Using Side-Scan Sonar Instrument to Characterize and Map of Seabed Identification Target in Punggur Sea of the Riau Islands, Indonesia.

Punggur sea has many habitats, object, and structured of seabed with hight tide and wave. Side scan sonar is an underwater acoustic instrument for identification of seabed. This research aims to classify types of seabed and measure seabed identification into the sea water with grain size (dB), location, altitude (m) and target using side scan sonar instrument. This research also uses one types of side scan sonar in one places with 3 line of collecting data to get more variant seabed. Side scan sonar data of 20 km of side-scan sonar profiling (CM2, C-MAX Ltd, UK) with altitude max 20 m and a working acoustic frequency of 325 kHz with the zone is taken in the punggur sea (104°08.7102 E, 1°03.2448 N until 1°03.3977N 104°08.8133 E). The data side scan sonar processed using max view software to display the image of the seabed. Results of seabed imagery in the punggur sea on track 1 have Objects found on the ship coordinates 03.3101N 1 ° and 104 ° 08.7362 E with the highest gain value is 6 dB, altitude 18 m on ping 75. Linear regression has y = 0.7016x+12.952 with R2 = 0.4125 (41%). Track 2 has target 1 is the sunken object on the seabed, while objects in the form of sand can be seen clearly. Objects found on the sunken object coordinates 1°02.8143 N ° and 104°08.5228 E with highest gain value is 9 dB with altitude 17.7 m and data ping 69. Linear regression has y = 0.2093+12.577 with R2 = 0.2093 (20%). Track 3 has Target 1 is the ship object on the seabed, while objects in the form of sand can be seen clearly. Objects found on the sunken object coordinates 1°02.5817 N and 104°08.7337 E with the highest gain value is 8 dB with altitude 16.5 m and data ping 3984. Linear regression has y = 0.5106x +12.84 with R2 = 0.5106 (51%). Track 1 has many targets identification results compared Track 2 and 3.


Int r oduct i on
Punggur sea is the part of the Riau Islands in Indonesia. Generally Punggur sea still rarely done research on the identification of seabed using the acoustic w ave technology. Acoustic w ave technology is a hydroacoustic m ethod are increasingly being used in all kinds of aquatic ecosystem s in order to acquire detailed inform ation about stock estim ation about fish abundance and seabed identification (Lubis and W enang 2016).
The acoustic instrument has sound w aves through the m edium of w ater that w ill be backscatter by objects in the w ater column and seabed.
That backscatter on w aveform characteristics can be Analyzed to get inform ation base object seabed. Side Scan Sonar is acoustic instruments can be transm itted pulse by the beam or Sound W aves To the left and right side w ith a specific frequency . The aim of this hydroacoustic survey w as to estim ate the total biom ass of fish in Sikka regency w aters using long transects sam pling patterns and calculation m ethods of biom ass in hydroacoustic m ethod Pujiyati, 2016, Lubis et al., 2016). Research on the seabed using side scan sonar has been done, such as det ection and interpretation on the seabed using side scan sonar instruments (Sari and M anik 2009).
Side scan data are traditionally displayed as gray im ages and interpreted w ith som e know ledge of the side-scan syst em and the sea-floor geology, together w ith som e independent observations (so- (Somers et al., 1978). the sonar data are preprocessed to correct for the influences of the sonar beam pattern and tim evarying gain (TVG) (Capus et al., 2004 andDiaz et al., 2002) This paper seeks to consider about identification of the target position on the outcom e of the identification image of the seabed, the value of Gain (dB), altitude (m ), beam sw eep area of side scan sonar, and object ident ification in punggur sea of the Riau Islands in Indonesia.

