RF Cascade Workbook for Excel
RF & Electronics Symbols for Visio
RF & Electronics Symbols for Office
RF & Electronics Stencils for Visio
RF Workbench
T-Shirts, Mugs, Cups, Ball Caps, Mouse Pads
Espresso Engineering Workbook™
Smith Chart™ for Excel
|
 |
Wideband FM @70MHz? - RF Cafe Forums
|
Mike_From_Plano
Post subject: Wideband FM @70MHz? Posted: Tue Apr
21, 2009 5:13 pm
Captain
Joined: Mon Apr 20, 2009 2:04
pm
Posts: 14
Hello,
I've been workng on a fiber optic
video link and I chose to try 70MHz FM. This used to be fairly easy
using components from Signetics; they had a 70MHz IF chip with a built
in qud detector and a 150 MHz PLL.
Well, I'm feeling a bit like
Rip Van Winkle, I look around and there are all of these phase modulation
parts and PLLs that are up in the GHz, but I'm not finding anything
quite like I was used to. I'm also on a tight power budget (battery
powered...), so I don't think anything the digital folks offer would
be of any help.
Anybody have any suggestion for an OLD analog
engineer?
Best Regards,
Mike
Top
yendori
Post subject: Re: Wideband FM @70MHz?Posted: Wed Apr 22, 2009 2:28
pm
General
Joined: Thu Sep 25, 2003 1:19 am
Posts:
50
Location: texarcana
Hi Mike,
This is Rod from Plano.
Here are some links you may or may not have already checked.
http://www.freescale.com/
http://www.nxp.com/
http://www.intersil.com/cda/home/
http://www.analog.com/en/index.html
http://www.ti.com/
http://www.national.com/analog
http://www.linxtechnologies.com/
http://sanyo.com/
http://www.digikey.com/
http://www.mouser.com/
Good Luck,
Rod
Top
biff44
Post subject: Re: Wideband FM @70MHz?Posted: Wed
Apr 22, 2009 8:56 pm
Colonel
Joined: Wed Apr 08, 2009
11:07 am
Posts: 33
Good luck! I am in a similar situation. I
am doing a non-coherent coding gain experiment with fsk receivers, and
needed a simple 915 MHz receiver chip with an ANALOG fm demod out. I
searched around for hours. Nada. Everything nowadays is too complex,
data slicers, no access to the analog output, no access to the ADC outputs,
etc. I did finally find a small quantity of old RFM chips on ebay, and
am all set. You might find the chip style you are looking for on ebay,
especially where the HAMs are selling stuff.
You could probably
find a chip if you are willing to go down to either 10.7 or 13 MHz.
A lot of wireless keyboards and mice were designed at 13 MHz, so the
reciever chips are probably still available. They just recently moved
up to bluetooth frequencies.
You could probably find a receiver
with some sort of zero IF with an fsk demod output.
Good luck
Rich
_________________
Rich
Maguffin Microwave Consulting
www.MaguffinMicrowave.com
Top
Mike_From_Plano
Post
subject: Re: Wideband FM @70MHz?Posted: Thu Apr 23, 2009 1:04 am
Captain
Joined: Mon Apr 20, 2009 2:04 pm
Posts: 14
Thanks guys,
I appreciate your support. It seems we're caught
up in the knowledge of the ancients. I'm contemplating going old-school
on this thing - complete with messy cans.
Hmmm, I wonder how
good the ol' SA602 would be as a quad detector? It has the bandwidth.
Then, I need a good IF, complete with limiting.
Anybody have
any suggestions for the IF / limiter? I'd hate to go bone knives and
bear skins on it...
Mike
Top
biff44
Post
subject: Re: Wideband FM @70MHz?Posted: Thu Apr 23, 2009 4:52 pm
Colonel
Joined: Wed Apr 08, 2009 11:07 am
Posts: 33
As long as you are not endeavoring to construct a mnemonic memory,
you should do fine.
_________________
Rich
Maguffin Microwave
Consulting
www.MaguffinMicrowave.com
Top
biff44
Post subject: Re: Wideband FM @70MHz?Posted: Fri Apr 24, 2009 11:59
am
Colonel
Joined: Wed Apr 08, 2009 11:07 am
Posts:
33
seen on ebay:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ...
0193331528
not sure if that price is for 1 or 10 pcs.
_________________
Rich
Maguffin Microwave Consulting
www.MaguffinMicrowave.com
Top
Mike_From_Plano
Post subject: Re: Wideband FM @70MHz?Posted:
Fri Apr 24, 2009 4:10 pm
Captain
Joined: Mon Apr 20,
2009 2:04 pm
Posts: 14
Hey Rich,
Pretty sweet chip, but
I gotta move these things into production. I spoke with a fellow at
Analog Devices and he suggested the AD603 as an IF. It's good for 90MHz,
has an AGC, and high output drive. I think I'll give it a shot with
an attenuator (to reduce reflection), and a pair of schottky's for limiting.
That still leaves me looking for a modulator / demodulator that
can give me the bandwidth at 70 MHz. I'm tempted, on the demodulator,
to run a 1/4 wave delay off of the limiter and beat it against the original.
I don't know what it would do for my S/N, since the signal would be
small, but it'd sure be simple.
PLLs make my head hurt. Fast
PLLs make it hurt worse....
Posted 11/12/2012
|
|
|
|
 |
