Television signal level meter
Contents
1. LINDY 119 JY 809 909 209 009 5 291 285 Sheet 3 of 6 1 1994 U S Patent U S Patent Mar 1 1994 Sheet 4 of 6 5 291 285 MULTI CHANNEL Fig 4 DISPLAY FLOW SET 700 SET SP CH FROM STEPS 722 732 CALCULATE FETCH LEVEL FOR 5 714 TO STEP 716 U S Patent Mar 1 1994 Sheet 5 of 6 5 291 285 Fig 4B FROM STEP 74 CALCULATE DISPLAYED 716 POSITION DISPLAY LEVEL BARS 718 TO ST 7 AND NUMERICAL VALUES 1 722 720 YES NO CALCULATE LEVEL 724 DIFFERENCE FOR CHI DETERMINE 726 SCALE RANGE CALCULATE 728 MEDIAN LEVEL TO STEP 702 DETERMINE MEDIAN 730 LEVEL VALUE 1 732 DISPLAY SCALE 751 5 291 285 Sheet 6 of 6 Mar 1 1994 U S Patent TIAA 5 291 285 1 TELEVISION SIGNAL LEVEL METER BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to a television TV signal level meter electric field strength meter and more particu larly to a meter of this kind for use in measuring and displaying an electric field strength of a radio wave of each television channel included in the VHF UHF ranges or the like 2 Prior Art Conventionally TV signal level meter or spec trum analyzer is used for measuring an electric field str2. 1 4 in the frequency increasing order 2 One of TMP1 TEP4 to be programmed is selected by the PRG RECALL key 3 A PRG WRITE key is pressed 4 One of the function keys F 1 F 4 respectively for specifying the channel groups 1 4 is pressed to program a group of channels stored in the selected memory TMP into a channel group memory PRG corresponding to the pressed function key By repeating the above steps 1 4 the channel groups PRG1 PRG4 can be pro grammed A second channel setting method a method of changing the setting of any of channel CH 1 CH 8 from one channel to another in a selected channel table 20 25 30 40 45 50 55 60 65 6 uses MEASURE keys and EDIT keys and comprises the following steps as will be understood from the fore going explanation of the keys 1 Selecting a channel group to be changed by the PRG RECALL key 2 Selecting a CH name item by using the ITEM key changing the display from PRGn to TMPn 3 Posi tioning a cursor mark 95 to a location within the region 93 to be changed by the CHANNEL key 4 Changing a channel by the CHARACTER key and 5 Programming the channel change in a selected one of PRG1 PRG4 by pressing the PRG WRITE key and one of the function keys after the change has been com pleted A third method a method of changing the set ting of any of channels CH 1 CH 8 from a channel of a frequency in a selected channel table to one not in the tabl
3. channel display flow executed by a microcomputer constituting a control circuit shown in FIG 2 and FIG 5 is a diagram illustrating another display on a screen shown in FIG 3 5 291 285 3 DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will herein after be described with reference to the accompanying drawings Referring to FIG 1 the basic configuration of a TV signal level meter A according to the invention is shown The TV level meter A comprises a channel CH signal level measuring means 1 connected to input terminal adapted to receive a signal input a dis play means 2 connected to the measuring means 1 a setting means 3 for designating numbers of a multitude of channels to be measured a specifying means 4 for specifying at least one channel whose level value LV measured is to be numerically displayed and an input means 5 for other inputs The level measuring means 1 comprises a channel signal level detector means 10 a multi channel signal level memory 12 and a channel selector means 14 The selector means 14 receives a multitude of designated channel numbers from the setting means 3 and selects one of the designated channels in each measurement cycle in order to sequentially output the selected chan nel numbers to the detector means 10 When an output from the selector means 14 is received the detector means 10 detects and outputs the level of the compo nents in the rec
4. great deal of labor Further since the number of channels which require measurements of signal levels has been increasing with the recently wide spread installation of a city type CATV or the like the labor for measuring and checking signal levels of these channels becomes immense This problem can be alleviated to some extent by the foregoing multi channel type TV signal level meter MODEL NLC W901 This TV level meter however divides a measurable level range into a high region 60 100 and a low region 30 70 dBy and thus has a narrow dynamic range for the simultaneous dis play of measured results Specifically if there is a large difference in level among channels the measured levels of all channels cannot be displayed at one time Thus the TV signal level meter of this model is not suitable for the requirement of the collective residence The model also suffers a drawback that selection and change of channels to be measured take much time If a spectrum analyzer is employed for measuring TV channel signal levels the levels of all signals present within a certain frequency range are displayed Due to this it is inconvenient to find the signals of TV channels to be measured There is another drawback that the device itself is very expensive 10 20 35 40 45 50 55 60 65 2 SUMMARY OF THE INVENTION In view of the above mentioned problems an object of the present invention is to provide a TV signal
