winradio WR G655DDCe receiver, SDR Console, SDRc2RSS, and RSS 2.9.80. The RSP1B is a suitable SDR for Radio JOVE Citizen science studies and is affordable for many young students. Thanks. Larry K4LED
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Re: Views of the Solar "Storm" from the Dark Sky Observatory May 13, 2025
Sabine, It is not the calibrator nor SDRc2RSS nor SDR Console. Below is a plot from my $5k receiver.? It is the difference between a low cost consumer product and a scientific grade product with high quality linear parts and quality circuit design. The RSP1B is fine for Radio JOVE Citizen Scientist work given its reasonable cost many young students can afford. Plot using Jim Sky DIY Calibrator,?Winradio WR G65DDCe, on?SDR Console, SDRc2RSS, RSS 2.9.80. Thanks. Larry K4LED
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Re: The FFT and nuclear weapons
Dave, That's a very good history of the DFFT. I think you sent that video to me before and it's excellent. Thanks. It¡¯s amazing to me that current discoveries are actually based on work by others decades?ago. Gauss, Maxwell, Einstein, Hawking, Penrose (Roger is 93) and others had/have a gift of understanding far beyond anyone else. Why were they so gifted?? Einstein was rejected by every?university he applied to for professorship. Had to do humble work in a patent office to feed his family.? On a sad note I just read where USA sold our latest AI technology to the Arabs for a few $$$$. Scary thought. AI in unethical hands is dangerous to humanity. Same with Quantum computing technology. Those two technologies are set to change human life drastically.? Larry _______________________ On Mon, May 19, 2025 at 10:20?PM Dave Typinski via <davetyp=[email protected]> wrote: Here's a very interesting explanation of how and why the modern FFT came to |
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Re: Views of the Solar "Storm" from the Dark Sky Observatory May 13, 2025
On Sun, May 18, 2025 at 01:12 PM, Huub Hameleers SWL/JO21JN wrote:
Not the most pretty curve I have to admit but I guess that's how the RX888 MKII behaves. When I look at the calibration curve that Chuck created with the RSP1B, I would suspect that the curve is messed up somewhere in SDRconsole or SDRc2RSS.
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Sabine
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Germany Standard time: UTC +1 hour |
Dave Typinski
Larry Dodd
salvador aguirre
Chuck Higgins
john sommer
Alfi Hasan
Sabine Cremer