Full opinion text
ROBSON, District Judge. FINDINGS OF FACT I. NATURE OF ACTION AND PLEADINGS 1. This is an action under the patent laws of the United States for infringement of the following three patents: a. Patent No. 1,941,066 (hereinafter called the ’066 patent), issued December 26,1933, to Edwin EL Armstrong on an application filed July 30, 1930. Plaintiff relies on claims 8, 9 and 10. b. Patent No. 1,941,069 (hereinafter called the ’069 patent), issued December 26, 1933, to Edwin H. Armstrong on an application filed January 24, 1933. Plaintiff relies on claims 1 and 2. c. Reissue Patent No. 21,660 (hereinafter called the Reissue patent) issued December 17, 1940, to Edwin H. Armstrong on a reissue application filed October 21, 1940. This is a reissue of original Patent No. 2,215,284, issued September 17, 1940, on an application filed February 19, 1940. Plaintiff relies on claims 1, 2, 4 and 6. Patents ’066 and ’069 had expired on December 26, 1950, and the Reissue expired September 17, 1957. 2. The complaint, filed on January 6, 1954, charges Motorola, Inc., with infringing, during the six years preceding the filing of the complaint and until their expiration, Letters Patent Nos. 1,-941,066, 1,941,069 and Reissue 21,660. The complaint also charges infringement of United States Letters Patent Nos. 1,-941.068 and 2,098,698. Plaintiff dropped her charge of infringement of such patents, and at the trial the Court on January 3, 1962, granted a motion to dismiss with respect to U. S. patents Nos. 1.941.068 and 2,098,698 (Trial Record 5101-2). 3. The answer, filed on January 6, 1956, raises the defenses of noninfringement, license, invalidity of the patents in suit and laches. II. THE PARTIES 4. Plaintiff is Esther Marion Armstrong, the widow and Executrix of the Last Will of Edwin Howard Armstrong, the original plaintiff in this action. Major Armstrong died on February 1, 1954. He was the sole owner of the three patents in suit. After a ruling on a contested motion, Esther Marion Armstrong was substituted as plaintiff by orders of this Court dated March 28, 1955, and April 12, 1955. 5. Defendant is Motorola, Inc. (pri- or to 1947 being known as Galvin Manufacturing Corporation and herein referred to as Motorola), an Illinois corporation organized in 1928, having a place of business in the City of Chicago, within the Northern District of Illinois, Eastern Division. III. RADIO APPARATUS INVOLVED IN THIS ACTION 6. Plaintiff charges infringement of the three patents in suit by virtue of the manufacture and sale by Motorola of the following radio apparatus: a. The frequency modulation broadcast receiver included in chassis HS87 for Motorola AM-FM radios, referred to herein as “HS87” (Plaintiff’s Exhibit 25); b. The frequency modulation broadcast receiver included in chassis HS89 for Motorola AM-FM radios, referred to herein as “HS89”' (Plaintiff’s Exhibit 26); c. The frequency modulation sound receiver included in chassis TS-5 or TS-7 for Motorola home television broadcast receiving sets, referred to herein as “TS-5” (Plaintiff’s Exhibit 27); d. The frequency modulation sound receiver included in chassis TS-4D for Motorola home television broadcast receiving sets, referred to herein as “TS-4” (Plaintiff’s Exhibits 28, 29): e. The two-way FM communication equipment operating on frequencies between 25 and 50 megacycles, referred to herein as “25-50 Me” (Plaintiff’s Exhibit 30); f. The two-way FM communication equipment operating on frequencies between 152 and 162 megacycles, referred to herein as “152-162 Me” (Plaintiff’s Exhibit 31) ; and g. All other FM broadcast receivers, television sound receivers and FM communication equipment which are materially similar to the foregoing apparatus in structural and operating characteristics and which were manufactured and sold by Motorola within six years of the filing of the complaint herein and before the expiration of the patents in suit. Major Armstrong gave Motorola notice of infringement by letters dated December 15 and 20, 1948 (Plaintiff’s Exhibits 12 and 13; Trial Record 3731-2). IV. PROCEEDINGS BEFORE TRIAL 7. Motorola’s motion for a separate trial on its defense of laches and estoppel was denied by order of this Court on December 14, 1959. 8. ; On January 20, 1961, Dean George 'R.-Town was appointed, by order of this Court and with the consent of the parties, to act as an impartial technical expert for the Court. 9. On April 19, 1961, Motorola filed a motion for summary judgment as to plaintiff’s charges of infringement under patents numbers 1,941,069 and the Reissue patent with respect to FM broadcast receivers and television sound receivers and with respect to the validity of claims 4 and 6 of the Reissue patent. Defendant’s motion for summary judgment was denied by this Court in a memorandum opinion dated June 14, 1961. 10. The action came on for trial before Judge Robson on October 30, 1961, and proceeded from day to day until January 5, 1962. During the trial, seven witnesses were called by plaintiff and eight witnesses were called by defendant. Dean George R. Town was called as a witness by the Court and testified in response to questions by the Court and each of the parties. V. ARMSTRONG PATENT NO. 1,941,069 A. The Discovery 11. Major Armstrong informed the radio engineering profession how the audible effects of noise in radio telephony could be reduced by employing a particular kind of frequency modulation and by operating over a bandwidth substantially wider than was theretofore employed in conventional radio signaling (Trial Record 5152-3; 4366). 12. The teaching of Major Armstrong concerning the wide band FM system was contrary to earlier practice and theory, both as to the results obtained and the method whereby such results were obtained (Trial Record 5153, 2691-2; 4101-4; 810-3). 13. The emergence of the wide band FM system was a development which profoundly influenced the radio art (Trial Record 5153, 4427-9; Court Exhibit 1, pp. 40-45 ). 14. The basic characteristics of the wide band FM system are as follows: a. That the swing of the carrier at the transmitter in accordance with the intelligence to be transmitted shall be substantially greater than the range of audible frequencies for the system; b. That the receiver in all of its radio and intermediate frequency stages shall have a pass band sufficiently wide to receive and amplify the wide swinging carrier throughout the full extent of its excursions; c. That the receiver shall be substantially nonresponsive to amplitude variations caused by the disturbances ; and d. That the receiver shall have a selective system which provides for full audible response to the wide swings of the carrier and provides for substantially less audible response to the narrow swings of the carrier at audible rates which are caused by the disturbances. (Plaintiff’s Exhibits 24, 40, 90, 91, 92; Trial Record 5153, 5422; Court Exhibit 1, pp. 40-45). 15. Major Armstrong’s teaching was based in part on his observation that in a frequency modulation receiver, tube noise and other spectrum-like disturbances may manifest themselves as frequency variations in the received signaling wave and that such frequency variations will, in the presence of a strong carrier, be limited in extent in so far as they are capable of producing an audible response from the receiver (Trial Record 143, 200-6, 3278, 4093-4101; ’069 patent, p. 3, lines 116-121; Plaintiff’s Exhibit 24, pp. 705-709; Plaintiff’s Exhibit 40, pp. 4-5). 