hi! i want to demodulate AM signal with DSP...i found an article that says like this : demodulator is illustrated as decimation integration...

hi! i want to demodulate AM signal with DSP...i found an article that says like this : demodulator is illustrated as decimation integration filter. It includes a multiplier portion and an integration/decimation portion. so can we demodulate AM using decimation method? and what is decimation integration filter? thank you...

Dear all, Just found this great forum on DSP. This is my first post and hope someone can help. I am searching for the knowledge on GMSK...

Dear all, Just found this great forum on DSP. This is my first post and hope someone can help. I am searching for the knowledge on GMSK demodulation and found that some articles say that some carrier/timing recovery algorithms (like Gardner, Early-Late etc) are only applicable to LINEAR modulation scheme. my questions are: 1) what does linear and nonlinear modulation mean? what is the di...

To demodulate QPSK requires a carrier recovery circuit.Without a recovered and properly phased carrier it is not possible to demodulate the I and...

To demodulate QPSK requires a carrier recovery circuit.Without a recovered and properly phased carrier it is not possible to demodulate the I and Q channels. In the analog world there are circuits like the squaring ckt or the Costas Loop which recovers the carrier. However--modern QPSK radios use DSP to demodulate a non-coherent received signal. By non-coherent I mean that the carrier frequ...

I have some data that I think is single side band (it comes from an ultrasound scanner). I wish to demodulate this so that the frequency...

I have some data that I think is single side band (it comes from an ultrasound scanner). I wish to demodulate this so that the frequency spectrum is centred on th ecentre of the sideband. I know the original carrier frequency, but not the sideband width or centre. How can I demodulate to the centre of the sideband? One way i see used is to do an envelope detection (basically, square/ ...

Hi All An SDR Software (SDRSharp) plays the file containing two stations one at 0hz and other at 8khz. By Clicking at both the stations one by...

Hi All An SDR Software (SDRSharp) plays the file containing two stations one at 0hz and other at 8khz. By Clicking at both the stations one by one (FFT Display) stations can be heard. I tried to demodulate them in my software and always able to hear station at 0Hz after demodulation. even i have shifted 8Khz signal to 0Hz but i am able to hear only station that was initially at 0Hz. Maybe i am ...

Hello, I have searched thoroughly all over the internet for information on how to demodulate 802.15.4/Zigbee O-QPSK (MSK) signals. Slide 10...

Hello, I have searched thoroughly all over the internet for information on how to demodulate 802.15.4/Zigbee O-QPSK (MSK) signals. Slide 10 on http://www.ceesar.ch/cms/upload/pdf/emw08/EMW2008_talk.pdf shows the base band signal, and also says (slide 12) that O-QPSK may be demodulated both with and without regenerating the carrier (coherent and non-coherent demodulation). Is this true? Figur...

Hi, I am building QPSK demodulator on FPGA. I am basically performing demodulation with the help of Costas loop. My QPSK Digital...

Hi, I am building QPSK demodulator on FPGA. I am basically performing demodulation with the help of Costas loop. My QPSK Digital Demodulator should have following features: 1)It should adhere with DVB-S, DVB-S2 Standard. 2)It should perform carrier phase recovery and clock recovery. I have the following querries: 1)Costas loop need Sine/Cosine table for multiplication with the ...

Hi, My idea is simple but is it working in noisy channel ? I first send my IF signal to an ADC, then multiply it with COS and SIN from a...

Hi, My idea is simple but is it working in noisy channel ? I first send my IF signal to an ADC, then multiply it with COS and SIN from a CORDIC algorithm, then send theses two outputs to low pass filter to obtain I and Q signals. I send I an Q signals to another CORDIC algoritm to compute the angle information, average this angle information ? (for better perfromance in noisy cases) a...

I am working on a tutorial about IQ modulation and demodulation. I have been thinking about this topic for a long time and have begun putting...

I am working on a tutorial about IQ modulation and demodulation. I have been thinking about this topic for a long time and have begun putting together some stuff. Here is an interactive page (exclusively for comp.dsp to look at :-) This shows the difference between an FFT that is stuffed with real data and an FFT that is stuffed with complex data. This has been real eye opening for me t...

where can I find more information about V.27ter other than ITU standard. And what are the main phases for decoding V.27ter...

where can I find more information about V.27ter other than ITU standard. And what are the main phases for decoding V.27ter faxes???(i.e: demodulation descrambling....?) and what else.

Hi all, I've been developing an OFDM receiver for some time. I wrote demodulation routines in the complex baseband, where I can access a...

Hi all, I've been developing an OFDM receiver for some time. I wrote demodulation routines in the complex baseband, where I can access a digital baseband signal resulting from a general purpose RF digitizer or a vector analyser. As the bandwidth of my digitizer is much larger than my signal bandwidth and there is no IF bandpass filter I decided to implement an FIR lowpass filter in baseband. Bu...

