1. Development of a GIS based software
for real time noise maps update
andrea cerniglia

2. Scale and sum
Main idea of the system is to scale a set of pre-computed noise maps according acquired noise data, and sum them together in order to obtain the map of the whole area.

3. Dynamap

4. Scale and sum

5. Communication between monitoring stations and data collecting unit
is not limited to the transmission of the acquired data but it is, in fact,
a two-way communication

6. Thanks to this bi-directional communication is possible to set-up
and update the monitoring station remotely

7. Delay between Timestamp arrival and time
The calculation of this parameter permits to detect the amount of
queued data (i.e. data transmission channel fault)

8. Delay between Data Sent and ACK received
The calculation of this parameter permits to detect problems related to
bandwidth of transmission channel (i.e. insufficient bandwidth)

9. The scaling and sum of 10 maps with 300,000 points each involves:
3,000,000 sums (10 x 300,000)
3,000,000 divisions
3,000,000 antilog
300,000 sums with 10 terms per sum
300,000 log calculation
300,000 products

10. In order to optimize the ‘calculation power compsumption’ needed for this enourmous amount of operations, some tricks are possible to simplify complex operation like log and antilog, to faster operation.

11. This can be done by pre-compute una-tantum all the possible antilog in the acoustic range (20 to 120 dB) and by storing them in a table so, pratically, the 3,000,000 antilog calculation consists then just in a fetching peration on a table, like in an abakus.

12. Also the division by ten and multiplication by ten can be semplified to a simple sum by using logaritms properties

13. After the implementation of these ‘tricks’, the scaling and sum of 10 maps with 300,000 points each involves ‘only…’
3,000,000 sums (10 x 300,000)
300,000 sums with 10 terms per sum
300,000 log calculation

14. Similar approches are used for the log calculation process and for the sum process.
More in details, the ‘trick’ is to pre-compute all the numbers in the intervals which gives each 10 log (x) possible value, and just fetch the correct value in a pre- computed table.

15. System configuration

16. With the above mentioned configuration and with the implementation of the algorithm for computation time optimization, the time needed for scaling and sum 10 maps of points each, on a medium level machine, is less than 5 seconds.
The most critical aspect in terms of time consuming is related with the disc access time (for retrieve data and store results) which can improved by means of SSD insead of standard mechanical disk (in progress).

17. Databases
· Dynamap_Mon_Data
· Dynamap_Mon_Results
· Dynamap_Basic_Maps
· Dynamap_Maps_Results
· Dynamap_Access_Privileges
· Dynamap_Administration

18. Dynamap_Mon_Data database: location table

19. Dynamap_Mon_Data database: Values table
Noise values are stored in Bel instead of decibel, once more to
deal only with integers (instead of real numbers) and thus
improove memory allocation and operation speed

20. Dynamap_Mon_Results database
The system automatically compute hourly Laeq values for each monitoring station and store them in a database

21. Dynamap_Basic_Maps database: Values table

22. Dynamap_Maps_result database: Values table

23. At the end of the ‘scale and sum’ process, all the computed
values are avaible to another part of the system (still under
development, ready to be released in autumn 2016), able
to produce web-based noise maps on demand, and able to
to show them to citizens.

24. Thanks for your attention