Hello, I wrote a program in Java that does a DFT on raw 8bit samples stored in memory from a RF ADC (Post processing). This allows me to...

Hello, I wrote a program in Java that does a DFT on raw 8bit samples stored in memory from a RF ADC (Post processing). This allows me to easily adjust the span (zoom) when I'm viewing the spectrum. Works great, but slow as hell. So I'm now trying an FFT with a Chirp Z-Transform so I can zoom in on the desired frequency and look for subtle modulation characteristics. I borrowed this code fr...

Hi all I want to receive 70 MHz PM+BPSK modulated signal. Video bandwidth:138 kHz Modulation index for PM: 1.2 radian Subcarrier frequency...

Hi all I want to receive 70 MHz PM+BPSK modulated signal. Video bandwidth:138 kHz Modulation index for PM: 1.2 radian Subcarrier frequency of BPSK:65536 Hz. I have been using Matlab /Simulink and TMS320C6713 DSK. 1. I need suitable ADC daughtercard for C6713 DSK. 2. What is the sampling rate according to this spec.s? How can I calculate? I want to proof my calculation method. ...

Hi all I want to receive 70 MHz PM+BPSK modulated signal. Video bandwidth:138 kHz Modulation index for PM: 1.2 radian Subcarrier frequency...

Hi all I want to receive 70 MHz PM+BPSK modulated signal. Video bandwidth:138 kHz Modulation index for PM: 1.2 radian Subcarrier frequency of BPSK:65536 Hz. I have been using Matlab /Simulink and TMS320C6713 DSK. 1. I need suitable ADC daughtercard for C6713 DSK. 2. What is the sampling rate according to this spec.s? How can I calculate? I want to proof my calculation method. ...

Hi everbody, I have implemented a QPSK modulator and demodulator using classic text-book examples: Square Root Raised Cosine Impulse shaping...

Hi everbody, I have implemented a QPSK modulator and demodulator using classic text-book examples: Square Root Raised Cosine Impulse shaping and Matched Filtering. The problem is that I've been told that I could only used square waves for the modulation instead of sine waves on the emitter side (only +/-Vmod) and this really degrades the performance of the communication. After further inv...

I have a doubt. Gain code is defined as the reduction, usually expresed in decibels, in the required Eb/No to achieve a especified error...

I have a doubt. Gain code is defined as the reduction, usually expresed in decibels, in the required Eb/No to achieve a especified error probability of the coded system over an uncoded system with the same modulation and channel characteristics. But, what about Bit rate? The definition considers the same Bit Rate in both cases?????. For example: I have implemented a Viterbi Receptor(r=1/2 ...

There is a basic binary FSK with rectangular pulse. The modulation rate is 300 baud. The "0" corresponds to 4 periods of 1200 Hz, and "1"...

There is a basic binary FSK with rectangular pulse. The modulation rate is 300 baud. The "0" corresponds to 4 periods of 1200 Hz, and "1" corresponds to 8 periods of 2400 Hz. Let's make the phase of the carrier equal zero at the beginning of each bit. So we have a continuos signal consisting of the pieces of the sinusoids. So far so good. Now, let's make the amplitude of the 2400 ...

Hi, When we compute the true loglikelihood ratios in bit interleaved co-ordinate modulation, it has a factor of the noise variance and hence the...

Hi, When we compute the true loglikelihood ratios in bit interleaved co-ordinate modulation, it has a factor of the noise variance and hence the LLRs can be very large when the SNR is high(or equivalently the noise variance is low). The LLRs need to be quantized to be sent to the decoder. Can anyone explain or proivde a reference to the criteria used for LLR quantization. Should th

I'm looking for a portable arbitrary waveform generator that meets the following requirements: 1) Playback standard sample files (e.g., wav,...

I'm looking for a portable arbitrary waveform generator that meets the following requirements: 1) Playback standard sample files (e.g., wav, raw) at up to 12 MSPS. 2) At least 640 Mbytes of playback memory 3) Stores a library of playback files in non-volatile memory 4) Weighs less than 10 pounds There is no requirement for an RF modulation capability. I don't need the features of an exp...

hi i am into a little confusion the itu-t v.23 says that "Modulation rates and characteristic frequencies for the...

hi i am into a little confusion the itu-t v.23 says that "Modulation rates and characteristic frequencies for the forward data-transmission channel are for Mode2 up to 1200 bauds 1300 Hz (symbol 1, mark) and 2100 Hz (symbol 0, space) " According to my preception 1300 Hz means - if 1300 cycles are received in one second it means a 'one' is received and similerly 2100 Hz m...

Hi Guys, I'm tryin' to learn something about the "haf-sine" filters used in the IEEE 802.15.4 standard (ZIGBEE) which uses OQPSK as a...

