GRATTEN GA1022CAL Скачать руководство пользователя страница 93

Страница: 93 / 134

Rule setup

Skip to a rule setup menu.

Back

Back to the pass/fail main menu.

Back

Page 2/2

Back to page 1 of the pass/fail menu.

Table 2-49 Page 1 of the rule setup menu:

Option

Setup

Description

Horizontal

regulation

Use the [UNIVERSAL] knob to set a horizontal

tolerance range: 0.04div-4.00div

Vertical

regulation

Use the [UNIVERSAL] knob to set a vertical

tolerance range: 0.04div-4.00div

Build rules

Build a rule template according to the two

setups above.

Save position

Inside

Outside

Select a save position for the rule.

Page 1/2

Skip to page 2 of the rule setup menu.

Figure 2-75 Page 1 of rule setup menu Figure 2-76 Page 2 of rule setup menu

Table 2-50 Rule setup menu 2:

Option

Setup

Description

Save

Save the rule setups.

Recall

Recall the waved rule setups.

Back

Back to the rule setup main menu.

Back

Page 2/2

Back to page 1 of the rule setup menu.

Содержание GA1022CAL

Страница 1: ......

Страница 2: ...gistered trademark of NANJING GLARUN ATTEN TECHNOLOGY CO LTD Declaration The products of the company are under protection of the People s Republic of China Patent that has been approved or is pending...

Страница 3: ......

Страница 4: ...the product The following terms may appear on the product Danger It represents that harms may be caused to you at once if you perform the operation Warning It represents that latent harms may be caus...

Страница 5: ......

Страница 6: ...B flash disc GA1000 series of oscilloscope has excellent performance various functions and competitive cost to performance ratio Model Bandwidth Sampling Rate GA1102CAL 100MHz 1GSa s GA1202CAL 200MHz...

Страница 7: ...re flexible and more natural for users operations Various kinds of language interface display Chinese and English On line help system Shortcut key PRINT support print screen Standard configuration int...

Страница 8: ...plication Example includes many measure examples offered for reference for users Chapter System Prompt and Fault Recovery introduces the system prompts and lists some simple faults and solutions so th...

Страница 9: ......

Страница 10: ...robe compensation 7 Chapter 2 Function Introduction and Operation 9 2 1 Menu and control button 9 2 2 Connector 11 2 3 Default setting 12 2 4 Universal knob 13 2 5 Vertical system 14 2 5 1 Channels CH...

Страница 11: ...Y mode 50 2 10 Measurement system 52 2 10 1 Scale measurement 52 2 10 2 Cursor measurement 52 2 10 3 Measurement 56 2 11 Storage system 63 2 12 Auxiliary system 69 2 12 1 System status 71 2 12 2 Lang...

Страница 12: ...gnal observation 87 3 4 2 Separation of signal from noise 87 3 5 Application of X Y function 88 3 6 Application of arithmetical operation in communication signal difference analysis 90 3 7 Screen capt...

Страница 13: ...Appendix C Daily maintenance and cleaning 106...

Страница 14: ...an be measured by a ground voltage as reference This chapter introduces how to implement the following tasks Accidence of front panel and user interface Implement brief function checks Match probe att...

Страница 15: ......

Страница 16: ...have been arranged in a row on the left side of a display screen are option keys The current menu can be provided with different options The other keys are function keys that can be set in different f...

Страница 17: ...ll the pre triggering data and is ready to accept a trigger Trig d The oscilloscope has caught a single trigger and acquires the data after triggering Stop The oscilloscope has stopped acquiring wavef...

Страница 18: ...annel waveform The identifier is displayed only when the channel is open The identifier displays a trigger electrical level The identifier displays bandwidth limit of the channel The identifier displa...

Страница 19: ...as shown in the figure below 4 1 2 3 1 Pass Fail output port output a Pass Fail detection pulse 2 RS 232 interface connect test software or waveform printing a bit slow 3 USB Device interface connect...

Страница 20: ...connector CH1BNC of the oscilloscope Connect a hook shaped head of the probe to a probe compensation signal connector marked with 1KHz and clamp a grounding hook marked with GND by a grounding clamp...

Страница 21: ...en using the probe Do not contact the metal part on the top of the probe when the probe is connected to a voltage source The signal measured by the oscilloscope uses ground as reference voltage and th...

