From analogue-request@magnus.acs.ohio-state.edu Thu May 6 11:14:21 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA01306; Thu, 6 May 93 11:10:43 -0400 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from sihp03.si.estec.esa.nl by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA01299; Thu, 6 May 93 11:10:37 -0400 Message-Id: <9305061510.AA01299@quark.magnus.acs.ohio-state.edu> Received: by sihp03.si.estec.esa.nl (16.7/16.2) id AA01786; Thu, 6 May 93 17:17:27 +0100 From: Andrea TONI Subject: -- FTV converter -- To: analogue@magnus.acs.ohio-state.edu Date: Thu, 6 May 93 17:17:27 MET Organization: ESA-ESTEC (European Space Research and Technology Center) Keplerlaan 1 2200 AG Noordwijk (EUROPA) Phone: Int +31 1719 83606 Fax: Int +31 1719 84697 Machine: HP-UX sihp03 A.B8.05 A 9000/730 941406112 Mailer: Elm [revision: 66.33] Status: OR Hi, Basically a FtV looks like .. Sig (f) | \ --->----| \ | | | | |OA >--->--| One Shot |--->--| LPF |---------> out (CV tension) --| / | | | | | | / | / GND the OA is an OP amp that function as comparator that is suppose to "square" the signal (sig(f) frequency) in a kind of zero-crossing fashion in which the positive front are used to trigger the O.S producing every time a pulse of Tm. The LPF is used to find the average value generated by the OS. Since this pulses are all equal in length and amplitude, the average value depends in a unique fashion by their frequency .. (that is indeed the freq of SIg(f). SO the tension going out by the LPF is proportional to the pitch of the used note and can then be used to CV and tune the VCO . this diagram can help a bit more ... Sig (f) | | ^ ^ | / \ / \ |/___\______/ ___ \_________________________________ t \ / \ / \ / \ / v v OP comparator | |--- ----- ---- | | | | | | |__|________|___|____________|__|_________________ t One Shot | Tm |-- --- --- | | | | | | |_|_________|_|______________|_|___________________ t LPF | | ___________________ | ___________________________/ |_____________________________________________ t Nice he .. to draw in ascii mode !!!!!!! arghhh I just would like to add that the length of Tm has to be smaller then the shortest Ts of sig(f) otherwise the OS wouldn't be able to keep track of sig(f). The drawing is of course an ideal situation .. but in the reality the LPF is a bit slow in catching up the quick frequency variation. The most difficult thing is of course in the accuracy and stability required. In the standard Cv/Oct two semitone are equal to a difference of 83 millivolt (!!) and since ears are able to fetch a de-tune of 1/4 of semitone .. we can assume that errors need to be in the range of 10 millivolt .. and in the analog domain you know what it means !!! (minimum noise .. thermal attentions, hi-level components .. ) But the advantage compare to a digital pitch-to-midi is the uniform functioning of the circuit .. the converter doesn't have to discriminate between a legato, vibrato or glissato .. the output tension (CV) will *dummyly* follow the frequency of sig(f). From here the name pitch-follower may seems more appropriate since the circuit doesn't detect the sig(f) but it barely make a conversion. In a pitch-to-midi device instead everything is much more complicated since the box has to discriminate semitones closer to the real pitch and to approximate to the real freq of the pitch-bend command. I have both an analog (Korg MS20) and a digital (Roland VP70) PtV(Midi) and even if the Korg looks simpler it is in practice more usable .. the digital one required a lot more attention when you feed in voice (no bending no rapid detuning etc etc ..) The Analog Devices Databooks (89/90) contain a lot of hi-level IC already suited for the purpose .. AD537 (VtoF) AD650 (FtoV and VtoF) AD652 (VtoF) AD654 (VtoF) Low cost .. ADVFC32 (FtoV and VtoF) .. and of course if you find any old databook (the new ones are as bad as digital synth compare to analog ..!!! ) you may find several application notes and proper explanations .. Enjoy !! Ciao, ------------------------------------------------ENV---ENV---ENV---------------- Andrea TONI (andrea@sihp03.si.estec.esa.nl) | | | Planetary and Space VCO-->VCF-->VCA--> DUCATI 900SS Science Division (SI) | | | ------------------------------------------------LFO---LFO---LFO---------------- From analogue-request@magnus.acs.ohio-state.edu Thu May 6 13:07:26 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA01306; Thu, 6 May 93 11:10:43 -0400 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from sihp03.si.estec.esa.nl by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA01299; Thu, 6 May 93 11:10:37 -0400 Message-Id: <9305061510.AA01299@quark.magnus.acs.ohio-state.edu> Received: by sihp03.si.estec.esa.nl (16.7/16.2) id AA01786; Thu, 6 May 93 17:17:27 +0100 From: Andrea TONI Subject: -- FTV converter -- To: analogue@magnus.acs.ohio-state.edu Date: Thu, 6 May 93 17:17:27 MET Organization: ESA-ESTEC (European Space Research and Technology Center) Keplerlaan 1 2200 AG Noordwijk (EUROPA) Phone: Int +31 1719 83606 Fax: Int +31 1719 84697 Machine: HP-UX sihp03 A.B8.05 A 9000/730 941406112 Mailer: Elm [revision: 66.33] Status: OR Hi, Basically a FtV looks like .. Sig (f) | \ --->----| \ | | | | |OA >--->--| One Shot |--->--| LPF |---------> out (CV tension) --| / | | | | | | / | / GND the OA is an OP amp that function as comparator that is suppose to "square" the signal (sig(f) frequency) in a kind of zero-crossing fashion in which the positive front are used to trigger the O.S producing every time a pulse of Tm. The LPF