OT: Pop-up archival transmitting tags (PAT) for tracking fis

[John Doe]

Anybody familiar with them? I didn't know such a portable device can
transmit all the way to a satellite.

I can imagine it works something like this... The satellite broadcasts
an activation signal. Any PAT that gets the signal broadcasts a tiny
pulse containing its location, then... The satellite focuses on that
location so the PAT can transmit data to the satellite. But that assumes
a satellite can focus its receiver on a specific location. I doubt the
PAT is capable of focusing its signal in any specific direction. I could
try researching it, but not sure it will get that detailed.

Some obvious benefits of transmitting from the ocean's surface... No
trees or other obstacles in the way. No competing signals. Possible
water vapor, I guess, but the satellite could know enough not to
activate PATs during a storm.

 

[bitrex]

On 3/23/2020 7:16 AM, John Doe wrote:

Anybody familiar with them? I didn't know such a portable device can
transmit all the way to a satellite.

I can imagine it works something like this... The satellite broadcasts
an activation signal. Any PAT that gets the signal broadcasts a tiny
pulse containing its location, then... The satellite focuses on that
location so the PAT can transmit data to the satellite. But that assumes
a satellite can focus its receiver on a specific location. I doubt the
PAT is capable of focusing its signal in any specific direction. I could
try researching it, but not sure it will get that detailed.

Some obvious benefits of transmitting from the ocean's surface... No
trees or other obstacles in the way. No competing signals. Possible
water vapor, I guess, but the satellite could know enough not to
activate PATs during a storm.

A small transmitter like that being able to dynamically focus like,
phased-array or something?

Reminds me of a startup's patent I saw for charging cell phones and
mobile devices wirelessly, not inductive but radiatively from a
centrally located transmitter somewhere in a room or building. Looked
plausible "in theory" but there were a lot of "black boxes" of circuits
in their patent. To transmit significant power from a small array the
phases have to be so precisely aligned...I dunno the timing constraints
for the set of PLLs must be nuts at 2.4 GHz. Devil is definitely in the
details of that one. AFAIK the startup has never demonstrated a working
device to the public that could be examined. Vaporware so far.

 

[bitrex]

On 3/23/2020 7:16 AM, John Doe wrote:

Anybody familiar with them? I didn't know such a portable device can
transmit all the way to a satellite.

I can imagine it works something like this... The satellite broadcasts
an activation signal. Any PAT that gets the signal broadcasts a tiny
pulse containing its location, then... The satellite focuses on that
location so the PAT can transmit data to the satellite. But that assumes
a satellite can focus its receiver on a specific location. I doubt the
PAT is capable of focusing its signal in any specific direction. I could
try researching it, but not sure it will get that detailed.

Some obvious benefits of transmitting from the ocean's surface... No
trees or other obstacles in the way. No competing signals. Possible
water vapor, I guess, but the satellite could know enough not to
activate PATs during a storm.

the tag is probably just sending pretty low-bandwidth data and the
satellite has pretty good omnidirectional gain. the Argos satellites
have an apogee of only ~500 miles they're in fairly low orbit.