16. Major Armstrong taught that tube noise and spectrum-like disturbances would also manifest themselves as amplitude variations on the carrier, and that the effect of such amplitude variations, when of less strength than the carrier, could be effectively suppressed or eliminated in the receiver (Plaintiff’s Exhibit 24, pp. 703-6; ’069 patent, p. 3, lines 38-46). 17. In radio communication by amplitude modulation, the bandwidth for the transmitter and the receiver depends upon the range of audible frequencies to be reproduced in the receiver. In the normal practice with amplitude modulation, the bandwidth is substantially equal to twice the range of audible frequencies to be reproduced (Trial Record 4105-8, 5158; Plaintiff’s Exhibit 32E, p. 69). 18. In the wide band FM system, the bandwidth for the transmitter and the receiver is not twice the range of audible frequencies to be reproduced. The bandwidth depends on the range of excursion of the wide swinging carrier and is several times the bandwidth required for amplitude modulation (Plaintiff’s Exhibit 24, pp. 709-16; Trial Record 4090-7, 5422; Plaintiff’s Exhibit 127). 19. The receiver in the wide band FM system is made substantially nonresponsive to amplitude variations of the received wave caused by tube noise and other disturbances when such noise and disturbances occur in the receiver at levels of strength which are lower than the received carrier. Such nonresponsiveness is brought about by limiting and balancing (Trial Record 1278-85; Plaintiff’s Exhibit 24, pp. 702-6; ’069 patent). 20. Armstrong published a formula for the improvement with respect to the suppression of noise which could be obtained with the wide band FM system as compared with amplitude modulation when operating at the same carrier frequency and power and transmitting and receiving the same signal. His formula is that the improvement in terms of voltage ratio for noise in the two systems is equal to about 1.7 times the deviation of the wide band carrier (y2 peak-to-peak swing) divided by the audible frequency range for the two systems. The formula provides a correct measure of the improvement in suppression of noise that may be obtained in the wide band FM system as compared with amplitude modulation (Plaintiff’s Exhibit 24, p. 710; Trial Record 1643-5, 3011-2, 3420-6, 3444-6). 21. The wide band FM system is effective, as compared with amplitude modulation, in reducing the effects of disturbances caused by tube noise and other random noise caused by fluctuation in the motion of electrons in the receiver, ignition noise and other interference caused by electrical equipment not intended for radio purposes, static caused by thunderstorms and other natural electrical phenomena, multipath interference and interference from other radio stations (Trial Record 796-812, 3134). 22. The wide band FM system was also effective in the late ’30s and thereafter to extend the practical range of communication in radio signaling as compared with amplitude modulation operating at the same carrier frequencies (Trial Record 796-812, 2281-4, 3116-23, 5154-5). B. Disclosure of Armstrong Patent No. 1,941,069 23. The ’069 patent disclosed the essential structural and operating characteristics of the wide band FM system (Trial Record 5154). 24. The ’069 patent described in qualitative terms the art of suppressing noise by a particular system of frequency modulation as follows: “I have discovered that by imparting a greater swing to the frequency of the transmitted wave than can exist in the disturbances due to tube irregularities and providing means for selecting these large swings of frequency which are at the same time substantially not responsive to the lesser swings due to the tube disturbances or to the variations in amplitude due to these disturbances, that a very great improvement in transmission can be produced.” (’069 patent, p. 1, lines 71-80) 25. The '069 patent disclosed that the frequency variations caused by noise and spectrum-like disturbances in the presence of a strong carrier and which are capable of creating an audible response from the receiver will be limited in extent and not substantially greater than the audible frequency range of the receiver (Trial Record 143-4; ’069 patent, p. 3, lines 116-20). 26. The ’069 patent disclosed that the swing of the carrier was to be many times greater than the audible frequency range (’069 patent, p. 2, lines 66-72). 27. In the particular example described in the ’069 patent, the swing was equal to ten times the audible frequency range for that embodiment. The swing was 100,000 cycles and the audible frequency range was 10,000 cycles. The ’069 patent was not limited in its teaching to any particular audible frequency range or to any particular optimum swing for various distances of transmission and for different classes of services (Trial Record 4090-7, 5323-6, 5331). 28. The ’069 patent disclosed that for use in the system described therein, the transmitter described in the ’068 patent is to be modified by adding multipliers and increasing the bandwidth so as to provide for a swing many times greater than the audible frequency range (’069 patent, p. 2, lines 66-72, p. 3, line 139, to p. 4, line 10; Trial Record 171-4). 29. The '069 patent disclosed that a receiver for use in the wide band FM system might employ the same general method for translating variations in frequency of radio currents into currents of audible frequency that was disclosed in the 1,941,447 (hereinafter referred to as ’447) patent. That general method comprised (a) the use of networks for providing a linear or proportional response to variations in frequency over the range for which the receiver was designed, as illustrated in the ’447 patent (Fig. 2) by the networks 40, 41 and 39, 40, 41, and in the ’069 patent (Fig. 2) by the networks 52, 54 and 53, 55 and (b) the method of balancing the currents of audible frequency from each of the detectors illustrated in Fig. 2 of the ’447 patent and Fig. 2 of the ’069 patent (’069 patent, p. 2, lines 31-45, 73-84; ’447 patent, p. 2, lines 64-79). 30. The ’069 patent disclosed that the receiver for use in the wide band FM system was to be constructed so that all of its circuits, including the radio frequency stages, the intermediate stages, the limiter and the discriminator would have a bandwidth several times greater than the bandwidth required in an amplitued modulation receiver (’069 patent, p. 2, line 73, to p. 3, line 90; p. 4, lines 11-83; Trial Record 147-50). 31. The ’069 patent disclosed that the receiver for the wide band FM system might be made adequately nonresponsive to amplitude variations caused by the disturbances by means of limiting in the receiver (’069 patent, p. 3, lines 38-46, p. 4, lines 25-46) and by the use of balanced detectors (’069 patent, p. 3, lines 69-90). 32. The ’069 patent disclosed that in a wide band receiver as therein described the balancing action at the detectors would be particularly effective (more effective than in a narrow band receiver) in making the receiver substantially non-responsive to amplitude variations caused by the disturbances (Trial Record 190-3; ’069 patent, p. 3, lines 69-127). 