Orbital Satellite HRPT Image Reception
Posted: Mon Nov 06, 2017 2:21 am
Post 1 of 2
HRPT weather satellite signals have much higher resolution than APT images; however, HRPT image reception is a little more complex than receiving APT images from passing orbital weather satellites. First, the operating frequency is much higher and second, it is important to have the ability to track the satellites. The image decoding also takes a lot more processing power. In this example, the RSP2 is being used with a 26 director element loop yagi (approximately 20 dBi and 6 ft in length) in conjunction with a 21dB gain LNA with a noise figure of 0.36 dB. Additionally, the cost of equipment and software is higher, so you will want to read through this article and get a good idea of all of the software and components, and related expenses, before starting.
The tracking system employed is a repurposed Meade Instruments DS2090AT mount with 497 controller. If you use one of these, be sure to obtain the latest version which has a blue band around it showing the position rather than a black band. Older versions of the mount may not work as well without some modification for this application (they may slip in vertical movement, given that the antenna is near the maximum out-of-balance weight for the newer mounts – if it should slip and tightening does not solve the problem, pull the vertical control portion apart and insert a rubber washer such that it is between the friction plate and the original gripping section; alternatively, you may be able to add some non-metallic weight to the back of the boom to better balance the antenna in the mount). Given that the diameter of a 90 cm telescope tube is near that of the loop yagi in the 1.7 GHz range and the antenna weight is comparable to that of a telescope tube, making use of a used telescope mount capable of tracking satellites worked well in this instance. Meade Instruments has downloadable software on its web site to allow uploading the most recent versions of software and TLE (satellite data) files to the 497 controller using an RS-232 serial cable. Refer to the Autostar™ Software Updater. Additionally, Meade has downloadable Autostar™ Suite software to enable using the mount to point to any position in the observable sky as well as to track orbital satellites passing overhead.
The LNA used is a TriQuint/Qorvo TQP3M9037-PCB evaluation PCBA which provides approximately 21dB gain with a noise figure of 0.36dB. The LNA in this image has been modified to apply a 10uH inductor 220 mA (PN 9250A-103-RC) and 33uF 25VDC capacitor (PN TAP336K025SCS) to supply power via the coaxial cable from the RSP2 using the RSP2’s BIAS-T feature on Antenna Port B. The TriQuint TQP3M9037-PCB evaluation PCBA only requires around 47mA at 5VDC. Operation off of the RSP2 Bias-T power can be used, if a band pass filter is not needed in your area. Be sure to use flexible (to allow the antenna mount to move properly), low loss cable, such as LMR-240 to connect the LNA (and filter) is used to go the short distance to the RSP2 (or a line driver, If the RSP2 will be mounted far away from the antenna).
Continued in Post 2 of 2
HRPT weather satellite signals have much higher resolution than APT images; however, HRPT image reception is a little more complex than receiving APT images from passing orbital weather satellites. First, the operating frequency is much higher and second, it is important to have the ability to track the satellites. The image decoding also takes a lot more processing power. In this example, the RSP2 is being used with a 26 director element loop yagi (approximately 20 dBi and 6 ft in length) in conjunction with a 21dB gain LNA with a noise figure of 0.36 dB. Additionally, the cost of equipment and software is higher, so you will want to read through this article and get a good idea of all of the software and components, and related expenses, before starting.
The tracking system employed is a repurposed Meade Instruments DS2090AT mount with 497 controller. If you use one of these, be sure to obtain the latest version which has a blue band around it showing the position rather than a black band. Older versions of the mount may not work as well without some modification for this application (they may slip in vertical movement, given that the antenna is near the maximum out-of-balance weight for the newer mounts – if it should slip and tightening does not solve the problem, pull the vertical control portion apart and insert a rubber washer such that it is between the friction plate and the original gripping section; alternatively, you may be able to add some non-metallic weight to the back of the boom to better balance the antenna in the mount). Given that the diameter of a 90 cm telescope tube is near that of the loop yagi in the 1.7 GHz range and the antenna weight is comparable to that of a telescope tube, making use of a used telescope mount capable of tracking satellites worked well in this instance. Meade Instruments has downloadable software on its web site to allow uploading the most recent versions of software and TLE (satellite data) files to the 497 controller using an RS-232 serial cable. Refer to the Autostar™ Software Updater. Additionally, Meade has downloadable Autostar™ Suite software to enable using the mount to point to any position in the observable sky as well as to track orbital satellites passing overhead.
The LNA used is a TriQuint/Qorvo TQP3M9037-PCB evaluation PCBA which provides approximately 21dB gain with a noise figure of 0.36dB. The LNA in this image has been modified to apply a 10uH inductor 220 mA (PN 9250A-103-RC) and 33uF 25VDC capacitor (PN TAP336K025SCS) to supply power via the coaxial cable from the RSP2 using the RSP2’s BIAS-T feature on Antenna Port B. The TriQuint TQP3M9037-PCB evaluation PCBA only requires around 47mA at 5VDC. Operation off of the RSP2 Bias-T power can be used, if a band pass filter is not needed in your area. Be sure to use flexible (to allow the antenna mount to move properly), low loss cable, such as LMR-240 to connect the LNA (and filter) is used to go the short distance to the RSP2 (or a line driver, If the RSP2 will be mounted far away from the antenna).
Continued in Post 2 of 2