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Reviews with images
Great tandem performance with astro spectrometer
Amateur radio enthusiasts now have amazing and powerful technical capabilities at their disposal. My initial plan was to replicate some of the results documented by a group of students on the Internet. Their project demonstrated how the native H1 frequency (1420.4 Mhz) of neutral hydrogen can become red and blue-shifted due to the Doppler effect and the rotation of our Milky Way galaxy (MWG). Likewise used the spectrometer software from the West Virginia University Radio Astronomy project (WVU RAIL) which employs the polyphase filter bank technique to enhance harvesting of weak astronomical signals from the noise clutter. Instead of a horn antenna, a simple grid-wifi dish was used in conjunction with a dipole feed element tuned to 1420 Mhz via return-loss testing. The Sawbird+H1 served as the upstream LNA because of its lower published noise figure and a spectrum analyzer confirmed a relatively flat 30 db passband. Downstream devices included a Raspberry Pi-4 running the spectrometer software and an NESDR Smartee sampling at 2.4 MSPS.The accompanying image has the dish pointed in the vicinity of the star Alya near the galactic plane with coordinates of approximately +35 degrees longitude and 0 degrees latitude. There is a noticeable peak at roughly 1420.56 Mhz, followed by a dip, and then another slight peak at 1420.59 Mhz. These blue-shifted frequencies appear related to H1 concentrations in regions of the spiral arms of the MWG that are moving toward the observer. The frequency deviations from the baseline H1 correspond to a tangential (line-of-sight) velocity of 33.8 km/sec and 40.1 km/sec, respectively. By factoring in the Sun's velocity relative to the galactic core, the rotational speed of the galaxy can be estimated. Calibration of the spectrometer using its "hot" and "cold" benchmark temperatures is vital prior to observation.
Top reviews from the United States
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Reviewed in the United States on March 11, 2020
The accompanying image has the dish pointed in the vicinity of the star Alya near the galactic plane with coordinates of approximately +35 degrees longitude and 0 degrees latitude. There is a noticeable peak at roughly 1420.56 Mhz, followed by a dip, and then another slight peak at 1420.59 Mhz. These blue-shifted frequencies appear related to H1 concentrations in regions of the spiral arms of the MWG that are moving toward the observer. The frequency deviations from the baseline H1 correspond to a tangential (line-of-sight) velocity of 33.8 km/sec and 40.1 km/sec, respectively. By factoring in the Sun's velocity relative to the galactic core, the rotational speed of the galaxy can be estimated. Calibration of the spectrometer using its "hot" and "cold" benchmark temperatures is vital prior to observation.
Great tandem performance with astro spectrometer
Reviewed in the United States on March 11, 2020
Amateur radio enthusiasts now have amazing and powerful technical capabilities at their disposal. My initial plan was to replicate some of the results documented by a group of students on the Internet. Their project demonstrated how the native H1 frequency (1420.4 Mhz) of neutral hydrogen can become red and blue-shifted due to the Doppler effect and the rotation of our Milky Way galaxy (MWG). Likewise used the spectrometer software from the West Virginia University Radio Astronomy project (WVU RAIL) which employs the polyphase filter bank technique to enhance harvesting of weak astronomical signals from the noise clutter. Instead of a horn antenna, a simple grid-wifi dish was used in conjunction with a dipole feed element tuned to 1420 Mhz via return-loss testing. The Sawbird+H1 served as the upstream LNA because of its lower published noise figure and a spectrum analyzer confirmed a relatively flat 30 db passband. Downstream devices included a Raspberry Pi-4 running the spectrometer software and an NESDR Smartee sampling at 2.4 MSPS.Reviewed in the United States on March 11, 2020
The accompanying image has the dish pointed in the vicinity of the star Alya near the galactic plane with coordinates of approximately +35 degrees longitude and 0 degrees latitude. There is a noticeable peak at roughly 1420.56 Mhz, followed by a dip, and then another slight peak at 1420.59 Mhz. These blue-shifted frequencies appear related to H1 concentrations in regions of the spiral arms of the MWG that are moving toward the observer. The frequency deviations from the baseline H1 correspond to a tangential (line-of-sight) velocity of 33.8 km/sec and 40.1 km/sec, respectively. By factoring in the Sun's velocity relative to the galactic core, the rotational speed of the galaxy can be estimated. Calibration of the spectrometer using its "hot" and "cold" benchmark temperatures is vital prior to observation.