33. The ’069 patent did not state that there was any criticality in the sequence of steps whereby the receiver would be made substantially nonresponsive to amplitude variations caused by the disturbances and to frequency variations caused by the disturbances (Trial Record 636). C. The Impact — Prior Art Practice and Theory 34. In the 1920s and early ’30s, the «circuits for transmitters and receivers •employed in radio signaling were narrow in bandwidth, the bandwidth being about twice the range of modulating frequencies to be transmitted and received. It was accepted engineering practice that to reduce the effects of noise, the bandwidth of the circuits should be decreased ■and maintained at the minimum required for adequate reception of the intelligence. 'This was so widely known and generally .accepted among those conversant in the •art that in all of the literature of the period, including patents, it must be .taken as understood or implied that the «circuits were narrow unless the contrary were expressly stated. Specifically, any suggestion that noise might be reduced by means of a system employing wide band circuits would have been considered . so exceedingly radical that the suggestion could not have been conveyed except by ■ express reference to the wide band feature — as it was for the first time in the ’069 patent and as it was not in any •of the prior references cited by defendant in this case (Trial Record 4107-8, '5158-60). 35. During the 1920s, frequency modulation was proposed as a method for narrowing the bandwidth for radio communication as compared with the bandwidth requirements for amplitude modulation. The scheme was wrong as a matter of theory and unsuccessful in practice (Trial Record 812-3, 3083-93, 4104-5, 4362-6; Plaintiff’s Exhibit 33, Defendant’s Exhibit 7 Carson article •“‘Notes on Theory of Modulation,” 1922). 36. During the late 1920s and early : 1930s, it was widely accepted in the radio engineering profession that frequency modulation would inherently distort the signal and that there were no compensating advantages as compared with amplitude modulation (Trial Record 813, 3074-3104, 4104-5). Some inventors, however, believed in frequency modulation, procuring patents in respect thereto, some of which involved narrow bands. . 37. In the early proposals for the use of frequency modulation before 1933, it was contemplated that the bandwidth for the receiver would be the same or less than the bandwidth for an amplitude modulation receiver designed to reproduce the same range of modulating frequencies. Such a frequency modulation system would have no significant advantage over amplitude modulation in the reduction of noise (Plaintiff’s Exhibit 90, p. 7, col. 3, last paragraph; Trial Record 3128-33, 3141-3, 3444-6, 5417-8). 38. In 1935, Armstrong presented a paper on the wide band FM system to the Institute of Radio Engineers (IRE) entitled “A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation,” and he gave a demonstration at that meeting. The IRE paper is a classic paper in the radio art (Plaintiff’s Exhibit 24; Trial Record 4371, 4399). 39. In his IRE paper, Major Armstrong reported on field tests of the wide band FM system and thereby demonstrated that the results which he claimed for the system were not simply a matter of theory and laboratory experiment which, as in the case of many other so-called static eliminators, would not materialize when subjected to actual operating conditions (Plaintiff’s Exhibit 24; Trial Record 691, 3124-5, 4371). 40. In the IRE paper, Major Armstrong pointed out and explained the striking phenomenon that in the wide band FM system which he had built and tested there was an immunity from interference created by other stations that was of the same order of magnitude as the immunity of the system to tube noise (Plaintiff’s Exhibit 24, pp. 727-9; Trial Record 3135). 41. In July, 1937, John R. Carson, associated with the Bell Laboratories and a leading authority on modulation theory, published, with Thornton Fry as coauthor, an article which confirmed as a matter of theory that wide band frequency modulation would provide the suppression of noise which Armstrong had demonstrated and reported on in practice in his IRE paper (Trial Record 1132, 3077-85, 3125; Plaintiff’s Exhibit 109, cited by Everitt as leading reference in Plaintiff’s Exhibit 90; Trial Record 4104). 42. Hans Roder, well known for his writings on frequency modulation, published articles in 1937 in which he revised his theory of frequency modulation and confirmed as a matter of theory that noise could be suppressed in radio communication by using wide band frequency modulation as described by Major Armstrong in his IRE paper (Plaintiff’s Exhibit 110, p. 13; Trial Record 3148-50; see references to Roder in Plaintiff’s Exhibits 90, 92 and 24). 43. In June, 1940, William L. Everitt, defendant’s principal expert at the trial, presented a paper before the American Institute of Electrical Engineers, entitled “Frequency Modulation” (Plaintiff’s Exhibit 90). The paper gives an excellent account and explanation in scientific terms of how noise and interference can be reduced by frequency modulation and is a leading reference for students of the subject (Trial Record 5196-7). In the paper, Everitt stated that Armstrong had demonstrated that frequency modulation provides an important method of distinguishing between desired and undesired signals and that the earlier proposals for the use of frequency modulation were such that there would be no advantages over amplitude modulation (Court Exhibit 1, pp. 41-2; Trial Record 3124-5, 3141-2; Plaintiff’s Exhibit 90, p. 1, col. 3, p. 2, col. 1, p. 7, col. 3, p. 8, col. 1). 44. At the trial, Daniel E. Noble, an Executive Vice President of Motorola and well qualified to testify concerning the development of frequency modulation, characterized Major Armstrong’s work as being “creative” (Trial Record 4397-8, 4413-5, 4427-9). D. The Claims in Patent No. 1,941,069 45. The term “variation in frequency” appearing in the two claims of the ’069 patent means, in the light of the specification, the peak-to-peak swing in frequency of the wave as distinguished from its deviation from center frequency (’069 patent, p. 3, lines 91-108 and claims 1 and 2). 46. The requirement in the two claims of the ’069 patent that such variation in frequency shall be substantially greater in extent than the range of good audibility means that such variation in frequency shall be several times greater than the audible frequency range to be transmitted and reproduced at the receiver (’069 patent, p. 2, lines 66-73; Trial Record 138-143). 47. The term “range of good audibility” appearing in the claims of the ’069 patent means the range of frequencies from the output of the receiver which are of a “really audible character” (’069 patent, p. 3, lines 56-68; Trial Record 144-6). 48. The requirement in the claims of the ’069 patent that amplitude variations shall be substantially eliminated or limited means that the receiver shall be substantially nonresponsive to amplitude variations caused by the disturbances. (The words “elimination,” “removal” or “substantial elimination” are equivalent in radio usage and in the ’069 patent to substantial or significant nonresponsiveness. Trial Record 643-50, 1278-85, 1523, 2598-2600, 2919, 2937-8, 5406-7; Plaintiff’s Exhibit 90, p. 10, col. 1, lines 13-17.) 