frequency modulation
in [DSP]
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From: bos1234 on 16 Jun 2010 23:16 [IMG]http://i49.tinypic.com/219w36q.png[/IMG] Question reads: Give the required value of frequency multiplication, n. Also, fully define the mixer by giving two permissible frequencies for the local oscillator. Am I correct in saying that D_1=0.05 and D_2=20?, However the solution has Solution: f_d2=nf_d1 20=n(0.05) n=400 [IMG]http://i50.tinypic.com/im4083.png[/IMG] The problem I'm having is what frequency is coming into the multiplier? 100Mhz or 44Khz?
From: Jerry Avins on 17 Jun 2010 00:35 On 6/16/2010 11:16 PM, bos1234 wrote: > [IMG]http://i49.tinypic.com/219w36q.png[/IMG] > Question reads: > Give the required value of frequency multiplication, n. Also, fully define > the mixer by giving two permissible frequencies for the local oscillator. > > Am I correct in saying that D_1=0.05 and D_2=20?, > However the solution has > > Solution: > f_d2=nf_d1 > 20=n(0.05) > n=400 > > [IMG]http://i50.tinypic.com/im4083.png[/IMG] > > The problem I'm having is what frequency is coming into the multiplier? > 100Mhz or 44Khz? There seems to be an error. Both the carrier frequency and the deviation are multiplied by the same factor, so the deviation ratio is the same before and after the frequency multiplier. The deviation (not the deviation ratio) is the same before and after the mixer. Can you take it from there? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
From: Mark on 19 Jun 2010 19:07 On Jun 17, 12:35 am, Jerry Avins <j...(a)ieee.org> wrote: > On 6/16/2010 11:16 PM, bos1234 wrote: > > > > > [IMG]http://i49.tinypic.com/219w36q.png[/IMG] > > Question reads: > > Give the required value of frequency multiplication, n. Also, fully define > > the mixer by giving two permissible frequencies for the local oscillator. > > > Am I correct in saying that D_1=0.05 and D_2=20?, > > However the solution has > > > Solution: > > f_d2=nf_d1 > > 20=n(0.05) > > n=400 > > > [IMG]http://i50.tinypic.com/im4083.png[/IMG] > > > The problem I'm having is what frequency is coming into the multiplier? > > 100Mhz or 44Khz? > > There seems to be an error. Both the carrier frequency and the deviation > are multiplied by the same factor, so the deviation ratio is the same > before and after the frequency multiplier. The deviation (not the > deviation ratio) is the same before and after the mixer. Can you take it > from there? > > Jerry > -- > Engineering is the art of making what you want from things you can get. > ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ If "deviation ratio" is taken to mean what most people call BETA which is DEVIATION/MODULATION FREQ , then it DOES increase going through the multiplier. Mark
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