Страница 22: ...nect the channel for the first time so as to match the probe with the channel Under compensation or Over compensation of the probe may cause measurement errors or mistakes Figure 1 7 Probe compensatio...

Страница 23: ...3 Check the shape of the displayed waveform under compensated suitable compensated over compensated 4 If necessary rotate the adjustable capacitor on the probe handle to realize suitable compensated 8...

Страница 24: ...ollowing functions of the oscilloscope are needed to be known Menu and control keys Connector Automatic setup Default setup Universal knob Vertical system Horizontal system Triggering system Signal ac...

Страница 25: ......

Страница 26: ...t the trigger electric level as midpoint of the signal amplitude FORCE It is used for finishing acquisition of the current waveform no matter whether the oscilloscope detects trigger and it is mainly...

Страница 27: ...recall the default factory setup HELP enter the on line help system AUTO automatically set the control state of the oscilloscope so as to display suitable waveform RUN STOP continuously acquire wavefo...

Страница 28: ...acquiring data in two channels Probe compensation The probe compensation signal is output and grounded so that the probe is matched with the channels of the oscilloscope This product is grounded by a...

Страница 29: ...3 Default setup key The DEFAULT SETUP key represents the default setup function most of the options and control setups of the factory are recalled by pressing them some setups are not changed and the...

Страница 30: ...idth setup specified row in video trigger upper limit and lower limit of filter frequency horizontal tolerance range and vertical tolerance range for regulating PASS FAIL function waveform frame numbe...

Страница 31: ...reover the waveform display of the corresponding channel can be started or stopped by pressing CH1 or CH2 2 5 1 Channels CH1 and CH2 Table 2 3 Function menu 1 of CH1 and CH2 Option setup Description D...

Страница 32: ...hase waveform of a reference electric level Stop Stop the waveform inverse function Digital filter Press this key to skip to the digital filter menu seen in table 2 5 Back Page2 2 Press the key to get...

Страница 33: ...zero volt reference electric level Setups of channels CH1 and CH2 1 Setups of channel coupling By using CH1 as an example the measured signal is a sine signal with DC offset Press CH1 Coupling AC and...

Страница 34: ...d as shown in figure 2 9 Press CH1 Bandwidth limit OFF and set the bandwidth limit as OFF state The amplitude of the high frequency component contained in the measured signal is unlimited as shown in...

Страница 35: ...but is a little smaller when the waveform is displayed at the next gear as shown in figure 2 12 Figure 2 11 Coarse tuning Figure 2 12 Fine tuning 4 Probe proportion setup To be matched with the probe...

Страница 36: ...e 2 15 Figure 2 14 Inverse OFF Figure 2 15 Inverse ON 6 Digital filter setup Press CH1 Next Digital filter and display digital filter function menu FILTER select Filter type then select Frequency uppe...

Страница 37: ...al offset to zero Volt div knob 1 The knob can be used for regulating the vertical gear of the channel in where the knob is so as to amplify or attenuate the signal of the channel waveform The gear in...

Страница 38: ...rithmetical operation function Operation Setup Description CH1 CH2 Add the waveform of signal source 1 with the waveform of signal source 2 CH1 CH2 Subtract the waveform of signal source 2 from the wa...

Страница 39: ...ve component and distortion in the measurement system Analyze the noise characteristics in a DC power supply Test the pulse response of the system Analyze vibration Table 2 8 Page 1 of the function me...

Страница 40: ...oint and the end point and no interruption is caused to the waveform But when the period number is not an integer the waveform has different amplitude at the start point and the end point so that high...

Страница 41: ...resolution Single frequency signal find higher subharmonic Carry out the following steps to use FFT mode Set time domain waveform Access the signal to CH1 or CH2 and press AUTO to display a YT wavefor...

Страница 42: ...litude and use the vertical cursor to measure the frequency 1 Measure FFT spectrum amplitude and use CH2 as an example the operation is as follows 1 Input a sine signal to CH2 and press AUTO 2 Press M...

Страница 43: ...Cursor measurement of spectrum amplitude of spectrum frequency 2 Measure the FFT spectrum frequency by the following steps 1 Repeat previous steps 1 7 for measuring the spectrum amplitude 2 Press Type...

Страница 44: ...easurement the waveform can be compared with the reference waveform so as to judge failure causes This method is particularly applicable at a condition that detailed circuit working point reference wa...

