Discussion of "A History of Some Foundations of Modern Radio-Electronics Technology" Page 1265

Office. On January 29, 1923, he wrote: “There is no appeal from this holding of the Examiners-in-Chief that Count 4 is patentable. . . . This patent to Scheller does not, in my judgement, disclose any ‘means for selecting a component of said selected energy’. . . . The decision of the Examiners-in-Chief is affirmed.” And on April 13, 1923, Mr. Kirman further wrote: “As to the allowance of the claim to the party Hammond, it may be allowed in any application in which it can be properly made.” The case is finished, the Telephone Company bought rights under the Hammond patents, the patent numbers were put upon equipments, the patents have expired. It is rather late for a consultant of the Telephone Company to now suggest that the Patent Office overlooked such a well-known “Telefunken” art and that the Telephone Company bought patents that were invalid.

37) Critique. “Hammond cannot be credited with originating the double-detection technique, starting, as it did, with audio-frequency IF.”

Rebuttal. Readers will be amazed to find someone who as of the present date will refer to an audio-frequency intermediate frequency.

38) Critique. “Of Alexanderson’s 1912 tuned-radio-frequency circuit shown in Fig. 12. . . .”

Rebuttal. The caption of this figure does not justify this interpretation. The circuit shown originated with Alexanderson after his invention of TRF in Gloucester, and came to Hammond in a letter of October 21, 1912.³³ The word “later” in our paper should not be overlooked. For the purpose of showing the relations between the TRF system of Alexanderson and the IF system of Hammond, we were entitled to hypothesize the devices commonly termed “Audion detectors” or simply “detectors,” either as actual detectors or as actual amplifiers.

39) Critique. “One reads: ‘Fig. 82 illustrates a type of transmitter-receiver unit suggested by the writer in 1911.’”

Rebuttal. The implication of this statement is most readily refuted. Fig. 82 of the book cited corresponds almost exactly with two figures of U. S. Patent 1,491,773. That Hammond was the inventor of the patented material shown in this patent is evidenced by his signature at the end of the specifications. If our critic does not consider this sufficient, the fact that Miessner was not the inventor of the patented material is evidenced by his signature as a witness. Our critic presumably has failed to note an alleged relation between the receiver system of the figure cited and the TRF circuitry of Alexanderson, available in a reference³⁴ cited in our previous paper.

40) Critique. “Another claim for a ‘first’ must be corrected.”

Rebuttal. In preparing our paper, we endeavored to leave out any reference to the word “Hammond” wherever we considered that there would be no misinterpretation as to the meaning. Most readers, we believe, made a mental insertion of the words by Hammond after “was first applied” in the cited passage.

41) Critique. “The apparatus is said to have been. . . .”

Rebuttal. Some may construe this method of expression to convey doubts on the part of the critic that the alleged equipment ever existed, or, if it existed, that it ever went to France. Our records show that on November 2, 1918, a conference was held at the Department of Development and Inspection,³⁵ Signal Corps, A.E.F., in France, to discuss this Hammond equipment with Messrs. Chaffee and Buswell of the Hammond Staff. Present were General Russel, Colonel Carty, Captain Armstrong, and Lieutenant Fahys. From published biographical material, it is most certain that Colonel Carty (“who during the whole interview was polite and cordial”) was then also the chief engineer of the Telephone Company, and one with whom Hammond had had dealings in 1912 in the Lowenstein amplifier matter. Our critic undoubtedly can check with the records of the Telephone Company to settle his doubts in this matter.

42) Critique. “. . . the short wave multiplex radio telephone system developed by the Western Electric Company. . . .”

Comment. This is presumably the equipment upon which the party Heising properly wrote the patent claim which has been cited. If so, this equipment was later proven to be subservient to the prior Hammond art. The time lag between installation and publication is noted, but without surprise. Contemporary equipment upon which publication was also delayed included the Hammond IF system that had been previously used in control work, and that upon which construction was started in 1917 and which was delivered in Europe in 1918. The comparison between the merits of the Heising naval equipment and the Hammond military equipment is out of order. The Telephone Company work was in communication between ships; the Hammond work was in finding a military solution to such problems as avoiding the necessity of requiring U. S. Infantry to advance into its own Artillery barrage.