49. The requirement in the claims of the ’069 patent that the “selective system” (claim 1) or “detector system” (claim 2) shall be fully responsive to the ■wide variations in frequency of the signal but substantially not responsive to the lesser variations in frequency of the spectrum-like disturbances means that the translating system (discriminator) ■shall provide a nearly linear or proportional response to all variations in frequency within the range of the peak-to-peak swing of the carrier and that the bandwidth of all circuits in the receiver up to the audio detectors shall be suffi■ciently wide to pass all frequencies within the range of the wide swing of the-•carrier. The requirement reflects the teaching of the patent that the variations in frequency caused by the disturbances are small as compared with the wide variations of the signal and will provide a comparably small response from a wide band discriminator or translating system (Trial Record 5339-40; ’069 patent, Fig. 5 and p. 3, lines 91-127; contrast Trial Record 3043-5). 50. Each of the two claims of the ’069 patent particularly points out and distinctly claims the system or art of eliminating or suppressing noise in radio by the wide band FM system. E. The Prior References Cited by Motorola Purington Patent No. 1,599,586 Filed April 27, 1922 — Issued Sept. 14, 1926 51. The Purington patent related to a system for use in telegraphy or telephony in which a wobble was produced at the transmitter and the input circuit of the receiver was tuned on one portion of the wobble to provide a response to the wobble in frequency (Defendant’s Exhibit 7 Purington patent, p. 2, lines 59-68; Trial Record 3382-6, 4117-20). 52. The apparatus specifically described in the Purington patent was intended for operation on frequencies near the standard broadcast band (Trial Record 5177). 53. The Purington patent did not state or suggest anything concerning noise in radio signaling or concerning the reduction of noise in radio signaling (Trial Record 4120, 5177). . . v, 54. The Purington patent expressly stated that the receiver for telegraphy was to be adjusted for sharp resonance (Trial Record 4117, 5168-9). It expressly stated that the bandwidth of the receiver was to be less wide than the bandwidth to be provided for the transmitter circuits (Patent p. 2, lines 30-34 and 59-64; p. 3, lines 98-125). The Purington patent did not expressly state that the sharply resonant receiver which was particularly described was to be redesigned and increased in bandwidth if the receiver were used for telephony (Trial Record 4121, 5168-9). 55. The Purington patent showed a lack of basic understanding of frequency modulation and disclosed no advantage or utility for any particular range of wobble in frequency (Trial Record 4117-20, 5168-76). The patent purported to give numerical examples for range of wobble and receiver bandwidth, but there were numerical errors and discrepancies in connection with each of such examples (Trial Record 2943-4, 5169-76). The numerical example given by Purington for the bandwidth of a discriminator in a receiver was 16 kilocycles. (See reference to “right hand curve” in text by Pierce (Patent p. 4, col. 2, lines 73-83) and compare with right hand curve in Defendant’s Exhibit 99, Trial Record 5175; contrast Trial Record 5011-6). 56. The Purington patent showed no kind of limiter circuit (Trial Record 4120, 5179-80). A limiter could not be used in the kind of receiver described in the Purington patent (Trial Record 5180). 57. The Purington patent did not disclose the wide band FM system and did not anticipate the ’069 patent. Armstrong Patent No. 1,941,447 Filed May 18, 1927 — Issued Dec. 26, 1933 58. The ’447 patent disclosed circuits for a frequency modulation transmitter and frequency modulation receiver and stated that such apparatus would reduce the effects of fading and static in radio telephone transmission (Trial Record 2591-5). 59. The ’447 patent taught that in order to reduce noise, the bandwidth should be as narrow as possible (Trial Record 2610-2). 60. The patent disclosed a narrow band system, and taught that the bandwidth of the transmitter and receiver (for an audio range of about 2500 cycles) should be 5000 cycles or less (Trial Record 2584, 2598-2600, 5157-8). There is definite internal evidence the ’447 patent is a narrow band system. 61. The ’447 patent did not disclose that tube noise and other spectrum-like disturbances might cause a variation in frequency and that in the presence of a strong carrier such variations in frequency would be limited in extent in so far as they were capable of producing an audible response (’447 patent). 62. The limiter in the ’447 patent was for the express purpose of removing amplitude variations caused by fading (Trial Record 2591-5, 2583-91). Also it showed that amplitude variations due to static will also be greatly reduced (’447 patent, p. 2, lines 84-88). 63. The limiter disclosed in the ’447 patent was not as effective for removing amplitude variations caused by disturbances as was the limiter later disclosed in the ’069 patent (Trial Record 2586-93, 2608-9). 64. A receiver built in accordance with the specific instruction of the ’447 patent would not be capable of operation or of adjustment to operate over a bandwidth several times the bandwidth required for amplitude modulation (Trial Record 2594, 5312-4). 65. The ’447 patent did not disclose the wide band FM system and did not anticipate the ’069 patent. Dome Patent No. 1,917,102 Filed July 22, 1929 — Issued July 4, 1933 66. The Dome patent related to a frequency modulation transmitter and disclosed nothing concerning the operating characteristics or structure of a frequency modulation receiver (Defendant’s Exhibit 7, Dome patent; Trial Record 3249, 4116). 67. The Dome patent contained no' express reference to the problem of noise in radio signaling and contained no-teaching concerning how noise might be reduced (Trial Record 4116, 5162-3). 68. The Dome patent did not state or suggest that the variation in frequency at the transmitter should be greater than the range of modulating frequencies or the audible frequency range to be transmitted and received (Trial Record 3247— 9, 4116-7, 5163, 5166-7). 69. The Dome patent did not expressly distinguish between what is now called the swing (peak-to-peak variation in frequency) and the deviation, defined as the variation from center frequency of the carrier (Trial Record 3240, 5163). 70. The example of a change of frequency of 20,000 cycles referred to on page 3 of the Dome patent can be interpreted as an example of a total variation in frequency (peak-to-peak swing of the carrier) that might be obtained by multiplication at the transmitter (Trial Record 3240-5, 4110-5, 5164-5). But it is probable he intended, in the light of the other sections of the patent, the 20,000 cycles to refer to the “deviation” which is one-half the total variation or “peak-to-peak swing.” 71. The Dome patent expressly mentioned, inter alia, a modulating frequency of 20,000 cycles (Trial Record 3243-4). 72. The Dome patent disclosed erroneously that the effect of the side bands caused by amplitude modulation in the transmitter might be removed by the action of the multipliers in multiplying the frequencies of the side bands beyond the range of audibility (Trial Record 4109, 4116, 4840-1, 5165-6). 73. The Dome patent did not teach that the bandwidth of a frequency modulation transmitter or receiver should be greater than the bandwidth in amplitude modulation for transmitting and receiving a comparable audible frequency range (Trial Record 4116-7, 5166-7). 