5. receiving an output from the IF amplifier detector 608 In order to control the circuits 602 and 604 the tuner 6 is further provided with a pro grammable counter 612 a phase comparator connected to receive an output from the programmable counter 612 and an output from a reference frequency cir cuit 614 for example 50 KHz a charge pump circuit 618 coupled to receive an output from the phase comparator for generating a DC voltage and a local oscillator circuit 620 coupled to receive the DC voltage outputted from the charge pump circuit 618 to apply an oscillation output to a second input of the mixer circuit 604 The DC voltage output generated by the charge pump circuit 618 is used to determine a tuned frequency for the tuner circuit 602 as well as an oscillation fre quency fz for the local oscillator circuit 620 Specifically the programmable counter 612 divides the oscillation frequency fz from the local oscillator circuit 620 by a division ratio supplied from the control circuit 7 and applies the divided output to the phase comparator 616 The phase comparator 616 adjusts the DC voltage generated by the charge pump circuit 618 in such a direction that the difference between the fre quency of the divided output and the reference fre quency fr is decreased thereby controlling the oscilla tion frequency of the local oscillator 620 to generate a local oscillation frequency dictated by the division ra tio For the tuner 6
6. storing the detected signal levels and C display means responsive to said plurality of tele vision channels from said channel setting means and a plurality of said stored levels from said level measuring means including i a plurality of level image display regions for displaying signal levels for the plurality of chan nels in a predetermined scale and ii a plurality of channel number image display regions for displaying channel numbers associ ated with the plurality of channels respectively the positions of said plurality of channel number image display regions being correlated to the positions of said plurality of level image display regions respectively iii display control means comprising a scale forming means responsive to said plural ity of stored signal levels for detecting maxi mum and minimum values thereof and form ing said predetermined scale having a range depending on the maximum and minimum values b level image forming means responsive to said plurality of stored signal levels for forming 5 291 285 9 said level images representing said signal lev els and c number image forming means responsive to said plurality of channels for forming number images representing the numbers of said chan 5 nels 2 A television meter according to claim 1 further comprising means for specifying in said plurality of channels at least one channel the signal level of which is to be displayed by a numeri
7. thus constructed the control circuit 7 supplies the counter 612 with a division ratio associated with the frequency of a TV channel to be tuned as stated above as well as the two programmable attenua tors 600 606 with outputs for specifying respective attenuation ratios for the auto range operation In the embodiment the level comparator circuit 610 deter mines whether or not the IF output from the circuit 608 is within a dynamic range of 9 dB and supplies the control circuit 7 with a signal via a line a indicating within the range above the range or below the range together with a detected level via a line b When a signal other than that indicating within the range is outputted the control circuit 7 changes a set of attenuation ratio specifying signals for the two P ATTs 600 606 as will be later described The control circuit 7 is provided with the keyboard 8 for a variety of inputs The keyboard 8 has keys as seen on a control panel 80 in FIG 3 The display 9 con nected to the control circuit 7 has a LCD liquid crystal display screen 90 also shown in FIG 3 The screen 90 is divided into a scale display region 91 a region 92 within the scale display region 91 for displaying level images such as bars 97 associated with respective TV channels a region 93 below the region 92 for displaying TV channel numbers a region 94 for displaying digital 5 291 285 5 values and other data for specified ch
8. Agent or Firm Fish amp Richardson 57 ABSTRACT A television signal level meter is provided which is capable of simultaneously displaying levels for a mukti tude of television channels in a scale having a variable dynamic range The television meter includes a level image forming means for displaying signal levels of a multitude of channels a scale forming means for form ing a scale suitable for simultaneously displaying the signal levels of the channels and an image forming means for displaying channel numbers associated with the channels 8 Claims 6 Drawing Sheets Sheet 1 of 6 5 291 285 Mar 1 1994 U S Patent SNYIN __ T SNVAW LAN SNVAW ONIASIDAdS H LINN SNVAW SNVAW AV 1510 194185 1356 HO ILTINW lt lt 50153434 13431 H 1 eee 122 1081409 L BAAL i 615 5 291 285 Sheet 2 of 6 1 1994 U S Patent 7 8 6 4 919 YALNNOO 1950 W907 LINDUID LIND YOLVYVdWOO 30193134 Z ANY 11
