Need advice on a tracking device

psychotick said:

Hi,

Not sure why your people don't have phones. Everyone else seems to these days (except me). But failing that and considering that it's sci fi, why bother with the details? Assume these people have chips implanted - a little bit more advanced than a simple RFID. They're talking about doing this now by the way - chips that will hold the details of your credit cards, perhaps be implanted in your hand, and which will let you pay for goods simply by waving your hand sans card, over the reader.

Now assume that these chips send out signals keyed to an individual frequency constantly, so they are RFIDs I suppose, but with a permanent power supply (nuclear battery?) and that everyone can be found wherever they are - no satellites or GPS needed. And the tracker device is actually a future style watch - it just has a tracker function. Push a button or speak a command and the tracker function switches on and replaces the hands. Then enter the individual frequency of the chip / person you want to find, and it gives you a pointer hand and an estimated distance to target based on signal strength. Then you just get in your car and drive in that direction, following the watch.

Cheers, Greg.

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Two things stood out to me.

1. ID would not be by frequency. It has to be some form of unique data.

2. Signal strength is not proportional to distance. Signal strength varies greatly with terrain and buildings. If the receiver is not in line of sight the signal strength could drop to zero. Also, carrier frequency directly affects signal propagation. Some frequencies are better at going through walls or trees. It gets much more complex than that.

On open flat land you might get a signal that is 5 km away. That same transmitter and receiver might get no signal 200 meters apart in the city.

I think Jackie is just going to have to not disclose the technology as there is no magic wand in the real world to do this with the constraints the story needs.

Loren said:

Signal strength is not proportional to distance. Signal strength varies greatly with terrain and buildings.

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It's inverse square law in the open. Much worse in cities. so x10 distance needs a bit more than 100x more power in built up areas. Add up to x10 more power if indoors!

Loren said:

I think Jackie is just going to have to not disclose the technology as there is no magic wand in the real world to do this with the constraints the story needs.

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Yes. Any technically believable system even using yet to be developed tech needs two world wide infrastructures, one for navigation (terrestrial beacons or satellite) and one for interpersonal communication (loads of cell phone masts, or future equivalent). Even if a mythical x10 better battery is invented it would need charged every week.
Basic physics, not hypothetical inventions is the limitation. A watch sized tracker is possible. But it needs something equivalent to a mobile phone network and GPS, if not using current phone cell towers and satellite navigation. Ideally it would use encryption.

So just have a watch / bracelet that displays time or distance and direction (and/or co-ordinates). Don't bother explaining it. After all it's trivial to do a mutual tracker on a phone (about a days programming) that can communicate automatically using SMS (even using manually estimated co-ordinates).

Two way pocket trackers exist today. They silently use the mobile phone network. As do trackers on trucks etc. Hardly anyone knows how they work and in a contemporary spy/detective story you'd not destroy the story flow by explaining.

This may be a dumb question to the smart guys here, but if our infrastructure went down, would we lose things such as satelite navigation? Does that run through terrestrial infrastructure too?
I know everything else does, but never considered sat navs.

Hi Loren,

Are we talking about the same physics that once told us we'd never be able to go faster than thirty mph because any faster and we couldn't breath? Or that heavier than air flight was impossible? From what I gather this is a sci fi story or specualtive fiction, and the fact that we don't yet know how to get around these limitations does not mean that we will not be able to do so in time.

Cheers, Greg.

psychotick said:

same physics that once told us we'd never be able to go faster than thirty mph because any faster and we couldn't breath? Or that heavier than air flight was impossible?

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No.
And educated people in the field didn't believe those limitations. Those were the historical equivalent of media / man in street.

There is Speculative Fiction and Fantasy ... obviously there is a grey area some place in between. No discovery is going to repeal basic mathematics, logic or the three laws of thermodynamics or physics of light / radio waves.

Some limitations can be got round by inventions, technology not practical (but we know how it would work). Some limitations can be got round by discoveries in physics. Other limitations are so basic that any "getting round them" is magic or pure fantasy. (Free Energy = perpetual motion machine, inverse square law for transmission and reception etc).

It's quite acceptable to have a wrist mounted mutual tracker. It's not reasonable to start to explain how it works anywhere (if it isn't using some sort of "everywhere" infrastructure) unless it's magic. Either you don't explain at all, or it's using some future equivalent of cell masts (or cell masts) or it's magic. Magic is more believable than Star Trek style fake technobabble that violates very basic physics.

1. There are all kinds of things we don't know how to make, that are not intrinsically impossible. That's viable for Speculative fiction for Inventions.
2. There are things that we don't even know how they might work, but don't violate basic logic, mathematics, Physics etc. That's viable for Speculative fiction for science discoveries.
3. There are kinds of things that make no sense even on internal logic, mathematics or very basic physics that can't be wrong*. That's only viable for Fantasy.

There is a grey area between 1 & 2, where the size or power consumption might in reality not be achievable.
There is a grey area between 2 & 3 were some aspect of physics might be terribly misunderstood, but generally new science discoveries are a superset. Any new "law" has to explain all the existing observations and results ideally explain some phenomenon not understood, or a new observation and be testable in some fashion.