Страница 45: ...eform 4 Select REF A or REF B as storage location of the reference waveform 5 Press Save to save the current screen waveform as a waveform reference 6 Select REF A ON or REF B ON to recall the referen...

Страница 46: ...mplemented at this menu Besides horizontal displacement can be set by the horizontal POSITION knob M represents a main time base and Z represents an expanded time base Figure 2 25 Main time base Figur...

Страница 47: ...trigger the position relative to the center of the display screen of the waveform including MATH The resolution of this control knob is changed according to the time base 2 Use the press down function...

Страница 48: ...ow expansion time base is the higher the horizontal expansion multiple of the waveform is Carry out the following steps to observe details of local waveform 1 Press HORI MENU to display the HORIZON me...

Страница 49: ...gure below one knob and three keys are in the trigger control region TRIGGER Trigger electric level knob Figure 2 28 Trigger keys and knob TRIG MENU Press the key to recall the TRIGGER menu LEVEL knob...

Страница 50: ...lay trigger information For instance if burrs generated by the circuit are caught the causes of generation of the burrs may be found out by observing and analyzing the pre trigger data Attention pre t...

Страница 51: ...This extends the trigger level range Signal source AC Line This selection uses a signal derived from the power line as the trigger source trigger coupling is set to DC and the trigger level to 0 volts...

Страница 52: ...er menu Operation steps Set the types 1 Press TRIG MENU to display the TRIGGER menu 2 Press Type to select Edge trigger Set the signal sources 3 Press Signal source to select CH1 CH2 EXT EXT 5 or AC L...

Страница 53: ...u Option Setup Description Type Pulse Trigger the pulse satisfying the condition when selecting pulse Signal source CH1 CH2 EXT EXT 5 See the signal source shown in 2 7 1 Condition Positive pulse widt...

Страница 54: ...ress TRIG MENU to display TRIGGER menu 2 Press Type to select Pulse Setup of the pulse trigger is similar with that of the edge trigger Set the condition 3 Press the Condition option key to select pos...

Страница 55: ...nchronization All rows Specified row Odd field Even field Select suitable video for synchronization Next Page 1 2 Skip to page 2 of the video trigger function menu Figure 2 31 Page 1 of video trigger...

Страница 56: ...e that of the edge trigger Set the polarity 3 Press Polarity to select or Set the synchronization 4 Press Synchronization to select All row Specified row Odd field or Even field Revolve the UNIVERSAL...

Страница 57: ...trigger menu Figure 2 33 Page 1 of slope trigger menu Figure 2 34 Page 2 of slope trigger menu Table 2 20 Page 2 of the slope trigger function menu Option Setup Description Type Slope Vertical window...

Страница 58: ...indow to select window boundary 10 Revolve the trigger electric level LEVEL knob until the waveform is stably triggered Alternating trigger When alternating trigger is selected the trigger signal come...

Страница 59: ...used to determine which part of signal passes through the trigger circuit It is conductive to stably display the waveform Press TRIG MENU to use trigger coupling Select the Coupling option in the Setu...

Страница 60: ...ay the TRIGGER menu 2 Press Type to select the trigger type 3 Press the Setup option to skip to the trigger setup menu 4 Press the Trigger hold off function 5 Regulate the UNIVERSAL knob to change the...

Страница 61: ...rrs and reducing Fake wave phenomenon For reducing random or unrelated noise in signal display Average time 4 16 32 64 128 256 Select average time Interpolation type Sine Linear Enable sine interpolat...

Страница 62: ...d noise is displayed at the mode Average value The oscilloscope acquires a plurality of waveforms and displays the final waveforms after averaging the waveforms Advantage Random or unrelated noises in...

Страница 63: ...e storage space is full 5 Display the lately acquired waveform Time base Use the s div knob to regulate the time base The time base is a quantization unit of the time namely the time represented by a...

Страница 64: ...hat the measurement precision is improved Sine interpolation is suitable for sine while linear interpolation is suitable for triangular wave square wave and similar As shown in figure 2 43 below after...

Страница 65: ...k line is displayed between the sampling points Display sample points directly Persist OFF 1s 2s 5s Infinite Set the maintained display time length of each displayed sampling point Intensity Set the w...

