Segment Data and Related Information - Schedule of Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenue	$ 38,406	$ 23,850	$ 71,832	$ 49,332
Gross profit	14,634	6,427	27,206	13,901
R&D expense	3,771	4,584	8,067	9,226
Operating income (loss)	4,583	(4,981)	7,090	(6,434)
Unallocated expense:
Selling, general, and administrative	6,062	7,139	11,860	13,026
Loss (gain) on sale of assets	218	(315)	189	(1,917)
Interest expense (income), net	49	(1)	98	14
Foreign exchange loss (gain)	68	156	(169)	9
Total unallocated expense	6,397	6,979	11,978	11,132
Income (loss) before income tax expense (benefit)	4,466	(5,136)	7,161	(6,457)
Operating segments
Segment Reporting Information [Line Items]
Revenue	38,406	23,850	71,832	49,332
Operating income (loss)	10,863	1,843	19,139	4,675
Operating segments \| Aerospace And Defense
Segment Reporting Information [Line Items]
Revenue	13,134	13,013	26,770	26,717
Gross profit	3,775	2,844	7,875	7,332
R&D expense	3,157	3,991	6,843	7,942
Operating income (loss)	618	(1,147)	1,032	(610)
Operating segments \| Broadband
Segment Reporting Information [Line Items]
Revenue	25,272	10,837	45,062	22,615
Gross profit	10,859	3,583	19,331	6,569
R&D expense	614	593	1,224	1,284
Operating income (loss)	$ 10,245	$ 2,990	$ 18,107	$ 5,285

The amount of unallocated income (expense) which was not separately allocated to segments.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Amount of gain (loss) on sale or disposal of assets utilized in financial service operations.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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The net amount of operating interest income (expense).

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The net result for the period of deducting operating expenses from operating revenues.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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