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I was reading this article about NASA's PhoneSat Flight Demonstrations and came across this sentence.

"To achieve this, NASA's PhoneSat design makes extensive use of commercial-off-the-shelf components, including an unmodified, consumer-grade smartphone. Out of the box smartphones already offer a wealth of capabilities needed for satellite systems, including fast processors, versatile operating systems, multiple miniature sensors, high-resolution cameras, GPS receivers, and several radios."

My Question: Is this just enthusiastic writing, or can "Out of the box smartphones ... offer ... capabilities needed for satellite systems, including ... GPS receivers..."? Is it known if they (or anyone) has tried it? Possibly with firmware modification? (see below)

Background: (phones in sats)

NASA's PhoneSats use ordinary smart phones as the main control system for the nanosatellite. University of Surrey's STRaND-1 uses a smart phone to control some functions, but with a more standard computer to share in the satellite's operation. It was the first 'smart phone satellite' in space. From here:

"During phase two, the STRaND-1 team plan to switch the satellite’s in-orbit operations to the smartphone, thereby testing the capabilities of a number of standard smartphone components for a space environment. The satellite is operated from the Surrey Space Centre’s ground station at the University of Surrey."

Based on all of the information and comments in this question and answer pair, I'm guessing that the GPS chips inside off-the-shelf smart phones would never provide data when in orbit, either because they are moving too fast, or the altitude is too high, or both. (I think that some manufacturers apply the 'OR', others the 'AND' of the two conditions) The block is usually applied in Firmware, so could conceivably be circumvented by clever hacking programming of the phone. This comment mentions this YouTube video from Adafruit's founder Limor "Ladyada" Fried (read more) where the firmware has been modified to extend the altitude to at least 50km as an example.

The article says further on:

"NASA's PhoneSat 1.0 satellite has a basic mission goal–to stay alive in space for a short period of time, sending back digital imagery of Earth and space via its camera, while also sending back information about the satellite's health."

and then:

"PhoneSat 2.0 also will supplement the capabilities of PhoneSat 1.0 by adding a two-way S-band radio to allow engineers to command the satellite from Earth, solar panels to enable longer-duration missions, and a GPS receiver. In addition, PhoneSat 2.0 will add magnetorquer coils – electro-magnets that interact with Earth's magnetic field – and reaction wheels to actively control the satellite's orientation in space. "

Which suggests that the "GPS and several radios" of the smartphones may not have been used. I'm curious if it's ever been attempted and then written about.

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No, they didn't. (personal knowledge)

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  • $\begingroup$ I'm not sure if your answer is considered binary, or boolean, but it's certainly to-the-point. Thanks! Do you mean NASA PhoneSats only, or does it include Surrey's STRaND-1 also? Wisely or not, I've included information from both, but it seems I'm just asking about the former. So I'll be a happy camper with either one. $\endgroup$ – uhoh May 3 '16 at 6:47
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    $\begingroup$ Both,actually :) $\endgroup$ – pericynthion May 3 '16 at 16:14
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They could not have used it without some serious modifications. Most GPS systems fall under what is known as the "CoCom", which prohibits GPS from working over 60,000 feet or 1200 miles per hour. Thus it could not have functioned without some significant improvements in the firmware.

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    $\begingroup$ I think CoCom was a voluntary (and widely followed) guideline for export of GPS devices, not a law about operating them, which expired in 1994, correct me if I'm wrong. It still exists in spirit, and in two other evolved forms known as the Wassenaar Arrangement and MTCR - see this comment below the answer I've already linked to. I think they are also both voluntary agreements on export. $\endgroup$ – uhoh May 3 '16 at 12:13
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    $\begingroup$ If the firmware exists, it would certainly be legal for NASA to make the update to fly a satellite. The question becomes does it even exist? And the answer might very well be no. $\endgroup$ – PearsonArtPhoto May 3 '16 at 12:24
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    $\begingroup$ That might hold true for the altitude, but the speed very well could be another matter entirely. Computing a fix at orbital speed might well require some serious upgrades in the algorithm, from one second to the next the distance will vary considerably. $\endgroup$ – PearsonArtPhoto May 3 '16 at 12:36
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    $\begingroup$ @uhoh I'm almost positive that while what you said is true, most Phone receivers depend on knowing at least approximately where one is to work. They have a limited range of correlations that they can reference. A cold start GPS solution is something rather difficult to achieve. $\endgroup$ – PearsonArtPhoto Jun 6 '16 at 14:26
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    $\begingroup$ @uhoh yes, what you said is correct, but despite having lots of correlators, a device will probably only search the range of dopplers that it considers plausible both to save power and to avoid false decodes that could degrade the position. If the chip doesn't think that it's possible to be going several km/s, then it won't achieve a lock under those conditions. $\endgroup$ – hobbs Jul 30 '18 at 20:31

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