10+ Qualcomm Hardware Engineer Interview Questions and Answers

The number of ways to arrange sets of coloured balls in a line.

• The number of ways to arrange the red balls is the factorial of the number of red balls.

• The number of ways to arrange the blue balls is the factorial of the number of blue balls.

• The number of ways to arrange the green balls is the factorial of the number of green balls.

• To find the total number of arrangements, multiply the number of arrangements for each set.

Overlap-add method of convolution is implemented by dividing the input signal into overlapping segments and convolving each segment with a filter.

• Divide the input signal into overlapping segments

• Apply the filter to each segment

• Add the convolved segments together to get the output signal

• The length of each segment should be greater than or equal to the length of the filter

• The overlap between adjacent segments should be greater than or equal to the length of the filter minus one

The in-phase and quadrature components of a real pass-band signal can be obtained using a complex mixer.

• A complex mixer is used to convert the real pass-band signal to a complex baseband signal.

• The in-phase component is obtained by multiplying the pass-band signal with a local oscillator signal in-phase with the carrier frequency.

• The quadrature component is obtained by multiplying the pass-band signal with a local oscillator signal 90 degrees out of phase with the carrier fre...read more

The bit-rate for quantization of a band-limited signal can be obtained by considering the Nyquist-Shannon sampling theorem.

• The Nyquist-Shannon sampling theorem states that in order to accurately represent a band-limited signal, the sampling rate must be at least twice the highest frequency component of the signal.

• The bit-rate for quantization is determined by the number of bits used to represent each sample. It is typically calculated as the product of the sampling rate and t...read more

Interpolation in discrete-time domain involves estimating values between known data points.

• Interpolation is used to fill in missing data or estimate values between known data points.

• Common interpolation techniques include linear interpolation, polynomial interpolation, and spline interpolation.

• Linear interpolation calculates values along a straight line between two known data points.

• Polynomial interpolation uses a polynomial function to estimate values between data points.

• Spl...read more

Nyquist sampling frequency for unevenly distributed band-limited signal.

• Determine the highest frequency component in the signal

• Use Nyquist theorem to calculate the minimum sampling frequency

• Sampling frequency should be at least twice the highest frequency component

Demodulating a QAM signal involves separating the amplitude and phase components to recover the original data.

• QAM signals combine amplitude and phase modulation

• Demodulation involves separating the amplitude and phase components

• Techniques like coherent demodulation and quadrature demodulation are used

• Coherent demodulation uses a local oscillator to recover the phase component

• Quadrature demodulation separates the in-phase and quadrature components

The Nyquist criterion states that in order to accurately sample a signal, the sampling rate must be at least twice the highest frequency component of the signal.

• The Nyquist criterion is used in digital signal processing and communication systems.

• It ensures that the original signal can be accurately reconstructed from its samples.

• The sampling rate should be at least twice the bandwidth of the signal to avoid aliasing.

• For example, if a signal has a maximum frequency of 10 kHz, ...read more

Overlap-add is implemented by dividing the input signal into overlapping segments, applying a window function, and adding the segments together.

• Overlap-add is a method used in digital signal processing to efficiently convolve long signals with finite impulse response (FIR) filters.

• The input signal is divided into overlapping segments, typically with a length equal to the filter length.

• A window function, such as the Hamming window, is applied to each segment to reduce spectral...read more

D flip flop is a digital circuit that stores a single bit of data and is used in sequential logic circuits.

• D flip flop has a data input (D), a clock input (CLK), a set input (S), and a reset input (R).

• When the clock input is high, the value of D is transferred to the output Q.

• When the set input is high, the output Q is set to high.

• When the reset input is high, the output Q is reset to low.

• D flip flop is used in applications like shift registers, counters, and memory units.

Use a 4:1 mux to create a 3 input XOR gate.

• Connect two of the inputs to the select lines of the mux.

• Connect the third input to one of the data inputs of the mux.

• Connect the other data input of the mux to the output of an XOR gate between the first two inputs.

• Use the output of the mux as the output of the 3 input XOR gate.

To find duplicates in a string, we can use a hash table to keep track of the frequency of each character.

• Iterate through the string and add each character to the hash table with its frequency

• If a character already exists in the hash table, it is a duplicate

• Return a list of all the duplicate characters found