74. The Dome patent did not disclose the wide band FM system and did not anticipate the ’069 patent. Van der Pol Article 75. The article written by Balth. Van der Pol, a Dutch mathematical physicist, and published by the Institute of Radio Engineers in 1930, was a mathematical treatment and analysis of the side frequencies which may occur when a carrier frequency is varied in frequency at any particular rate. The Van der Pol article was expressly directed to the problem of the disturbances and interference which such variations in frequency might cause in radio signaling and the width of band which would be occupied by such variations in frequency. The article pointed out that such disturbances may occur unintentionally when signaling by amplitude modulation (Defendant’s Exhibit 7, Van der Pol article). 76. The Van der Pol article did not disclose the form of a frequency modulated wave or the side frequencies which would be present when the carrier was modulated by more than one frequency at a time (Trial Record 2027-8). 77. The Van der Pol article disclosed nothing concerning the reception of frequency modulated waves and the reproduction of signals therefrom (Van der Pol article). 78. The Van der Pol article suggested nothing concerning the peak-to-peak swing or the deviation which ought to be employed in a practical frequency modulation system (Van der Pol article). Wright Patent No. 1,964,375 Filed Feb. 20, 1926 — Issued June 26, 1934 79. The Wright patent disclosed a proposal for transmitting and receiving pictures by frequency modulation (Defendant’s Exhibit 7, Wright patent, p. 1, cols. 1 and 2). 80. The Wright patent was directed to the problem of removing the effects of fading and static (Patent p. 1, lines 27-51; Trial Record 4128, 4543-6). 81. The Wright patent referred to employing a limiter in a receiver and disclosed no structural characteristics for such limiter (Patent p. 2, lines 35-73; Trial Record 4129). 82. The Wright patent disclosed that the function and purpose of the limiter in the receiver was to remove amplitude variations caused by fading and also by static and strays. (Patent p. 2, lines 35-73, p. 1, lines 80-87). 83. The Wright patent stated nothing concerning the swing or extent of frequency variation which was to be employed and contemplated narrow band operation (Trial Record 4127, 5042). 84. The Wright patent stated nothing concerning tube noise or other spectrum-like disturbances which might be generated in the receiver. 85. The Wright patent did not disclose the wide band FM system and did not anticipate the ’069 patent. Demarest Patent No. 2,047,312 Filed Dee. 1, 1926 — Issued July 14, 1936 86. The Demarest patent proposed the use of frequency modulation to reduce the effects of fading in radio signaling (Defendant’s Exhibit 7, Demarest patent, p. 1, col. 1, lines 9-36, col. 2, lines 19-66). 87. Demarest built no apparatus in connection with the disclosure of the Demarest patent (Trial Record 4124-5). 88. The Demarest patent disclosed that conventional circuits were to be employed for the radio frequency and intermediate frequency stages of the receiver (Patent, p. 2, col. 1, lines 29-36). 89. In 1926, a characteristic of conventional radio frequency and intermediate frequency stages was that the circuits would be as sharply selective as possible and that the bandwidth of the receiver would be confined to the band required to pass the audible frequency range to be transmitted and received (Trial Record 4125, 5158). In the absence of any suggestion to the contrary, and in view of the state of the art at the time, it is evident that the receiver circuits in the Demarest patent were intended to be narrow. 90. The Demarest patent suggested a power limiter such as was shown in a textbook by Van der Bijl published in 1920 and the textbook had nothing to do with frequency modulation (Trial Record 3275). Summary of Prior References 91. The prior references as to which evidence was received at the trial did not disclose, singly or in combination, that noise could be suppressed or reduced by employing frequency modulation with a bandwidth at the transmitter and receiver substantially greater than the bandwidth required in amplitude modulation. 92. None of such prior references disclosed that the bandwidth for a frequency modulation receiver should be greater than the bandwidth for an amplitude modulation receiver operating on the same frequencies. 93. In none of such prior references was there any teaching that the peak-to-peak swing or total variation in frequency should be greater than the range of audible frequencies or modulating frequencies to be reproduced at the receiver. 94. None of the prior references disclosed that noise and disturbances in the receiver could manifest themselves as a frequency variation in the received signaling wave and that such frequency variations would in the presence of a strong carrier be limited in extent in so far as they were capable of producing an audible response. 95. The prior references, singly or in combination, did not disclose the wide band FM system. VI. ARMSTRONG PATENT NO. 1,941,066 A. The Disclosure 96. The ’066 patent disclosed a principle of operation for receiving and detecting a frequency modulated wave which involved heterodyning or combining the received frequency modulated wave with itself to reproduce the signal,, hereinafter referred to as the synchronous heterodyne principle for frequency modulation reception (Trial Record 246— 7, 4131-4, 5180-5, 5422A). 97. The synchronous heterodyne principle for frequency modulation reception consists in combining or beating at the detector the received radio wave (which is dynamically varying in frequency in accordance with the signal) with the same received wave which has been modified by being passed through reactance elements in the receiver. The combination of the waves in a nonlinear device, such as the detector, results in a heterodyning action and in reproduction of the signal (Trial Record 4131-4, 4162, 5180-5). 98. A frequency modulation receiver operating in accordance with the aforementioned principle is characterized by having at least two paths in the receiver for the received modulated wave, such paths having different characteristics of transmission for the received wave. The waves from each of the two paths are then combined at the detector (or each of the detectors if there are two detectors in the receiver) to reproduce the signal (Trial Record 5180-5, Plaintiff’s Exhibit 22, p. 1). 99. The ’066 patent describes a particular example of a frequency modulation receiver for telephony operating in accordance with the synchronous hetero-dyne principle of operation. In such a receiver, there are two paths for the received wave to each detector. One of those paths is through the amplifier stages (61 or 62 of Fig. 2 of the ’066 patent) to each of the detectors. The other path is through stage 70 (Fig. 2, supra) to each of the detectors (Trial Record 265-8). 100. The ’066 patent does not state that the resistance in the reactance network 58, 59, 60 must be zero for practical operation of the circuit (Trial Record 4135-44). If resistance were present in network 58, 59, 60, a continuous variation in phase with variation in frequency of the received wave would be produced (Trial Record 4136-42). 