9. United States Patent Yokoyama et al 54 TELEVISION SIGNAL LEVEL METER Itoshi Yokoyama Tokyo Masaaki Nagai Kakuya Saito both of Kanagawa all of Japan Leader Electronics Yokohama 75 Inventors 73 Assignee Japan 21 Appl No 890 135 22 Filed May 29 1992 30 Foreign Application Priority Data 31 1991 JP 3 129567 151 int HO4N 17 00 52 U S 348 180 348 185 348 739 58 Field of Search 358 139 10 230 HO4N 17 00 56 References Cited U S PATENT DOCUMENTS 4 058 826 11 1977 Schneider 358 139 X 4 685 065 8 1987 Braun etal 5 166 791 11 1992 Crawford 358 139 5 216 492 6 1993 Borrough et al 358 139 X FOREIGN PATENT DOCUMENTS 55 150572 10 1980 Japan US005291285A Patent Number 5 291 285 45 Date of Patent 1 1994 PUBLICATIONS Bandscope Technology of Marantz Wide Band Re ceiver AX700 HAM Journal No 59 1989 pp 62 67 Leader Electronics Corp TV VHF UHF DBS IF Level Meters 1989 catalog Meters WINDOW II and WINDOW LITE catalog 1991 exact date unknown Catalog and User s Manual of Field Strength Mea suring Instrument Model NLC W901 sold by Nippon Antenna Co exact date of publishing unknown Primary Examiner Victor R Kostak Attorney
10. annel 5 and a region for displaying other data items Keys on the keyboard 8 which are involved with the invention will be described A MULTI SINGLE key is used to switch between a multiple bar graph display provided in accordance with the invention and a single bar graph display A PRG RECALL key calls one of four channel groups 1 4 in the multi channel display In FIG 3 the channel group 2 is selected Each group includes eight channels CHANNEL keys are used to specify one among designated channels i e a channel surrounded by a rectangle 95 or Channel 1 in FIG 3 in order to display a digital level value thereof in the multiple bar graph display ITEM keys select an item to be edited among items a received channel PICTURE SOUND the initial character of PICTURE or SOUND is added after a channel number such as 1 P or 4 P when PIC TURE is selected a frequency and so on POSI TION keys are used to select a position to be modified in a numerical value or a character string when an item selected by the ITEM key is a channel name a fre quency and so on represented by such a character string or a numerical value CHARACTER keys are used to modify the contents of the position selected by the POSITION key A SEARCH key is used to automatically measure signal levels of all of previously selected channels in the VHF and UHF bands selec
11. ars displayed on the screen depending on the number of designated chan nels Further while the number of channels whose signal levels are digitally displayed is one in the forego ing embodiment the number of such channels may be increased if necessary Also the digital values of levels of all channels may be displayed on the screen According to the TV signal level meter described above in detail a level of a signal received at each TV channel is individually measured by adjusting the pro grammable attenuators so that the measurement and display can be carried out over a wide dynamic range thereby making it possible to graphically display the levels of signals for a maximum number of TV channels displayable on the screen at the same time It is there fore possible to adjust equipment to be measured such as an antenna while simultaneously confirming the levels of all displayed channels Also the frequency of a chan ne switching operation can be minimized and a manual switching of the attenuators can be made unnecessary thereby facilitating manipulations of the meter during measurement What is claimed is 1 A television signal level meter comprising A channel setting means for setting a plurality of television channels the levels of which are to be measured B level measuring means coupled to receive an input for detecting in said input the levels of signals received in each of said plurality of television chan nels and
12. cal value wherein said display means further comprises at least one numerical level value image display region for displaying a numerical level value image of a chan nel and wherein said display contro means comprises numer ical level value image forming means responsive to a specified channel from said specifying means for forming an image representing the numerical value of said stored signal level of the specified channel 3 A television meter according to any of claims 1 2 wherein said level image forming means forms a num ber of level images corresponding in number to the plurality of channels 4 A television signal level meter according to claim 1 wherein said display means further comprises at least one channel image display region for displaying a chan nel number and frequency of a channel 5 A television signal level meter according to claim 2 further comprising data storage means for storing data representing measured levels in a memory 6 A television signal level meter according to any of claims 1 2 wherein said display means updates the level 10 20 25 30 35 45 50 55 65 10 image display regions in response to changes in the signal levels of the plurality of channels 7 method of measuring and simultaneously indicat ing signal levels for a plurality of television channels comprising the steps of a setting a plurality of television channels the levels of which are to be measu