43) Critique. “Of course both detectors were ‘of an oscillatory nature,’ detection of oscillations being their function.”

Rebuttal. This statement is improperly based upon a confused concept of an oscillatory detector. Crystal diode detectors were detectors of oscillations but they were not therefore oscillatory detectors. Although the first detector of the equipment under discussion was advisedly used in the non-oscillatory condition for the proper reception from the corresponding military transmitter, it did often oscillate during the course of making adjustments. Under these conditions, the circuit most certainly had the structure of a CW “superheterodyne” regardless of whether or not there was any CW to be received. We fail to understand why our critic is disturbed by our remark upon this point, since the CW “superheterodyne” is an Alexanderson invention in whatever respects it is not a Hammond invention, as now to be recorded.

44) Critique. “The first to arrive at the true superheterodyne and apply for a patent upon it, was one Lucian Lévy of Paris.”

Rebuttal. This is in error. The French patent to Lévy was filed August 4, 1917, and his U. S. Patent 1,734,038 was filed August 12, 1918, with an additional figure. This U. S. patent later received claims 1, 2, 3, 6, 7, 8, and 9 from the well-known Armstrong patent. These claims relate to the amplification of readily amplifiable intermediate frequencies in the telephonic-type superheterodyne. At the same time, and in the same manner, Armstrong claims 4 and 5 went to Alexanderson U. S. Patent 1,508,151, and claim 4 remained there as claim 20. This relates to the amplification of readily amplifiable intermediate frequencies in the CW-type superheterodyne. This U. S. patent was a divisional patent based upon disclosures that are also in a prior Alexanderson patent 1,465,961, filed April 19, 1916, over a year before the date of Lévy’s filing in France. This is the effective filing date of both the Alexanderson patents, and it takes precedence over Lévy as to the general concept of amplifying a readily amplifiable IF in a superheterodyne. Before both Alexanderson and Lévy, Hammond in 1912 had filed upon his U. S. 1,491,774 which specifically covers the telephonic-type superheterodyne structure, but of course without the addition of tuned amplification of superaudible frequencies which was a later Alexanderson contribution, also of 1912.

45) Critique. “Hammond’s works were entirely unknown in France in 1917.”

Rebuttal. This statement is in error. Hammond at that time had several patents pending in the French Patent Office. Radiodynamic patents 474,906 and 475,888 had been published in 1915; intermediate-frequency patent 519,811 was entered into the French Office on December 12, 1917, based upon U. S. Patent 1,491,775, filed September 28, 1916.

46) Critique. “Thus it is apparent that IF technology came into being and went into service quite independently of Hammond’s more secret efforts in the field.”

Rebuttal. This statement is not justifiable by the facts. That Hammond’s efforts were not secret even from the pioneer in the commercialization of the superheterodyne, and that they had a very definite technological bearing is evident from the following incident. On November 8, 1918, Captain E. H. Armstrong requested the presence of Dr. E. L. Chaffee to explain a technical point as to the proper design of intermediate-frequency transformers. The desired information was freely given.

V. FREQUENCY MODULATION AND RELATED SYSTEMS

47) Critique. “A Hammond patent is cited. . . .”

Rebuttal. Our critic apparently cannot think back to the period of the filing date of this patent, when receivers were very broadband, CW signal rates were twenty words per minute, and key shifts were 300 cycles. The patent certainly could be practiced without serious cross-signalling, just as can its modern television counterpart. There are other patents in the Hammond group, and other pertinent Hammond activities, that make the tie between the early patent and

³³ Alexanderson to Hammond, October 21, 1912.
³⁴ Authors’ previous paper, footnote 32, p. 1198; see p. 1366 of the reference.
³⁵ Compare this address with that of p. 5 of the reference in the authors’ previous paper, footnote 62.