Hi In the acquisition of direct sequence spread spectrum signals with low signal-to-noise ratio and wide dynamic...

Hi In the acquisition of direct sequence spread spectrum signals with low signal-to-noise ratio and wide dynamic range.the system use all-digital quadrature demodulation of DS/SS signals.Long pseudo-noise spread spectrum codes with carrier doppler are detected by a method in which the signal is successively IF integrated,differential detected and video integrated. After cor...

Hi, I modulate a 10.7 MHz center frequency with 20 kHz deviation. When I send a 1 kHz sinus signal to modulate the 10.7MHz, I demodulate this...

Hi, I modulate a 10.7 MHz center frequency with 20 kHz deviation. When I send a 1 kHz sinus signal to modulate the 10.7MHz, I demodulate this FM signal with IdQ-QdI. So this result is a goos sinusoide signal at 1 kHz But when I calculate I=B2+Q=B2, there's a 20 kHz sinus on this signal and so when I do (IdQ-QdI)/(I=B2+Q=B2) I have this 20 kHz signal modulated on my 1 kHz sinus wanted.. ...

Hi folks, I just implemented a MLSE software module for GSM signal demodulation and now want to test its performance by following 3GPP SPEC...

Hi folks, I just implemented a MLSE software module for GSM signal demodulation and now want to test its performance by following 3GPP SPEC (TS45.005 section 6). The problem I am facing now is how to apply the multipath channel specified in the above spec. The Annex C of TS45.005 gives many tables in terms of Relative delay time and average relative power. My question is how to make use of t...

Hi All: while looking at GSM literature, i found it quite interesting in how GMSK is demodulated. In simulink library, the baseband GMSK...

Hi All: while looking at GSM literature, i found it quite interesting in how GMSK is demodulated. In simulink library, the baseband GMSK demodulator included a hard decision viterbi decoder. In my mind viterbi decoder is used for error correction of convolutional encoded channel data. In one GSM simulink model i was looking at, after demodulator(which included viterbi decoder), the data ...

Hello, I am writing a BPSK demodulator using VHDL for a Xilinx Vertex2 Pro FPGA. I will be getting IQ data on which I'll do the...

Hello, I am writing a BPSK demodulator using VHDL for a Xilinx Vertex2 Pro FPGA. I will be getting IQ data on which I'll do the demodulation. However, the IQ data has varying phase and frequency offsets which need to be corrected before hard decision decoding can be carried out. Has anyone implemented frequency and phase offset removal using VHDL/fixed point algorithms? How can I approac...

Hi, I have done convolutional codeing (length =3, rate=1/2) and viterbi hard decoding. The steps I have followed are: Data --> Convolutional...

Hi, I have done convolutional codeing (length =3, rate=1/2) and viterbi hard decoding. The steps I have followed are: Data --> Convolutional Encoder --> QPSK Modulation --> Channel --> Demodulation --> Viterbi Hard Decoding The above steps give me good result for AWGN channel. Can anyone plz tell me how is the Soft Viterbi Decoding differ from the above mentioned hard viterbi decoding? w

I have downloaded a wave file of **SDRSharp SDR** that contains FM data I/Q samples for demodulation. The file attributes are sample...

I have downloaded a wave file of **SDRSharp SDR** that contains FM data I/Q samples for demodulation. The file attributes are sample rate=22050, samples=32 bit float. When i play it in SDRSharp, it demodulates FM signal and also shows frequency spectrum of the original signal i.e 50 Mhz. My question is how a wav file with 22050 sample rate can store 50 Mhz RF samples? If it is possible then it ...

All, i build two simulink models to watch the benifit of convolutional code. The first one is: Burnoulli bits ----- 16QAM ------...

All, i build two simulink models to watch the benifit of convolutional code. The first one is: Burnoulli bits ----- 16QAM ------ modulation ---- AWGN ----- demodulation. The parameter of 16QAM modulation module is: 'normalizztion method'= average power and 'average power'=1 watt. The parameter of the AWGN channel module is 'Eb/N0'=14.55 and 'input signal power'=1 watt. The BER is about ...

When it comes to basic modulation method, ASK/FSK/PSK, there is a sentence in some textbooks: the carrier frequency should be far more than...

When it comes to basic modulation method, ASK/FSK/PSK, there is a sentence in some textbooks: the carrier frequency should be far more than the baseband signal frequency. However, no one give the detail. I need to analyze the data rate upper limit of a communication system using QPSK coherent demodulation in a band-limited AWGN channel when the carrier frequency and channel bandwidth is kno...

