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TI Calculator Spectrum Analyzer
Posted by Travis on 27 July 2010, 07:43 GMT

Michael Vincent has posted plans for a 2.4 GHz spectrum analyzer that can be used with TI calculators. The device uses a PCA8574 I2C expander to interface the link port to a CYWM6935 SPI transceiver. The software scans the 2.4 GHz band and plots the signal strengths at different frequencies. Wireless networks, microwave ovens, and other devices using the 2.4 GHz band can be detected.

The PCA8574 chip could be used to allow the link port to control other digital I/O devices such as LCDs or EEPROMs.

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Re: TI Calculator Spectrum Analyzer
elfprince13 Account Info
(Web Page)

This sounds pretty nifty. Not sure what I'd use it for, but sounds nifty.

Reply to this comment    27 July 2010, 13:26 GMT

Re: Re: TI Calculator Spectrum Analyzer
mapar007 Account Info
(Web Page)

That's one nice project, Michael!

Reply to this comment    27 July 2010, 16:09 GMT


Re: Re: TI Calculator Spectrum Analyzer
Michael Vincent  Account Info
(Web Page)

The main thing is that I've realized how many different I2C devices exist that you can connect to the calculator.

There are 1 Mb flash chips that would run off the link port power alone and would work in a circuit consisting of a few wires, two diodes, and a capacitor. It could even fit inside a calculator. Too bad we didn't have this when the TI-86 was popular.

Reply to this comment    28 July 2010, 23:47 GMT


Re: Re: Re: TI Calculator Spectrum Analyzer
Diane Stevenson  Account Info

No doubt, the TI-86 was IT!!!! At least when I went through calculus I and II. Just through it out the other day because the LCD went bad, now I'm hating it since I probably could've repaired it. Jeez, I loved that one. When I started radar school, I gave up the ghost and purchased the TI-89 Titanium...What a machine!

Reply to this comment    10 August 2010, 15:21 GMT

Re: TI Calculator Spectrum Analyzer
schoolhacker hacker  Account Info
(Web Page)

NICE!
this is perfect!
now people dont need an expensive signal availability checking device at the fields!

At large fields where many people fly RC planes, a signal checker is basically a standard for people who dont want to get interference from other, or cause interference and cause crashes of others.

Reply to this comment    27 July 2010, 16:49 GMT

Re: TI Calculator Spectrum Analyzer
Eeems Account Info

I wonder if it could be modified to also transmit, then we could do a lot of stuff with it :P

Reply to this comment    28 July 2010, 21:40 GMT


Re: Re: TI Calculator Spectrum Analyzer
Michael Vincent  Account Info
(Web Page)

It absolutely can transmit (and receive). Making a two calculator radio link would be simple. The question is if people would find it useful in this day and age.

Reply to this comment    28 July 2010, 23:31 GMT


Re: Re: Re: TI Calculator Spectrum Analyzer
Lewk Account Info
(Web Page)

Well damn, looks like I'm going to need to brush up on my soldering. :)

Will this unit receive/transmit as-is, or would modifications need to be done for that? Is the calculator just acting more or less like a display here, or is it actually analyzing the signal itself?

Reply to this comment    29 July 2010, 15:15 GMT


Re: Re: Re: Re: TI Calculator Spectrum Analyzer
Michael Vincent  Account Info
(Web Page)

Transmitting/receiving would just mean sending different values to the transceiver, no hardware changes required.

The calculator is only displaying values. It sends commands to the transceiver to report the signal strength of each channel, reads those values, then plots them.

You can find the datasheet online or search for CYWM6935 examples with microcontrollers (lots of people use them to build two-way radio links).

Reply to this comment    30 July 2010, 05:57 GMT

Re: TI Calculator Spectrum Analyzer
crcasey  Account Info

I cross posted this project and it made it as a headline article on HackADay.com

Congrats and thanks for the great work.

-C

Reply to this comment    31 July 2010, 03:10 GMT

Re: TI Calculator Spectrum Analyzer
Diane Stevenson  Account Info

Michael or any other user,

What is the full spectrum that can be displayed using the U3 as listed? Can I use the TI-89?

I have 2 radar channels, one at 2020 MHz and another at 2090 MHz. Would love try this if it would display, even if the center shifted...

Have you used it to check for sidelobes or power?

This could possibly be useful other than my normal spectrum analyzer, though I would never use it for certification (don't worry yall!).

Thanks much,
Diane

Reply to this comment    10 August 2010, 15:16 GMT

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