M at er i als and M et hod
The research w as conducted in Decem ber 2016 in the punggur sea of the Riau Islands in Indonesia. (104°08.7102 E, 1°03.2448 N until 1°03.3977N 104°08.8133 E) (Fig 2). Tracking of cruise side scan sonar and research location have 3 tracking line ( Fig  2).
Acoustic data acquisition w as done using instruments CM 2 Side Scan Sonar system w as used to survey the M odiolus bed off the Point of Ayre. The side-scan-sonar tow fish w as set at high frequency (325 kHz) and w ith a total sw ath w idth of 200 m (Fig 1).
The tow fish w as tow ed at a speed of approxim ately 4 Knots at an altitude of 12-18 m above the seabed. The broad-scale surface sedim ents characterization w as perform ed using a high-resolution C-M ax CM 2 Side Scan Sonar, providing digital side-scan sonar im agery. The system allow ed t he user to operate it under dual acoustic signal frequencies, at 325 KHz.
The syst em gain G includes the effect s of tim evaried gain and correlation as w ell as t he transducer pressure-voltage gains and am plifier gains. The 12bit value is then com pressed into a coded 8-bit value before being stored. Our estim ate of G is probably accurate to w ithin 6 dB; this is one of the largest sources of error in our calculations.This Tim e-Varied Gain (TVG) is used to com pensate for the decreasing intensity of the backscattered signal and keeps the signal output w ithin the dynam ic range of the recorder. The TVG is not continuous but is actually produced in a series of 1.5-dB steps (M itchell & Som ers 1989). The tim e-varied gain function (ignoring the step-like nature of the TVG) is approxim ated by: Where T is the pulse length (usually 2 s), show ed in   3. Result and di scussi on 3.1 Im age Classi fi cat i on Sedi m ent Im age classification of sedim ent carried by the qualitative analysis, w hich is to distinguish the type of sedim ent is based on the results of the scan sonar im agery. The result s of C-M ax CM 2 Side Scan Sonar (SSS) is an im age w ith a high frequency of 325 kHz.
M ax-view capable of displaying in Fig 4, Total ping 2336 pings, m easure select ed record is 362 m , and the distance betw een pins is 13900 km (Fig 4). This happens because of side -Max CM 2 Side Scan Sonar (SSS) has a short duration pulse w ith sim ultaneous observations (M acLennan and Sim m onds 2005). Target, tim e, location, ping, gain, and altitude value on track 1, Punggur sea show ed in Table 1  Target 6 is the object of the sunken ship on the seabed, w hile objects in the form of sand can be seen clearly. Objects found on the ship coordinates 03.3101N 1 ° and 104 ° 08.7362 E w ith the highest gain value is 6 dB w ith altitude 18 m eter. The port (right side) seen t he entrenchm ent of a lighter color. Their excavation led to differences in texture, roughness, and slope of the seabed sedim ents. Besides excavation occurred on the seabed allegedly causing sedim ent coarser grain size larger particles beneath it lifted up. According to Urick (1983) grain size, scale sedim ent surface roughness and slope significant variations can be the im portant role in the acoustic response. Linear regression has y = 0.7016x+12.952 w ith R 2 = 0.4125, by looking at the equation it is clear that the correlation betw een the gain and the alti tude at the track 1 by 41% w ith alpha is 5 (Fig 3). Colliers and Brow n (2005), said that the phenom enon of backscattering seabed has relationships w ith the roughness. The m ore coarse sedim ent w ould reflect highest backscatter. Im age classification and position target 1-6 on sedim ent track 2 show ed in  Linear (Series1) Fig 4 show s the im age of seabed sedim ents that have a target number of 6. Target 1 is the sunken object on the seabed, w hile objects in the form of sand can be seen clearly. Objects found on the sunken object coordinates 1°02.8143 N ° and 104°08.5228 E w ith highest gain value is 9 dB w ith altitude 17.7 m and data ping 69 . The port (right side) seen t he entrenchm ent of a dark color (shadow zone). According to (Kenny et al., 2003) sw eep of side scan sonar can produce m osaics, geological and sedim entology features that are easily recognized and int erpreted qualitatively so as to provide inform ation about the dynam ics of the seabed.
Based on data from the m ovem ent of side scan sonar found on the sensor pitch m ovem ents occur up to 15 degrees from a standstill 0 degrees roll m ovem ents occur up to 10 degrees from i ts current position silent 0 degrees. Unlike the sedim ent m ud, sand sedim ent has particularly rough look more like in Fig. 4.
Linear regression has y = 0.2093+12.577 w ith R 2 = 0.2093, by looking at the equation it is clear that the correlation betw een t he gain and the alti tude at the track 2 by 20% w ith alpha is 5 (Fig 5). Differences in sedim ent form ing m aterial thought to affect the im age side scan sonar that biogenic sand looks m ore rugged. Effect of seabed slope in the Punggur sea w ill also affect the condition of sedim ent due to gravitational forces. How ever, based on the im age side scan sonar can be seen clear differences in texture and roughness on the sand sedim ents, biogenic sand and clay. Image classification and position target 1-5 on sedim ent track 2 show ed in  Gai n (dB)

Series1
Linear (Series1) Fig 4 show s the im age of seabed sedim ents that have a target number of 6. Target 1 is the ship object on the seabed, w hile objects in the form of sand can be seen clearly. Objects found on the sunken object coordinates 1°02.5817 N and 104°08.7337 E w ith the highest gain value is 8 dB w ith altitude 16.5 m and data ping 3984. Linear regression has y = 0.5106x +12.84 w ith R 2 = 0.5106, by looking at the equation it is clear that the correlation betw een the gain and the altitude at the track 3 by 51% w ith alpha is 5 (Fig 7). The Blind zone is shadow zone in tracking figure of side scan sonar instrument. The influence factor of w idth blind zone w ill be has im age seabed identification not be specific. The influence w idth of the blind zone so sm all in the area is result sw eep of side scan sonar instrument (Figure 2, 4, and 6).

Conclusi on
Research in Punggur sea using C-M ax CM 2 Side Scan Sonar system w ith a frequency of 325 kHz, obtained on the seabed is the sedim ent of sand than clay and find the shipw reck t hat sunk in Track 1 and Track 3.
Highest gain value is on Line 2 in the coordinates 1 02.8143 ° N 08.5228 ° and 104 ° E, and is the low est That is on Track 1 at coordinates 03.3101N 1 ° and 104 ° 08.7362 E. Relations betw een Value Gain And heights That have the highest correlation on track 3 (51%). Track 1 has m any targets identification result s com pared Track 2 and 3. The influence factor of w idth blind zone is beam pattern of side scan sonar instrument w ith altitude from posit ion of tow fish.