101. If the resistance in the network 58, 59, 60 were completely neutralized, the network would produce variations in amplitude in accordance with variations in frequency of the received wave and there would be a reversal in phase at the center frequency (Trial Record 4143-4). B. The Claims and Their History The Claims 102. Each of claims 8, 9 and 10 requires that there shall be at least two paths in the receiver for passing the frequency modulated wave or currents derived therefrom. This requirement emphasizes that in the receiver two distinct waves are derived from the received wave (Trial Record 5397-5400). 103. Claim 8 requires that the waves from the separate paths shall be heterodyned with each other. That means that the waves shall be combined with each other in a nonlinear device such as a detector (Trial Record 4162-3, 5180-5, 5397-8). 104. Each of claims 9 and 10 requires that the currents from the separate paths shall be combined with each other in a detector. The requirement, when interpreted in accordance with Armstrong’s use of the word “detector” in the specification, describes a heterodyning action at one or both of the detectors in the receiver and does not describe the combining of audio currents as disclosed in Armstrong’s ’447 patent (Trial Record 273-4, 291-2, 4246-7, 5186-9). During the prosecution of the ’066 patent application, the Patent Office Examiner questioned the use of the word “hetero-dyne” in the application, and in the amendment of October 26, 1931, Armstrong explained the operation as follows : “The combination of the two currents is effected in a balanced detecting device in which the heterodyne current is supplied differentially with respect to the signalling current so that the effect on one detector is additive while the effect on the other detector is subtractive.” (Defendant’s Exhibit D2, p. 23) 105. Claim 8 requires that there shall be a combination of reactance elements in one of the paths referred to therein. 106. Claim 9 requires that the two paths shall have different characteristics of transmission for the received frequency modulated wave. This claim 9 is read in the light of the specifications covering phase characteristics of the two paths. Claim 9 of the ’066 patent includes the steps “passing the currents of all said frequencies through two paths having different characteristics of transmission for said currents and combining the output currents of these two paths in a detector to recreate the transmitted signal.” 107. Claim 10 requires that in one of the paths the phase of the current shall be changed with respect to that of the current in the other path. Claim 10 of the ’066 patent includes the steps “causing one of said paths to change the phase of the current passing therethrough with respect to that of the other, and combining the output currents of these two paths in a detector to recreate the transmitted signal.” 108. Each of claims 8, 9 and 10 particularly points out and distinctly claims the synchronous heterodyne system and principle of operation for the detector circuit of a frequency modulation receiver. In the amendment filed October 26, 1931, in the ’066 application, the solicitor of Armstrong stated (Defendant’s Exhibit D2, p. 23): “The principal idea of the present case is to take the received wave and derive from it two currents, one of which is fed into a device which converts the variations in frequency into variations of amplitude which is then combined with the other current of variable frequency and constant amplitude, the second current in this case acting as a synchronous or zero-beat heterodyne." The History of the Claims 109. The application as filed on July 30, 1930, contained inter alia, the following proposed claims: (1) The step in the method of detecting frequency modulated waves which consists in subjecting a current derived from said waves to the heterodyning action of a second current also derived from said waves. (3) In combination, a circuit for receiving frequency modulated waves, means for deriving from said waves a plurality of currents, and means for subjecting one of said currents to the heterodyning action of the other (Defendant’s Exhibit 2). The aforementioned original claims pointed broadly to the synchronous heterodyne principle for receiving a frequency modulated wave (without so denominating it). 110. Claims 8, 9 and 10 of the ’066 patent here in suit were involved in an interference with an application for patent of Crosby, owned by RCA, having Serial No. 618,154, filed June 20, 1932, and which resulted in Crosby patent No. 2,229,640 (Plaintiff’s Exhibits 22, 22A, 96). Claims 8, 9 and 10 of the ’066 patent wrere introduced in the ’066 application by amendment of March 18, 1933, as claims 12, 13 and 14 (Defendant’s Exhibit D2, pages 49-52). Crosby patent 2,229,640, the application for which was in a patent interference with the ’066 patent, describes a frequency modulation detector having two paths, each of which is separate and independent of the other as are the paths in the ’066 patent. 111. In its final decision in the interference, on July 7,1939, the Board of Appeals of the Patent Office defined the scope of claims 8, 9 and 10 here in suit as follows: “The subject matter of the interference relates to a radio receiver for receiving frequency modulated waves. There are two paths provided, each capable of passing all of the frequencies of the received signal band and having different characteristics of transmission for the received signal. One set is subjected to the heterodyning action of the other and means responsive to the resulting current are arranged.” The Board of Appeals thereby affirmed that claims 8, 9 and 10 broadly cover the synchronous heterodyne principle for frequency modulation reception (Plaintiff’s Exhibit 22, p. 1). 112. Crosby patent No. 2,229,640 and the application therefor in interference with the '066 patent disclosed several versions of a receiver embodying the synchronous heterodyne principle, including (1) circuits for a frequency modulation receiver in which a continuous variation in phase with frequency in one of the paths was produced (illustrated in Figs. 1 and 3a of the Crosby patent and by the Foster-Seeley discriminator later used by Motorola and others) and (2) circuits for a frequency modulation receiver in which a variation in amplitude in accordance with variations in frequency of the received wave was produced in one of the paths accompanied by a reversal in phase at the center frequency (illustrated in the Crosby patent in Fig. 3 and Fig. 1 when operated with an undamped or open circuit transmission line and in the ’066 patent, Fig. 2, when the effective resistance in network 58, 59, 60 is zero) (Trial Record 4180-2; Plaintiff’s Exhibit 96). 113. In the interference proceeding, RCA contended that it was entitled to the claims at issue because of the Crosby disclosure and that Armstrong was not entitled to such claims on the ground that the claims at issue were not supported by the disclosure of the ’066 patent and particularly the disclosure relating to Fig. 2 thereof (Plaintiff’s Exhibit 22, p. 3). 114. In rejecting the contention of RCA and in awarding priority to Armstrong on the subject matter of the interference, the Board of Appeals of the Patent Office held that the disclosure of the ’066 patent adequately supported such claims, that Armstrong was the prior inventor of the synchronous heterodyne principle for frequency modulation reception and that he was entitled as against RCA to claims 8, 9 and 10 commensurate with the full scope thereof (Plaintiff’s Exhibit 22). C. The Prior References Cited by Motorola Horton Patent No. 1,856,707 Filed March 28, 1928 — Issued May 3, 1932 115. The Horton patent did not disclose a method or system for receiving and detecting frequency modulated waves (Trial Record 4147-8, 5189-90). 