13. displayed in a time division manner At step 720 since X 1 is smaller than 8 the value X is incremented by one at step 722 and then the above described process is repeated for the channel CH 2 the TV channel 3 in this instance After the measuring display loop has been repeated n times and the n th bar i e bar for TV channel 42 in this instance has been displayed an answer at step 720 is NO Then a scale determination display process is executed at steps 724 731 Explaining next the scale determination display pro cess at the first step 724 the difference between the maximum and minimum values of the detected levels for the channels CH 1 CH n is calculated Then a scale range is determined corresponding to the magnitude of the level difference For example if the difference is less than 12 dB between 10 and 30 dB between 25 and 60 dB and between 50 and 100 dB the range is established with 2 dB DIV 5 dB DIV 10 dB DIV and 20 dB DIV respectively When the range is changed a hysteresis operation is performed At the next step 728 a median level is calculated from the maximum and minimum level values and the value of the median level of the scale is determined at step 730 The data obtained at the above steps 724 730 are displayed in the scale display region 91 at step 731 Finally at step 732 the value X is incremented by one whereby the value X is returned to 1 followed by the flow returning to step 702 T
14. e also uses the groups of MEASURE keys and EDIT keys in a manner similar to the second method and comprises the following steps 1 Selecting chan nel group by the PRG RECALL key 2 Positioning the cursor to a location to be changed by the CHANNEL key 3 Selecting a frequency item by the ITEM key 4 Positioning the cursor to a digit to be changed by the POSITION key 5 Changing the value of the digit by the CHARACTER key 6 Changing a CH name item by the same key manipulations as the steps 3 4 and 5 after the value has been changed and 7 Pressing the PRG WRITE key after the change of the CH name item has been completed Then the change is pro grammed in one of PRG1 PRG4 by the same manipula tion as the second method Referring back to FIG 4A at step 701 relatively fixed images for instance channel numbers 42 P PRG2 the rectangular mark 95 indicating a speci fied channel and other character and numerical images shown in FIG 3 are displayed Then a channel num ber X is set to 1 at step 702 and then level measu ring display processing for the channel 1 by a group of the subsequent steps 704 720 is executed Specifically first at step 704 the frequency of the TV channel 1 i e picture frequency in the instance shown in FIG 3 is searched from a channel frequency table stored in the memory and a division ratio corresponding to the fre quency is outputted to the counter 612 so that the tuner set i
15. e having a range depending on the values b level image forming means responsive to the plurality of stored signal levels for forming the level images repre senting the signal levels and c number image forming means responsive to the plurality of channels for form ing number images representing the numbers for the channels respectively According to the present invention the TV meter may further comprise means for specifying in the plural ity of channels at least one channel the signal level of which is to be displayed by a numerical value The display means may further comprise at least one numeri cal level value image display region for displaying a numerical level value image of a channel Also the display control means may comprise numerical level value image forming means responsive to a specified channel from the specifying means for forming an image representing the numerical value of the stored signal level of the specified channel BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a block diagram illustrating the basic config uration of a TV signal level meter according to the invention FIG 2 is a circuit block diagram illustrating a TV signal level meter which embodies the basic configura tion of the TV signal level meter shown in FIG 1 FIG 3 is a diagram illustrating a front panel of the TV signal level meter shown in FIG 2 including a control panel and a screen FIGS 4A and 4B are flow charts illustrating multi
16. eived input which are in a frequency band associated with a selected channel The level memory 12 then stores the detected level The display means 2 generally consists of a display control means 20 and a display unit 22 The display control means 20 includes four image forming means 200 202 204 and 206 as shown in FIG 1 and a screen image forming means 208 which synthesizes images from the four image forming means to generate a screen image to be displayed Specifically the scale forming means 200 receives a multitude of detected levels stored in the level memory 12 and forms the image of a scale suitable for displaying the multitude of detected levels The multi channel level image forming means 202 re ceives the detected levels stored in the level memory 12 and a multitude of designated channel numbers from the setting means 3 to form images representing the magni tudes of levels for the respective channels Preferably such images may include bars each having a length corresponding to each level The SP CH numerical LV image forming means 204 receives the detected levels stored in the level memory 12 and a specified channel SP CH number from the specifying means 4 and fet ches the detected level for the specified channel to form a numerical image indicative of the level value LV of the detected level The last image forming means 206 is connected to the setting means 3 the specifying means 4 and the input means 5 The means 206
