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Old August 16th 05, 12:54 PM
Howard Long
 
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Hello Polymath

I wonder if anyone has successfully converted a
thrown-away cell-phone into a spectrum analyser?

We would seem to have all the necessary components
in there for free - keyboard, graphical display,
post-demodulation DSP, Frequency Synthesizer,
RF good up to 1 GHz (2G5Hz if an ex-WCDMA unit)

Here would seem to be an opportunity to equip
all Radio Hams with a reasonably state-of-the-art
piece of test gear, that when coupled with an
IF generator would give us all a network analyser
into the bargain!


If you have web access, I have built a scalar network analyser from one of
the commonly available TV transmitters
http://www.g6lvb.com/Articles/NetAn/index.htm.

These TV transmitters use the SP5055 2.6GHz I2C frequency synthesisers and
are easily programmed from a PIC. You could build yourself a spectrum
analyser using the synthesiser as the sweep oscillator as I did.

If you successfully reverse engineer a cellphone enough to be able to use
any of the parts you describe I am sure that there would be a great deal of
interest if you published the information for any particular model.

73, Howard G6LVB


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Old August 16th 05, 09:23 PM
G1LVN \(for it is he\)
 
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"Howard Long" wrote in message
...
Hello Polymath

If you successfully reverse engineer a cellphone enough to be able to use
any of the parts you describe I am sure that there would be a great deal
of
interest if you published the information for any particular model.


Sweep oscillator on the X axis of an old junk oscilloscope and the IF stage
of an old multiband radio always did the job for me, mind you that was until
I went to university of course when we found a new use for the spectrum
analyser - listening to Radio 1 in the lab mainly.



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Old August 16th 05, 09:33 PM
ZZZZPK
 
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"G1LVN \(for it is he\)" wrote:

: I went to university of course when we found a new use for the spectrum
: analyser - listening to Radio 1 in the lab mainly.

you mean you didnt use it to heat the place on a cold morning ?


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Old August 17th 05, 12:08 AM
James F. Mayer
 
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"ZZZZPK "

wrote in message ...
"G1LVN \(for it is he\)" wrote:

: I went to university of course when we found a new use for the spectrum
: analyser - listening to Radio 1 in the lab mainly.

you mean you didnt use it to heat the place on a cold morning ?



That's what you use the Tektronix 555 for.




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Old August 20th 05, 11:50 AM
ZZZZPK
 
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"James F. Mayer" wrote:

: you mean you didnt use it to heat the place on a cold morning ?
:
: That's what you use the Tektronix 555 for.

tee hee...

had a dream the other night that i was back fixing 621-a3's !!



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Old August 21st 05, 01:15 PM
Alex Gibson
 
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"Polymath" wrote in message
ups.com...
I wonder if anyone has successfully converted a
thrown-away cell-phone into a spectrum analyser?

We would seem to have all the necessary components
in there for free - keyboard, graphical display,
post-demodulation DSP, Frequency Synthesizer,
RF good up to 1 GHz (2G5Hz if an ex-WCDMA unit)

Here would seem to be an opportunity to equip
all Radio Hams with a reasonably state-of-the-art
piece of test gear, that when coupled with an
IF generator would give us all a network analyser
into the bargain!


A few people are looking at turning one of the xilinx S3 (spartan3)
starter kits into spectrum analysers and logic analyser with a vga output.
http://www.xilinx.com/xlnx/xebiz/des...ey=DO-SPAR3-DK

http://www.fpga4fun.com/digitalscope.html
http://www.fpga4fun.com/board_flashy.html

Problem with a lot of the phone stuff is getting access to the chips pins
for programming
(if they had them in the first place).
Chips are factory programmed and not reprogrammable.



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Old August 21st 05, 07:08 PM
dlharmon
 
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Alex Gibson wrote:

A few people are looking at turning one of the xilinx S3 (spartan3)
starter kits into spectrum analysers and logic analyser with a vga output.
http://www.xilinx.com/xlnx/xebiz/des...ey=DO-SPAR3-DK

http://www.fpga4fun.com/digitalscope.html
http://www.fpga4fun.com/board_flashy.html

Problem with a lot of the phone stuff is getting access to the chips pins
for programming
(if they had them in the first place).
Chips are factory programmed and not reprogrammable.


I really like the idea of an FPGA based spectrum analyzer. I have been
planning to put one together for a while and have started on
schematics. Rather than doing VGA output I am using USB to a PC. I
have the FPGA/DSP board up and running.

It will probably be some form of a dual conversion design with the
input signal being upconverted to an IF around 2GHz and then fed to a
quadrature demodulator.

One other really nice thing that can be done with a FPGA easily is a
Arbitrary waveform generator using block rams as a lookup table.

http://dlharmon.com/dspcard/adcdac.html

Darrell Harmon

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