R/time_match_signals.R

In Nature40/UM2Radiotracking: Toolkit for handling radiotracking data

#' Time match of tracking signals
#'
#' @description Matches signals of different stations at the same time for bearing calculation
#'
#' @param data data.frame. radiotracking data
#' @param station_time_error numeric. tolerance time between incoming signals in seconds
#' @param progess logical. print progress
#'
#'
#' @return data.frame of radiotracking data with matching tags
#'
#' @author RadioTracking EU
#'
#' @export
#'


time_match_signals <- function(data,station_time_error=0.3, progress=F){
  matched_data<-NULL
  cnt_stats=0
  #for each station
  for(i in unique(data$Name)){
    if (progress) {
      setProgress(value=cnt_stats)
      incProgress(amount=0, detail = paste0("Station: ",i))
    }
    tmp_s<-subset(data,Name==i)
    num_tags=length(unique(tmp_s$freq_tag))
    #for each frequency tag
    for(l in unique(tmp_s$freq_tag)){
      tmp_sf<-subset(tmp_s,freq_tag==l)
      tmp_sf<-tmp_sf[order(tmp_sf$timestamp),]
      #calculate timedifference between the loggings
      tmp_sf$td<-c(0,diff(tmp_sf$timestamp))
      tmp_s$ti <- as.POSIXct(NA, origin = "1970-01-01")
      gc<-0
      tmp_sf$ti[1]<-tmp_sf$timestamp[1]
      for(i in 2:nrow(tmp_sf)){
        if(sum(tmp_sf$td[(i-gc):i])<=station_time_error){
          tmp_sf$ti[i]<- tmp_sf$timestamp[i-gc-1]
          if(any(duplicated(tmp_sf$receiver[(i-gc-1):i]))){
            tmp_sf$ti[i]<- tmp_sf$timestamp[i]
            gc<--1
          }
          gc<-gc+1
        }else{
          tmp_sf$ti[i]<- tmp_sf$timestamp[i]
          gc<-0
        }
      }
      matched_data<-rbind(matched_data,tmp_sf)
    }
    cnt_stats<-cnt_stats+1
  }

  matched_data$timestamp<-as.POSIXct(matched_data$ti, origin = "1970-01-01")
  return(matched_data)
}