[* Newtonian Physics isn't "wrong" as such, just is a subset of Einsteinian physics. The newer physics doesn't provide a way to bypass Newtonian "laws" in everyday life and gadgets. GPS has to apply Einsteinian physics to avoid errors due to the extreme accuracy and altitude of the on board atomic clocks. If pure Newton was used, it would just be less accurate navigation]

There's nothing wrong with using a physically implausible communications device in a sci-fi story. If you don't want to explain how it works, just don't.

However, I disagree with the statement that you "can't" explain how it works. There are plenty of ways to do this.

For example,
1) The wrist tracker taps into the barely-functional remnants of pre-apocalypse telecom. Signal's too degraded to communicate, but you can locate someone! (Extra bonus: when you want to get a character lost, you can have his tracker lose its signal)

2) The wrist tracker uses hyper-advanced fantasy tech. It shoots neutrinos, completely ignoring line of sight. It induces a miniscule, self-perpetuating oscillation in the Earth's core. It communicates with the Trisolaran Sophons that permeate every molecule of the Earth's surface. It communicates through The Warp. It's a freaking Ansible.

3) The wrist tracker uses ordinary radio waves and the author chooses to ignore the real-world limitations of radio waves. Stuff like this happens *all the time* in otherwise plausible fiction. This is cheating, but it's not a bad problem if the story is otherwise fun to read.

Piousflea84 said:

barely-functional remnants of pre-apocalypse telecom.

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Telecom (Mobile) is INCREDIBLY fragile. It needs data centres, terrestrial fibre, ATM, ISDN and Microwave networks, special switching gateway exchanges. Pretty much it all works or none of it. It would not whatsover survive any sort of apocalypse, nor would modern fixed line. Satellite also uses ground stations to work, though Iridium was originally meant to have some self contained features.

1 & 3 are not viable unless it's fantasy, in which case why not go for 2.

Piousflea84 said:

Stuff like this happens *all the time* in otherwise plausible fiction.

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No, I think only on totally implausible TV/Cinema. Most books are better researched and more accurate. Hollywood doesn't care!

Jackie Bee said:

Hi everyone! I need help. For my SciFi WIP I need to come up with some kind of a gadget that will allow two people who got separated to find each other again. Anyone knows of such technologies? It can be something that doesn't exist yet, but it must sound believable. The thing must be small and not draw others' attention. I thought maybe they have some special rings or bracelets that allow them to track each other, but I need a bit of technolgy behind this, and I have no ideas. Anyone can help?...Thanks!

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How advanced is the tech? You could have a trans-dermal implant in each that works on a frequency tied to their unique DNA sequence?

Tim Murray said:

How advanced is the tech? You could have a trans-dermal implant in each that works on a frequency tied to their unique DNA sequence?

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Nope, it should be something two unprepared people can grab and use to track each other. I'll probably just say they have a tracker watch and won't go into details of how it works.

Jackie Bee said:

Nope, it should be something two unprepared people can grab and use to track each other. I'll probably just say they have a tracker watch and won't go into details of how it works.

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I saw a movie with Dennis Quaid, his character dies in the beginning. His son grows up and during a rare solar storm, contacts his long dead father in the past on a ham radio set.

You might have them come across a believable quirk of nature, or science, or both.

Hi,

Ironically enough the movie was called Frequency and I have to admit I quite liked it. But there were some monumental plot hole issues. For a start when the baddie loses his hand in the past and it withers in the future - why didn't his entire past history change with him?

Cheers, Greg.

Tim Murray said:

during a rare solar storm, contacts his long dead father in the past on a ham radio set

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A really stupid plot, Only worthwhile if as fun as Ghostbusters. Not SF.

Sometimes it's fun to have an otherwise logical plot driven by a few blatantly illogical assumptions. Heck, that's pretty much the synopsis of every Michael Crichton novel ever, and he's one of my favorite authors of all time. In fact, many of Crichton's works hung a lampshade on the more implausible pieces of technology. There's the "Timeline" scientists pointing out that their time travel device really *shouldn't* work, and pretty much everyone in "Next" reacting to the human-parrot hybrid Gerard. Neither of those "technologies" were physically plausible, but the rest of the novel showed believable consequences of what might happen if such a thing "magically" worked.

For a more modern example: Andy Weir wrote "The Martian" with a very high level of realism, and at one point he was troubled by the physically-impossible nature of the sandstorm that strands Watney on Mars. Andy Weir actually wrote an alternate opening where Watney was stranded by an equipment malfunction instead. However, his blog readers told him that the sandstorm was far more exciting, and they didn't mind a minor loss of realism... so he went back to the physically-implausible sandstorm opening.

Not everything in fiction needs to be realistic to be believable. After all, the cozy mystery genre wouldn't exist without reality-stretching feats of deduction... and the romance genre definitely wouldn't exist without reality-defying levels of sappiness and naivete.

Virtual cat whiskers that identify other cats in the vicinity, proceeding out from the matrix hard chip interwoven in their spinal processes.
I call it "cadar".

What Piousflea84 said. You don't have to be a fact Nazi when it comes to writing fiction. The narrative drive is far more important than the small facts.

pH