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Blaine Bateman

Digital Tuning for RF Analog Front End

Blaine Bateman
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Elo´se
Elo´se
10/12/2016 4:55:22 AM
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Re: M is for Mechanical
Great post !

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eafpres1
eafpres1
7/3/2013 7:59:04 PM
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Re: Other applications
@Derek--Ah, I see.  I read an article today that Google is again talking about "stratocells" which would be broadband repeaters on weather balloons.  In certain cases the doppler could be 200 mph; that might be an issue.  I understand there are some commercial baloon-based services that do work, so perhaps it is isn't too huge as long as the balloons don't get into the jetstream.

I like your idea of automatically tuning out the doppler for a HAM using a bounce off a satellite.  

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RedDerek
RedDerek
7/3/2013 7:55:31 PM
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Re: Other applications
I agree the sat-phone may not have an issue. I was thinking the HAM radio folks. To really work with ISS passing and other sat-repeaters, one needs to frequency adjust as the satellite approaches and receeds from one's position.

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eafpres1
eafpres1
7/3/2013 7:34:28 PM
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Re: Other applications
@Derek--"Another application in the SDR is to account for doppler shifts"

That is an interesting problem.  Do you know how significant the impact is on, say, satellite telephone service?  As I understand it most such services use geostationary satellites, otherwise the doppler shifts would be really large.  What are the cases you are thinking about?

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RedDerek
RedDerek
7/3/2013 3:34:55 PM
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Other applications
Another application in the SDR is to account for doppler shifts. Using the tuning cap would be useful for hand held radios doing satellite communications to adjust the send/receive frequency based on the upcoming satellite / ISS approach and passing.

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Scott Elder
Scott Elder
6/27/2013 6:27:34 PM
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Re: M is for Mechanical
"The short answer would be the holding force supplied by the steady state current far, far exceeds the net force due to acceleration from anything that would not otherwise damage the phone."

I'm with you now.  I was wondering about that holding power statement.  Initially I was thinking this was like a stepper motor where one causes a movement in plate to plate distance to change the capacitance, but then the system is de-energized.

Thanks for the education.

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eafpres1
eafpres1
6/27/2013 6:17:13 PM
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Re: M is for Mechanical
@Scott--Mr. Morrell responds: "In the case of these MEMS devices the mass is so small that the shock (acceleration) would need to be thousands of G's to have any effect on devices.  The devices survive orders of magnitude greater shock than other items on the phone (such as: screen, connectors, solder joints.)"

The short answer would be the holding force supplied by the steady state current far, far exceeds the net force due to acceleration from anything that would not otherwise damage the phone.

That is consistent with what I expected and with the existing experience of other MEMS devices (accelerometers, microphones, etc.) in phones.

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eafpres1
eafpres1
6/27/2013 2:16:22 PM
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Re: M is for Mechanical
@Netcrawl--Thanks for your comments.  

What is exciting for me is that I get to see technologies that were "way out there" early in my career become real and now go into commercial and consumer applications.  RF MEMS has been a while coming but there will be more.  The possibilities for a complete software defined RF system are starting to look more real.  Just imagine a cell phone in the future that can work on any network anywhere by sensing then changing the frequency of the radio, the protocol, and the tuning of the antennas.  This will be a huge simplification to handset manufacturers and bring prices down (more volume on fewer platforms).

 

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Netcrawl
Netcrawl
6/27/2013 9:49:57 AM
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Re: M is for Mechanical
@Blaine great article, today many technologies offer a useful RF capability, traditional such as switched capcitor networks, as well as MEMS are now in use and still making a big role. These RF technologies are enabling new innovation and frontier in the industry, especially in the wireless space.

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eafpres1
eafpres1
6/27/2013 9:46:54 AM
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Re: M is for Mechanical
Hi Scott--a reasonable question.  My sense is that other MEMS devices already widely deployed in handsets don't have issues with normal vibration etc., but let me ask the folks at Cavendish and report back.

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