I'm trying to find the imaginary and real parts (I and Q) of a bandpass signal (i'll call this bandpass signal "s"). To find the imaginary...

I'm trying to find the imaginary and real parts (I and Q) of a bandpass signal (i'll call this bandpass signal "s"). To find the imaginary part, i first multiply the bandpass signal (s) by sin(2*pi*t*fc), where t is the time in seconds and fc is the center frequency of the signal's energy distribution. s * sin(2*pi*t*fc) = m Next, i need to low pass filter this signal (m). This filtering...

Hi, I've designed a complete FM demodulator under Simulink, but I've got a problem. My FM IF is 70 MHz, 250 kHz deviation, 250 kHz message,...

Hi, I've designed a complete FM demodulator under Simulink, but I've got a problem. My FM IF is 70 MHz, 250 kHz deviation, 250 kHz message, so my bandpass signal is 1 MHz large (Carson BW =3D 2* (Delta F + Fmax message) =3D 1 MHz I first undersample the IF at 13.75 MHz so my FM signal is translated to 1.25 MHz, then I multiply with cosinus and sinus (1.25 MHz) to obtain I and Q signal...

Hello On trying to demodulate an OFDM signal based on the DVB-T standard, I immediately encountered difficulties in doing so. The problem lies...

Hello On trying to demodulate an OFDM signal based on the DVB-T standard, I immediately encountered difficulties in doing so. The problem lies in: 1. Frequency offset estimation. 2. Symbol timing estimation (symbol timing ambiguity occurs during the sampling process at the receiver A/D converter. 3. Channel coefficient estimation. Problem 1 is addressed in a straightforward manner usi...

Hi I am trying to Extract Caller ID from FSK v.23 Encoded CLI Packet which has been stored in audio format in pc. To demdulate FSK i am using...

Hi I am trying to Extract Caller ID from FSK v.23 Encoded CLI Packet which has been stored in audio format in pc. To demdulate FSK i am using two Bandpass Filters centered at Mark and Space Frequency. According to FSK V.23 1300 hz is frequency for mark(1) 2100 hz is frequency for spcae(0) 1200 is baud rate my sample rate is 8000/s i have 1/1200=833 us to check for the new arrival. In 833 ...

Hi All, I have read out Richard Lyons's book about approximation envelope detection. In the book got mentione after taking magniture of...

Hi All, I have read out Richard Lyons's book about approximation envelope detection. In the book got mentione after taking magniture of analytic signal, which is square root[square(I)+ square(Q)] and the result need to be low pass filter to smoothen the signal. From the maths, the resultant of the modulus of analytic signal will be only carrie(DC) plus message signal(which is the envelope)....

Hi all! Do you have any experience with an early-late gate timing? I've built one and observed strange behavior in weak S/N rate. Even though, I...

Hi all! Do you have any experience with an early-late gate timing? I've built one and observed strange behavior in weak S/N rate. Even though, I can observe acceptable scatterplot using Matlab function - demodulated data have a trend to loss time base (with still proper demodulation). Is it because of not proper phase recovery (5 to 10 degrees phase error) or maybe these 3 points in early -l...

I want to plot Eb/N0 vs BER bpsk demodulation in Matlab. I am using BPSK modulated signal @ carrier frequencey 8KHz, data rate 1KHz. Sampling...

I want to plot Eb/N0 vs BER bpsk demodulation in Matlab. I am using BPSK modulated signal @ carrier frequencey 8KHz, data rate 1KHz. Sampling rate is set I have tried to use awgn function for adding noise. This signal accepts Signal to noise ratio (SNR)in parameters. In order to convert into Eb/N0 for BPSK signal. I have used following relation SNR = Eb/N0 + 10log(R/B) (This formula i h...

* Does anyone know of source code for decoding Biphase/Manchester encoding from analog signal? I am looking for source code for a biphase...

* Does anyone know of source code for decoding Biphase/Manchester encoding from analog signal? I am looking for source code for a biphase decoder. The application is extracting SMPTE/EBU time code data from analog audio signals (recorded by professional audio/video equipment). I found source code that looks at signal crossing an adjustable threshold (by Maarten de Boer) ftp://www.iua...

Hi all, If I have a 1 Mbps MSK modulator. I know that I can demodulate it with IdQ-QdI simply in digital with two sample by...

Hi all, If I have a 1 Mbps MSK modulator. I know that I can demodulate it with IdQ-QdI simply in digital with two sample by symbol... Can I demodulate with only one sample by symbol using a Gardner synchronizer loop (the loop works at 2 sample/symbol) but can sample on the middle of the symbol like for QPSK demod for example. Can I use the Gardner loop with MSK signal ? Thanks. ...