Multi-tone Test

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Yusri Maslamani
Bleal Azaar
Mohammad Essa
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Multitone testing represent an advanced technique used for testing electronic devices whether it can be passive devices like filters or active like amplifiers and diodes, accordingly this test done for linear and nonlinear behavior devices, so in this report we aim to apply this test to linear device like band bass filter (BBF). Multitone testing considered as a sophisticated method because of the number of tones used to test device under test (DUT) more greater than traditional technique like single tone and two tone testing. This test stand for an operation of generating multitone signals consist of a summation of sine waves connected to the DUT which are connected to spectrum analyzer to obtain the frequency response and analyze it  for  the tested device,if it satisfied the determined specification needed ,then we decide to accept this device or neglect it by calculating a crest factor (CF) which give us an important indication about our judge and this practicability one of many applications of multitone testing. Moreover, this test considered as a practical mechanism done in manufacturing of electronic devices before product launch in the market to make sure the product meets the specifications that labeled to this item. This represent an advanced test which could be more complicated compared with the previous tests. For example if we want to generate a multitone signal (200 sine waves combined to each other in the conventional test mentioned before this idea has one meaning that we need 200 signal generators to generate multitone signal and this action requires a lot of money and time. In this project the signal generator which give us the multitone replaced by constructing a code in matlab meets our requirement of getting the multitone signals. In this project the multitone signal represents the test stimulus for the device under test DUT. The DUT parameters are extracted by using a spectrum analyzer from the DUT output, we can compute the crest factor. The crest factor can be considered as a good indicator to decide if the DUT meets the desired specifications or not. Figure 6 demonstrate the terminology of what we conduct in this projectThis principle of multitone  allows to acquire the result of several measurement functions at different frequencies in a single step only, although this mechanism aims to overcome the time bottleneck . the multi-tone testing will be applied to a linear passive network. The linear passive network chosen to test the multi-tone stimulus is a parallel RLC circuit It bases on the principle of simultaneously transmitting all the sinusoidal tones -frequencies- of interest in a single burst. This stimulus is called multitone signal. The basic idea from both ways of test the BPF that we could get the results from the VCO circuit and the experiment which done on DSP kit  after we analyze the both sources we calculate the Crest Factor (Cf) and the time duration to be able to judge which test is the best .We find that using the multitone teqnique and the crest factor to judge for the device to be accepted or not is an efficient way since any change in any parameters on the device lead to change the crest factor and this what we are looking for that this test can let us compare between any two devices easily and with a negligple time could reach to micro second .This mean this test can give and accurate results in less time due to compare with using a VCO and single tone principle which need more time and less in accuracy and hard to judge when comparing between any active or passive device .