Страница 66: ...d grid and coordinates Turn off the background grid Turn off the background grid and coordinates Menu display 2s 5s 10s 20s Infinite Set the duration time of the menu display Back Page 2 2 Back to pag...

Страница 67: ...the grid is displayed on the screen Set the menu display Press the Menu display option key to select 2s 5s 10s 20s or Infinite to set the maintained display time length of the menu on the screen 2 9...

Страница 68: ...div knob to regulate the sampling rate so as to observe the waveform better In XY display format the following functions are not available Waveform arithmetical operation Cursor Auto setup the displa...

Страница 69: ...unction key for cursor measurement CURSORS The cursor measurement includes two modes Manual mode and Tracking mode 1 Manual mode Horizontal cursors or vertical cursors appear in pair to measure time o...

Страница 70: ...or measurement mode is used for measuring the coordinate values and increments of one pair of horizontal or vertical cursors Ensure the signal source to be set rightly when using the cursors as shown...

Страница 71: ...asurement mode Table 2 33 Cursor tracking function menu Option Setup Description Cursor mode Tracking Set the tracking cursor measurement Cursor A CH1 CH2 No cursor Set an input channel for cursor A t...

Страница 72: ...nput channel CH1 or CH2 of the tracked signal 5 Select Cur A and rotate the UNIVERSAL knob to horizontally move cursor A 6 Select Cur B and rotate the UNIVERSAL knob to horizontally move cursor B 7 Di...

Страница 73: ...are 32 measurement minor items in total At most five items can be displayed once Press MEASURE to skip to the measurement menu to display the measurement result at first as shown in figure 2 53 and p...

Страница 74: ...VERShoot FOVERShoot RPREShoot FPREShoot Press Measurement type or revolve the UNIVERSAL knob to select voltage measurement parameters types Display the icons and measured values corresponding to the s...

Страница 75: ...ay measurement parameters Types Display the icons and the measured values corresponding to the measurement parameters Back Back to the measurement function menu 1 Table 2 39 All measurement function m...

Страница 76: ...orm in the first period Average value Calculate the arithmetic mean voltage in the whole recording Periodic mean square root Namely an effective value Calculate the actual mean square root value of th...

Страница 77: ...er or later than another waveform and use degree to represent the time quantity wherein 360 degrees form a period FRR Time between the first rise edges of signal source 1 and signal source 2 FRF Time...

Страница 78: ...Specific item measurement 6 When get back to the measurement result region in the homepage the selected parameters and the corresponding values will be displayed in the first option Other option measu...

Страница 79: ...62 values will be simultaneously displayed on the screen As shown in figure 2 56 Figure 2 56 All measurement...

Страница 80: ...is CSV It is only saved in a USB flash disc and opened by computer EXCEL software Factory setups The factory setups are inherent in the oscilloscope when the oscilloscope leaves factory and are recal...

Страница 81: ...4 Press Equipment to select NO 1 save position 5 Press Save to save the current setups in equipment NO 1 Prompt Data is saved successfully after storage is ended Recall the setups from the equipment...

Страница 82: ...y of the USB flash disc and the file name is defaulted as GASxxxx SET such as GAS0001 SET Recall the setups from the USB flash disc 1 Press SAVE RECALL and select the Setup save type as shown in figur...

Страница 83: ...ages are saved in the root directory of the USB flash disc and the file name is defaulted as ASxxxx BMP such as GAS0001 BMP Table 2 41 Image save function menu Option Setup Description Type Image save...

Страница 84: ...saving the CSV file Save Save the interface As shown in figure 2 62 the following steps can be carried out to save the CSV file in the USB flash disc 1 Press SAVE RECALL to skip to the SAVE RECALL me...

Страница 85: ...ory setups When the save type is set as factory setup press the Recall key to restore the factory setups The shortcut key is DEFAULT SETUP CAUTION Restore to factory setting will erase all the previou...

Страница 86: ...p the frequency meter function Language Simplified Chinese English Simplified Chinese English Next Page 1 4 Press the option key to skip to page 2 of the menu Figure 2 63 Page 1 of auxiliary Figure 2...

Страница 87: ...the menu Table 2 45 Page 3 of the auxiliary system function menu Option Setup Description Upgrade firmware Upgrade the software by the USB flash disc The upgrading needs about 5 minutes Pass Fail Pre...

