Aka Signum MFT 7272M version 100c User Manual
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ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] 11 Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. This may also lead to targets air testing as iron, as well as a false increase in sensitivity when air testing. Remember that for every 1 degree of ground balance offset from the 0 or neutral point we get a corresponding increase or decrease in the VDI scale for a given target. IE a 1 degree+ ground balance will increase the VDI by +1. For example, if you are air testing a large copper coin that would normally give a VDI of +82 to +84 but is now air testing with a VDI of -86. The result is that the device ground balance is set +10 to +12 degrees too positive for performing an accurate air test. Balancing with a piece of ferrite is required before performing an air test of the device. Put the device on a non-metal surface, turn on automatic ground balance mode, count to three, then bring the ferrite to the center surface of the coil from a distance of 25-30 cm (10”to12”) to complete the balancing procedure. Puzzled? Let's make it easier: Take a CD and pass it flatwise in front of the search coil. If the CD gives a vertical hodograph and VDI of 0 (+1 or -1), then the device is ready for “air" tests. If the VDI of the CD differs from these values, then in auto GB click (to enter manual GB) and adjust the phase of the ground balance in the desired direction. When the VDI of the CD is at 0 (+1 or – 1) your device is ready for air testing. BALANCING PROCEDURE. We would like to bring your attention to the automatic balancing procedure developed by experienced users. 1. Find a metal-free area. You can find it by the threshold tone response in RT mode. On an unbalanced device there will be a response to the clean ground, however the sound will be soft and diffused, without a strong localization. While the sound would be sharp and with a strong increase in sound above a metal object. Select an area with no localized sharp threshold tone increase while swinging the search coil 5- 10 cm to the left and to the right above the ground. If there is no localized sharp threshold tone increase then the area is suitable for balancing. 2. Having found the metal-free area, raise the coil 30-40 cm above the ground press wait for 3 seconds, and move the coil to the ground smoothly but not too slow. Warning! Do not move the coil to the ground closer than 10% of the search coil diameter (for the searchcoilØ26 cm – 2-3 cm). This is related to the change in the pattern of the search coils physical interaction with the ground in what is called the Close Zone and it may impact balancing accuracy resulting in false responses in clean areas with high levels of sensitivity. A short tone (Hum) signifies the completed balancing procedure. If there is no tone or it does not sound during lowering, but sounds when moving up, repeat the procedure with the same formula: 30-40 cm above the ground, 3 seconds, and then lower the coil to the ground. Follow the ground vector on the screen during the process. Its shape should be a strait, slightly trembling line, on the horizontal axis of the ground scale.
12 ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. If it makes sharp angles or is “chaotic” on the screen, this means that you are trying to balance near a metal object in the ground. In this case, the device may perform a ground balance, however it will be incorrect and you will notice multiple false signals from the ground. If this occurs, simply re-balance the detector in an area clear of any metal targets. Once you have chosen a clean location to balance the detector and have done so, note the value in the lower left hand corner of the ground balance screen. Now, should you chose to ground balance again later on and there is a sharp difference between this value now, as compared to the previous ground balance, there is good reason to suspect that there was metal close by and you will need to ground balance again. If the coil all the same was a metal object, giving an automatic balance (items with VDI close to 0, e.g. foil), the device will give two consecutive tones, similar in tone to that of iron in the search mode, while at the same time the screen will display an exclamation point within a triangle. Accordingly, you will need to ground balance again on a clean spot of land. After balancing, in the lower left corner of the screen will display a numerical value of balance (phase), this is the amount by which the device will adjust the VDI, excluding the effect of the soil. In the right corner of the screen it should be noted that the average phase angle ground balance is different for each instance of the device and can also depend on the technological variability in parameters of the coil and the ambient temperature. However do not forget that your device remains in the automatic balancing mode and at any moment may deem it was time to rebalance to your shovel, boots, or hunting partner. If you want to review the results and values of the current automatic ground balance procedure press to enter manual mode and disable automatic balancing. In the upper right corner of the screen will appear M instead of the letter A. To exit the ground balancing, click on the instrument panel. Switching between modes is as simple as performing successive clicks of. While in the manual balance mode by pressing or one is able to adjust the ground balance in the proper direction. Bob the coil vertically above the ground (rising to 20 -30cm / dropping by 3-5cm), making sure that the vector of the soil is along the horizontal axis and that the hum is gone when raising or lowering the coil. Vector of improperly balanced soil (fig 7) fig. 7 Vector of properly balanced soil (fig 8) When working on the ground with uneven salinity, Fig. 8 such as arable land, it is not always possible to accurately ground balance the unit in automatic mode. This can be due to the uneven or lumpy nature of the soil. This can sometimes leads to false responses from the identification channel. In this situation the phase of the ground balance can vary by more than 3
ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] 13 Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. degrees. If you encounter this problem then perform the ground balance procedure as follows. Find a clean patch of ground with a width of 60 centimeters. Switch to manual ground balance and making short horizontal search sweeps with a width of 50cm at a height 3-5cm above the ground, you will see a straight line on the ground the screen (if the line jumps, then there is metal present). In this case, if the balance is wrong, you will hear a buzz from the soil and the soil line on the on the screen will not be horizontal. Press and until the line is horizontal and the buzz disappears. Your device is fine-tuned to the ground. For a small increase in the depth of the identification of large silver and copper coins (kettles, basins and other large pieces of highly conductive metals) it is possible, after performing automatic ground balancing, to enter the manual balance mode and set the GB point from -1 to -2 from the automatic GB reference point. Care should be taken when setting the ground balance point either negative or positive. When set negative it increases the possibility of receiving false positive responses when bumping the coil on vegetation or the ground. When set positive you risk the chance of losing sensitivity to large silver or copper coins that will either become “invisible” or ID as iron. In the event that a “clean” patch of ground is not found you can excavate a small amount of local soil (1-1.5 kg), removing all metal objects, and place in a bag for convenience. Now lean the detector with the coil facing up against a bush or tree with the coil at least 40-50cm off the ground. With the bag of soil in hand you can now and press the GB button and count 1,2,3. Then smooth and slow, (starting from a distance of 30-40 cm) present the soil to coil. (As if doing auto balance on the ground in the normal mode, but now you are moving the soil to the coil instead of vice versa) Placing the excavated soil on the ground is not desirable. Since you were not able to perform a ground balance previously, due to the presence of metal in ground, placing the bag of soil on the ground may cause an incorrect ground balance. Attention! If the signal from the ground is too small (such as quartz sand) and the auto balance cannot be performed then the balancing procedure can be performed either by using a piece of ferrite or a piece of red brick. These can be placed on the ground and the auto balance procedure performed. In principle, using the procedure for balancing for “an air test” will also work and you may set the balance point 1 or 2 degrees negative if you are searching for large objects. Sharp temperature changes on the search coil may impact balancing accuracy, the balance may shift and become incorrect with such changes. That is why, if you take the device from a heated car and start working in a low temperature conditions (early spring, late fall), rebalance one or two times while the coil adapts to the ambient temperature. In case of large temperature drops of more, than 15°С (compared to a normal air temp of 20C), we recommend that you perform electronic module and search coil
14 ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. adaptation procedure one more time (see Search coil Replacement). In this case the processor of your detector will choose the optimum frequency of the excitation current for the current temperature conditions. In saltwater beach operations and other complicated soils with high conductivity we recommend you use the Economy Mode option for better ground balance accuracy. Sometimes decreasing sensitivity will allow for a more accurate ground balance especially on beaches. In rare cases, such as after replacement of the coil or attempting to balance on a metal object, a situation may arise when you cannot perform an automatic ground balance. This occurs because the current value of the phase vector moves out of the locked system acquisition sheet (such as a significant change in ambient temperature). You can solve the problem by balancing in manual mode. To do this, while in the automatic balancing press the t o g o t o t h e manual mode and using the buttons and get the vector of the ground signal moving from left to right in strictly the horizontal direction. After that, the balancing procedure will operate normally. DISCRIMINATION SEARCH MODE AND SETUP Discrimination is the ability of the device to respond to certain types of objects and ignore the others. For example, you can configure the appliance so that it will respond only to objects of non-ferrous metals while ignoring everything else. In some cases, this allows you to increase the comfort of the search. Be aware, however, that the more discrimination that is used there is an increased risk in missing valuable objects. In any event, the choice is yours. The discrimination range is set to the position and width of the search sector. The metal detector will respond only to those objects that have travel time curves (Hodographs) which fall between the left and Right border sector. For example, to search for non-ferrous objects your sector search screen may look like that in Fig. 9. Pressing Button allows the user to fig.9 quickly switch between modes “All Metal” and “Discrimination” and then back again. The sector on the screen indicates that you are in a discriminatory setup. An Audio response will occur only on those objects that fall in the clear Hodograph area while targets that fall within the hatched area will not generate an audio response.
ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] 15 Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. To configure the discrimination, click. Now, by positioning the left and right edges of the search sector you can set the desired area (level) of discrimination. At the top left and top right of the screen are the current values of the search sector. These are in degrees of inclination relative to the vertical axis of the screen. The currently selected border sector is highlighted by a rectangular frame (fig. 10). To change the position of the border sector use the search buttons and To set up another border sector Click. fig. 10 As already noted in the discrimination mode, due to the influence of the soil, there is a risk of missing objects if the search sector borders are set too narrow. To exit discrimination click SEARCH MODE “All Metal” Using the search mode all metal “as opposed to “discrimination” mode you can detect any metal objects whether they be ferrous or non-ferrous. Which mode is best to use is a personal preference. However, it should be noted that searching in the discrimination setup can miss some of the weaker signals from good targets. This is due to the effect of the soil on the vector signal of the target and causes the signal to go beyond the search vector boundary. The disadvantages of the “all metal “mode can include difficulty working in trashy areas due to the extreme amount of signals and sounds received. Since the sector boundaries in the “all metal mode are fully open, it may be full of signals from so called “hot rocks”. The detector will issue high-pitched signals from these objects. This is useful for finding stones of meteorite origin. Identifying these “hot rocks” can be done by noting the high ratings from the VDI (+86) and the stretching of the signal. If these are bothersome you may use the discrimination mode and set your sector boundaries at -86 to +86 respectively. This will act much the same as “all metal” accept with the elimination of the “hot rocks”. You may also use the algorithm suppression “Disc. of Hot rocks “(see page 15).
16 ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. DYNAMIC AND STATIC MODES Dynamic mode is the main mode of operation of the detector. It is characterized in that the processor constantly adjusts to relatively slow changes in ground conditions. Therefore, in this mode, the instrument responds to the desired objects only when moving the coil. If the coil is stationary over an object, then after a while the sound will disappear. This is the primary mode your detector is in every time you turn it on. Static mode is used as an additional and serves mainly to clarify the location of the found object (Pinpoint). Unlike dynamic mode there is no constant adjusting and therefore, it is not intended for a lengthy search. To switch the appliance from the basic search mode to static mode (Pinpoint) Click. In the right-hand side of the Fig. 11 Screen there will appear the letter C, and on the left the value of the gain for the static mode along with the ability to change this parameter by using the buttons and (fig. 11). The gain of the static mode is selected experimentally depending on the specific conditions. The choice of this parameter will depend on the relief of the ground, littered area, temperature changes, etc. We recommend starting values of 6-7. As already mentioned, the active mode (pinpoint) is used to determine the the exact location of the object. Let us give some practical tips on how to Use this mode. After locating an object, in the static mode, and deciding it is worth digging it is time to define its exact location. To do this, move the search coil off of the approximate center of the target either left or right (line A see Figure 12). Then turn on the static mode (Pinpoint). As accurately as possible, while maintaining the distance between the ground and the coil, scan the object backwards. Determine on line A the location (coordinate) where the tone of the sound was the highest. Fig.12
ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] 17 Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. Then move the coil away from the target perpendicular to the primary direction (A) scanning (e.g. forward) along this line. This retraction of the coil in this direction must pass through the original coordinate. Re- enable the static mode. Scan the object along the line as accurately as possible keeping a minimum distance between the ground and the sensor. The recorded coordinate of the maximum frequency tones sound on line B, will determine the exact location of the object. To return to the dynamic mode press the button again . MODE “TURBO” In the Turbo mode the search coil operates at the forced excitation current. This mode allows you to increase the sensitivity of the device and to improve the immunity of the device from external electromagnetic interference. Attention! The “Turbo” mode greatly increases current consumption and as such battery operating time is greatly reduced! Switch to TURBO and back by using the button while in search mode. It is necessary to ensure that the settings ST/RT sensitivity and volume on the display screen are not displayed. MODE “ECONOMY” In the Economy the sensor operates at the minimum excitation current. This mode allows you to improve the comfort of your search on soils with a complex and variable salinity (for example in the surf of the beach), or at locations with extreme iron debris. Attention! After switching to “Economy” mode it is advised to ground balance the device. For reference, the detection range in this mode, when air testing a large 43cm copper coin, such as a Victorian Penny, is approximately 35cm (10” DD coil @ 6,5-7 kHz). Thanks to the significant reduction in the consumption of power in this mode you can run up to 40 hours on a set of fully charged batteries. Switching to the turbo is made through the "Extras” Menu, section “Extra Settings”"(see below). MODE S ALGORITHM From our experience we know that the majority of metal detectors react to flat iron objects as nonferrous. To assist in solving this problem the specially developed S algorithm is used to assist in properly identifying these targets. The most effective use of this algorithm is in identifying small flat iron objects (15 cm2), such as beer caps, rusted pieces roof tin, etc., with a signal rating greater than 10. If the device detects an object with a questionable non-ferrous signal (high tone) and it has a rating over 10 then using the S-Algorithm can help to identify these type targets.
18 ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. There is no need to use this algorithm for a definitive low-pitched signal, i.e. when the subject is clearly iron. Remember though, to monitor the signal rating level of the target. It should be pointed out that this mode does not apply to general searching, but only to help clarify the type of metal of a non-ferrous response and to decide on the need to dig. The S Algorithm has virtually no effect on the hodograph display of non-ferrous targets It should also be noted that when increasing the surface area of iron objects the effectiveness of the S-algorithm decreases. To switch to this mode, use the button , the values of the parameters RT and ST sensitivity and volume should be displayed. To return to the main search mode press the button again. . MULTI-FREQUENCY You may be interested to know that most of the detectors manufactured in the world will have a comparable sensitivity, for example, a brass disk with a diameter Ø25 mm and copper disc at Ø50 mm, despite the fact that the second object is much larger. It is also known that small targets (coins) are detected better at higher coil excitation frequencies. The fact is that by the virtue of certain physical laws each target class has its own optimal frequency at which the sensitivity to these targets are maximized. In order to give the unit the opportunity to search effectively for both large and small targets, many manufacturers produce 2, 3 or 4-frequency metal detectors. The Signum MFT 7272M allows you to work with coils with the operating frequencies from 1 to 30 kHz, thus maintaining acceptable sensitivity to almost any type of target. The metal detector can be equipped with the following sensors: 15DD -3 (7) kHz, 9.5 x12, 5DD - 7 (3, 14) kHz, 10DD - 7 (3) kHz 6h10DD - 7 (14) KHz. What could be the practical guidelines for choosing a coil with a different operating frequency? 3 kHz can be successfully used on non-trashy areas to search for both ferrous and non-ferrous targets as well as the spoils of war. 7 kHz –Is the average universal frequency for a wide range of applications. You can search for both medium and small coins as well as the spoils of war. This frequency is convenient for terrain reconnaissance. 14 kHz - Frequency optimized for small and medium-sized coins especially when the latter are located on edge. This frequency is the best choice for hunting on the saltwater beach.
ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] 19 Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. PARAMETER MENU By pressing the button you have access to a number of additional parameters, which are divided into 3 groups (Fig. 13). Navigating the menu Fig. 13 By using the buttons , and The value in the upper-right corner of the screen indicates the user program number that you are currently editing. SEARCH OPTIONS Conv. Search. [Normal. (Normal), MM (metal trash), AF1 (Filtering algorithm), AF2, AF3] These options are designed to optimize the operation of the device under normal conditions, under various degrees of trash within the search area, as well as under various amounts of electromagnetic interference. Trashy is defined as an area where the distance between small metal objects (nails) is 1/2 the diameter of the coil. To work in these areas use the MM. Otherwise, we recommend you use the mode Normal.” Mode MM is characterized by a fast algorithm for the signal processing, although there is a nominal loss in sensitivity (30%). When searching in areas of tall vegetation or in plowed fields with an uneven surface it is inevitable that bumping of the coil will occur. In these situations, it is recommended that you use the search modes AF1, AF2, AF3, where AF indicates the presence of an additional filtering algorithm of the signal. These modes can also be useful in areas with high levels of electromagnetic interference (EMI). However, it should be remembered that such filters may slow down the detector process speed. Which AF mode is best will depend on user experimentation in the local area. DHR (Discrimination of hot rocks) [On. / Off.]. This option includes the ability to suppress the sound response in the (ST) channel to the hot rocks (HR). We can describe these as rocks with a high ferrous content. Because of the physical features of the interaction of the Coil with the “HR”, the reaction to them is often confused with the reaction to large copper or silver coins. This algorithm helps to distinguish between these two types of responses and to eliminate the audio response to the Hot Rocks.
20 ООО «фирма «АКА», +7(495)621-0481, http://aka.2000.ru [email protected] Селективный металлодетектор «Сигнум MFT» 7272М. Руководство по эксплуатации. Optionally the software can be switched off. The inclusion of DHR is reflected on the screen in the form of an inscription of HR in the upper right-hand corner under the low-battery indicator. Reaction to these in the RT channel remains. Attention! The algorithm is turned off automatically in the program “MM1” and “MM2” Speed of Auto tracking AGT [off/1 .. 6]. This option allows you to set the speed limit of the auto tracking of the ground (not to be confused with balancing on a ground). Auto tracking allows the device to automatically adjust to the slow changes of temperature and salinity of the soil. It should be noted that this action should in no way replace the procedure for ground balancing, and only adjusts the balance of soil in small amounts during the search. In some cases (large amounts of metal trash or a cluster of hot stones) APB may not work properly. In these circumstances, you should disable the APB. Attention! If the device has not been used for a long time, for correct operation of APB it is necessary to ground balance Gain [1..10] This parameter is used to set the sensitivity of the device in the Real Time and Identification channels at the same time. In most cases, we recommend that this value is not set to more than 7. Smaller values can be useful, for example, to search for large objects that are not deep or in trashy areas. Shift Frequency [ -5. .. the Central frequency of the device. +5]. This parameter adjusts the operating frequency shift and is designed to reduce the effect of the mutual influence of devices operating in close proximity to each other. By adjusting this parameter, on both instruments, the users can achieve a minimum influence on each other and improve the comfort of working together at close distances without significant loss of sensitivity and identification. For a more effective suppression of the mutual influence of two nearby detectors it is recommended to spread their operating frequencies. Always remember that nearby operating instruments can significantly reduce the search depth. It is best to choose the level of difference between the operating frequencies experimentally by setting the distance between the devices and testing the sensitivity of the devices. Remember that the detectors must be located in the same plane, which corresponds to their actual relative position during the search. Attention! After adjusting the frequency shift of the device remember to perform the ground balance procedure DISPLAY SETTINGS Backlight. Allows you to change the brightness of the screen. The far left light indicator corresponds to the complete shutdown of the backlight. Remember that too much backlight level reduces the operating time of the battery life. Contrast. Sets the desired level of contrast of the display. Accumulation [1..4]. Option allows you to store the display from 1 to 4 hodograph images simultaneously. Displaying multiple hodographs may be useful, for example, in the analysis of responses from the same target while scanning from different angles or directions.