116. The Horton patent disclosed frequency measuring circuits (Defendant’s Exhibit 7, Horton patent, p. 1, lines 1-13; Trial Record 2500-6, 2517-8, 4144-6, 5189-90). 117. The Horton patent did not expressly disclose anything about a frequency modulation receiver and stated nothing concerning the problem of detecting a wave which was dynamically varying in frequency (Trial Record 4147-8). 118. Heising testified that “Horton invented a measuring device for measuring the frequency * * * and it is to be expected that he meant measurement — measure a frequency which was not varying.” (Trial Record 4144) The Horton patent did not specify whether or not the wave was varying in frequency. 119. To produce a useful result from the Horton circuits as specifically described, the primary circuit would be manually tuned to the frequency of the incoming wave and a reading of the frequency would be taken (Trial Record 2484-7, 4144-6). 120. The Horton patent did not disclose the synchronous heterodyne principle for frequency modulation reception and did not anticipate the ’066 patent. Armstrong Patent No. 1,941,447 121. The ’447 patent did not disclose two paths for the received wave leading to each detector (Trial Record 4246, 5189). 122. The ’447 patent did not disclose a frequency modulation receiver in which the received wave was heterodyned with itself to provide currents which activate the detector to reproduce the signal (Trial Record 4246-7). 123. The ’447 patent did not disclose the synchronous heterodyne principle for frequency modulation reception (Trial Record 4246-7, 5189). Usselman Patent No. 1,794,932 Filed Sept. 1, 1927 — Issued Mar. 3, 1931 124. The Usselman patent disclosed a frequency modulation receiver but did not disclose two paths for the received wave leading to each detector (Trial Record 2860). 125. The Usselman patent did not disclose a frequency modulation receiver in which the received wave was heterodyned with itself to provide currents which activate each detector (Trial Record 2854-66). 126. The Usselman patent did not disclose the synchronous heterodyne principle for frequency modulation reception and did not anticipate the ’066 patent. Hansell Patent No. 1,938,657 Filed Feb. 1,1929 — Issued Dec. 12, 1933 127. The Hansell patent related to a frequency modulation receiver but did not disclose two paths for the received wave leading to each detector (Trial Record 4159-60, 5390-1). 128. The Hansell patent did not disclose a frequency modulation receiver in which the received wave was heterodyned with itself at the detector to reproduce the signal (Trial Record 4152-63, 5388-91). 129. The Hansell patent did not disclose the synchronous heterodyne principle for frequency modulation reception and did not anticipate the ’066 patent (Trial Record 4152-63, 5388-91). Heising Patent No. 1,620,204 Filed Dec. 29, 1924 — Issued Mar. 8, 1927 130. The Heising patent, like the Horton patent, disclosed a frequency measuring instrument (Trial Record 4164). 131. The Heising patent disclosed nothing about a frequency modulation receiver (Trial Record 4165). 132. The Heising patent did not disclose the synchronous heterodyne principle for frequency modulation reception and did not anticipate the ’066 patent (Trial Record 4164-5). German Patent No. 428,643 Filed April 4, 1925 — Issued May 14, 1926 133. The German patent relates to a frequency measuring instrument and discloses nothing which was not also disclosed in the Horton and Heising patents (Trial Record 4148-51). (It may be noted that Heising, Motorola’s witness on the German patent, did not testify that the German patent disclosed anything about frequency modulation reception (Trial Record 2183-95). He was correct in not doing so. See Defendant’s Exhibit 15.) Summary of Prior References 134. The prior references did not disclose singly or in combination, the synchronous heterodyne principle for frequency modulation reception and did not anticipate claims 8, 9 and 10 of the ’066 patent. VII. ARMSTRONG REISSUE PATENT NO. 21,660 A. The Disclosure 135. The Reissue patent disclosed how the signal-to-noise ratio in the wide band FM system could be increased by employing a particular and practical type and degree of pre-emphasis and de-emphasis and by substantially widening the detector circuits at the receiver in order to minimize distortion when pre-emphasis and de-emphasis are used (Trial Record 321-7, 2813-16, 4189-91, 4201, 4217, 5204-8, 5423). 136. The Reissue patent disclosed a particular characteristic for the pre-emphasis (predistortion of the signaling or audio frequencies at the transmitter) and gave specifications for the networks that might be used (Reissue patent, Figs. 3 and 16). The shape of the pre-emphasis was shown in Fig. 5 of the Reissue patent and results in amplification of modulating frequencies above about 10,000 cycles by about 10 times as compared with modulating frequencies in the region of 1,000 cycles (Pat. p. 2, col. 1, lines 7-17). 137. The particular pre-emphasis disclosed in the Reissue patent is in accord with the characteristic of a resistance-inductance network having a time constant of 75 microseconds (Trial Record 5204; Pat. p. 3, col. 2, lines 14-21). 138. The Reissue patent did not express the pre-emphasis characteristic in terms of a 75 microsecond time constant circuit, and there is no evidence that Armstrong was aware that it could be expressed in such cryptic and yet definite terms (Trial Record 5205). Everitt testified that during the trial he had found that the pre-emphasis characteristic could be approximated in mathematical terms by a complex exponential function (Trial Record 3346-7; Defendant’s Exhibit 80A). 139. The pre-emphasis curve disclosed in the Reissue patent is such that audio frequencies below about 2,000 cycles are not significantly predistorted (Defendant’s Exhibit 80; Pat. Fig. 5; Trial Record 4201). Accordingly, the particular pre-emphasis disclosed in the patent is not only a matter of the degree or amount of predistortion of the audio frequencies, it also involves predistortion of a particular “shape” (Trial Record 5206, ef. 5204-5). The degree or amount and the shape of the pre-emphasis are shown in the Reissue patent in Figure 5. This is essentially the same pre-emphasis as that given by a simple resistance-inductance circuit having a time constant of 75 microseconds (Trial Record 5204-5). 140. The Reissue patent disclosed that distortion may occur at the receiver, particularly when the higher modulating frequencies at the transmitter have been accentuated by pre-emphasis (Pat. p. 1, col. 2, lines 20-34; p. 2, col. 1, line 40, to col. 2, line 37). That distortion was experienced in early FM broadcasting is evidenced by the reduction in pre-emphasis from 100 to 75 microsecond time constant to overcome it. 141. The Reissue patent disclosed that such distortion may result primarily from (1) lack of linearity of the detector characteristic and (2) destruction of the form of the higher modulating frequencies by cross-modulation with noise or by over-modulation (Pat. p. 2, col. 2, lines 19-37). 142. The Reissue patent disclosed that in the system described therein it is not necessary to lower the level of modulation and thereby lose signal-to-noise ratio in order to avoid such distortion (Pat. p. 3, col. 1, lines 23-34). 