17. ength of a radio wave received in a TV channel The TV signal level meters may be classified into a single channel type and a multi channel type One such single channel type TV meter is a VHF UHF signal level meter LFC 945 manufactured by the present assignee which is adapted to measure and indicate an electronic field strength level of a selected single channel On the other hand one type of multi channel type TV signal level meter is MODEL NLC W901 manufactured by Nippon Antenna Co which simultaneously measures and indicates electric field strength levels of up to a predetermined number of channels for example seven channels A spectrum analyzer though not exclusively employed for the measurement of TV signal levels can also be used for measuring the electric field strength magnitudes of TV channels since it can display the levels of received signals within a certain frequency range Since the above mentioned single channel type TV signal level meter cannot simultaneously display elec tric field strength levels of a plurality of channels it takes a long time to measure the levels of a large number of channels In condominiums and apartment complexes and so on it has been required that outputs from an installed common antenna to respective dwelling units must have signal levels not lower than a predetermined value at any channel In meeting such a requirement adjustment of the antenna by using a single channel type TV meter requires a
18. forms relatively fixed images for example images for channel numbers and a channel specifying mark and other character graphic images which constitute a screen image to gether with the aforementioned images When the foregoing formed images are received the screen image forming means 208 synthesizes them in a certain selected format to form a screen image which is outputted to the display unit 22 Then the display unit 22 displays it on the screen thereof Referring now to FIG 2 a TV signal level meter AA which embodies the basic configuration of FIG 1 will be described hereinafter The TV level meter AA shown in FIG 2 comprises a tuner 6 a control circuit 7 20 25 35 40 45 50 55 65 4 composed of microcomputer with memory board 8 and a display 9 The tuner 6 which is a conven tional one having an auto range function has two pro grammable attenuators P ATTs for the auto range function More specifically the tuner 6 includes a radio frequency RF programmable attenuator P ATT 600 connected to an input terminal an RF tuner circuit 602 receiving an attenuated output from the attenuator 600 a mixer circuit 604 connected to the output of the RF tuner 602 an intermediate frequency IF programma ble attenuator P ATT 606 connected to the output of the mixer 604 an IF amplifier detector 608 receiving an attenuated output from the IF P ATT 606 and a level comparator circuit 610
19. he above described process is repeated for the channels CH 1 CH n until an interrupt occurs due to a change of the channel group PRG power off or the like During the above process is executed when the meter of the present invention is used in adjusting the orientation of an antenna a bar display a digital value display and the scale change for example as shown in FIG 5 each time the antenna is moved Referring to FIG 5 since the level of a signal received at the TV channel 3 is below 20 dB a triangular sign directed downward is added to the bar representing the detected level of the channel 3 Also since the level of a signal 5 20 25 40 45 55 65 8 received at the TV channel 10 is above 120 dB a white triangular sign directed upward is added on the bar for the TV channel 10 Thus even if levels of signals at different TV channels largely fluctuate they are all displayed at the same time While an embodiment of the invention has been de scribed the following changes are possible First the image representing a level of each TV channel may be another graphical representation other than the bar chart as employed in the illustrative embodiment Se condly although the number of bars simultaneously displayed on the screen is determined to be eight this number may be changed if necessary as long as the level image display region on the screen permits It is also possible to change the number of b
20. ks
21. level meter which is capable of measuring and simultaneously indicating the levels of signals for a multitude of TV channels The above object is realized by a TV signal level meter according to the present invention which com prises a channel setting means for setting a plurality of television channels the levels of which are to be mea sured b level measuring means coupled to receive an input for detecting the level of a signal received in each of the plurality of television channels from the input and storing the detected signal levels and c display means responsive to the plurality of television channels from the channel setting means and a plurality of said stored signal levels from the level measuring means including cl a plurality of level image display regions for dis playing signal levels for the respective channels in a given form of image in a predetermined scale and c2 a plurality of channel number image display regions for displaying channel numbers associated with the respec tive channels the positions of the plurality of channel number image display regions being correlated to the plurality of level image display regions respectively According to the present invention the display means may further include display control means which comprises a scale forming means responsive to the plurality of stored signal levels for detecting maximum and minimum values thereof and forming the predeter mined scal