Hi everyone, I'm trying to demodulate the following in order to obtain "signal" - cos(cos(2*PI*11025*i/88200.0) + signal) I'm using a...

Hi everyone, I'm trying to demodulate the following in order to obtain "signal" - cos(cos(2*PI*11025*i/88200.0) + signal) I'm using a signal of - cos(2*PI*1102.5*i/88200.0) so I'm actually demodulating - intensity[i] = cos( cos(2*PI*11025*i/88200.0) + cos(2*PI*1102.5*i/88200.0)) To demodulate this signal, I consider two bands. The first band is around 11025Hz, and the sec...

Hello, I would like to know how to make a bit synchronizer for QPSK demodulation using an Early / Late Gate Synchronization ? I have an...

Hello, I would like to know how to make a bit synchronizer for QPSK demodulation using an Early / Late Gate Synchronization ? I have an early / late gate synchronizer which works only on a real signal (NRZ data input) and not on a complex signal (I and Q) Is the Early / Late gate can synchronize with an IQ signal (QPSK, 8PSK, 16QAM... ) ? thanks

Hi,all i build 3 simulink model to watch the benifit of convolution code. model 1: bernoulli binary------16QAM modulation--------awgn...

Hi,all i build 3 simulink model to watch the benifit of convolution code. model 1: bernoulli binary------16QAM modulation--------awgn channel---------16QAM demodulation---------Rx binary model 2: bernoulli binary------CC coding puncture 4/6------16QAM mod--------awgn channel-------16QAM demod---------CC decoding de-puncture 4/6-------Rx binary model 3: bermoulli binary------CC cod...

Dear all, I've created a SDM ( Sigma Delta Modulation) system. For the signal input, I used a 3000 Hz signal, but I need a 1500 Hz LPF (Low Pass...

Dear all, I've created a SDM ( Sigma Delta Modulation) system. For the signal input, I used a 3000 Hz signal, but I need a 1500 Hz LPF (Low Pass Filter) with - 80 db / dekade slope for output signal after the signal being modulated and in demodulation process. my spec for SDM system: Input frequency 3000 Hz Output frequency 1500 Hz frequency sampling 25000 Hz If I used 3000 Hz LPF, the outp...

Hi all, I have build a simulation system to test my Error Correcting Code. And now I add modulation/demodulation module. When I apply BPSK...

Hi all, I have build a simulation system to test my Error Correcting Code. And now I add modulation/demodulation module. When I apply BPSK and QPSK to system, I found their BER versus SNR curve almost identical, is it right in theory? My code rate is 0.9, code length > 10000. BTW, I found BPSK and QPSK have identical uncoded BER versus SNR curve, is above similar? Any suggestions wi

On Fri, 05 Nov 2004 18:31:35 +0800, Steve Underwood wrote: > Allan Herriman wrote: > > > On Fri, 05 Nov 2004 10:11:08 +0800, Steve...

On Fri, 05 Nov 2004 18:31:35 +0800, Steve Underwood wrote: > Allan Herriman wrote: > > > On Fri, 05 Nov 2004 10:11:08 +0800, Steve Underwood > > wrote: > > > > > > > > > Allan Herriman wrote: > > > > > > > > > > > > > All "solid state" finals for broadcast FM have been around since the > > > > '80s. At the time, they were better in terms of reliability, but not > > >

I'm looking for some DOS/Win32 software that will emulate a Bell 103 and ITU-T v.21 modem that uses a WAVE format file or a computer's sound...

I'm looking for some DOS/Win32 software that will emulate a Bell 103 and ITU-T v.21 modem that uses a WAVE format file or a computer's sound card for the modulation/demodulation audio signal output/input. These modems use AFSK modulation at 300 baud and 300 bps, at the following frequencies (in Hertz): Bell 103 Originate 1170 = Carrier 1070 = Space (Carrier - 100Hz) 1270 = ...

hi! i make an envelope detector for AM demodulation using Hilbert Transform and complex envelope... but i don't really understand about the...

hi! i make an envelope detector for AM demodulation using Hilbert Transform and complex envelope... but i don't really understand about the advantages of using Hilbert Transform and complex envelope... what is the advantages of using Hilbert Transform and complex envelope? why using Hilbert Transform method is more effective than square-law? and i think i can make an envelope detector...