steve@bambi.UUCP (Steve Miller) (10/10/86)
I'm looking for a device that will perform Frequency Shift Keying
decoding, with input frequencies of 1500 Hz (mark) and 2300 Hz (space),
at a faily rapid rate (300 baud or better). Also, I would like to
find a device that will convert frequency to voltage, continuously,
over the same range.
I could sure use some help. Thanks, Steve Miller WA4LDA
ihnp4!bellcore!bambi!steveapn@nonvon.UUCP (10/11/86)
In article <550@bambi.UUCP>, steve@bambi.UUCP (Steve Miller) writes: > I'm looking for a device that will perform Frequency Shift Keying > decoding, with input frequencies of 1500 Hz (mark) and 2300 Hz (space), > at a faily rapid rate (300 baud or better). Also, I would like to > find a device that will convert frequency to voltage, continuously, > over the same range. > > I could sure use some help. Thanks, Steve Miller WA4LDA > ihnp4!bellcore!bambi!steve I suggest you contact EXAR. They manufacture several IC's that are usefull building blocks in such circuits. i.e. FSK modulators, decoders, modem filters.... If you're around the 408 area code, I think their distributors are "Bell Industries" @408 734 8570. Also another company... Silicon Systems makes some parts in like this. Of course, you could always get a standard PLL and start from there. BTW, the EXAR people have several data books that have tons of MODEM and PLL circuits. Hope this helps... -apn uucp: ihnp4!ptsfa!nonvon!apn
larry@kitty.UUCP (Larry Lippman) (10/12/86)
In article <550@bambi.UUCP>, steve@bambi.UUCP (Steve Miller) writes: > I'm looking for a device that will perform Frequency Shift Keying > decoding, with input frequencies of 1500 Hz (mark) and 2300 Hz (space), > at a faily rapid rate (300 baud or better). Also, I would like to Since those frequencies are neither Bell nor CCITT V.2X, I can't direct you to an integrated modem chip. The frequencies sound like radioteletype with an 800 Hz shift - but I don't know of any integrated FSK converter chips for that application. So, you can take two approaches: 1. Use an phase-locked loop, either a LM565 or LM567. Check National Semiconductor Application Note AN-46 for design details and examples. 2. Use a switched-capacitor filter in a narrow bandpass configuration for each frequency, with a simple op amp AC level detector at the filter output. This is a more state-of-the-art method; while more complex in design than a PLL, these filter-based FSK detectors are far superior to a PLL. Consider the National Semiconductor MF-10 as a starting point, and get a copy of the National "Switched-Capacitor Filter Handbook" for design details. > Also, I would like to > find a device that will convert frequency to voltage, continuously, > over the same range. Consider the National Semiconductor LM2907, which is a building block circuit providing F/V conversion for tachometer and other applications. ==> Larry Lippman @ Recognition Research Corp., Clarence, New York ==> UUCP: {allegra|decvax|rocksanne|rocksvax|watmath}!sunybcs!kitty!larry ==> VOICE: 716/688-1231 {hplabs|ihnp4|seismo|utzoo}!/ ==> FAX: 716/741-9635 {G1,G2,G3} "Have you hugged your cat today?"