Страница 88: ...display the system state As shown in figure 2 67 the system state includes software and hardware versions local model number and sequence number Figure 2 67 System state Figure 2 68 Language selectio...

Страница 89: ...d run the self correction program according to a screen prompt Figure 2 69 Self correction 2 12 4 Self test Press UTILITY and press Self test in page 2 of the UTILITY menu The self test includes scree...

Страница 90: ...nobs respond correctly The corresponding region of the screen will be in white during operation Tested keys are in green and the knob region is in red such as 16 in the figure counterclockwise rotatio...

Страница 91: ...flash disc in which a firmware program is saved in USB Host interface on the front panel of the oscilloscope 2 Press UTILITY to skip to the UTILITY menu 3 Press the Next option key to skip to page 3 o...

Страница 92: ...op pass fail Display information Open waveform pass fail time display information Close waveform pass fail time display information Next Skip to page 2 to the pass fail menu Figure 2 73 Page 1 of pass...

Страница 93: ...SAL knob to set a vertical tolerance range 0 04div 4 00div Build rules Build a rule template according to the two setups above Save position Inside Outside Select a save position for the rule Next Pag...

Страница 94: ...ontal tolerance range and the vertical tolerance range 9 Press Build rule to build a rule template or press the Recall key in the next page of the menu to recall the saved rules 10 Get back to skip to...

Страница 95: ...t end frame number Table 2 51 Waveform recording function menu Option Setup Description Mode Run Stop Set a recording function menu Set a replay function menu Signal source Record Replay Set a recordi...

Страница 96: ...forms Table 2 52 Page 1 of the waveform replay function menu Option Setup Description Mode Replay Set a replay function menu Operation Start to replay the waveform Stop replaying the waveform Replay m...

Страница 97: ...y 3 Select Replay mode as or 4 Press Time interval to set the time interval of the replayed waveform frame to frame 5 Press Next Page1 2 to skip to page 2 of the replay function menu 6 Press Start fra...

Страница 98: ...l the corresponding help information by pressing the keys when entering the help state The submenus in each main menu have the corresponding help information Attention in order to check the help infor...

Страница 99: ......

Страница 100: ...illoscope for your reference so as to solve your actual test problems Simple measurement Cursor measurement Single signal catching Detailed information of analysis signal Application of X Y function A...

Страница 101: ......

Страница 102: ...ment The oscilloscope can be used for automatically measuring most of the display signals and the frequency and peak to peak values of the signal are measured according to the following steps Measure...

Страница 103: ...to peak value according to the MEASURE TYPE The corresponding icons and measured values will be displayed in the third option Display of the measurement results on the screen is changed with the chang...

Страница 104: ...of the spike pulse 6 Press the CurB option key and revolve the UNIVERSAL knob to place the cursor B at an edge that is clearest to the spike pulse As shown in figure 3 1 time increment Delta T and fr...

Страница 105: ...lse 6 Press the CurB option key and revolve the UNIVERSAL knob to place the cursor B at the lowest point of the spike pulse As shown in figure 3 2 the following measurement results will be displayed o...

Страница 106: ...rigger mode as ONCE and set the coupling as DIRECT CURRENT 3 Regulate the horizontal time base and the vertical gear to a suitable range 4 Revolve LEVEL to regulate a suitable trigger electric level 5...

Страница 107: ...tter 1 Press ACQUIRE to display the ACQUIRE menu 2 Press the ACQUIRE MODE key or revolve the UNIVERSAL knob to select PEAK VALUE DETECTION 3 4 2 Separate the signal from the noise Carry out the follow...

Страница 108: ...make that the signal amplitudes displayed on the two channels are roughly the same 7 Press DISPLAY and select XY in a format option A Lissajous pattern is displayed on the screen to represent input a...

Страница 109: ...The Lissajous pattern of the special signals is shown in figure 3 4 wherein m n is a frequency ratio K represents a phase difference coefficient and theta K x pi 4 Figure 2 49 is a measured Lissajous...

Страница 110: ...vating the difference signal connected to channel 1 and channel 2 1 Press CH1 to set the attenuation of the PROBE option as 10 2 Press CH2 to set the attenuation of the PROBE option as 10 3 Set the sw...