Hi Guys, I'm tryin' to learn something about the "haf-sine" filters used in the IEEE 802.15.4 standard (ZIGBEE) which uses OQPSK as a digital modulation scheme. When I searched (Google) the Internet I downloaded 5-6 PDF files but they didn't describe exactly what is a "half-sine" filter. Maybe the concept of a "half-sine" filter is one of those ideas that: "everyone...

hello, any of you has experience with different methods for symbol synchronization so you can help me to implement one of them in a receiver for...

hello, any of you has experience with different methods for symbol synchronization so you can help me to implement one of them in a receiver for bpsk modulation? i've implemented a costas loop for carrier recovery and the code i've found for symbol synchronization is too heavy and takes too much time. this is the matlab code: tnow=del*oversampling+1; tau=0; xs=zeros(1,length(y)); % i...

Hello All, Can anybody tell me what would be the diffference in the constellation for pi/2-shift QPSK (not pi/4 QPSK). and normal QPSK. This...

Hello All, Can anybody tell me what would be the diffference in the constellation for pi/2-shift QPSK (not pi/4 QPSK). and normal QPSK. This is one of the modulation types proposed as part of the TG3c proposal(IEEE 802.15). There is also mention about pi/2 BPSK, pi/2 QAM etc. With regards to pi/2 BPSK, I understand that the constellation would have four points but I was not sure on pi/...

Hello All, I have created a simple routine in MATLAB that simulates a second order sigma delta modulator. I am now trying (with some...

Hello All, I have created a simple routine in MATLAB that simulates a second order sigma delta modulator. I am now trying (with some difficulty) to calculate the SNR of the modulator given sinusoidal inputs. My understanding of how this procedure should be carried out is as follows, 1) Build the output of the modulator by running my routine. The quantization error in the ouput would then b...

I some old papers that talk about PSK modulation, apart from carrier frequency, carrier phase they also mention Keying Rate and phase...

I some old papers that talk about PSK modulation, apart from carrier frequency, carrier phase they also mention Keying Rate and phase keying timing. Are these old terms used to refer to bit rate or symbol rate?? In all simulations I have done I never used these parameter, at least that I know. Are these parameters needed for something or simply set to default values (i.e. equal to 1) in simul...

Hi All I have been facing this problem for some long time and I have lost my patience. and I am not able to solve it. I would be really...

Hi All I have been facing this problem for some long time and I have lost my patience. and I am not able to solve it. I would be really thankful if you can show me some way out. Problem: to model time varying frequency selective multipath channel. My simulation is at baseband, one sample per symbol and QPSK modulation. And the delay are symbol spaced. lets say there are three paths. If...

Hi, I am writing a Matlab simulation of "Pragmatic-TCM" (see "A pragmatic approach to trellis coded modulation", Viterbi et al, IEEE...

Hi, I am writing a Matlab simulation of "Pragmatic-TCM" (see "A pragmatic approach to trellis coded modulation", Viterbi et al, IEEE Comms magazine, July, 1989, p.11). One point I am unsure of is how to compute the metrics for the Viterbi algorithm which decodes the least-significant bits of the received signal point. I understand that when you receive a point for decoding, you first ...

Hi All, I have collected few classic papers on channel coding,MLSE and Viterbi Algorithm written by the pioneers during 1966-1972 - Including...

Hi All, I have collected few classic papers on channel coding,MLSE and Viterbi Algorithm written by the pioneers during 1966-1972 - Including works of Hancock,Gallager,Viterbi,G.D.Froney,Omura,Lucky etc. I have found a later paper written by Ungerboeck at IEEE trans on info theory,Jan,1982 where he introduced the idea of set partitioning later popularized by S U H Quereshi et al as RSSE - ...

Hi, If I have a 16-QAM demodulator I know I can use the I and Q values to access a lookup table and output soft codes for a Viterbi uisng...

Hi, If I have a 16-QAM demodulator I know I can use the I and Q values to access a lookup table and output soft codes for a Viterbi uisng LLR What do I do if I'm using 16-PAM? If my information is right its just amplitude modulation. So out of the demodulator I will get 1 of 16 values. How do I then create the soft codes indicating how strong, or weak the '1's and '0's are? Thanks Mike ...

I have finished a basic OFDM simulation with BPSK modulation on it. Now I want to use the convolutional code in transmitter and a...

I have finished a basic OFDM simulation with BPSK modulation on it. Now I want to use the convolutional code in transmitter and a multipath channel with AWGN. At receiver , a viterbi decoder would be used. But I have some question in it.First,when the data have done FFT at the receiver.There would be still imaginary part in signal,should I discard the imaginary part or not? Second,because ...

> On May 12, 5:36 am, "dvo" wrote: > > Hi, > > I am new about constant envelope OFDM. Anyone knows what is good and/or > > bad about...

> On May 12, 5:36 am, "dvo" wrote: > > Hi, > > I am new about constant envelope OFDM. Anyone knows what is good and/or > > bad about this? > > Thanks > > -dvo > > > > I guess the good is that it's constant envelope and has the > advantages of OFDM. The "traditional" OFDM can have large > peak-to-average ratio which makes the dynamic range larger > than other modulation schemes.