Acquisition performance for NDA symbol‐timing recovery with simple adaptive first‐order loops

Abstract

SUMMARYPowerful feedforward estimators for symbol-timing recovery are more or less mandatory for efficient acquisition in time-division multiple access (TDMA) modems. However, in many cases, feedback solutions are much less complex from the computational point of view. The latter can be an attractive alternative for continuous transmission of data like DVB, where rapid acquisition is not so important as with TDMA. In order to describe analytically the acquisition performance of first-order loops with Gardner detectors, it is shown that the related analog model can be successfully applied. In the sequel, this approach is used to demonstrate that the acquisition process may be accelerated significantly via simple adaptive loop filters.

Coarse recovery of carrier frequency and symbol timing in multibeam satellite channels

“…Of course, lower values of γ 0 = E 0 / N 0 exhibit a larger jitter variance, which might be reduced by a smaller loop bandwidth. If the increased convergence period is unacceptable, however, one could resort to a simple adaptive approach, where the filter constant decreases with proceeding timing indexes according to a predefined function, eg, in a linear or exponential manner starting with the initial values of the loop bandwidth, say B L T u = B L T e =10 −3 , and ending up with the final ones, say B L T u = B L T e =10 −4 .…”

Open‐loop analysis and self‐noise performance of an NDA synchroniser for carrier‐independent symbol timing recovery at baud rate

“…Assuming M-ary PSK signals, their analytical work focuses on the linearised loop with small deviations from the stable equilibrium point, discussed in Reference [4] as well. For larger deviations, as they are typical for the acquisition process in feedback loops, the detector characteristic (S-curve) must be available [5,6]. For a special but important case, this has been achieved in a recently published paper [7], where it could be shown that the S-curve follows a nearly perfect sinusoidal shape as it is known from the Gardner (GA) algorithm.…”