is used to find the average value generated by the OS. Since this pulses are all equal in length and amplitude, the average value depends in a unique fashion by their frequency .. (that is indeed the freq of SIg(f). SO the tension going out by the LPF is proportional to the pitch of the used note and can then be used to CV and tune the VCO . this diagram can help a bit more ... Sig (f) | | ^ ^ | / \ / \ |/___\______/ ___ \_________________________________ t \ / \ / \ / \ / v v OP comparator | |--- ----- ---- | | | | | | |__|________|___|____________|__|_________________ t One Shot | Tm |-- --- --- | | | | | | |_|_________|_|______________|_|___________________ t LPF | | ___________________ | ___________________________/ |_____________________________________________ t Nice he .. to draw in ascii mode !!!!!!! arghhh I just would like to add that the length of Tm has to be smaller then the shortest Ts of sig(f) otherwise the OS wouldn't be able to keep track of sig(f). The drawing is of course an ideal situation .. but in the reality the LPF is a bit slow in catching up the quick frequency variation. The most difficult thing is of course in the accuracy and stability required. In the standard Cv/Oct two semitone are equal to a difference of 83 millivolt (!!) and since ears are able to fetch a de-tune of 1/4 of semitone .. we can assume that errors need to be in the range of 10 millivolt .. and in the analog domain you know what it means !!! (minimum noise .. thermal attentions, hi-level components .. ) But the advantage compare to a digital pitch-to-midi is the uniform functioning of the circuit .. the converter doesn't have to discriminate between a legato, vibrato or glissato .. the output tension (CV) will *dummyly* follow the frequency of sig(f). From here the name pitch-follower may seems more appropriate since the circuit doesn't detect the sig(f) but it barely make a conversion. In a pitch-to-midi device instead everything is much more complicated since the box has to discriminate semitones closer to the real pitch and to approximate to the real freq of the pitch-bend command. I have both an analog (Korg MS20) and a digital (Roland VP70) PtV(Midi) and even if the Korg looks simpler it is in practice more usable .. the digital one required a lot more attention when you feed in voice (no bending no rapid detuning etc etc ..) The Analog Devices Databooks (89/90) contain a lot of hi-level IC already suited for the purpose .. AD537 (VtoF) AD650 (FtoV and VtoF) AD652 (VtoF) AD654 (VtoF) Low cost .. ADVFC32 (FtoV and VtoF) .. and of course if you find any old databook (the new ones are as bad as digital synth compare to analog ..!!! ) you may find several application notes and proper explanations .. Enjoy !! Ciao, ------------------------------------------------ENV---ENV---ENV---------------- Andrea TONI (andrea@sihp03.si.estec.esa.nl) | | | Planetary and Space VCO-->VCF-->VCA--> DUCATI 900SS Science Division (SI) | | | ------------------------------------------------LFO---LFO---LFO---------------- From analogue-request@magnus.acs.ohio-state.edu Thu May 6 10:11:41 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA28345; Thu, 6 May 93 10:11:14 -0400 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from motgate.mot.com by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA28340; Thu, 6 May 93 10:11:12 -0400 Received: from pobox.mot.com ([129.188.137.100]) by motgate.mot.com with SMTP (5.65c/IDA-1.4.4/MOT-2.14 for ) id AA01099; Thu, 6 May 1993 09:11:09 -0500 Received: from comm.mot.com (il02dns1.comm.mot.com) by pobox.mot.com with SMTP (5.65c/IDA-1.4.4/MOT-2.14) id AA01080; Thu, 6 May 1993 09:11:08 -0500 Received: from dub-tse (dub-tsw1.comm.mot.com) by comm.mot.com (4.1/SMI-4.0) id AA01192; Thu, 6 May 93 09:13:06 CDT Message-Id: <9305061413.AA01192@comm.mot.com> Received: by dub-tse (16.6/16.2) id AA24403; Thu, 6 May 93 15:07:13 +0100 From: Peter Cassidy Subject: Re: FTV converter To: RICK@sara.nl (Rick Jansen) Date: Thu, 6 May 93 15:07:11 BST Cc: ANALOGUE@magnus.acs.ohio-state.edu (Analogue Mail List) In-Reply-To: <9305061216.AA110723@diamond.sara.nl>; from "Rick Jansen" at May 06, 93 1:16 pm Mailer: Elm [revision: 66.25] Status: OR > > > Hey thanks! I didn't know there were standard ic's for this function. > I'm looking forward to the device numbers. > > -Rick. > > -- > rick@sara.nl > > She's a Module and she's looking good > OK. Here's one, straight from the R.S catalog: ---------------------------------- TC9400CPD, TC9401CPD, TC9402CPD ( Varying accuracies) Teledyne Components 14-pin IC Works as Freq-to-voltage and Voltage-to-freq Linear freq to voltage ratio. Single or dual supply, 8 - 15 V or +-4 to +-7.5V 10Hz - 100KHz operation. Worst linearity 9401 = 0.25% Best linearity 9401 = 0.004% ************ Ibias * 1 **** * Vdd ZERO ADJUST * ** * N.C. Iin * * AMPLIFIER OUT Vss * 9400 * COMPARATOR IN Vrefout * * FREQ/2 OUT GND * * OUTPUT COMMON Vref * * PULSE FREQ. OUT ************ R.S Part number 264-951 ----------------------------------- This looks like a suitable candidate. Are you trying Voice to CV conversion or vocoding ?? I would be really interested to hear how you get on !!! -- Regards, Peter ------------------------------------------------------------------------------ | M O T O R O L A B . V . I R E L A N D | | ----------------------------------------- | | Peter Cassidy - T.S.E Dublin | Phone : 353-1-840-8866 Ext. 417 | | MACCVM : C10404 | X400 : peterc@comm.mot.com | ------------------------------------------------------------------------------