Страница 111: ...s a signal to channel 1 and press CH1 to select COUPLING MODE as ALTERNATING CURRENT 4 Regulate the vertical gear Volt div and the time base gear s div to display the best waveform 5 Plug the USB flas...

Страница 112: ...4 This chapter mainly introduces the problems about system prompt and fault recovery DIGITAL STORAGE OSCILLOSCOPE System prompt and fault recovery...

Страница 113: ......

Страница 114: ...being regulated to the fastest or slowest gear Hold off time reaches the limit The system will prompt this message when the hold off time is regulated to a smallest or largest value by revolving the k...

Страница 115: ...orm data is successfully called out from the oscilloscope or the USB flash disc USB storage device is unconnected This message will be prompted if the USB flash disc is not plugged for storage when th...

Страница 116: ...be measured signal point 5 Reacquire the signal once 3 Check whether the channel attenuation coefficient accords with the probe attenuation ratio actually used if the measured voltage amplitude is 10...

Страница 117: ...is ladder like 1 This appearance is normal 2 The horizontal time base gear may be too low and the display can be improved by increasing the horizontal time base to increase the horizontal resolution...

Страница 118: ...5 This chapter mainly introduces the related information of the service and support of the oscilloscope product DIGITAL STORAGE OSCILLOSCOPE Service and Support...

Страница 119: ......

Страница 120: ...ervices according to detailed provision on the warranty bill Please contact the nearest sales and service agency of Gratten if needing services or requesting a complete copy of the warranty bill Excep...

Страница 121: ......

Страница 122: ...6 This chapter introduces the technical specifications and default settings of the GA1000 series of oscilloscope DIGITAL STORAGE OSCILLOSCOPE Appendix...

Страница 123: ......

Страница 124: ...on can be carried out by the AUXILIARY FUNCTION menu All the specifications are ensured to satisfy the requirement except that marked with TYPICAL sign Technical specifications Input Input coupling AC...

Страница 125: ...s only to GA1202CAL 14ns only to GA1022CAL Vertical coupling AC DC GND Arithmetical operation FFT FFT Window mode Hanning Hamming Blackman Sampling points 1024 Bandwidth limit 20MHz 3dB Horizontal sys...

Страница 126: ...range 100ns 10s Edge trigger Type rise descend rise and descend edge Pulse width trigger Type positive pulse width negative pulse width Pulse width 20ns 10s Pulse width resolution 5ns or 1 take the hi...

Страница 127: ...ontal system and the trigger position Save recall 2 groups of reference waveform 20 groups of common waveform 16 groups of setups save and recall from USB flash drive of the waveform setups CSV and bi...

Страница 128: ...inear interpolation Screen color mode Normal inverse phase Display language Simplified Chinese English Power supply Power voltage 100 240 VAC CAT II auto selection AC power supply frequency range 45Hz...

Страница 129: ...obe 1 Inverse phase OFF Volt div 200mV CH1 CH2 Digital filter OFF Operation CH1 CH2 FFT operation Signal source CH1 Window Hanning Horizontal amplification 1 MATH Vertical scale dBVrms Window Main tim...

Страница 130: ...CQUIRE Interpolation type Sine type vector Go on OFF Waveform brightness 100 Grid brightness 100 Format YT DISPLAY Menu display Infinite Type Save setup Save to Equipment SAVE RECALL Set No 1 Signal s...

Страница 131: ...ng Direct current TRIGGER EDGE Electric level 0 00mV Type Pulse Signal source CH1 Condition Pulse width setup 20 00ns Trigger mode Auto TRIGGER PULSE Coupling Direct current Type Video Signal source C...

Страница 132: ...105 Time setup 20 00ns Trigger mode Auto Type Alternation Signal source CH1 Trigger mode Edge Coupling Direct current TRIGGER ALTERNATION Slope Rise edge...

Страница 133: ...o the following steps 1 Use a soft rag to wipe surface dust outside the instrument and the probe and do not scratch the transparent plastic protective screen when cleaning the liquid crystal displayer...

Страница 134: ......

Результаты поиска

Содержание GA1022CAL

Отзывы:

Похожие инструкции для GA1022CAL

Бренды по названию

Популярные бренды

GRATTEN GA1022CAL, Руководство пользователя

Результаты поиска

Содержание GA1022CAL

Отзывы:

Похожие инструкции для GA1022CAL

Бренды по названию

Популярные бренды