Hi All, I would like to build a receiver, single frequency (978 MHz). The signal is FSK modulated. I see a lot of dedicated ICs but they are for lower frequencies or limited to narrow bands.
Does anyone know of a "tunable" ic that can do this? Perhaps with a SAW filter input?
Thanks
Rich
Superheterodyne receiver:
.--------. .------. | | 45MHz | | o-----| filter |---> X ------->| RX |------>
| | | | '--------' A '------' | | .------------. | | | | | oscillator |----' | | 933MHz '------------' (created by AACircuit v1.28.6 beta 04/19/05
Find a FSK receiver that'll do what you want, shift the frequency to what you need.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
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I just learned that the data rate is 1Mbs, way beyond any off the shelf IC I have found so far......... I WAS looking at TI's CC1000
Rich
What frequency shift?
You should be able to do that with an I/Q downconverter, and baseband demodulation. Or any of a bazillion other ways, but that's one that comes to mind easily.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
You're not the first
Sounds like a challenging project!
-- Rich Webb Norfolk, VA
Nordic NRF905 ?
I remember, back in the early days of satellite TV, some brands of receivers used an NE564 PLL chip to demodulate the video. IIRC, the IF in those receivers was 40 MHz, and fed directly into the NE564 for demodulation. Demodulated video came out the other side, with a bandwidth of around 6 MHz. Datasheet is at
-- David dgminala at mediacombb dot net
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The specs are the same as the other posting:
Frequency 978 MHz, +/- 20 PPM Delta f/2 +312.5 kHz
-Delta f/2 -312.5 kHz Modulation Type Continuous Phase FSK Modulation Rate 1.041667 MBPS Sensitivity -93 dBm
I was looking at the TI CC1000 but the data rate was low. How about taking the IF output from that device and filtering/demodulating? I have been search for a well defined PLL based demodulator design but, given my lack of experience in this area it is all as clear as mud.
Tim, I will look into using an I/Q downconverter, and baseband demodulator. (whatever those are) ;-)
Thanks again.
Rich
Video was amplitude modulated, your are looking for an FSK demod.
vers
MHz.
e .Satellite analog video was FM.
The audio was on an FM sub-carrier of the video typcally 5 to 6 MHz.
You are thinking of terrestrial video which was AM.
Mark
Yes I was thinking of OTA (off the air as you know)
By the way Do you know of any magazine dedicated to OTA High Definition ? It's very hard to get program info on the sub channels like X.1 .2 .3 .4
John
What about the TV section of your local paper? Or google "TV listings." Right now I'm using the TV Guide website, but I'm not terribly happy with it, mainly because it's so junked up with ads and stuff; I was using the AOL listings but a week or so ago, they disappeared.
Good Luck! Rich
'Terrestrial video' was Vestigial Sideband: One side of the AM signal was mostly removed, leaving the carrier and other sideband to conserve both spectrum & power.
-- It's easy to think outside the box, when you have a cutting torch.
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