# What does dj(u) mean in kth impulse radio transmitter output signal of UWB ?

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#### frankuser

##### Newbie level 4
Hi,guys.a signal model of UWB time-hopping system
a typical time-hopping format of the kth impulse radio transmitter output signal
S(u,t) is given by this equation in many papers:
S(u,t)=∑ω(t-jTf-Cj(u)×Tc-dj(u)) ( -∞<j<∞ )
where ω(t) represent the transmitted monocycle waveform that normally begins at time zero on the transmitter clock,Cj(u) a TH sequence.
but I want to know what does dj(u) mean and what factors cause it?

#### Sal

##### Full Member level 4
A basic UWB problem

HI

you can realise from your equation that you didnt identified where thi information bits are transmitted, did you?. Therefore assuming that the type of modulation is pulse position modulation (PPM) it might represent the time dispacement concecuence of the modulation, basically dj(u) = 0, if the transmitted bit is "0" and some value if it is "1" otherwise, or viceversa.

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Sal

### frankuser

Points: 2

#### frankuser

##### Newbie level 4
A basic UWB problem

Thanks,but i think i have not expressed my problem clearly.
In the paper :Ultra-wide bandwidth time-hopping spread-spectrum impulse radio for wireless multiple-access communications,IEEE 47 thVehicular Technology Conference, vol. 1, May 4-7, 1997 pp. 251 – 255.The sequence {dj(u)} ( -∞<j<∞ ) is a sample sequence from a wide-sense stationary random process
d(u,t) ,with samples taken a rate of 1/Tf.Where Tf is the frame rate.
So do you mean the {dj(u)} is the data sequence and the time delay dj(u) carries the information?
Your answer is helpful for me,but i think maybe the {dj(u)} represents some other things.
Can you help me and give me some interpretation?

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