While calculating LO SSB integrated phase noise we need to specify minimum and maximum offset frequencies and phase noise profile within the limits. How to chose the practical minimum and maximum offset to calculate the integrated phase noise.
Take a look at this publication
http://drum.lib.umd.edu/bitstream/1903/2391/1/umi-umd-2252.pdf
Dear Bikshu
The phase noise can be cosidered as an unwanted signal modulating the oscillator. Assuming that local oscillator with a frequency flo will be used to frequency shift a base band signal extending from fl to fh. Then the resulting frequency spectrum after mixing will be an upper band extending from flo+fl, flo+fh and a lower band extending from flo-fl, flo-fh. Therefore, the phase noise that lay inside the range of the modulating signal will contaminate the signal and super impose on it. So, the minimum range will be from flo+ fl to flo+fh on the bandwidth of the base band provided that the base band will be filtered after the demodulation with a band pass filter covering only the bandwidth of the base band.
wish you success
Dear Gerson,
Thank you for the reply, I have gone through the thesis.
I need to calculate the phase noise using leeson's formula in order to find the SNR. If we look at page-32 of the thesis, to find the RMS phase error we need to integrated the leeson's distribution for a particular bandwidth (In thesis from 'a' to 'b'), as the author mentioned 'a' should be close to carrier and 'b' is based on the channel bandwidth. Is there anyway to characterize lower limit which is 'a' ?
Regards,
Bikshu.
Dear Bikshu,
I think the answer is specific to a certain communication standard. For OFDM, half the total bandwidth is often used as the upper limit. This corresponds to the middle-carrier weighting function of @J. Stott, 1998. The lower limit depends on the useful symbol length (the inverse sub-carrier spacing Delta_f). A first guess for the lower limit is given by f_L=(sqrt(3)/pi)*Delta_f, see: DOI: 10.1109/ISCAS.2017.8051000 For IEEE 802.11ad (60 GHz) we have Delta_f=5.15625MHz, resulting in f_L=2.84 MHz as the lower limit, and f_H=B/2=N*(Delta_f/2) as the upper limit, where N is the number of OFDM sub-carriers. Here, I assumed that the common phase error (CPE) is removed as usual. Hope it helps.
Hi Bikshu
Phase noise contributes measurement noise when a phase-sensitive comparison is made between a reference signal and an earlier version of the same signal, usually with phase information added to it.
For example, a coherent radar transmits a pulse derived from a reference oscillator. The electromagnetic wave bounces off a target and returns to the radar, delayed by the transit time to the target and back. In the radar receiver the phase of the received echo signal is compared with the phase of the reference oscillator.
Phase information from repeated measurements may be used to determine the Doppler shift from a moving target.
Phase noise causes the phase measurements to be noisy.
The phase noise for each measurement is determined by the integral of the phase noise. The upper limit of integration is determined by the system bandwidth. The lower limit depends on the time delay of the echo signal. The lower limit frequency of integration is taken as the inverse of the time delay of the return signal.
The phase noise contributes white noise to a series of measurements since each measurement is an independent experiment.
Regards
Pieter
- Badges
- Science topic