Perseverance- Computational Systems & Software, technical discussion of all things digital |
Perseverance- Computational Systems & Software, technical discussion of all things digital |
Mar 21 2021, 10:49 PM
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#1
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
A member requested a thread dedicated to this topic, so here it is. Please review recently-added rule 1.4 & keep it in mind (as well as the rest of them). Enjoy!
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Mar 24 2021, 03:47 AM
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#2
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Member Group: Members Posts: 427 Joined: 18-September 17 Member No.: 8250 |
Technically it's still part of Perseverance...
There was discussion today during the Ingenuity preview press conference that the helicopter's CPU was 100s of times faster than all previous planetary mission flight computers combined. Someone also mentioned/thanked Qualcom as a partner. Internet search says Ingenuity CPU is a Qualcomm Snapdragon 801. Specs at https://www.qualcomm.com/products/snapdragon-processors-801 I started to wonder if that chip's Wi-Fi/Bluetooth would be used to communicated with Perseverance, but wikipedia say comm is via 900 MHz Zigbee. |
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Mar 24 2021, 08:37 AM
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#3
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Member Group: Members Posts: 153 Joined: 4-May 11 From: Pardubice, CZ Member No.: 5979 |
I started to wonder if that chip's Wi-Fi/Bluetooth would be used to communicated with Perseverance, but wikipedia say comm is via 900 MHz Zigbee. That's correct. Here is a bit more details about Ingenuity telecommunication system: "Once separated from the host spacecraft (lander or rover), the Mars Helicopter can only communicate to or be commanded from Earth via radio link. This link is implemented using a COTS 802:15:4 (Zig-Bee) standard 900 MHz chipset, SiFlex 02, originally manufactured by LS Research. Two identical SiFlex parts are used, one of which is an integral part of a base station mounted on the host spacecraft, the other being included in the helicopter electronics. These radios are mounted on identical, custom PC boards which provide mechanical support, power, heat distribution, and other necessary infrastructure. The boards on each side of the link are connected to their respective custom antennas. The helicopter antenna is a loaded quarter wave monopole positioned near the center of the solar panel (which also serves as ground plane) at the top of the entire helicopter assembly and is fed through a miniature coaxial cable routed through the mast to the electronics below. The radio is configured and exchanges data with the helicopter and base station system computers via UART. One challenge in using off-the-shelf assemblies for electronics systems to be used on Mars is the low temperatures expected on the surface. At night, the antenna and cable assemblies will see temperatures as low as -140 C. Electronics assemblies on both base station and helicopter will be kept “warm” (not below -15 C) by heaters as required. Another challenge is antenna placement and accommodation on the larger host spacecraft. Each radio emits approximately 0.75 W power at 900 MHz with the board consuming up to 3 W supply power when transmitting and approximately 0.15 W while receiving. The link is designed to relay data at over-the-air rates of 20 kbps or 250 kbps over distances of up to 1000 m. A one-way data transmission mode is used to recover data from the helicopter in real time during its brief sorties. When landed, a secure two-way mode is used. Due to protocol overhead and channel management, a maximum return throughput in flight of 200 kbps is expected while two-way throughputs as low as 10 kbps are supported if required by marginal, landed circumstances." |
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Mar 24 2021, 04:30 PM
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#4
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
A citation for the above quoted text: https://trs.jpl.nasa.gov/bitstream/handle/2...L%2317-6243.pdf I believe.
A more detailed reference for the telecom system with some good detail about the helicopter in general is https://trs.jpl.nasa.gov/bitstream/handle/2...L%2318-3381.pdf -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Mar 24 2021, 04:45 PM
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#5
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Hundreds of times faster is an eye-catching claim. It seems that Ingenuity's CPU's clock speed is about 14x that of the Curiosity rover, which is a considerable difference, and it has four cores, and apparently twice the bus width of the former, and 14 * 4 * 2 is indeed over 100. It's not straightforward to compare computing power in objective units, but it seems like the claim is at least approximate if not literal.
Moore's "law," holding that CPU speeds increase exponentially over time more or less held true from the 1950s through 2010. Spacecraft computers tend to be about 10 years older than the launch date, so here we are ~10 years after Moore's law ran out of steam. This might make Perseverance part of the last generation of spacecraft with computational power much greater than its predecessors. N.B., virtually every part of what I just said merits at least one grain of salt. |
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Mar 24 2021, 05:14 PM
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#6
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Senior Member Group: Members Posts: 4256 Joined: 17-January 05 Member No.: 152 |
Hundreds of times faster is an eye-catching claim. It's worth pointing out that the Ingenuity computer wasn't required to last long on the surface so didn't need to be rated for the environment as the rover's was, so could be newer hardware. I wonder if the image processing demands of Ingenuity are greater though, and maybe that factored in. The rover handled the EDL image processing, but I'd guess that the timescales are shorter for Ingenuity flights so the computational requirements greater. |
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Mar 24 2021, 05:27 PM
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#7
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
It's not straightforward to compare computing power in objective units... Indeed. "Lies, damn lies, and benchmarks", to paraphrase Twain. Who cares how fast anything is if it's fast enough to do what it needs to do? All the MSSS embedded processors on Mars are 40 MHz IPC=1 RISCS with 128Kbytes of SRAM. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Mar 24 2021, 11:03 PM
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#8
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Forum Contributor Group: Members Posts: 1374 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
They said Ingenuity is a tech demo so they pretty much could use what they wanted, long term survivability was not an objective, so hence the capability of using a modern processor. Also Ingenuity's nav cam takes 30 frames per second pictures for flying navigation purposes. I think they said they did do a little hardening of the CPU, but not the amount a processor would get designed to last a decade or more on Mars.
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