Forums

PM demodulation

Started by Sam November 2, 2004
Hello all !

I would like to know if there is a quite simple (but efficient) way to 
demodulate a PM signal who is digitalized.

I have seen some for FM demod, especially with CORDIC. Does something 
exist for PM as well ?

Many thanks !

Sam
Sam wrote:
> Hello all ! > > I would like to know if there is a quite simple (but efficient) way to > demodulate a PM signal who is digitalized. > > I have seen some for FM demod, especially with CORDIC. Does something > exist for PM as well ? > > Many thanks ! > > Sam
PM and FM are essentially the same thing; if you run PM through an FM demodulator and integrate it you should get your desired signal. Depending on the details of the algorithm you may even get some low-frequency noise thrown in free of charge. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Tim Wescott <tim@wescottnospamdesign.com> writes:

> PM and FM are essentially the same thing; if you run PM through an FM > demodulator and integrate it you should get your desired > signal.
Tim, Would you then say that position and velocity are essentially the same thing? If you integrate velocity you get position. Yes, I'm being a bit smart/cute, but then again I'm not. PM is no more FM than BPSK is FSK. This is one of those engineering -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124
Randy Yates <randy.yates@sonyericsson.com> writes:
> [...] > This is one of those engineering
... concepts which are essentially wrong. (Like the use of 2/T in the BT, but let's not go there...). -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124

Sam wrote:

> Hello all ! > > I would like to know if there is a quite simple (but efficient) way to > demodulate a PM signal who is digitalized.
Yes, I know the way of doing that. Just pay me $500 and the job will be done simple and efficient.
> I have seen some for FM demod, especially with CORDIC. Does something > exist for PM as well ?
CORDIC for FM? Auch! Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
            I dQ/dt  -  Q  dI/dt
w =  ---------------------------
                I^2  + Q^2

If the receiver limits, then the denominator can be replaced by 1.
Then need to apply the proper pre-de-emphasis curves.

The above is from Frerking, "Digital Signal Processing in Communictions 
Systems"
equation 6.76. He caustions a bit about the choice of taps for the 
differentiator.

    -- Tom




"Sam" <totalsam-n.o-s.p.a.m@hotmail.com> wrote in message 
news:4187fcd4$0$28020$5402220f@news.sunrise.ch...
> Hello all ! > > I would like to know if there is a quite simple (but efficient) way to > demodulate a PM signal who is digitalized. > > I have seen some for FM demod, especially with CORDIC. Does something > exist for PM as well ? > > Many thanks ! > > Sam
Randy Yates wrote:
> Tim Wescott <tim@wescottnospamdesign.com> writes: > > >>PM and FM are essentially the same thing; if you run PM through an FM >>demodulator and integrate it you should get your desired >>signal. > > > Tim, > > Would you then say that position and velocity are essentially the same > thing? If you integrate velocity you get position. > > Yes, I'm being a bit smart/cute, but then again I'm not. PM is no more > FM than BPSK is FSK. This is one of those engineering
Are you arguing with my terminology, or the fact that integrating the output of an FM demodulator result in perfectly good PM demodulation? -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Randy Yates wrote:

> Randy Yates <randy.yates@sonyericsson.com> writes: > >>[...] >>This is one of those engineering > > > ... concepts which are essentially wrong. (Like the > use of 2/T in the BT, but let's not go there...).
FM with pre-emphasis is essentially PM above the turnover frequency. Will you buy that? Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
"Jerry Avins" <jya@ieee.org> wrote in message
news:2uqp2pF2d1hq5U2@uni-berlin.de...
> Randy Yates wrote: > > > Randy Yates <randy.yates@sonyericsson.com> writes: > > > >>[...] > >>This is one of those engineering > > > > > > ... concepts which are essentially wrong. (Like the > > use of 2/T in the BT, but let's not go there...). > > FM with pre-emphasis is essentially PM above the turnover frequency. > Will you buy that? >
You took the words from my mouth. Tom
"Sam" <totalsam-n.o-s.p.a.m@hotmail.com> wrote in message
news:4187fcd4$0$28020$5402220f@news.sunrise.ch...
> Hello all ! > > I would like to know if there is a quite simple (but efficient) way to > demodulate a PM signal who is digitalized. > > I have seen some for FM demod, especially with CORDIC. Does something > exist for PM as well ? > > Many thanks ! > > Sam
Use a PLL then integrate the output. Tom