AllanDeviations.jl is a package for the Julia programming language and provides various frequency- and phase-stability deviations (or variances) in overlapping and consecutive forms.

Currently implemented are:

Deviation | Function name | Phase Data | Frequency Data | Consecutive | Overlapping |
---|---|---|---|---|---|

Allan deviation | `allandev` |
✓ | ✓ | ✓ | ✓ |

Modified Allan deviation | `mallandev` |
✓ | ✓ | ✓ | ✓ |

Hadamard deviation | `hadamarddev` |
✓ | ✓ | ✓ | ✓ |

Time deviation | `timedev` |
✓ | ✓ | ✓ | ✓ |

Total deviation | `totaldev` |
✓ | ✓ | ✓ | ✓ |

Maximal time interval error | `mtie` |
✓ | ✓ | ✓ | ✓ |

Build & Tests (Julia v1.0.0 & upwards) |
Code test coverage | Documentation | ||
---|---|---|---|---|

To install AllanDeviations.jl open up a Julia REPL/Console and type:

```
using Pkg;
Pkg.add("AllanDeviations")
```

This installs the package along with any dependencies needed.

The following code calculates the overlapping Allan deviation of a given data array `arr`

and rate `r`

with log2 spaced averaging times τ.

```
using AllanDeviations
(tau, deviation, error, count) = allandev(arr, r) #assuming phase data
(tau, deviation, error, count) = allandev(arr, r, frequency = true) #assuming frequency data
(tau, deviation, error, count) = allandev(arr, r, overlapping = false) #non-overlapping/consecutive
```

Every function returns a simple named tuple `(tau, deviation, error, count)`

. `tau`

is an array of the averaging times used. `deviation`

are the respective calculated deviations, `error`

the respective errors of the deviations and `count`

is the number of terms contributing to every deviation.

The errors are calculated by `error .= deviation ./ sqrt.(count)`

.

The averaging times τ can also be finely tuned:

```
using AllanDeviations
allandev(arr, r) #log_2 spaced tau distribution: octave
allandev(arr, r, taus = AllTaus) #uses every possible tau value
allandev(arr, r, taus = Octave) #log_2 spaced: octave (default)
allandev(arr, r, taus = HalfOctave) #log_1.5 spaced: half octave
allandev(arr, r, taus = QuarterOctave) #log_1.25 spaced: quarter octave
allandev(arr, r, taus = Decade) #log_10 spaced: decade
allandev(arr, r, taus = HalfDecade) #log_5 spaced: half decade
allandev(arr, r, taus = 1.1) #log_1.1 spaced
allandev(arr, r, taus = [1.0, 2.0, 3.0]) #calculates at τ = 1.0, τ = 2.0 and τ = 3.0 if possible
allandev(arr, r, taus = [0.4]) #calculates at τ = 0.4 if possible
```

This example shows how to load data from a csv file (via the CSV package), calculate the overlapping allan deviation with it and to output a plot (via the Plots package) in the same directory:

```
using AllanDeviations, CSV, Plots
data = CSV.read("fractionalFrequencyData.csv") #load data
freq = data[:, 2] #extract fractional frequency
rate = length(data[:, 1]) / data[end, 1] #calculate rate
result = allandev(freq, rate, frequency = true) #calculate overlapping allan deviation
plot(result.tau, result.deviation, xscale = :log10, yscale = :log10) #log-log plot everything
savefig("allanDevPlot.png") #save the plot
```