143. The Reissue patent disclosed that such distortion might be avoided by the particular expedient of widening the admittance band of the discriminator to such an extent that the over-modulation and cross-modulation illustrated in Figures 7 and 8 of the patent would not occur (Pat. p. 3, col. 1, lines 30-42). 144. The Reissue patent disclosed and provided specifications for restorer networks in the receiver to compensate for the particular pre-emphasis described for the transmitter (Pat. p. 3, col. 2, lines 22-27; Figs. 4 and 17). B. State of the Art Before February 19, 1940 — the Filing Date of the Reissue Patent — and Impact of Armstrong’s Pre-emphasis and De-emphasis 145. Before 1940, it was not known (excluding Armstrong and his licensees) whether any kind of pre-emphasis and de-emphasis would provide a useful result in the wide band FM system or what kind or degree of pre-emphasis and deemphasis would give an improvement (Trial Record 3959-60, 4244-5, 5206-8; Plaintiff’s Exhibit 90, p. 7, col. 3). 146. The suggestion that the detector circuits should be widened substantially beyond the range of swing was contrary to prevailing engineering techniques (Trial Record 3961-6, 3999-4005, 4037-8). 147. Skilled engineers other than Armstrong had speculated that predistortion might be used in FM broadcasting but “guessed wrong” as to the form of predistortion which should be employed and made specific suggestions which, if adopted, might have degraded rather than improved the FM performance (Trial Record 4203-7, 4209-18, 4234-6, 5207-8). 148. In 1940, the Federal Communications Commission adopted pre-emphasis for FM broadcasting having the characteristics of a network with a time constant of 100 microseconds (Plaintiff’s Exhibit 67, p. 4). In 1941, the Commission adopted the same pre-emphasis standard for television sound (Plaintiff’s Exhibit 67, p. 9). 149. In 1945, and after field experience had shown that the 100 microsecond standard was not satisfactory, pre-emphasis with a time constant of 75 microseconds was, upon recommendation of the industry, adopted by the Federal Communications Commission for FM broadcasting and television sound (Trial Record 2810; Plaintiff’s Exhibit 67, pp. 7 and 12). Such pre-emphasis at the ■transmitter and corresponding de-emphasis at the receiver, specifically as disclosed in the Reissue patent (but expressed in other terms) are now in general use in those services. C. The Claims and Their History The Claims 150. Each of the claims 1 and 2 requires that the high frequencies in the band of signaling frequencies shall be amplified to a substantially greater degree than the low frequencies in such band. The meaning- is that there shall be predistortion at the transmitter substantially as described in the specification (See Findings 136, 137, 138). (Armstrong was deemed to be his own lexicographer and his claims are to be given a construction in accordance with the actual teaching of the patent. Minneapolis-Honeywell Regulator Company v. Midwestern Instruments, Inc., 188 F. Supp. 248 (N.D.III.1960), aff’d 7 Cir., 298 F.2d 36. As was said there by this court (188 F.Supp. p. 253), mutatis mutandis : “This is just another instance of a patentee’s being his own ‘lexicographer and an asserted infringer . seeking refuge in a strained and strict construction of patentee’s claim terminology.” Further authorities on the point are Flexwood Co. v. Faussner & Co., 145 F. 2d 528, 536 (7th Cir. 1944); Scherbatskoy v. United States Steel Corp., 287 F.2d 552, 556-557 (7th Cir. 1961); National Slug Rejectors v. A. B. T. Mfg. Corporation, 164 F.2d 333, 339 (7th Cir. 1947); W. F. & John Barnes Co. v. International Harvester Co., 51 F.Supp. 254, 324 (N.D.Ill.E.D.1943); Reynolds v. Whitin Machine Works, 167 F.2d 78, 85 (4th Cir. 1948) ; Westinghouse Electric & Mfg. Co. v. Quackenbush, 53 F.2d 632, 634 (6th Cir. 1931)). 151. Each of claims 4 and 6 requires that the lower frequencies in the audio currents from the detector at the receiver shall be amplified to a substantially greater degree than the signaling currents of the higher frequencies. The meaning is that the receiver shall include a restorer network which shall compensate for predistortion at the transmitter substantially in accordance with the characteristic described in the specification (Pat. p. 4, col. 1, line" 32 to col. 2, line 2; col. 2, lines 80-32). 152. Claim 1 requires that the transmitted wave shall comprise a wide band of frequency variations (p. 3, col. 2, lines 38-40). Claim 2 requires means for varying the carrier wave over a wide range (p. 3, col. 2, lines 61-62). The meaning is that the transmitted wave shall be a wide swing wave as described in the ’069 patent and then on the air from Major Armstrong’s Alpine Station. 153. Each of claims 4 and 6 refers to the wide swing of the received wave (p. 4, col. 1, lines 24-25). The meaning is that the receiver shall be a wide band receiver as disclosed in the ’069 patent and as employed by Major Armstrong and others in receiving transmissions from the Alpine Station and other experimental FM stations then on the air. 154. Claim 1 requires that the detecting device shall have an admittance band substantially wider than said wide band of frequency variations. The meaning is that the discriminator and detector circuits shall be substantially widened as compared with the peak-to-peak swing and thereby avoid the distortion described in the specification (Plaintiff’s Exhibit 21, pp. 6,11-12). 155. Claim 2 requires that the discriminator shall have an admittance bandwidth substantially greater than the width of the said wide range of carrier frequencies (p. 3, col. 2, lines 65-70). The meaning is that the discriminator shall have an admittance band substantially greater than the peak-to-peak swing of the signal in accordance with the teaching of the specification and thereby avoid the distortion disclosed in the specification (Plaintiff’s Exhibit 21, pp. 6, 11-12). 156. Each of claims 4 and 6 requires that the discriminator or the detecting device shall have an admittance band substantially greater or wider than the width of the wide swing of the received wave. The meaning is that the admittance band of the discriminator shall be made substantially greater than the pealc-to-peak swing of the received wave in accordance with the teaching of the specification and thereby avoid the distortion referred to in the specification (Plaintiff’s Exhibit 21, pp. 6, 11-12; Trial Record 5423). 157. The words “substantially greater” or “substantially wider” appearing in claims 1, 2, 4 and 6 of the Reissue patent with respect to the admittance band emphasize that the greater width of the admittance band is of significance in the combination and not merely trivial or incidental (Plaintiff’s Exhibit 21, p. 6). The History of the Claims 158. Claims 1, 2, 4 and 6 here in suit and the other claims of the Reissue patent were involved in an interference proceeding in the United States Patent Office with an application of Hansell, owned by RCA, having Serial No. 297,777, and which issued as Hansell patent No. 2,465,-448 on March 29, 1949 (Plaintiff’s Exhibits 21 and 99). 159. The Hansell ’448 patent disclosed a system of predistortion in which the modulating frequencies below 3,000 cycles would be amplified to a greater extent than the higher modulating frequencies from 5,000 to 10,000 (Trial R