Class: Alien::AlienTag

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/alien/alientag.rb

Overview

A storage class for RFID tag data elements.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(taglist_entry) ⇒ AlienTag

Populate the instance variables from a taglist entry string. The following field separators are supported in the taglist entry string:

'tag:', 'disc:', 'last:', 'count:', 'ant:', 'proto:', 'speed:', 'rssi:'



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# File 'lib/alien/alientag.rb', line 33

def initialize(taglist_entry)
  @disc = @last  = @last_last = 0
  @ant  = @count = @proto = @rssi = @speed = @freq = 0
  @speed_smooth  = @speed_last = 0
  @pos_smooth    = @pos_last = @pos_min = 0

  create(taglist_entry)
end

Instance Attribute Details

#ant ⇒ Object

Antenna on which the last read was made



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# File 'lib/alien/alientag.rb', line 20

def ant
  @ant
end

#count ⇒ Object

Number of times the tag has been read since discovery



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# File 'lib/alien/alientag.rb', line 21

def count
  @count
end

#disc ⇒ Object

Time of discovery



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# File 'lib/alien/alientag.rb', line 22

def disc
  @disc
end

#freq ⇒ Object

:nodoc:



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# File 'lib/alien/alientag.rb', line 28

def freq
  @freq
end

#id ⇒ Object

EPC code of the tag that was read



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# File 'lib/alien/alientag.rb', line 19

def id
  @id
end

#last ⇒ Object

Time of latest read



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# File 'lib/alien/alientag.rb', line 23

def last
  @last
end

#proto ⇒ Object

Protocol used to read the tag. A bit map where Gen2 = 16.



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# File 'lib/alien/alientag.rb', line 24

def proto
  @proto
end

#rssi ⇒ Object

Returns the value of attribute rssi.



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# File 'lib/alien/alientag.rb', line 26

def rssi
  @rssi
end

#speed ⇒ Object

Returns the value of attribute speed.



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# File 'lib/alien/alientag.rb', line 27

def speed
  @speed
end

Instance Method Details

#<=>(s) ⇒ Object

The ‘spaceship’ operator allows us to compare tags for sorting, etc.



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# File 'lib/alien/alientag.rb', line 64

def <=>(s)
  @id <=> s.id
end

#create(taglist_entry) ⇒ Object

Try to parse a taglist entry into a set of Tag object variables.

Uses a simple mapping from Alien ‘text’ format:

Tag:0102 0304 0506 0708 0900 0A0B, Disc:2008/10/28 10:49:35, Last:2008/10/28 10:49:35, Count:1, Ant:3, Proto:2

rssi and speed attributes are not included in the default text format. In order to have them parsed correctly the TagListFormat must be set to custom and the TagListCustomFormat fields must be separated by the following text tokens:

'tag:', 'disc:', 'last:', 'count:', 'ant:', 'proto:', 'speed:', 'rssi:'

For example:

@rdr.taglistcustomformat("Tag:%i, Disc:${DATE1} ${TIME1}, Last:${DATE2} ${TIME2}, Count:${COUNT}, Ant:${TX}, Proto:${PROTO#}, Speed:${SPEED}, rssi:${RSSI})"
@rdr.taglistformat("custom")



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# File 'lib/alien/alientag.rb', line 89

def create(taglist_entry)
  @id = ""
  return self if (taglist_entry=="(No Tags)")

  tagline = taglist_entry.split("\r\n")[0]
  tagbits = Hash.new("0")

  tagline.split(", ").each do |keyval|
    key, val = keyval.split(":", 2)
    if key.nil?
      raise "Trouble parsing taglist string. Text format expected. This string was: #{taglist_entry}"
    end
    tagbits[key.downcase] = val
  end

  if (!tagbits.empty?)
    #zero length ids can cause funny behavior
    if tagbits['tag'] != nil
      @id = tagbits['tag']
    end

    @ant       = tagbits['ant']
    @count     = tagbits['count']
    @disc      = tagbits['disc']
    @last      = DateTime.parse(tagbits['last'])
    @last_last = @last
    @proto     = tagbits['proto']
    @rssi      = tagbits['rssi']
    @freq      = tagbits['freq']
    @speed     = tagbits['speed']
  end
  return self
end

#inspect ⇒ Object

Return the contents of the tag object as a string (returns tag id as a string)



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# File 'lib/alien/alientag.rb', line 59

def inspect
  @id.to_s
end

#tag ⇒ Object

(Deprecated) Returns tag id.

This method is for backward compatibility with an earlier version of this API. Use id instead.



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# File 'lib/alien/alientag.rb', line 46

def tag
  @id
end

#tag=(val) ⇒ Object

(Deprecated) Sets tag id.

This method is for backward compatibility with an earlier version of this API. Use id= instead.



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# File 'lib/alien/alientag.rb', line 54

def tag=(val)
  @id = val
end

#to_s ⇒ Object

Returns a printable version of the tag object (returns tag id as a string)



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# File 'lib/alien/alientag.rb', line 69

def to_s
  @id.to_s
end

#update(new_tag) ⇒ Object

Updates an existing tag object from the new one by incrementing the count and setting the new last time



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# File 'lib/alien/alientag.rb', line 124

def update(new_tag)
  # Copy the last timestamp and increment the counts
  @last      = new_tag.last
  @count    += new_tag.count
  @last_last = @last
=begin
# Update the speed, smooth it, calculate distance
dt = (@last - @last_last) * 86400.0
smooth_coef   = 5
smooth_factor = Math.exp(-smooth_coef*dt)
thresh_zero1  = -0.01 # Any speeds between these thresholds are considered 0
thresh_zero2  = +0.01
puts
#printf("\ndt=%0.000010f, smooth_factor(init)=%0.00005f\n", dt, smooth_factor)

# Update the speed, smooth out jitter
@speed = new_tag.speed
if @speed.to_f > thresh_zero1 && @speed.to_f < thresh_zero2
# @speed = 0
end

#printf("speed_smooth(initial)=%+0.003f\n", @speed_smooth)
@speed_smooth = @speed_smooth*smooth_factor + @speed.to_f*(1 - smooth_factor)
@pos_last     = @pos_smooth
@pos_smooth  += @speed_last * dt/1000
@speed_last   = @speed_smooth

printf("speed=%+0.003f", @speed.to_s)
printf(", speed_smooth=%+0.003f", @speed_smooth.to_s)
printf(", pos=%+0.005f\n", @pos_smooth.to_s)

# Update new pos_min, if needed
@pos_min = @pos_smooth if (@pos_smooth < @pos_min)
printf("pos_last=%+0.5f, pos_min=%0.5f\n", @pos_last.to_s, @pos_min.to_s)
# If last position was the min and tag is moving away --> TopDeadCenter
if @pos_last == @pos_min && @pos_smooth > @pos_last
  puts "********************************************"
end
=end
end