Images in this review
Reviewed in the United States on September 20, 2023
Reviewed in the United States on July 20, 2021
Reviewed in the United States on December 27, 2019
Reviewed in the United States on December 30, 2019
A critical part of the radio telescope is the first, low noise amplifier. The NooElec Amplifier is custom designed for radio astronomy observations. It has high gain and a good RF filter for reducing interference. The 1st figure (with Red ruler) shows the amplifier attached to the feed horn. The second figure shows the NooElec Amplifier in a test horn pointing at the ground. In the background is the larger horn we use for the Milky Way Observations.
The three plots show the observations with the test horn. The figure with two separate graphs shows the "HOT" load, looking at the ground (Red upper line) and "COLD" load (lower, looking at the sky). The x axis is frequency in MHz, and y axis intensity in raw counts.
To make astronomical measurements requires calibration. Computing the ratio of HOT and COLD gives the temperature plot, with an excellent receiver temperature of between 90-110 Kelvin. This is very good performance. The Milky Way Spiral Arms are seen in the broad feature in the middle of the plot. The narrower lines are interference.
The 3rd plot shows the Milky Way galaxy with a baseline subtracted. The data were taken only with the all aluminum test horn (14 inches in diameter). The x axis is velocity of the hydrogen relative to the Earth and the y axis is intensity of the hydrogen at that velocity.
Excellent noise figure; high Gain amplifier for observing the Milky Way.
Reviewed in the United States on December 30, 2019
A group of high school teachers is working with West Virginia University and the National Science Foundation to build and test student build radio telescopes for observing the Milky Way Galaxy. These will teach the students about electronics and astronomy.Reviewed in the United States on December 30, 2019
A critical part of the radio telescope is the first, low noise amplifier. The NooElec Amplifier is custom designed for radio astronomy observations. It has high gain and a good RF filter for reducing interference. The 1st figure (with Red ruler) shows the amplifier attached to the feed horn. The second figure shows the NooElec Amplifier in a test horn pointing at the ground. In the background is the larger horn we use for the Milky Way Observations.
The three plots show the observations with the test horn. The figure with two separate graphs shows the "HOT" load, looking at the ground (Red upper line) and "COLD" load (lower, looking at the sky). The x axis is frequency in MHz, and y axis intensity in raw counts.
To make astronomical measurements requires calibration. Computing the ratio of HOT and COLD gives the temperature plot, with an excellent receiver temperature of between 90-110 Kelvin. This is very good performance. The Milky Way Spiral Arms are seen in the broad feature in the middle of the plot. The narrower lines are interference.
The 3rd plot shows the Milky Way galaxy with a baseline subtracted. The data were taken only with the all aluminum test horn (14 inches in diameter). The x axis is velocity of the hydrogen relative to the Earth and the y axis is intensity of the hydrogen at that velocity.
Images in this review
Top reviews from other countries
Hermann Fenger-Vegeler
Feiner LNA für einen guten Preis
Reviewed in Germany on October 24, 2023Daniel Gracia
Rendimiento acorde al esperado
Reviewed in Spain on April 27, 2020
Daniel Gracia
Reviewed in Spain on April 27, 2020
El rendimiento de nuestra unidad honra los valores anunciados: ganancia sensiblemente superior a los 40dB en la banda de trabajo, con un ancho de 67MHz. Como se aprecia en las imágenes, la banda de trabajo está sensiblemente desplazada hacia abajo respecto a la frecuencia de funcionamiento nominal.
Ahora, ¡a montarlo en una antena!
Images in this review
MannoLowLand
Empfindlicher, selektiver und rauscharmer Antennenvorverstärker
Reviewed in Germany on December 23, 2022
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