22. n a receiving state for the channel 1 Next at step 706 the programmable attenuators P ATTs 600 606 are adjusted so that the received TV signal level of the channel 1 falls within the predetermined dynamic range of 9 dB mentioned before Specifically the 600 which can be set for example to one of three ratios of 0 30 and 50 dB and the other P ATT 606 which can be set for example to fourteen ratios from 0 to 65 dB with 5 dB steps are adjusted to set a 65 dB ratio i e 30 dB at 600 plus 35 dB at 606 which usually correlates to the middle of a displaying dynamic range of 100 dB Then if the TV signal level is within the predetermined 9 dB dynamic range the 65 dB ratio is determined to constitute a proper range and the flow proceeds to the next step 708 On the contrary if it is not in that predetermined dynamic range the attenua tion rate is decreased by 30 dB when it is below the predetermined dynamic range while increased by 30 dB when above the dynamic range Then it is again deter mined whether or not the TV signal is within the prede termined dynamic range If the TV signal is still out of the range after the adjustment the attenuation ratio is likewise changed with a changing amount of 15 dB Thus the adjustment of the attenuation ratio is contin ued while switching an attenuation changing amount to 5 291 285 7 10 dB 5 dB the TV signal level falls within the predete
23. red b receiving an input signal c detecting in the input signal the level of signals received in each of the plurality of television chan nels d storing the detected signal levels e displaying signal levels for the plurality of chan nels in a plurality of level image display regions and f displaying channel numbers associated with the plurality of channels in a plurality of channel num ber image display regions wherein the step of displaying signal levels further comprises the steps of i scaling the detected signal levels to determine a display scale and ii displaying said detected signal levels accor dance with said display scale 8 The method of claim 7 further comprising the steps of g selecting a specific channel from the plurality of channels and h displaying a channel number and channel fre quency of the specific channel k amp UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT 5 291 285 DATED March 1 1994 INVENTOR S Itoshi Yokoyama et al It is certified that error appears in the above identified patent and that said Letters Patent is hereby corrected as shown below On the title page Item 73 Assignee Leader Electronics Yokohama Japan should read Leader Electronics Signed and Sealed this First Day of November 1994 BRUCE LEHMAN Attesting Officer Commissioner of Patents and Trademar
24. rmined dynamic range In this manner an ap propriate range for each channel is determined by changing the attenuation ratio maximum five times Finally determined attenuation ratios for a group of channels at the last measurement cycle are stored and then called to be used for corresponding channels at the subsequent measurement cycles If the TV signal of a channel does not fall within a proper range set by the called attenuation ratio the ratio is set to the above mentioned 65 dB and then the attenuation ratio is changed as described above When the TV signal level of the channel 1 enters proper range the level from the level comparator 610 is read at the next step 708 and stored at step 710 Then at step 712 the stored level is combined with the total attenuation ratio set at step 706 to calculate a detected level of the TV signal of the channel 1 Since the chan nel 1 is a specified channel the detected level of the channel 1 is fetched at step 714 its digital value is 76 1 dByV the instance shown in FIG 3 Next at step 716 a position on the screen for displaying a bar 96 FIG 3 representing the detected level of the channel 1 is calculated from value computed at step 712 and The bar 96 and a corresponding digital value are displayed at step 718 It should be noted that the level bars including 96 97 98 the digital level value of a specified channel and the scale described hereinafter are
25. t 32 channels which exhibit larger signal levels store the signal levels of the selected channels and display the signal levels of all eight channels at a time in the multi ple bar graph mode An AUTO SCALE key alter nately switches between auto and manual switching for level measurement range A DATA STORE key is used to store data representing measured levels in the memory which is capable of storing up to four sets of measured level data for groups of eight channels A FUNCTION CALL key enables keys denoted 1 F 2 F 3 4 and F 5 including the same keys as the foregoing ones to select one from a variety of other functions Referring now to FIGS 4A and 4B a multi channel display flow executed by the control circuit 7 will be described hereinafter In the multi channel display flow shown in FIG 4A it is assumed that channels CH 1 CH n in this instance channels CH 1 8 correspond to TV channels 1 3 4 6 8 10 12 and 42 respectively group PRG2 and a numerical level value displayed channel channel CH 1 in this instance have been set at the first step 700 Here the method of setting channels CH 1 CH 8 will be briefly explained As a first method channels CH 1 8 are set by the foregoing CH SEARCH key in the following manner 1 Every eight of the 32 channels selected by the key manipulation as described above are stored in memories TMPs TEMPORARY
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